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    About

Journal of Luminescence

Elsevier

1970-

ISSN: 0022-2313 (1872-7883)
Optics - Condensed Matter Physics - Atomic and Molecular Physics, and Optics - Biophysics - General Chemistry - Biochemistry
APC costs unknown

Recent articles

1 show abstract
0022-2313 * * 29815384
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Radosław Lisiecki, Michał Głowacki, Marek Berkowski, Witold Ryba-Romanowski



Gd3(Al,Ga)5O12:RE3+, Yb3+ single crystals (RE3+ = Tm3+, Er3+, Ho3+, Pr3+) were fabricated by the Czochralski technique. Effect of Yb3+ concentration on spectral distribution of luminescence emitted by interacting RE3+-Yb3+ ion pairs and on the dynamics of excitation energy flow in systems under study was investigated and interpreted referring to previously reported spectroscopic features of Gd3(Al,Ga)5O12:RE3+ systems. It was concluded that observed quenching of the Yb3+ emission by co-doped rare earth ions results from an interplay between phenomena of quantum cutting, down shifting and energy dissipation by multiphonon emission.

2 show abstract
0022-2313 * * 29815385
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Yu. Hizhnyi, I. Zatovsky, S. Nedilko, R. Boiko, Junzhi Li, Wei Han, N.I. Klyui



A set of ZnMoO4 polycrystalline samples was synthesized by solid state reaction method and characterized by XRD structural analysis, ICP elemental analysis, SEM-EDX analysis, UV–Vis diffuse reflectance spectroscopy. The photoluminescence (PL) properties of ZnMoO4 samples were studied in 8–300 K temperature range with use of synchrotron radiation as an excitation source. The geometry-optimized electronic structure calculations of perfect and defective ZnMoO4 crystals were carried out by the DFT-based band-structure methods, plane-wave pseudo-potential (CASTEP program package) and FP-LAPW (Wien2k package). A number of point defects which can influence the luminescence properties of ZnMoO4 was considered in calculations, namely the oxygen vacancy Vo, compensated vacancies Vo + VZn, tungsten impurity WMo and the MoO3-deficient phase Zn3Mo2O9. Comparative analysis of experimental data and calculation results allowed explanation of the origin of the red and blue-green luminescence emission bands of ZnMoO4 as well as formation of their excitation spectra. It is assumed that the green component of ZnMoO4 luminescence emission, like in other molybdates of MIIMoO4 family (MII = Ca, Sr, Cd, Pb) originates from radiative annihilation of excitons self-trapped on regular MoO4 groups. The Red component of ZnMoO4 emission has a defect-related origin and it originates from radiative transitions in MoO4 groups located near oxygen vacancies.

3 show abstract
0022-2313 * * 29815386
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Zisheng Wang, Shihui jiao, Ye Xu, Qi Zhang, Yan Chen, Guangsheng Pang, Shouhua Feng



To investigate the influence of annealing temperature on the structure and photoluminescence property, 5% wt. Eu3+ doped MgAl2O4 ceramics have been synthesized by a solution combustion reaction and thermally treated at 700, 800, 900, 1000, 1100, and 1200 °C. Powder XRD indicate that pure spinels were synthesized and the crystallinity increased with the increase of the heat treatment temperature. Low temperature heat capacities of these phosphors were measured and the data were fitted by T3 Debye model. The obtained Debye temperature of sample show positive relationship with the calcine temperature. Our results suggest that the heat treatment improves the crystallinity and decreases the structure defects of MgAl2O4:Eu3+. The SEM shows spongy structure of the particles is dependent on the calcine temperature. These phosphors exhibit hypersensitive red emission peaking at 613 nm, which corresponds to the electric-dipole 5D0 - 7F2 transition of Eu3+ ions. Comparison between the excitation and emission spectra has shown modification of their spectroscopic characteristics. The MgAl2O4:Eu3+ calcined at 900 °C shows the best performance based on the dominant red (5D0-7 F2) emission and the effective emission excited by near-UV 394 nm show potential applications in solid state lighting.

4 show abstract
0022-2313 * * 29815387
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Jan Šulc, Richard Švejkar, Martin Fibrich, Helena Jelínková, Lubomír Havlák, Vítězslav Jarý, Martin Ledinský, Martin Nikl, Jan Bárta, Maksym Buryi, Roberto Lorenzi, Francesca Cova, Anna Vedda



KLuS2 single crystal samples undoped and doped with a low (5 %) or high (38 %) concentration of trivalent thulium or ytterbium ions were synthesized in the form of thin hexagonal plates. The low phonon energy (


220

cm−1) was confirmed using Raman spectroscopy. Samples were studied also by using optical absorption and emission as well as electron paramagnetic resonance spectroscopy and the observed spectral features are discussed. In particular, the 5 % Yb doped samples demonstrate homogeneous dopant distribution inside the material over the lutetium sites. No other signals either from potassium site or the exchange coupled ions were detected. For infrared transitions the luminescence kinetic was determined. Significantly broad infrared emission bands (at 1.4, 1.8 and 2.3 μm for Tm3+, 1 μm for Yb3+) and long decay times (e.g. 0.4 ms from 3H4 to 19 ms from 3F4 levels of Tm3+, 1.4 ms from 2F5/2 level of Yb3+) make those materials perspective for future laser development.

5 show abstract
0022-2313 * * 29815388
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Yuzhao Zhang, Bin Xu, Yunshan Zhang, Yunyun Liu, Huiying Xu, Zhiping Cai, Chaoyang Tu



We report on diode-pumped continuous-wave Tm3+:CaLaGa3O7 lasers, for the first time to our knowledge. Maximum output powers of 176 mW, 148 mW and 102 mW are achieved at 1885 nm, 1913 nm and 1938 nm with slope efficiencies of about 2.3%, 1.8% and 1.1%, respectively. A wavelength tuning is also demonstrated with a range of about 101 nm via an intracavity undoped YAG etalon.

6 show abstract
0022-2313 * * 29815389
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Magdalena Barwiolek, Andrzej Wojtczak, Anna Kozakiewicz, Magdalena Babinska, Agnieszka Tafelska-Kaczmarek, Erik Larsen, Edward Szlyk



New ligands obtained in the reaction of o-phenylenediamine and series of aldehydes (L1-L5) were synthesized. Molecular architecture of the synthesized ligands L1-L5 has been determined by the X-ray crystal structure analysis. 1H NMR NOE diff. spectra (differential Nuclear Overhauser Effect) of ligands indicate that they have different conformation in the solution in comparison to the solid state (crystal structure). The substrates molar ratio and the reaction time allowed the controlled synthesis of mono substituted o-phenylenediamine or benzimidazole derivatives with no catalyst used. For all compounds the relatively high fluorescence efficiency was observed in the range 0.41–0.83 in MeCN and 0.48–0.96 in CH2Cl2 solution. Based on DFT calculations the fluorescence mechanism was associated with HOMO→LUMO transition between aromatic rings and benzimidazole moieties.

7 show abstract
0022-2313 * * 29815390
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Samuel Peter, Aum Patel, Adrian Kitai



Ce:YAG/YAG nanophosphors are synthesized using a two-step seed mediated glycothermal process. The need for the proposed process arises from the high sensitivity of Ce3+ to its local environment, the highly defective surfaces of nanoparticles, and increased proportion of Ce atoms near the surface due to the high ratio of surface area to volume of nanoparticles. Shell thickness was controlled by varying the molar concentration of material added during the second step of synthesis relative to the starting amount, denoted as the shell-to-seed ratio (SSR). It was found that an SSR of 1:1 yielded an average particle size of 186 ± 59 nm with a marked enhancement in photoluminescence and photostability compared to particles with no shell. EELS linescans confirm localization of the dopant to the core of the crystal.

8 show abstract
0022-2313 * * 29815391
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Ge Zhu, Zhuowei Li, Faguang Zhou, Miao Gao, Chuang Wang, Shuangyu Xin



A series of rare earth ions doped novel niobate phosphors SrBaNb4O12:Re3+ (Re= Eu, Dy, Sm and Pr) were successfully developed through solid state reaction. The phase composition and morphology were investigated through X-ray structure refinement, scanning electron microscopy and energy dispersive spectrometer. The layered crystal structure of SrBaNb4O12 and the local lattice environment of Re3+ were discussed in detail. The electronic structure property and density of states were calculated based on density functional theory. To investigate the characteristic luminescence property, the excitation and emission spectra, fluorescence lifetimes and Commission Internationale de l’E′clairage (CIE) chromaticity index of SrBaNb4O12:Re3+ (Re= Eu, Dy, Sm and Pr) series phosphors were determined as well.

9 show abstract
0022-2313 * * 29815392
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Jia Zhang, Guibin Chen



The N-doped Sr2.985Mg1-ySi2O8:0.005Eu2+,0.01Dy3+,yMn2+ (0 ≤ y ≤ 0.15) phosphors were designed to obtain long-persistent phosphors for white LEDs. All the samples were determined to be single-phase by XRD analysis. The particles show smooth surface with the help of the H3BO3 flux. The energy-dispersive X-ray spectrum indicates the existence of N element. Various Eu2+ emission centers have been gained and verified by the photoluminescence spectra and long-persistent emission spectra, and a red-shift of the Eu2+ emission was observed in the N-doped samples due to the nephelauxetic effect. In Eu2+-Mn2+ co-activated phosphors, tunable emission has been realized and an efficient energy transfer from Eu2+ to Mn2+ was found, which could belong to the dipole-dipole interaction mechanism. The optimal afterglow time was obtained in the Sr2.985MgSi2O7.76N0.16:0.005Eu2+,0.01Dy3+ sample, but doping Mn2+ reduces the afterglow time largely. The mechanism for the increase of luminescence intensity and afterglow time with N present was interpreted. The temperature-dependent luminescence was also evaluated.

10 show abstract
0022-2313 * * 29815393
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Zhengang Tian, Xi Li, Yaxin Cao, Yuhua Wang, Xingping Peng



In this work, a novel luminescence material, SSZ-39 zeolite doped by Eu2+ ions with tunable emission was obtained by the ion-exchange method followed by reducing atmosphere annealed process. And series of samples synthesized based on various reaction time of the ion-exchange process were investigated. SSZ-39 zeolite is a silicoaluminate material with large cavities interconnected through small pore openings, and exhibits excellent catalytic performance and good (hydro)thermal stability. It has been successfully synthesized and its structure was characterized by XRD, SEM, TG-DTA, FT-IR, TEM, EDX and XPS techniques. The cages of SSZ-39 zeolite provide an isolated and steady environment for the luminescent centers. The photoluminescence (PL) properties of the Eu2+-SSZ-39 zeolite samples were investigated in detail by emission and excitation spectra, decay curves, and temperature dependence spectra. The brightest sample under 338 nm UV light excitation could generate a broad emission band peaks at about 459 nm. In addition, the strong tunable blue emission and the good thermal stability properties indicate the potential application of Eu2+-SSZ-39 zeolite in the LED phosphor.

11 show abstract
0022-2313 * * 29815394
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Meilan Hu, Chenxing Liao, Libin Xia, Weixiong You, Zhifeng Li



A series of Mn4+ doped La2MgTiO6 red-emitting materials with double-perovskite structure and high efficient red emission have been successfully prepared by molten salt assisted method which LiCl acting as molten salt at a relatively low temperature. The effects of the reaction temperature and the usage amounts of LiCl on the structure and photoluminescence properties of phosphors were studied. Experimental results indicate that the synthesis temperature of the Mn4+-doped La2MgTiO6 by molten salt method is only 800 °C while the traditional solid phase method requires 1350 °C. The morphology and particle size of phosphors can be well controlled by adjusting the reaction temperature and the amount of molten salt. The thermal stability and quenching mechanism of phosphors were studied by temperature dependent emission spectra, which demonstrated that LiCl is benefit to improve the thermal stability of the Mn4+activated La2MgTiO6 phosphors.

12 show abstract
0022-2313 * * 29815395
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): V. Khanin, I. Venevtsev, K. Chernenko, P. Rodnyi, T. van Swieten, S. Spoor, J. Boerekamp, H. Wieczorek, I. Vrubel, A. Meijerink, C. Ronda



The shift of the conduction band (CB) edge for thirty different (Lu,Gd)3(Ga,Al)5O12:Ce compositions, with simultaneous variation in Lu/Gd and Ga/Al content was studied using thermally stimulated luminescence (TSL). Specific TSL peaks were related to impurities of Ta, Cr, Yb, Ti and Eu in Lu1Gd2Ga3Al2O12:Ce ceramics. The shift of Yb-related peak positions (in temperature and trap depth) with composition modification was investigated as well. In Gd-containing (Lu,Gd)3(Ga,Al)5O12 compositions a non-monotonous shift of the CB edge with increasing Ga content has been affirmed. The difference between thermal trap depths evaluated from our TSL experiments and optical trap depths obtained from the literature was explained by the role of lattice relaxation.

13 show abstract
0022-2313 * * 29815396
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Y. Anantha Lakshmi, K. Swapna, K. Siva Rama Krishna Reddy, M. Venkateswarlu, Sk. Mahamuda, A.S. Rao



Bismuth Boro Tellurite (BiBT) glasses doped with Er3+ ions (i.e., Er3+ = 0.1, 0.5, 1.0, 1.5, 2.0, 2.5 mol %) were prepared by using melt quenching technique and their structural, optical absorption, emission and up-conversion properties were investigated using XRD, Raman, absorption, emission and decay spectral studies. The oscillator strengths measured from the absorption spectral features were subjected to Judd-Ofelt theory to understand the radiative properties possessed by the as prepared glasses. The titled glasses excited under 379 nm exhibited green luminescence at 547 nm (4S3/2 → 4I15/2). Upon pumping with a laser diode of 980 nm (NIR), a broad NIR emission at around 1572 nm (4I13/2 → 4I15/2) was observed for which stimulated emission cross-section (σse), effective band width (Δλp), gain band width (σse × Δλp) and optical gain (σse × τR) parameters were evaluated. The up-conversion luminescence shown by these glasses has been analysed to understand the utility of these glasses as up-conversion lasers. Among all the as prepared glasses, 1 mol% of Er3+ ions doped BiBT glass exhibits better radiative properties compared to other glasses. The gain cross-section of the 1 mol% of Er3+ ions doped BiBT glass was derived using absorption cross-section (σa) and emission cross-section (σe) for different values of population inversion (γ). The Decay spectral features recorded under 980 nm excitation were used to measure the experimental lifetimes (τexp) and quantum efficiencies. All the aforementioned studies revealed that the Er3+ ions doped BiBT glasses are quite suitable to fabricate optoelectronic devices in visible green and NIR regions.

14 show abstract
0022-2313 * * 29815397
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Youfusheng Wu, Fengqin Lai, Tongxiang Liang, Yaochun Qiang, Jianhui Huang, Xinyu Ye, Weixiong You



Energy transfer (ET) and cross-relaxation (CR) processes play significant roles in regulating emitting colors and intensity of upconversion (UC) materials. Calculating the coefficients in ET and CR processes can provide visual descriptions for evaluating the UC luminescence properties. Here, we find that those ET and CR processes are responsible for the color-tunable properties in Gd2Ce2O7: Yb3+, Er3+ phosphors. By solving the rate equation, mathematical expressions are established to calculate the ET and CR coefficients based on the experimental UC spectra and lifetimes. The results are benefit to evaluate the efficiencies of ET and CR processes in quantization in different Yb3+ ion concentrations doped samples. The coefficients of ET process arise from 1.05 to 7.93 × 1017 cm3s−1 while those of CR process increase from 2.69 to 72.01 × 1017 cm3s−1 with increasing the Yb3+ ion concentration, which suggest that the CR and ET processes are efficient in Gd2Ce2O7 host. Furthermore, potential temperature sensing properties are also evaluated according to the fluorescence intensity ratio of 2H11/2 and 4S3/2 levels and the maximal sensitivity (S) is achieved about 0.00337 K−1 at 503 K. This work provides an insight into the evaluation of those UC processes and reveals the capacity in color-tunable and temperature sensing aspects.

15 show abstract
0022-2313 * * 29815398
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Yanchun Yang, Song Wei, Xiaojiao Kang, O. Tegus, Daocheng Pan



Employing the short-chain C4H9NH3X (X = Cl, Br, I) compound as the unique capping agent, highly quality CH3NH3PbX3 (X = Cl, Br, I) perovskite quantum dots can be synthesized at room temperature in the open air, which possess high photoluminescence quantum yields and tunable emission in the range of 440–660 nm. Besides, C4H9NH3Br can also improve the morphology of CH3NH3PbBr3 thin films by spin-coating the N, N-dimerthylformamide solution of CH3NH3Br, C4H9NH3Br and PbBr2, making the thin film dense and compact, and improving its optical properties.


Graphical abstract






16 show abstract
0022-2313 * * 29815399
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Jiwei Wang, Fengjuan Pan, Ka-Leung Wong, Peter A. Tanner



Excitation of samples of the elpasolite Cs2NaYbCl6, prepared using high purity Yb2O3, by an infrared laser at temperatures below ∼100 K produces a strong, structured emission near 700 nm. The emission is also observed for samples co-doped with other rare earth ions and it exhibits the characteristic power-intensity dependence of a 2-photon process. Analysis of the vibronic structure indicates that it can be assigned to one, and not several, electronic transitions. However, the transition energy does not correspond to any of the electronic transitions associated with Yb3+ or Yb2+. From evidence displayed in the electron spin resonance spectrum and from the spectral interpretation, the emission is associated with the MnCl6
2− ion.

17 show abstract
0022-2313 * * 29815400
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Feiyue Fan, Lei Zhao, Yifan Shang, Jing Liu, Wenbo Chen, Yanyan Li



A series of novel Eu3+-activated tellurate Ca(3-2x)EuxNaxTeO6 (x = 0.01–0.25) red-emitting phosphors were synthesized through a high-temperature solid-state route at 1220 °C. The phosphors were well crystallized in the space group P21/c (No. 14). Their photoluminescence emission and excitation spectra were investigated. The results indicate that the Ca3TeO6:Eu3+ phosphor can be effectively excited under 394 nm irradiation, which is suitable for UV LED chip. Upon 394 nm excitation, the Ca3TeO6:Eu3+ phosphor shows five peaks, corresponding to the 5D0–7FJ (J = 0, 1, 2, 3 and 4) transitions of Eu3+. The optimal doping concentration of Eu3+ in Ca3TeO6:xEu3+ was determined at 20 mol%. By temperature dependent emission spectra, the quenching temperature for Ca3TeO6:0.20Eu3+ was found to be over 500 K. The CIE chromaticity coordinates of Ca3TeO6:0.20Eu3+ are very close to the National Television System Committee (NTSC) standard red.

18 show abstract
0022-2313 * * 29815401
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Yisheng Huang, Feifei Yuan, Lizhen Zhang, Shijia Sun, Qi Wei, Zhoubin Lin



Four Cr3+:Ca0.93Mg1.07Si2O6 crystals with Cr concentrations in the range of 0.3–2.0 at. % were successfully grown by Czochralski technique. The structure of the crystal was determined by the single-crystal X-ray diffraction method. The absorption spectra, fluorescence spectra and fluorescence decay curve were measured. There are two broad absorption bands with peaks at around 446 nm and 650 nm, respectively. With the increasing of the Cr3+ ions concentrations in the crystals, the fluorescence spectra showed a large redshift, with the emission peaks shifted from 783 nm to 986 nm. It is found that the two crystallographic Mg sites in the structure lead to the two different emission bands. The crystal field splitting (Dq), Racah parameters Dq/B and the decay curves were analyzed to distinguish the origins of the two peaks. The results show that the Cr3+:Ca0.93Mg1.07Si2O6 crystals have unusual spectroscopic features and may have a potential application for tunable and ultrashort lasers.


Graphical abstract

Four Cr3+:Ca0.93Mg1.07Si2O6 crystals with Cr concentrations in the range of 0.3–2.0 at. % were successfully grown by Czochralski technique. With the increasing of the Cr3+ ions concentrations in the crystals, the fluorescence spectra showed a large redshift, with the emission peaks shifted from 783 nm to 986 nm.



19 show abstract
0022-2313 * * 29815402
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Haitao Zhu, Xuhai Liu, Renli Fu, Yahui Shi, He Wang, Qinjiang He, Xiufeng Song



Phosphor layer are essential in the application of phosphor-converted white light emitting diodes (pc-WLEDs). However, the conventional structure of red–green–blue (RGB) phosphor layers can cause severe re-absorption of blue light, resulting in low luminous efficiency and colour rendering index (CRI). In this paper, we fabricated a new WLEDs phosphor layer, which consisted of patterned RGB phosphor pixel arrays in a planar configuration, by the stencil printing technique. Optical simulation based on Monte-Carlo theory has been applied to assist designing the optimal pattern of the phosphor pixel arrays. By tuning the layout of the pixel arrays and the size of phosphor pixels, we achieved uniform output white light with high luminous intensity of 1.47 × 109 cd and CRI of 95.6, which are superior compared with the intensity of 1.11 × 109 cd and CRI of 93.5 obtained from WLEDs with conventional dispensing phosphor layer. Our newly-designed phosphor pixel-array layer possesses great potential for applications in advanced lighting and display devices with vast implications for industrial improvement in these research areas.

20 show abstract
0022-2313 * * 29815403
Publication date: July 2019

Source: Journal of Luminescence, Volume 211
Author(s): Renato Barbosa-Silva, Jefferson F. Silva, Ueslen Rocha, Carlos Jacinto, Cid B. de Araújo



Orthorhombic sodium niobate (NaNbO3) nanocrystals, transparent in the visible and near-infrared, were synthesized by using the Pechini's sol-gel method. Experiments were performed to measure the first hyperpolarizability of the nanoparticles by using a pulsed laser operating at 1064 nm. The hyper-Rayleigh scattering technique was used to analyze the second harmonic scattered light generated by the nanocrystals. By using the external reference method, with para-nitroaniline as the standard reference, we determined the NaNbO3 hyperpolarizability per nanoparticle volume (0.93 × 10−29 esu/nm3) for the first time, and show that the effective second-order susceptibility has the same order-of-magnitude as LiNbO3 and KNbO3 nanocrystals.


Graphical abstract






21 show abstract
0022-2313 * * 29815404
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Ying Gao, Shuang Ding, Zhong-Min Su, Yun Geng



In this work, iridium complexes 1–8 bearing bipyridine or pyridine-pyrimidine main ligand and picolinate ancillary ligand have been designed by varying the position of –OCH3 and phenyl groups at the ligands aiming at finding a better choice to design blue phosphors. The results indicate that an appropriate combination of –OCH3 and pyridine-pyrimidine ligand makes the emission wavelength a noticeable blue-shift. Moreover, the further introduction of phenyl group shifts the emission wavelength to a shorter region. In terms of the radiative decay rate constant (k
r), the position of –OCH3 has a slight influence on it, but the introduction of phenyl group is conductive to enhancing this value. In particular, the 7 has the largest k
r among the designed complexes up to 7.68 × 105 s−1. As for the non-radiative process, 1–6 have high barriers between 3MLCT and 3MC, indicating the difficulty of electron relaxation to the non-emissive 3MC structure. There is no transition state of 3MLCT↔3MC is found for 7 and 8 bearing pyridine-pyrimidine ligand. However, the barriers of all complexes for the S0/3MC minimum energy crossing point reaction are high, which is in favor of avoiding the system relaxes to the S0 geometry by non-radiative path.


Graphical abstract

Among iridium (Ⅲ)-based phosphorescent emitters, the red and green complexes are abundant, whereas the blue emitter is still rare due to lower efficiency and shorter lifetime. Therefore, we intend to modulate the blue-shift in phosphorescence using –OCH3 and phenyl groups. Based on iridium (Ⅲ) complexes bearing bipyridine or pyridine-pyrimidine cyclometalated ligand and picolinate ancillary ligand, we have designed 1–8 by introducing –OCH3 and phenyl groups into different positions of main ligands. Using density functional theory (DFT) and time-dependent density functional theory (TD-DFT), their photoelectronic properties have been calculated. The results indicate that varying the position of –OCH3 and phenyl groups results in remarkable changes in their emitting color. An appropriate combination of –OCH3 and pyridine-pyrimidine ligand makes the emission wavelength a noticeable blue-shift. Moreover, the further introduction of phenyl group shifts the emission wavelength to a shorter region. Meanwhile, the introduction of phenyl group is very beneficial for improving phosphorescence radiative rate. Considering the non-radiative decay process, 1–6 have high barriers between 3MLCT and 3MC, and the molecule of 3MLCT minimum energy is difficult to relax to the non-emissive 3MC structure. While, no transition state of 3MLCT↔3MC is found for 7 and 8 bearing pyridine-pyrimidine ligand, suggesting that the 3MC population originated from 3MLCT is in a barrierless manner. However, the barrier for the S0/3MC minimum energy crossing point reaction is high, so that a pre-equilibrated 3MLCT-3MC situation is easily accessible. In other word, the S0/3MC MECP is difficult to populate, avoiding the system relaxes to the S0 geometry by non-radiative path. That is beneficial to the photoluminescence quantum yields.



22 show abstract
0022-2313 * * 29815405
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Xiao Wang, Chenggong Xu, Haohan Song, Xiaoqiang Liu, Xinmei Xie, Xiaobin Pang, Yanmei Zhou



The biochemistry of hypochlorite (ClO−) play important role in the operation of life system. In this work, the water-soluble red-emitting fluorescent probe (probe 1) was prepared for sensing ClO−. Probe 1 which replies excellent sensitivity with the limit of detection (LOD) of 2.41 nM, rapid response time about 10 s and better selectivity to ClO− than relevant substances, was used to monitor enzymatically generated and exogenous ClO− in living cells. There is no doubt that probe 1 will be an promising tool for ClO− in bio-system.


Graphical abstract

A highly sensitive and selective red-emitting fluorescent probe for ClO− in test strips via naked eyes and in living cells.



23 show abstract
0022-2313 * * 29815406
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Jinze Lan, Liang Luo, Maomao Wang, Fan Li, Xiaoxia Wu, Fu Wang



CsPbX3 (X = Cl, Br, I) perovskite colloids have attracted considerable attention because of their excellent optical properties, low-threshold lasing, and multicolor electroluminescence. Much work on synthesis and application of CsPbX3 have been performed in the past several years. In this study, a novel robust one-pot synthesis method of CsPbBr3 nanocrystals (NCs) was developed, in which all the precursors are heated together in a flask. Gram-scale CsPbBX3 NCs with a fluorescence quantum yield of around 77% was achieved in a few minutes. A green light-emitting diode (LED) was fabricated by coasting CsPbBr3 NCs on the surface of an industrially available blue chip. The fabricated LED emitted bright-green light with high color purity. This method provides a simple and efficient method for the large-scale preparation of high-quality CsPbBr3 NCs, and might pave the way for their practical applications in green LEDs.

24 show abstract
0022-2313 * * 29815407
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): W.C. Wang, R. Zhou, H.Q. Le, Q.Y. Zhang, L. Wondraczek



Glasses containing multiple anions hold promise as a novel class of laser gain media, for nonlinear optical applications, or for encapsulating crystalline phases, e.g., in solid state lighting. In particular, the broadly tunable interionic competition between the varying anion species enables a wide variety of physical properties, ligand arrangements and, most notably, high flexibility in the design of crystal precipitation routes. Here, we report on Ni2+-doped fluorosulfate (FS) glasses in which devitrification leads to strong and broadband near-infrared luminescence from embedded crystalline sulfates and alumina. Luminescence occurs at ∼1300 nm with a full width at half maximum of ∼285 nm, resulting from the 3T2(F) → 3A2(F) transition of Ni2+ in octahedral coordination. This demonstrates the suitability of low-melting mixed-anion glasses for exploiting the luminescence behavior of sulfate species.

25 show abstract
0022-2313 * * 29815408
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): A.S. Souza, G.K.R. Cortes, H. Lima, M.A. Couto dos Santos


The local field correction contribution due to the Ln3+ ion induced dipole moments on its surrounding is discussed considering the reactive field effect. In this frame the Ln3+ ion is treated as an electron cloud oscillating inside the dielectrics. We also discuss the relevance of our results for the interpretation of the cavity models and spontaneous emission rate of excited Ln3+ doped nanocrystals immersed in fluids. Our predictions reproduce the known cavity models with adequate refractive index and agree with the measurements on the spontaneous emission rate in nanoparticles surrounding fluids media.
26 show abstract
0022-2313 * * 29815409
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): M. Seshadri, M. Radha, G.A. Mendes, M.J.V. Bell, V. Anjos



Borophosphate glasses doped with Ag ions have been successfully prepared by melt-quenching method. Their structure and luminescence properties were analyzed by XRD, ATR-FT-IR, TEM, EDS, optical absorption, and photoluminescence measurements. The unique properties of excitation/emission of silver oxide embedded glass matrix, the inhomogeneous broadband character of B (Ag+-Ag0 pairs) and C (Ag+-Ag+ pairs) centers were identified upon 310 nm and 400 nm excitation wavelengths. Under 310 nm excitation, for heat treated samples, the B-center emission becomes narrower with an unexpected blue shift (∼463 nm), and luminescence quenching. Additionally, at 400 nm excitation (surface plasmon resonance of Ag NPs), for all samples, a broadband emission (C-center) was identified at the 450–700 nm range. The suppression of B center emission followed by an inhomogeneous broad region toward the low energy side is interpreted as due to non-radiative energy transfer process. The nanosecond decay curves were recorded at 470 nm (λexc = 310 nm) and 550 nm (λexc = 400 nm), respectively, and were fitted by double exponential function. The observed increase of τ2 (longer lived decay) in HT samples is due to different size/site distribution of Ag nanoclusters/particles in glass. The evolution of τ2 of B and C with HT is an indicative of the energy transfer from B→C and Ag NP→B→C in the studied glasses.

27 show abstract
0022-2313 * * 29815410
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Vu Phi Tuyen, Vu Xuan Quang, Phan Van Do, Luong Duy Thanh, Nguyen Xuan Ca, Vu Xuan Hoa, Le van Tuat, Le Anh Thi, Masayuki Nogami



Dy3+-doped glasses with compositions of (69-x)B2O3 + 10TeO2 + 10Al2O3 + 10Li2O + xDy2O3 (x = 0.1; 0.5; 1.0 and 2.0 mol%) were prepared by a melt–quenching technique. An in-depth Judd-Ofelt analysis has been carried out to estimate the influence of the hypersensitive transitions (HST) of Dy3+on the validity of the obtained intensity parameters Ωλ (λ = 2, 4, 6). The thermalization effect of the three-levels system of 6H13/2 (level 0), 4F9/2 (level 1) and 4I15/2 (level 2) was taken into account to evaluate its radiative transition probabilities, life times and energy levels. The obtained results were compared with the experimental data to estimate the validity of the Judd-Ofelt analysis. The Inokuti-Hirayama model was used to analyze the luminescence decay curves. The dipole-dipole interaction was shown to be the dominant mechanism in energy transfer process through cross-relaxation between Dy3+ ions. The possibility to produce the light with chromaticity coordinates in the white-light region by mixing intense blue (484 nm, 4F9/2 → 6H15/2) and yellow (575 nm, 4F9/2 → 6H13/2) emissions of the single Dy3+doped alumino-lithium-telluroborate glass was observed and estimated.

28 show abstract
0022-2313 * * 29815411
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Maya Abdou, Santosh K. Gupta, Jose P. Zuniga, Yuanbing Mao



A2B2O7 type pyrochlores have been recently proposed as a potential nuclear waste host due to their many interesting properties. To assess and understand the performance of these compounds as nuclear waste hosts, the speciation and structural investigations on actinide-doped RE2Hf2O7 are needed since both are imperative from their application perspective. In this work, we investigated the effect of uranium doping at different concentrations in the range of 0–10% on the structural and optical properties of RE2Hf2O7:U (RE = Y, Gd, Nd, and Lu) nanoparticles (NPs). The Y2Hf2O7 NPs exist in slightly disordered pyrochlore structure and the extent of disordering increases as a function of uranium doping while the structure reaches a cotunnite phase at 10.0% doping level. The Nd2Hf2O7 NPs also exist in a distorted pyrochlore structure and their distortion increases with increasing uranium doping inducing a phase transition into a disordered fluorite structure at 10.0% uranium doping. Both Gd2Hf2O7 and Lu2Hf2O7 NPs exist in a disordered fluorite structure and transforms into cotunnite structure at higher U concentrations (≥5.0%). Photoluminescence spectroscopy showed that uranium ions are stabilized in +6 oxidation state in all samples: in the form of uranate ion UO6
6− in the Y2Hf2O7, Nd2Hf2O7 and Lu2Hf2O7 NPs while in the form of uranyl ion UO2
2+ in the Gd2Hf2O7 NPs. Therefore, this work deepens the understanding of the behavior of uranium ions doped in different RE2Hf2O7 host matrices in the perspective of their application as nuclear waste hosts.


Graphical abstract






29 show abstract
0022-2313 * * 29815412
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): J. Rodrigues, M. Fialho, S. Magalhães, K. Lorenz, E. Alves, T. Monteiro



AlxGa1-xN (x = 0.20) layers grown on (0001) sapphire substrates by metal organic chemical vapour deposition were implanted with terbium (Tb) ions at 150 keV with a fluence of 7 × 1014 Tb cm−2 at different temperatures. After thermal annealing, all layers evidenced the Tb-related 5D4-7FJ intra-4f

8
transitions, demonstrating an enhancement of their intensity with increasing implantation temperature. A detailed spectroscopic analysis of the optical properties of these layers was conducted using luminescence techniques. An atypical behaviour for the relative intensity of both the broad visible band and the intraionic lines was found as a function of temperature and its origin is discussed based on potential fluctuation phenomena and energy transfer processes. The 5D4-7FJ intra-4f

8
transitions exhibit thermal population with increasing temperature between ∼100 K and ∼200–230 K, with a subsequent decrease up to RT due to further competitive non-radiative recombination paths. The values calculated for the population energies of each sample are in good agreement with the ones obtained for the activation energies of the de-excitation of the yellow broad band also present in the spectra, suggesting a correlation between the host defect de-excitation processes and the population of the ion emitting levels.

30 show abstract
0022-2313 * * 29815413
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Zhiyu Yang, Zhaofeng Yang, Qianwen Wei, Qiang Zhou, Zhengliang Wang



Red-emitting phosphor Rb5Nb3OF18:Mn4+ was prepared by an ion exchange method and its crystal structure, luminescent properties and application were discussed. Mn4+ in Rb5Nb3OF18 which has appropriate band gap experiences a strong crystal field and emits intense red light around 633 nm with one broad excitation band at ∼470 nm. In addition, the light-emitting diodes (LEDs) coated Rb5Nb3OF18:Mn4+ exhibit excellent luminescent performances, such as the white LED can emit warm white light with high luminous efficiency (113.6 lm/W). Hence, Rb5Nb3OF18:Mn4+ could be a potential red component for white LEDs.


Graphical abstract






31 show abstract
0022-2313 * * 29815414
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): F. Bellarmine, E. Senthil Kumar, Ramanjaneyulu Mannam, M.S. Ramachandra Rao


We report on the fabrication of ZnO and Zn0.9Mg0.1O microrods using nanoparticle assisted pulsed laser deposition (NAPLD). Micro-photoluminescence studies reveal that Zn0.9Mg0.1O microrods exhibited a blue shift in the ultraviolet (UV) emission relative to unintentionally doped ZnO that was attributed to the increase in bandgap due to Mg doping. High-resolution micro-photoluminescence clearly indicated the presence of whispering gallery modes (WGMs) for both ZnO and Zn0.9Mg0.1O. Transverse electric (TE) and transverse magnetic (TM) optical WGMs were identified using the existing plane-wave model. The observation of lower order WGM modes in Zn0.9Mg0.1O microrods may be of great interest for future UV WGM lasing.

Graphical abstract






32 show abstract
0022-2313 * * 29815415
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): D.A. Gálico, E.R. Souza, I.O. Mazali, F.A. Sigoli



In this work, the photophysical properties of the [Eu2(mba)4(μ-mba)2(H2O)2] is evaluated as a function of temperature. The luminescence intensity ratio (LIR) between the ligand emission and the 5D0 → 7F2 transition band area is analyzed giving a maximum relative sensitivity of 4.55% K−1 at 313 K and a temperature uncertainly smaller than 0.015 K over the operational range (203–313 K) making this complex as a promising molecular temperature optical probe. These results may be explained by the small energy difference between the excited singlet (S1) and triplet (T1) states (∼1400 cm−1) leading to an inefficient intersystem crossing and consequently the fluorescence of the ligand competing with the 5D0 state emissions. The Mott-Seitz model involving three non-radiative recombination channels suggests that the europium(III) emission deactivation involves the energy back transfer to ligand states, the ligand-to-metal charge transfer state and the third harmonic of the O-H oscillator from a coordinated water molecule.

33 show abstract
0022-2313 * * 29815416
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Pooja Rawat, Sanjay Kumar Saroj, Jasleen Kaur, Rajamani Nagarajan



Mechanochemical synthesis of K2SbF5 by the successive grinding reactions of antimony (III) acetate with ammonium fluoride and potassium fluoride has been carried out. Powder X-ray diffraction pattern of K2SbF5 was refined successfully in orthorhombic space group (Cmcm) with a = 6.3214 (29) Å, b = 13.9380 (60) Å and c = 6.5817 (28) Å. Finger print vibrations of SbF5
2− units in the sample have also been confirmed from FT-IR and Raman spectra. 5 mol% of Eu, Tb and Er doped K2SbF5 have been synthesized by the same method and their optical properties have been analyzed. The Judd-Ofelt (J-O) parameter (Ω
J
) analyses of Eu doped samples have been carried out. On irradiating Er3+ doped sample with 980 nm laser, a bright green emission visible to the naked eye was evident. The decay times of these emissions have been estimated. Following a similar procedure, Rb2SbF5 has been synthesized for the first time.

34 show abstract
0022-2313 * * 29815417
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Zeqing Hu, Yanjie Zhang, Wenlu Liang, Muyao Wang, Jinghui Zhang, Jingjie Yu, Nianyu Zou



The photoluminescence properties and formation mechanism of oxygen vacancies in Ca4(PO4)2O crystal were studied. X-ray diffraction, photoluminescence spectra, and Fourier transform-infrared spectra were used to investigate the formation process of Ca4(PO4)2O crystal. Pure Ca4(PO4)2O crystal prepared in reducing atmosphere shows an intense emission at 405 nm under excitation of 330 nm, which is originated from oxygen vacancies in the lattice. It can be concluded that oxygen vacancies in Ca4(PO4)2O crystal exhibit a high thermal stability and the strong photoluminescence emission can be observed for the sample recalcined in air at 400 °C. The results of XRD and FTIR indicate a phase transformation process between Ca4(PO4)2O, Ca10(PO4)6O and Ca10(PO4)6(OH)2 phase and oxygen vacancies are also formed during this process. Furthermore, a novel Eu2+ singly doped phosphate phosphor with multi-color emission can be firstly developed through strictly controlling phase transformation of the host. Under NUV excitation, the color coordinates are calculated to be (0.3427, 0.3229) and (0.3872, 0.3429) closely corresponding to white/warm white light. The warm white light with high color rendering index (R
a: 87.6) and low correlated color temperature (3510 K) can be achieved based on the Eu2+ singly doped phosphate phosphor.

35 show abstract
0022-2313 * * 29815418
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): C.Y. Morassuti, L.H.C. Andrade, J.R. Silva, M.L. Baesso, F.B. Guimarães, J.H. Rohling, L.A.O. Nunes, G. Boulon, Y. Guyot, S.M. Lima



In this report, Pr3+-doped calcium aluminosilicate (CAS) glasses were synthesized and their spectroscopic properties investigated. The present subject was motivated by the red emission of the Pr3+ ion that can be combined with the green-yellow emission of other luminescent ions like Ce3+ or Eu2+ for white light generation. This combination of materials has been required since commercial diode devices for white lighting exhibit low color rendering index (CRI) and high correlated color temperature (CCT) due to their low emission intensity in the red region. The results showed that when Pr3+-doped CAS glasses are excited at 445 nm, red and green broadband emissions (FWHM ∼ 1300 and 1800 cm−1, respectively) with a strong dependence on the ion concentration can be observed. The (x, y) coordinates in the CIE-1931 chromaticity diagram changed from (0.61, 0.36) to (0.47, 0.41) when the Pr3+ concentration varied from 0.2 to 2.0 wt.%, what was explained in terms of cross-relaxation mechanisms between Pr3+ ions. The luminescence quantum yield (QY), in the visible range from 450  to 800 nm, of the Pr3+-doped CAS glass was determined by an integrating sphere as 0.37, which is a relatively high value for Pr3+-doped glasses. At high Pr3+ concentrations, the studied system is appropriate to be combined with other green-yellow phosphor material for white light generation.

36 show abstract
0022-2313 * * 29815419
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Ashok K. Satapathy, Santosh K. Behera, Ankit Yadav, Laxmi Narayan Mahour, C.V. Yelamaggad, K.L. Sandhya, Balaram Sahoo



We report the influence of intermolecular and intramolecular hydrogen bonding on the excited state proton transfer (ESPT) emission behavior of two bent core liquid crystal (BLC) molecules, C54H63NO9 (BLC3) and C60H75NO9 (BLC4), having a Schiff-base and two long alkyl chains at its two ends. Fluorescence spectra of these BLC molecules dispersed in different solvents show dual emission (at ∼ 365 nm and ∼425 nm) from the keto and enol tautomers. We observed that the population of these keto and enol tautomers and the corresponding intensities of fluorescence emission are strongly influenced by the solvent polarity. In protic solvents, formation of intermolecular hydrogen bond with the Schiff-base of the BLC molecules is highly favoured than the intramolecular hydrogen bonding. This intermolecular hydrogen bonding drastically reduces the population of the keto tautomers in the excited state, resulting in enhanced enol fluoroscence band along with a weak keto emission band. The observed intensity of the enol fluorescence band is the highest for the most studied polar solvent (methanol). On the other hand, in aprotic solvents, the intramolecular hydrogen bonding is highly favoured, which leads to the formation of keto tautomers in the excited state. Hence, an intense keto emission band is observed for the aprotic solvents along with a weak enol emission band. From the time resolved fluorescence studies we observed a longer life time for the keto band than that for the enol band. This is also related to the delayed emission associated with the vibrational bands resulting from the bulky alkyl chains attached to the ends of the BLC molecules.


Graphical abstract

The intensity of fluoroscence emission can be tuned through solvent polarity via formation of intramolecular or intermolecular hydrogen bonds.



37 show abstract
0022-2313 * * 29815420
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): C.L. Heng, W. Xiang, W.Y. Su, Y.K. Gao, P.G. Yin, T.G. Finstad



We studied the effect of europium (Eu) doping on the near band edge emission of ZnO thin films, fabricated by sputtering and high temperatures annealing. The doping concentration of Eu in the ZnO films was varied from 0.01 to 0.62 at.%. Photoluminescence (PL) spectra showed that the films ultra-violet (UV) emission was enhanced very much by high temperature treatment and was stronger for the Eu doped ZnO than that for the un-doped ZnO films after 1100 °C annealing. X-ray diffraction showed the films had hexagonal wurtzite structure, the width of the ZnO (002) plane diffraction peak was sensitive to the anneal temperature and also to the Eu doping concentration, and Zn silicates had formed after the 1100 °C annealing. Scanning electron microscopy showed that the surface morphology of the films became more uneven with increasing Eu concentration. The PL decay spectra inferred that the lifetime of the UV PL was correlated with the size of ZnO nanocrystals in the films. The results support that the intensity of the UV PL is primarily influenced by the crystalline perfection of the films which is also influenced by the Eu doping concentration.

38 show abstract
0022-2313 * * 29815421
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Xuemei Lu, Hongxing Li, Xuan Bao, Wen Liu, Xiaoxing Fan, Yufen Liu, Jia Li, Zhixun Guo, Yu Qiu, Lei Zhang, Shuning Lv, Xiuli Zhang, Tianya Tan, Jiwei Wang



(ZnxCd1-x)3Ga2GeO8:Cr3+, Yb3+, Ln3+ (Ln = Er, Ho, Tm) phosphors are developed in comparison to the reported Zn3Ga2GeO8:Cr3+, Yb3+, Er3+ phosphor. In these zinc and cadmium codoped gallogermanates, both f and d state upconversion of Ln3+ and Cr3+ ions are much stronger than those of zinc or cadmium singly doped samples under 980 nm excitation. Also, the enhancement of ultraviolet light irradiated Cr3+ persistent luminescence is observed in codoped substrates. Through fluorescence kinetic analysis, it is concluded that not only is there energy transfer from Ho3+ to Cr3+ ions but energy back transfer from Cr3+ to Ho3+ ions. The former one leads to the upconversion of Cr3+ and the latter to the red upconversion of Ho3+ ions. The change of phonon energy and symmetry of substrates due to codoping cadmium ions, should be responsible for the upconversion enhancements. Their combined effects yield an optimal value of Zn/Cd ratio for the highest upconversion efficiency.

39 show abstract
0022-2313 * * 29815422
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): I.S. Makhov, V.Yu. Panevin, D.A. Firsov, L.E. Vorobjev, A.P. Vasil'ev, N.A. Maleev



The low-temperature terahertz and near-infrared photoluminescence from the near-infrared laser nanostructure with GaAs/AlGaAs quantum wells doped with shallow donors is studied under intense interband optical excitation. The optical electron transitions involving excited and ground donor states in quantum wells are revealed in terahertz and near-infrared photoluminescence spectra. Impurity assisted near-infrared stimulated emission under interband optical pumping and its influence on the terahertz optical electron transitions are observed and investigated. It is demonstrated, that at the various pumping levels the competition between different impurity assisted stimulated optical transitions in the near-infrared range leads to appearance of the different impurity related emission lines in terahertz spectra.

40 show abstract
0022-2313 * * 29815423
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Rui-Qi Piao, Yan Wang, Qing Xu, Zi-Bo Zhang, De-Long Zhang


Visible and infrared absorption and emission spectra of Er3+-doped strontium gadolinium gallate (SrGdGa3O7) single-crystal were measured at room temperature. From the measured fluorescence spectra, the Er3+ emission cross section spectra were calculated at first. Then, by utilizing McCumber relation, the absorption cross section spectra were further calculated. In parallel, the absorption cross section spectra were also calculated from the measured absorption spectra of the crystal, and compared with those spectra calculated from the McCumber relation. The comparison shows that the absorption cross section spectra obtained using the McCumber relation are in reasonable agreement with those deduced from the measured absorption spectrum.

Graphical abstract

Visible, near-infrared, and mid-infrared emission and absorption cross section spectra of Er3+ in SrGdGa3O7 single-crystal have been calibrated from measured fluorescence spectra using the McCumber theory. The absorption cross-section spectrum was also calibrated from the measured absorption spectrum. Comparison shows that the absorption cross section spectra calibrated from the McCumber theory are reasonably consistent with those from the absorption spectrum. Present work presents complete cross section knowledge of the studied crystal.



41 show abstract
0022-2313 * * 29815424
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Albano N. Carneiro Neto, Renaldo T. Moura, Oscar L. Malta


In this work the aim is three-fold: 1) to call attention for shielding effects in the energy transfer rates between lanthanide ions. 2) to use a new model for treating the Judd-Ofelt


Ω


K


intensity parameters in centrosymmetric systems by using a thermal root mean squared displacement around each ligating atom (ion) in the analysis of the intensity parameters. This might have an important role in ion-ion energy transfer processes, particularly when the lanthanide ions occupy a center of inversion. 3) To call attention to the fact that the quadrupole-quadrupole mechanism is dominant for ion-ion distances as far as 20 Å, provided shielding effects are taken into account. An illustrating comparison with respect to the weak quadrupole mechanism of 4f‐4f transition rates is made.

Graphical abstract






42 show abstract
0022-2313 * * 29815425
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Ivan G.N. Silva, Alysson F. Morais, Danilo Mustafa


The luminescence quenching in RE3+-containing materials (RE: rare earth) has a close dependence with the water content on the first coordination sphere around the activator ions. The hydration content of [RE(TMA)] systems (TMA = 1,3,5-benzenetricarboxylic acid) is dependent on the RE3+ ionic radius, leading to elements smaller than Gd3+ to form anhydrous matrixes. It is noteworthy that [Sm(TMA)·6(H2O)] is hexahydrate, while [Y(TMA)] is anhydrous. In this work, we report the synthesis, characterization and the luminescent properties of [Y(TMA)] anhydrous metal organic frameworks (MOFs) serving as hosts for Sm3+ ions. The materials are synthesized by a quick and easy coprecipitation procedure in aqueous solution. Under calcination at mild conditions (starting at 500 °C, benzenecarboxylate method), the precursor complexes are converted into Y2O3:Sm3+ with strong Sm3+ photoluminescence. The compounds were characterized by different techniques (elemental analyses, infrared spectroscopy, thermogravimetry, powder X ray diffraction and photoluminescence). The phenomenological intensity parameters (Ω2,4,6) of Sm3+ were determined by a least squares procedure based on the Judd-Ofelt theory.
43 show abstract
0022-2313 * * 29815426
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Yun Chen, Zhijun Wang, Wenge Ding, Xue Li, Qi Bao, Jinjin Liu, Keliang Qiu, Xiangyu Meng, Zhiping Yang, Panlai Li


Series of Ce3+/Eu2+, Ce3+/Mn2+ and Ce3+/Eu2+/Mn2+ doped Ba3Y(PO4)3 samples were synthesized by a high temperature solid state reaction method. Phase formation, energy transfer, luminescence properties and thermal quenching properties were investigated carefully. The energy transfer from Ce3+ to Eu2+ and Ce3+ to Mn2+ in Ba3Y(PO4)3 were verified and discussed detailed. When Ce3+ and Eu2+ are co-doped, the energy transfer process from Ce3+ to Eu2+ is confirmed with electric dipole-dipole interaction. For Ce3+/Mn2+ co-doped phosphors, the energy transfer process from Ce3+ to Mn2+ is proved with electric dipole-dipole interaction. Besides, due to the existence of defects, the phosphors show excellent thermal stability. For Ce3+/Eu2+/Mn2+ tri-doped Ba3Y(PO4)3, the energy transfer Ce3+→Eu2+ (Mn2+) and Eu2+→Mn2+ are confirmed. The energy transfer priority among Ce3+, Eu2+ and Mn2+ is analyzed in detail basing on the change of emission intensity. The obtained tri-doped phosphors contain red, green and blue component, thus they can emit warm white light basing on the energy transfer. The results show that they may be novel white-light-emitting phosphors for ultraviolet white light emitting diodes.

Graphical abstract






44 show abstract
0022-2313 * * 29815427
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): S. Mukherjee, A. Pradhan, S. Mukherjee, T. Maitra, S. Sengupta, B. Satpati, S. Chakrabarti, A. Nayak, S. Bhunia


In this paper, we present a combined optical and structural study of GaAs-hosted InAs sub-monolayer QD (SML-QD) vertical multi-stacks. The main feature of this paper is to demonstrate the feasibility of sub-monolayer InAs QD with as low coverage as 0.4 ML which shows all the characteristics of QD excitonic emission, emitting in the NIR region (1.496 eV). This emission energy could be precisely tuned successfully by systematically controlling InAs coverage fraction in the range of 0.4–0.8 with corresponding emission in the range of 1.406–1.496 eV. The luminescence efficiency (4 K) exhibited an increasing trend with the decrease in InAs coverage. This paper elaborately discusses the interdependence of structure, strain and emission characteristics through a combined study of high resolution x-ray diffraction, Raman Scattering and Photoluminescence measurement. Strain-induced growth of the dots with different vertical size distribution (height~2.3–1.4 nm) have been explored which were found to depend strongly on the InAs coverage at low temperature. The varying size distribution of the dot ensembles lead to different degree of carrier confinement, capture and localization, as determined from the low temperature (4 K) PL spectra. Significant enhancement of carrier localization inside almost 2D-like exciton was achieved by reducing InAs coverage well below one monolayer. From the relative temperature dependent photoluminescence measurements, it has been shown that the coupling and relaxation pathways of photo-carriers through the SML-QD multi-structure can be controlled by adjusting the InAs coverage.
45 show abstract
0022-2313 * * 29815428
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Raosaheb S. Patil, Atul S. Patil, Vikas S. Patil, Harishchandra D. Jirimali, Pramod P. Mahulikar


Herein we report a simple and convenient, base promoted synthetic method for preparation of (Z)-2-(2-phenyl-4H-benzo[4,5]thiazolo[3,2-a]pyrimidin-4-ylidene)acetonitrile derivatives. The reactions involve ring transformation of 2H-pyran-3-carbonitriles 1 with 2-aminobenzthazole 2 using Cs2CO3 at room temperature. Absorption and emission properties of synthesized compounds were investigated in solvents of varying polarity. It was found that for all studied compounds no distinguishable behaviour was observed for absorption in different solvents whereas some notable changes were observed in emission fluorescence spectras. Solvent dependent spectral properties of compounds were investigated using Lippert-Mataga plot. A rational relationship is examined between fluorescence quantum efficiencies and calculated HOMO energies.

Graphical abstract






46 show abstract
0022-2313 * * 29815429
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Jyoti Dalal, Mandeep Dalal, Sushma Devi, Rekha Devi, Anju Hooda, Avni Khatkar, V.B. Taxak, S.P. Khatkar


High-brightness, red-emitting Ca9Gd1−x
(PO4)7:xEu3+ phosphors were developed via the facile route of solution-combustion. The Rietveld-assisted structural analysis of Ca9Gd(PO4)7 and Ca9Gd0.40Eu0.60(PO4)7 systems unveiled a trigonal crystal system having R3c(161) space-group symmetry. The absence of JCPDS data was compensated by simulating one from refined structural prototype. The band-gap for the host and best luminescent composition were determined to be 4.55 and 4.01 eV, respectively. The ratio of Judd-Ofelt parameters inferred a very high asymmetry around activator ion which can further be enhanced as a function of dopant concentration. The refractive index of Ca9Gd(PO4)7 was determined to be 2.34. The value of stimulated emission cross section, total radiative transition rate and non-radiative transition rate for Ca9Gd0.40Eu0.60(PO4)7 are calculated from detailed photo-luminescent (PL) analysis. Furthermore, very high value of quantum efficiency (98.13%) and radiative lifetime (1.85 ms) suggested that Ca9Gd0.40Eu0.60(PO4)7 nanophosphor have practical applicability in PC-WLEDs (components of solid-state lighting).

Graphical abstract






47 show abstract
0022-2313 * * 29815430
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Berenice González-Santiago, Obdulia Medina-Juárez, Carlos Alberto Benitez-Delgado, Fernando Rojas-González, Eduardo Salas-Bañales, Miguel Ángel Garcia-Sanchez


Synthesis and adsorption studies of the SBA-15 immobilizing perylene and pyrene dyes are described in this work. The functionalization is carried out with amine groups through post-synthesis using amino-propyl triethoxysilane (APTES) and ethanol or toluene as solvent. The resulting functionalized material is investigated as a matrix for the immobilization of perylene-3,4,9,10-tetracarboxylic dianhydride (PDA). Further exploration of the immobilization of 1-Pyrenecarboxaldehyde (PCA) is detailed. The obtained materials were characterized by FTIR and fluorescence spectroscopy, nitrogen adsorption analysis and X-ray diffraction (XRD). The textural characterization of the functionalized samples shows the decrement of the average pore sizes and the surface area as consequence of the APTES and fluorescent dyes immobilization. Compared with the pristine SBA-15, the solids obtained by functionalization with PDA yielded red-coloured samples, which show absorption bands at λ = 670 nm in solid state and λ = 570 nm in solution. The PDA dye is bonded to the SBA-15 network and it shows absorption or emissions properties for the new hybrid solids. The fluorescence of these species are preserved if the PDA molecules remains with a more flexible structure.
48 show abstract
0022-2313 * * 29815431
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Sachhidananda Shivanna, Nithin Kundachira Subramani, Shilpa Kasargod Nagaraj, Jagajeevan Raj Balasamudra Mutturaj, Siddaramaiah Basavaraj


A dramatic increase in UV endurance of polycarbonate (PC) films were achieved via thoughtful intercalation of cesium zincate (Cs2ZnO2) nanoparticles (NPs). The augmented UV endurance of PC/Cs2ZnO2 nanocomposite (NC) films were analyzed via yellowing index quantification and Fourier Transform Infrared (FTIR) measurements at 1713 cm−1. The foundation for improved UV stability was owed to Cs2ZnO2 NPs induced lessening of undesirable photo-degradation reactions. Moreover, the introduced NPs act to dissipate the high energy UV photons via polymer-nano metal oxide induced synergistic spectral down-conversion. The novel spectral down-conversion abilities and patina-green light emitting properties of PC/Cs2ZnO2 NC films were valued with UVA-transilluminator coupled fluorescence microscopic studies. Eventually, the synergistic combination of Cs2ZnO2 NPs with PC host, wherein the metal oxide offers protection against undesirable photo-degradation reactions, while the polymeric host guards the luminescence centers of nanostructured metal oxides are highly desirable for various photonic and opto-electronic applications.

Graphical abstract






49 show abstract
0022-2313 * * 29815432
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Dipak Ch. Deka, Amarjyoti Kalita, S. Bardaloi, Manos P.C. Kalita


ZnS nanocrystals with different capping agents viz. polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP) and cetyltrimethylammonium bromide (CTAB) were synthesized by the chemical co-precipitation method. The materials were characterized by using various methods such as X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, surface area analyzer, UV–visible absorption spectroscopy and photoluminescence (PL) spectroscopy. Williamson-Hall analyses of the X-ray diffraction patterns were carried out that showed the average crystallite sizes to be 2.6 nm, 2.7 nm and 2.6 nm for the PVA, PVP and CTAB capped ZnS nanocrystals, respectively. The PL studies revealed the presence of various defects such as zinc vacancy, sulphur vacancy, zinc interstitial and sulphur interstitial. The PVA, PVP and CTAB capped ZnS nanocrystals degraded methylene blue under simulated sunlight irradiation by 43%, 89% and 92%, respectively after 150 min of light irradiation. The results showed the presence of correlation between the PL properties and photocatalytic performances of the nanocrystals. Further, the observed higher specific surface areas of the PVP and CTAB capped ZnS nanocrystals compared to those capped by PVA have possibly resulted in their superior photocatalytic properties.
50 show abstract
0022-2313 * * 29815433
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Chengjun Wang, Ying Qian


A red emissive fluorescent probe 1,7-dimethyl-3,5-bis(4-methoxyphenyl-vinyl)-8-(10-n-butyl-10H-phenothiazine-3-yl)BODIPY 1,7-dimethyl-3,5-bis(4-methoxyphenyl-vinyl)-8-(10-n-butyl-10H-phenothiazine-3-yl)BODIPY (avyl-BODIPY-PTZ) with a special orthogonal donor-acceptor structure was designed and synthesized for rapid, sensitive, and selective discrimination of ClO−, over other reactive oxygen species and anions. The probe displays a linear ratiometric absorption (A578/A640) and fluorescence (F599/F660) response toward ClO− with a fast response velocity (~10 s). The limit of detection (LOD) for ClO− was obtained as 22.6 nM from the fluorescence titration experiment. The fluorescence enhancement of the probe can be observed from the 32-fold enhancement in ratiometric value (F599/F660) and the increasement of quantum yield from 0.01 at 660 nm to 0.28 at 599 nm. The oxidation of S atom in phenothiazine by ClO− to form the sulfoxide-type structure was proposed as the recognizing mechanism according to the Mass spectral analysis. The ratiometric enhancement of fluorescence was rationalized by the theoretical calculations. The orthogonal donor-acceptor structure according to optimized calculation and solvent effects of avyl-BODIPY-PTZ illustrated that the ClO− oxidation induced conversion from the nonradiative TICT process to the radiative LE process and caused the fluorescence ratiometric enhancement. The probe with low cytotoxity can successfully permeate into living cells and the cell images can be achieved in single channel. Moreover, after addition of ClO−, another bright red emission channel of the probe switched on and the probe displayed two-channel emission in living cells.

Graphical abstract






51 show abstract
0022-2313 * * 29815434
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Chaoyu You, Lina Yue, Cristóbal Colón, Francisco Fernández-Martínez, Longhui Lin, Ming Gao


Novel silver based rare earth tungstate-molybdate, AgLn(MoO4)(WO4), with scheelite-like structure have been synthesized by ceramic method. The crystal structure, luminescence properties and fluorescence lifetime of a series compounds were investigated systematically. Some special characteristic emission bands were observed which can be attributed by the energy transfer between Ag+ and Ln3+ ions. Especially, AgDy(MoO4)(WO4) and AgHo(MoO4)(WO4) phosphors can emit white light under near-UV excitation, with chromaticity coordinates at about (0.3605, 0.3652) and (0.3559, 0.3479) respectively. Fluorescence lifetime of Eu3+ and Tb3+ were measured in both room temperature and liquid nitrogen temperature. In excitation spectra, the evident blue shift of charge transfer (CT) band in the case of liquid nitrogen temperature indicates that the effective W-O and Mo-O covalence bond is lower at liquid nitrogen temperature which can be caused by the lower wave function overlaps of W-O and Mo-O. Furthermore, low temperature showed positive effect for longer fluorescence lifetime.
52 show abstract
0022-2313 * * 29815435
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Yuao Guo, Lijuan Zhao, Yuting Fu, Haotian Dong, Hua Yu


In this work, a strategy of K+ ions doping was visited with the aim of enhancing up-conversion luminescence (UCL) and sensitivity for optical thermometer of β-PbF2:Er3+ glass ceramics (GCs). Compared to K+-free β-PbF2:Er3+ GCs, the UCL intensity of green (521, 552 nm), red (668 nm), NIR (825 nm) emissions and absolute sensitivity (Sa) for optical thermometer of the β-PbF2:Er3+ GCs co-doped with 10 mol% K+ ions were increased by 176, 82, 18 and 1.5 times, respectively. Charge compensation and the distortion of the local symmetry around the Er3+ ions, when the K+ ions were introduced, were confirmed to be the origin of the enhancement. The results show that K+ ions simultaneous co-doping of β-PbF2:Er3+ glass ceramics (GCs) very effective way to integrate this material for advanced photonic applications.
53 show abstract
0022-2313 * * 29815436
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Chenchen Yang, Dianyi Liu, Alexander Renny, Padmanaban S. Kuttipillai, Richard R. Lunt


Visibly transparent luminescent solar concentrators (TLSCs) can convert existing window glazing systems and non-window surfaces into solar energy harvesting resources, dramatically improving energy utilization efficiency. While there has been a significant interest in improving the power conversion efficiency, little attention has been focused on the challenges of integrating luminescent solar concentrators (LSCs) onto non-window surfaces or windows with significant infrared absorption coefficients. In these situations, the total internal reflection (TIR) can be effectively disabled when LSCs are directly and seamlessly integrated onto surfaces that are highly absorptive or scattering to infrared light. To overcome this challenge, we utilize a low refractive index adhesive film with high transparency between the TLSC waveguide and the back surface, to maintain both the device functionality and aesthetic quality of the surface underneath. Photovoltaic measurements were conducted to show that the TIR is re-enabled with the presence of such a structure. Thus, this method can effectively improve LSC performance and scalability, and allows TLSCs to be integrated onto arbitrary surfaces such as automobiles, billboards, and buildings.
54 show abstract
0022-2313 * * 29815437
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Markus Suta, Claudia Wickleder


In this review, modern insights into the synthesis and fundamental optical properties as well as applications of divalent lanthanides as spectral energy converters are discussed, which have especially evolved within the last two decades. An emphasis is put on the state-of-the-art knowledge about the luminescence of other divalent lanthanides than the most commonly applied representative Eu2+ and what special features in their luminescence arises due to the different number of 4f
n
electrons. In particular, the luminescence of Sm2+, Tm2+, Yb2+ and the less stable ions Nd2+ and Dy2+ will be regarded. A broad overview over the synthetic approaches to inorganic compounds based on divalent lanthanide ions will be conveyed as well and shall demonstrate the fascinating developments in the field of inorganic solid-state chemistry of the lanthanides.
Besides their fundamental optical properties, also applications of the presented divalent lanthanide activators are discussed. Sm2+ is a well-known temperature and pressure sensor due to its interconvertible 4f‐4f and 5d-4f transitions. Moreover, nanocrystalline BaFCl:Sm2+ has an appreciable potential as novel X-ray storage phosphor. Tm2+ is interesting for upconversion in photovoltaic and lasing applications, whereas Yb2+ in halides may be a promising alternative to Eu2+ for scintillation materials and phosphors for light-emitting diodes (LEDs). Nd2+ and Dy2+ are currently emerging as novel near infrared (NIR)-absorbing and emitting activators that might become interesting as lasing ions. The spectroscopy of these unusual lanthanide ions provides many non-trivial features due to the excited two-open shell 4fn-15d1 configuration overlapping with the excited 4f
n
levels. Finally, a perspective for future developments will be given.
55 show abstract
0022-2313 * * 29815438
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Min Liao, Zhongfei Mu, Shaoan Zhang, Fugen Wu, Zhaogang Nie, Zhaoqiang Zheng, Xing Feng, Qingtian Zhang, Junqin Feng, Daoyun Zhu


In the past few decades, a variety of red phosphors have been designed and developed. However, most of them are not satisfying for the sake of low brightness and poor thermal stability. Here, we report the preparation and luminescence properties of a promising red phosphor Mg3Y2Ge3O12: Bi3+, Eu3+. Eu3+ singly doped samples can emit bright reddish light. In Bi3+ and Eu3+ co-doped samples, there exists effective energy transfer from Bi3+ to Eu3+. The co-doping of Bi3+ can remarkably enhance the luminescence of Eu3+. The integrated emission intensity of Mg3Y1.19Ge3O12: 0.01Bi3+, 0.8Eu3+ is greater than that of commercial red phosphor Y2O3: 0.05Eu3+. More importantly, the luminescence of this phosphor also shows excellent thermal stability and relatively high quantum efficiency (63.89%). When the ambient temperature rises to 423 K, the integrated emission intensity remains 94.42% of the one at room temperature and quantum efficiency still remains 51.24%. All these investigation results prove that Mg3Y2Ge3O12: Bi3+, Eu3+ is a promising red phosphor for white light-emitting diodes.
56 show abstract
0022-2313 * * 29815439
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Jianxu Hu, Yuanpeng Zhang, Bin Lu, Haiping Xia, Huanqing Ye, Baojiu Chen


Mn4+/Yb3+ co-doped CaGdAlO4 are prepared to achieve efficient spectral conversion. XRD Rietveld refinement analysis is performed to obtain the structural information of the synthesized materials. The results indicate the Al3+ and Gd3+ sites are substituted by the Mn4+ and Yb3+ ions, respectively. Intense NIR emission within the most sensitive response region of c-Si solar cells is observed under UV–visible excitation, indicating the existence of efficient energy transfer from Mn4+ to Yb3+ ions. The dipole-dipole interaction is verified to be the dominant energy transfer mechanism among the Mn4+-Yb3+ pair. The linear dependence of energy transfer rate on the Yb3+ concentration indicates that one NIR photon is generated with the absorption of one UV–visible photon. The broad excitation spanning from 250 to 600 nm monitored at NIR emission demonstrates that the Mn4+ ions in the CaGdAlO4 host can be efficient sensitizers for Yb3+ ions to enhance the performance of c-Si cells.

Graphical abstract

Efficient conversion of UV–visible light to near-infrared light is achieved in thermally stable Mn4+/Yb3+ co-doped CaGdAlO4 phosphors.



57 show abstract
0022-2313 * * 29815440
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Meng Xue, Cong Cao, Ming Xu, Xianmei Zou, Xiaobo Zhou, Yipeng Zhang, Fuyou Li, Tao Yi, Wei Feng


Exploiting the energy transfer (ET) direction is important in nanoscale fluorescent detection systems. In a typical detection system based on ET, the quenching efficiency was evaluated by decrease of donor's emission intensity, but there exists reabsorption process apart from nonradiative ET process. Here, we propose a method to analyze the individual contribution of nonradiative ET and reabsorption to quenching efficiency. These two processes influence in a different way on the nanoplatform consisting of NaYF4:20%Yb,2%Er UCNPs and a sulfonyl modified cyanine dye. We find that nonradiative ET process contributes more than reabsorption and possesses a better detection sensitivity (2.27 folds). Our work presents a thorough understanding of detection process, which will be conducive in evaluating the sensitivity of similar detection systems.

Graphical abstract






58 show abstract
0022-2313 * * 29815441
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Qingxuan Li, Bo Li, Lei Wang, Zhongming Zheng, Baoping Zhang, Ningyang Liu, Binhong Li, Mengxin Liu, Yang Huang, Zheng Gong, Zhitao Chen, Xinyu Liu, Jiajun Luo, Zhengsheng Han


Radiation effects of 10 MeV electrons on blue-lighting InGaN/GaN multiple quantum wells (MQWs) and ultraviolet-lighting GaN/AlGaN MQWs were investigated and compared by means of temperature-dependent and time-resolved photoluminescence (PL) methods. It was found that GaN/AlGaN MQWs showed better radiation tolerance than InGaN/GaN MQWs. In detail, the internal quantum efficiency of InGaN/GaN MQWs decreased sharply with increasing electron irradiation fluence whereas that of GaN/AlGaN MQWs remained nearly constant. The degradation of the emission properties of InGaN/GaN MQWs after irradiation was attributed to the generation of non-radiation recombination centers (NRCs) in MQWs. On the other hand, the radiation hardness of GaN/AlGaN MQWs was proved to be related to two factors: the irradiation-induced reduction of both exciton localization energy and NRC density. The results reported here are significant for the evaluation and design of GaN-based optoelectronic and electronic devices used in radiation environments.
59 show abstract
0022-2313 * * 29815442
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Xiao Li, Peixiong Zhang, Siqi Zhu, Hao Yin, Zhen Li, Zhenqiang Chen, Yi Zheng, Jin Yu


The use of Eu3+ codoped for the enhancement of the transition of Er3+: 4I11/2→4I13/2 ~2.75 µm emissions was observed in the Er/Eu co-doped PbF2 crystal for the first time. The ~2.75 µm energy transfer mechanism and fluorescence emission properties of the Eu/Er co-doped PbF2 crystal were investigated at length. The results show that the codoped of Eu3+ ion in Er/Eu: PbF2 crystal greatly enhances Er3+:2.75 µm emission under excitation of a common 970 nm laser diode. In addition, it is found that the Eu3+ ion depopulates the lower laser level of Er3+:4I13/2, and has little effect on the upper laser level of Er3+:4I11/2 at the same time. Moreover, the energy transfer efficiency from the Er3+:4I13/2 level to the Eu3+:7F6 level is as high as 88.07%, indicating that the Eu3+ ion is an effective deactivation ion for enhancing the ~2.75 µm emission in Er/Eu: PbF2 crystal. These advantageous spectroscopic characteristics suggest that the Er/Eu: PbF2 crystal may be a promising material for ~2.75 µm mid-infrared lasers under the pump of a conventional 970 nm LD.
60 show abstract
0022-2313 * * 29815443
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Shuxin Liu, Shuwei Ma, Shuxian Wang, Zhengmao Ye


Eu3+-doped SrGa2O4 from γ- to β-phases is successfully manipulated by controlling sintered temperature from 1273 K to 1673 K. The related structural changes are characterized by the thermal analysis, Rietveld refinement and Raman investigation. And on that basis, the photoluminescence (PL) survey is used to study the corresponding crystal-field splittings of Eu3+ ions in γ- and β-SrGa2O4, which shows the obvious difference in the 4f-4f energy transitions of Eu3+ ions between two SrGa2O4 phases, especially in the non-degenerate 5D0→7F0 transition region. Both γ- and β-SrGa2O4 show two 5D0→7F0 transition peaks, being in agreement with the two nonequivalent Sr sites in each SrGa2O4 phase. For γ-SrGa2O4, it is 580.8 nm (SrO7) and 579 nm (SrO8), respectively, and for β-SrGa2O4, it is 579.6 nm (SrO7) and 578.7 nm (SrO8), respectively. The difference of Eu3+ crystal field splitting between SrO7 sites and SrO8 sites in γ-SrGa2O4 is larger than that in β-SrGa2O4, which is mainly derived from the larger polyhedral difference between two Sr sites (SrO7 and SrO8). What discussed in this work manifests the sensitive response of Eu3+ ions for the change of local structural surroundings, and further indicates the potential application of rare-earth fluorescent probes in the field of phase identification.
61 show abstract
0022-2313 * * 29815444
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Haiming Cheng, Feng Hong, Guixia Liu, Dan Li, Qianli Ma, Xiangting Dong, Wensheng Yu


Novel Mn4+-activated red light-emitting phosphors, A2NaInF6:Mn4+ (A = K and NH4), have been designed and obtained through co-precipitation method. The phase identification, morphology and composition have been systematically investigated via X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometers (EDS), respectively. The excitation peaks of the red phosphors K2NaInF6:Mn4+ and (NH4)2NaInF6:Mn4+ are located at 300–550 nm, which means that (K,NH4)2NaInF6:Mn4+ can be applied in blue and ultraviolet chips. Excited by the blue light, the phosphors A2NaInF6:Mn4+ (A = K and NH4) exhibit red light emitting at 600–650 nm. The influence of reaction time, starting materials and the doping amounts of Mn4+ on the crystal structure and optical characteristic has been investigated. The temperature-dependent fluorescence results of K2NaInF6:Mn4+ samples have been also provided. The fabricated WLED with colour rendering index (Ra = 83.4) and low colour temperature (4444 K) is attained by using the prepared K2NaInF6:Mn4+ product. Therefore, the red light-emitting A2NaInF6:Mn4+ (A = K and NH4) phosphors could be regarded as good candidates for improving the performance of WLED.

Graphical abstract

Narrow-band red phosphors A2NaInF6 (A = K and NH4) were synthesized via co-precipitation methods, which can be fabricated for improving the performance of WLED.



62 show abstract
0022-2313 * * 29815445
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Shanming Li, Lianhan Zhang, Chun Li, Yuxin Leng, Mingzhu He, Guangzhu Chen, Yilun Yang, Shulong Zhang, Peixiong Zhang, Zhenqiang Chen, Min Xu, Yin Hang


The Tm3+ and Ho3+ ions co-doped LaF3 crystal was grown successfully by the Bridgman method for the first time. X-ray diffraction, thermal conductivity, absorption, and fluorescence properties were investigated systematically. The thermal conductivity is 1.99 W/(mK) at room temperature. The absorption cross-section at 792 nm and emission cross-section at 1987 nm are

0.18


×



10






20



cm2 and

0.32


×



10



20






cm


2


, respectively. The Tm,Ho:LaF3 crystal exhibits wide absorption band (38 nm) and emission band (140 nm), as well as long fluorescence lifetime (17.56 ms). With a 10-mm-long sample, the output power of 574 mW at 2047 nm was obtained for the incident power of 3.53 W with a slope efficiency of 18.5%. It can be proposed that Tm,Ho:LaF3 crystal can be a potential material for LD-pumped tunable and ultra-short pulse laser applications operating at around 2

μ
m

.
63 show abstract
0022-2313 * * 29815446
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): A.K. Choudhary, A. Dwivedi, A. Bahadur, S.B. Rai


In the present work, the upconversion emission spectra of Er3+/Yb3+co-doped CaAl2O4 (CAO), SrAl2O4 (SAO) and BaAl2O4 (BAO) phosphor samples have been studied in absence and presence of Zn2+. The samples were synthesized using high temperature solid state reaction technique at 1623 K. The X-ray diffraction (XRD) measurements have been carried out to verify the pure phase formation in all the three cases. Whereas the CAO and SAO samples show the monoclinic phase, the BAO sample shows hexagonal phase. The surface morphology of the three phosphor samples has been studied by scanning electron microscopy (SEM) technique. The Fourier-transform infrared (FTIR) and Raman measurements show the vibrational bands due to different groups present in the samples. The upconversion emission spectra of all the three samples show green and red emissions bands due to Er3+ ion on excitation with 980 nm laser. However, it is interesting to note that CAO phosphor emits very intense green and weak red emissions, the SAO and BAO phosphors give intense red and weak green emissions. However, the upconversion emission intensity (green as well as red both) in all the three samples is enhanced several times in presence of Zn2+ ions. The mechanism involved in UC emissions has been explained by partial energy level diagram.
64 show abstract
0022-2313 * * 29815447
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Frank Güell, Paulina R. Martínez-Alanis


The optical properties of ZnO nanowires, grown by the vapor-transport method using Au as catalyst over quartz, sapphire and SiO2/Si substrates, have been characterized as a function of the growth parameters such as temperature and time, and the thickness of the Au-catalyst film. The diameter and the length of the nanowires range from 40 to 200 nm and 0.2 to 2 µm, respectively. Room-temperature absorption and emission spectra show a well-defined exciton peak in the ultraviolet. Moreover, photoluminescence measurements show a very broad emission band in the visible range from 420 to 800 nm, which exhibits three distinct peak-like contributions in the Green, Yellow and Red at around 520, 590 and 720 nm (2.38, 2.10 and 1.72 eV), respectively. We observed that the intensity of the broad emission band in the visible increases relative to that of the exciton emission as the wire diameter decreases due to a surface effect. The origin of these visible contributions change as a function of the growth parameters and correspond to different defect-related recombination processes, which will be useful in the future applications of ZnO for optoelectronics.
65 show abstract
0022-2313 * * 29815448
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Xin Liu, Ruoshan Lei, Feifei Huang, Degang Deng, Huanping Wang, Shilong Zhao, Shiqing Xu


BaMoO4: Er3+/Yb3+ phosphors with different concentrations have been fabricated by a facile hydrothermal method. The morphology observation shows that the shape and size of BaMoO4 powders change after Er3+/Yb3+ doping. The upconversion luminescence spectra consist of intense green bands centered at 536 and 558 nm and a weak red emission band peaked at 668 nm upon 980 nm excitation. The excitation power and doping concentration have little impacts on the color emitted from the samples. Applying the fluorescence intensity ratio (FIR) technique, the temperature sensing behaviors are investigated based on thermally coupled levels (2H11/2 and 4S3/2) and non-thermally coupled levels (4F9/2 and 4S3/2), respectively. The thermometry is sensitive to the excitation power for 4F9/2 and 4S3/2 levels, leading to large measurement errors caused by the power variation. Such a problem can be solved by using the power-insensitive FIR between 2H11/2 and 4S3/2 levels, which also shows the advantage of high absolute sensitivity with the maximum of 110.7 × 10−4 K−1. So, the developed BaMoO4:Er3+/Yb3+ phosphors can be applied in green light upconverters, display devices and temperature sensors.
66 show abstract
0022-2313 * * 29815449
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Emmanuel M. Gomes, Douglas F. Franco, Sérgio L. Scarpari, Marcos V. Colaço, Monica S. Ferreira, Ricardo O. Freire, Lippy F. Marques


In this work, we present the synthesis, solid state characterization and complete photoluminescence study of new important homobimetallic lanthanide complexes containing the non-steroidal anti-inflammatory drug (NSAID) naproxen. The analytical and spectroscopic techniques reveals the formation of eight compounds of general formula [Ln

2

(nap)

6

(H

2

O)

4

] (Eu 1 and Gd 2), [Ln

2

(nap)

6

(bpy)

2

] (Eu 3 and Gd 4), [Ln

2

(nap)

6

(4,4'
-
dmbpy)

2

] (Eu 5 and Gd 6) and [Ln

2

(nap)

6

(phen)

2

] (Eu 7 and Gd 8), where: nap = naproxen ligand, bpy =2,2'
-
bipyridine, 4,4'
-
dmbpy = 4,4'
-
dimethyl
-
2,2'
-
bipyridine and phen = 1,10
-
phenanthroline. Using the RM1 model, the molecular structures of the EuIII complexes were calculated, with your optimized ground state geometries used to obtain all details involved in the energy transfer process. From the respective GdIII complexes were obtained the lowest ligand triplet states, proving that the photoluminescence in the EuIII naproxen complexes is proposed to be a ligand sensitized luminescence process. On the other hand, the position of the triplet states also explains the non-effective energy transfer in the TbIII naproxen complexes. The presence of N,N-donors ligands (bpy, 4,4'
-
dmbpy and phen) results in an 3–4-fold increase in the quantum efficiency when compared with the EuIII complex without nitrogen ligands. The high values of emission quantum efficiency (η ~ 70 - 98%) show the EuIII complexes can be potential candidates as emitters in biologic assays.

Graphical abstract






67 show abstract
0022-2313 * * 29815450
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Houari Brahim


In this work, we studied the structural and optical properties of the three complexes: 2,3-bis[(4-diethylamino-2-hydroxybenzylidene)-amino]but-2-enedinitrile (Pd-1), 2,3-bis[(4 diethylamino-2-hydroxybenzylidene)-amino]but-2-enedinitrile (Pt-1), and 2,3-bis(3,3,9,9-tetramethyl-2-hydroxyjulolidine)but-2-enedinitrile (Pd-2) using DFT and TD-DFT methods. The electronic and geometrical structures of the ground state (S0) and the first triplet excited state (T1) have been analyzed and compared. Observed absorption bands were assigned according to NTO analyzes, the agreement with the experience is good. LLCT character dominates the low-lying singlet excited states. Phosphorescence wavelengths of the studied complexes were calculated vertically and adiabatically. The adiabatic methods are more accurate. Phosphorescence spectra were simulated taking into account the vibronic coupling using FC/AH and FC/AS approaches. The normal modes involved in phosphorescence maxima were identified, analyzed and assigned to the observed emission maxima.

Graphical abstract






68 show abstract
0022-2313 * * 29815451
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Qiying Huang, Weihao Ye, Guangqi Hu, Xiaotang Liu


Bi3+ and Mn4+ co-activated Mg3.5Ge1.25O6 phosphors were synthesized via a solid-state method in air. Codoping Bi3+ into the matrix leads to effective enhancement of the deep-red emssion (659 nm) compared to Bi3+-free samples. The spectroscopic properties are discussed based on the Bi3+(6s2)→Ge4+(3d10) metal-to-metal charge transfer and energy transfer between Bi3+ and Mn4+. All samples emit deep-red emission ascribed to 2Eg→4A2g transition of Mn4+. We have carried out the X-ray power diffraction (XRD), photoluminescence spectrum (PL), field emission scanning electron microscope (FESEM), fourier transform infrared spectroscopy (FT-IR) and UV–Vis absorption measurement to investigate the influences induced by Bi3+ incorporation.
69 show abstract
0022-2313 * * 29815452
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Tianhui Jiang, Xinghong Gong, Yujin Chen, Yanfu Lin, Jianhua Huang, Zundu Luo, Yidong Huang


A Dy3+-doped NaBi(WO4)2 crystal was successfully grown by the Czochralski method. Spectroscopic properties of the crystal at room temperature were measured and analyzed. Peak absorption cross-sections of the 6H15/2 → 4I15/2 transition for the crystal are 1.4 × 10-21 and 2.3 × 10-21 cm2 with full widths at half maximum of 7.5 and 6.6 nm for σ and π polarizations, respectively, and at 454 nm for both polarizations. Meanwhile, the crystal exhibits a strong yellow emission at 574 nm corresponding to the 4F9/2 → 6H13/2 transition with peak cross-sections of 0.97 × 10-20 and 1.27 × 10-20 cm2 for σ and π polarizations, respectively. The fluorescence lifetime and quantum efficiency of the 4F9/2 multiplet were estimated to be 179 μs and 80%, respectively. It has been found that the cross relaxation plays an important role in the relaxation of the 4F9/2 multiplet. The results show that the Dy3+:NaBi(WO4)2 crystal may be a promising gain medium of the 574 nm yellow laser pumped by a blue laser diode at 454 nm.
70 show abstract
0022-2313 * * 29815453
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Jhuma Saha, Debiprasad Panda, Binita Tongbram, Debabrata Das, Vinayak Chavan, Subhananda Chakrabarti


Impact of combinational (In0.21Al0.21Ga0.58As/In0.15Ga0.85As and In0.15Ga0.85As/ In0.21Al0.21Ga0.58As) capping on the strain, photoluminescence, and thermal stability of self-assembled InAs quantum dots (QDs) have been analyzed in this article. The proposed combinational capped QDs exhibited redshift in the ground state photoluminescence (PL) peak compared to the previously reported conventional capped QDs. The thickness of capping layers has also been varied to realize the optimum combination with minimized strain in the heterostructure. Room temperature emission at 1.33 µm along with a narrower full width at half maximum (FWHM) has been obtained for the 2.5/2.5 nm In0.21Al0.21Ga0.58As/In0.15Ga0.85As capped QD, which comes under the O-band of telecommunication wavelength. The probability of pulse broadening is less in this region, which might not only enhance the coupling of dots to the optical field but also increase the modal gain of QD based lasers, necessary for efficient long-haul telecommunication. Furthermore, the interface quality across the capping layers of the proposed QD heterostructure has been found to be smooth from transmission electron microscopy images. Thermal stability of the proposed QD structures, with optimum capping thickness, has been investigated through rapid thermal annealing (RTA) treatment. To ensure the reliability of the optimized structure for infrared applications, QD based photodetectors were fabricated and characterized. The lowest dark current and spectral response (up to 90 K) at the mid-infrared (MIR) regime was offered by the device having In0.21Al0.21Ga0.58As/In0.15Ga0.85As as the capping layer. A concise study of the improvement in opto-electronic properties of QDs via proposed combinational capping have been done in this article, which ultimately motivates towards the fabrication of photodetectors/ photoemitters and their integration on photonic chips.

Graphical abstract






71 show abstract
0022-2313 * * 29815454
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Jie Pan, Di Zhang, Meng-Meng Shang, Ying Mu, Song-De Han, Guo-Ming Wang


A 2D anionic Cd-based coordination host was constructed from the linkage of the metal ions and 6-sulfonicotinic acid (SNA, in situ generated from the breaking of disulfide bond in 6,6’-dithiodinicotinic acid) whose interior spaces are occupied with cationic [(CH3)2NH2]+ guests. The compound exhibits an interesting ion-exchange behavior for both encapsulation of lanthanide (Ln) ions and organic dye. Through the fixation of Ln3+ within the host, the designed composite can be endowed with high photoluminescence property. Moreover, the free cations could be readily substituted by methylene blue (MB), with more than 90% of MB (10−5 M) being selectively absorbed after 12 h, making the title compound to be a great medium for dye adsorption and separation.

Graphical abstract

An anionic Cd-based coordination polymer was constructed, which can encapsulate Ln3+ for photoluminescence and absorb cationic dyes for pollutant treatment.



72 show abstract
0022-2313 * * 29815455
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Ru Cao, Chengshou An, Lianhua Tian


The photoluminescence properties of BaZn1.06Al9.94O17:Mn4+ are investigated in this paper. The excitation spectrum of BaZn1.06Al9.94O17:Mn4+ shows three bands. The absorption band centered at 295 nm is attributed to the overlap of the Mn4+ → O2- charge transfer transition and the 4A2 → 4T1g transition of Mn4+ ion, the other weak bands centered at 399 and 450 nm are due to the 4A2 → 2T2 and 4A2 → 4T2 transition of Mn4+ ion. The emission spectrum shows emission peak at 665 nm, owing to the spin-forbidden transition 2E→4A2 of Mn4+ ions. With increasing Mn4+ ion concentration, the lifetime of the phosphor decreases from 1.050 to 0.950 ms. The chromaticity coordinates is (0.717, 0.283) which is a deep red emission. The emission of BaZn1.06Al9.94O17:Mn4+ contributes to plant growth and can be applied to plant illumination sources.
73 show abstract
0022-2313 * * 29815456
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Danilo O. Junot, Ana G.M. Santos, Patrícia L. Antonio, Marcos V.S. Rezende, Divanizia N. Souza, Linda V.E. Caldas


The motivation of this work was to produce TL dosimeters based on crystals of CaSO4 doped with thulium and silver, by means of a suitable new route. The crystals were produced by an adaptation of the slow evaporation route using calcium carbonate (CaCO3) as precursor, and incorporating the dopants (Tm2O3 and silver nanoparticles) in a solution of sulfuric acid, which is evaporated resulting in CaSO4:Tm or CaSO4:Tm,Ag crystal powders. X-ray diffraction analyses showed that the produced samples exhibit only a single phase corresponding to the crystal structure of anhydrite. Optical characterization was performed to determine the band gap of the materials. Samples did not show a reasonable OSL signal after stimulation with blue LEDs. TL characteristics such as glow curves, linearity and reproducibility of response, minimum detectable dose and fading were evaluated. The CaSO4:Tm samples showed TL emission glow curves with peaks in temperatures proper for dosimetry. The CaSO4:Tm,Ag samples presented a very intense peak displaced to high temperatures that could only be observed by applying heating rates below 4 °C/s. Samples doped with thulium oxide and silver nanoparticles showed the highest TL intensity and lowest fading.
74 show abstract
0022-2313 * * 29815457
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Haoran Qin, Xinghong Gong, Yujin Chen, Jianhua Huang, Yanfu Lin, Zundu Luo, Yidong Huang


A stoichiometric Sr3Tb2(BO3)4 crystal was successfully grown by the Czochralski method. Polarized absorption and fluorescence spectra of the crystal were measured at room temperature. The peak absorption cross-section at 486 nm corresponding to the 7F6→5D4 transition of Tb3+ ions for the E//Z polarization is 1.32 × 10–22 cm2. Based on the Judd-Ofelt theory, fluorescence branching ratios of the 5D4→7F5 and 5D4→7F4 transitions of Tb3+ ions were calculated to be 64.86% and 7.69%, respectively. The radiative lifetime of the 5D4 multiplet was calculated to be 2.93 ms. The yellow fluorescence band centered at 586 nm corresponding to the 5D4→7F4 transition is flat and the full width at half the maximum of this band is 8.5 nm. The fluorescence lifetime of the 5D4 multiplet was measured to be 2 ms and the fluorescence quantum efficiency was estimated to be 69%. Above results show that the Sr3Tb2(BO3)4 crystal is a potential gain medium for yellow laser.
75 show abstract
0022-2313 * * 29815458
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): T. Zorenko, K. Paprocki, I. Levchuk, M. Batentschuk, B. Epelbaum, A. Fedorov, Yu. Zorenko


The work is dedicated to the investigation of the luminescent and scintillation properties of the LiLuP4O12:Ce tetraphosphate, as a new scintillation material. The LiLuP4O12:Ce polycrystalline samples were grown by the Micropulling down (MPD) method. Under e-beam excitation and excitation with energy above the band gap of host, the LiLuP4O12:Ce crystals possess very strong Ce3+ luminescence in the UV range in the bands peaked at 334 and 355 nm with a lifetime of 23 ns at room temperature. We have found that the scintillation light yield (LY) of polished plates prepared from MPD grown LiLuP4O12:Ce samples is relatively high and comparable with the LY of reference BGO crystal. Future improvement of the scintillation LY is expected at the optimization of the growth conditions of this compound. The energy structure of Ce3+ ions, related to the 4f-5d transitions of Ce3+ ions in the 3.7–25 eV range, was determined from the excitation and emission spectra of LiLuP4O12:Ce crystal under excitation by synchrotron radiation. We have also determined the energy of creation of excitons bound with Ce3+ ions and estimated the energy gap in LiLuP4O12 host, which is equal to 8.5 and> 9.0 eV, respectively.
76 show abstract
0022-2313 * * 29815459
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Yong Cheng, Shouyong Deng, Feifei Sun, Ying-Hua Zhou


Cu9S5 nanoclusters (Cu9S5 NCs) with photoluminescence emission in the visible region have been synthesized via a simple treatment of copper-2, 5-dimercapto-1, 3, 4-thiadiazole (Cu(II)-DMTD) coordination polymer with ammonium hydroxide. This procedure involves a desulfurative C-N cross-coupling route, in which one mercapto group was replaced by amine, resulting in 2-mercapto-5-amine-1,3,4-thiadiazole (AMTD) as protecting agent for Cu9S5 NCs. The product exhibits a fluorescence emission at 567 nm with a quantum yield (Φ) 0.068. The as-prepared Cu9S5 NCs were employed as a broad-range pH sensor by virtue of the fluorescence intensity responding sensitively to pH fluctuating in a linear range of 3.0–10.0.

Graphical abstract






77 show abstract
0022-2313 * * 29815460
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Yarui Zhu, Xinjie Shen, Minghan Zhou, Xiue Su, Jun Li, Gaobo Yang, Hanru Shao, Yaxun Zhou


Improving the infrared-band luminescent property of rare-earth doped materials is a challenging task. In this work, the enhanced 2.0 µm band emission study in Ho3+/ Yb3+/Er3+ tri-doped tellurite glasses with composition TeO2-ZnO-WO3-La2O3 was given. The tellurite glasses were prepared by conventional melt-quenching technique and characterized by absorption spectrum, emission spectrum, fluorescence decay curve, differential scanning calorimeter (DSC) curve, X-ray diffraction (XRD) pattern and Raman spectrum. The DSC curve displays the good thermal stability with glass transition temperature larger than 420 °C, the XRD pattern reveals the amorphous state nature and Raman spectrum clarifies the vibrational units of glass network. Based on the absorption spectrum, important spectroscopic parameters like spontaneous radiative transition probability, radiative lifetime, absorption and emission cross-sections, and gain coefficient are determined to predict the potential luminescent properties in near-infrared band, while the fluorescence spectrum demonstrates the enhanced 2.0 µm band emission of Ho3+:5I7 → 5I8 radiative transition aroused by Er3+ introduction. Compared with the Ho3+/Yb3+ co-doped sample, an enhancement of about 93% in 2.0 µm band emission intensity is appeared in the tri-doped tellurite glass after introducing 0.8 mol% amount of Er2O3 under the excitation of 980 nm. The enhanced 2.0 µm band emission is attributed to the energy transfers among Yb3+, Er3+ and Ho3+ ions, and fluorescence decay curves together with the energy transfer mechanism are analyzed to elucidate the observed luminescent enhanced phenomena. The results indicate that Ho3+/Yb3+/Er3+ tri-doped tellurite glass possesses excellent 2.0 µm band luminescent property and can be an attractive candidate for solid-state lasers.
78 show abstract
0022-2313 * * 29815461
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Gongke Wang, Chaowei Shao, Changling Yan, Dan Li, Yufang Liu


Silver is one of the most important heavy metals with a broad range of applications; however, it can have significant negative impacts on both the ambient environment and organisms. For this work, an interesting fluorescence polarization sensor based on SH-DNA functionalized gold nanoparticles (AuNPs) was proposed for the detection of Ag+ in aqueous solutions. Moreover, this sensing strategy is quite simple, sensitive, selective, and cost-effective. Ag+ ions can interact specifically with a cytosine–cytosine (C–C) mismatch in DNA duplexes to form stable metal-mediated cytosine–Ag+–cytosine (C–Ag+–C) base pairs. The creation of these C–Ag+–C complexes results in evident changes in the molecular volume and fluorescence polarization signal. The stable hybridization between the two probes occurs with the formation of the C–Ag+–C complex in the presence of Ag+ ions, which leads to obvious fluorescence quenching in contrast to the system without AuNP. This assay may be employed to identify nanomolar levels of Ag+ within 6 min at room temperature. Furthermore, the sensor was successfully adopted to detect Ag+ ions in environmental water samples, which may facilitate the potential development of a range of environmental monitoring applications.

Graphical abstract






79 show abstract
0022-2313 * * 29815462
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): Zewang Hu, Xiaopu Chen, Haohong Chen, Yun Shi, Xin Liu, Tengfei Xie, Huamin Kou, Yubai Pan, Eva Mihóková, Martin Nikl, Jiang Li


Pr:Lu3Al5O12 transparent ceramics with different doping concentrations (0% − 1 at%) were fabricated using the solid-state reaction and vacuum sintering method. The influence of doping concentration on the luminescent properties was investigated in detail. The 5d-4f emission slightly redshifts with the increase of doping concentration under UV light and X-ray excitation. The slow emission below 290 nm related to antisite defects can be suppressed by the increase of doping concentration at room temperature. The suppression of exciton related emission around 250 nm at 77 K is remarkable. The 0.3 at% Pr doped ceramics show the highest light yield that is 6900 ph/MeV with 1 μs shaping time under the excitation of γ-rays (137Cs). There exists slow components of scintillation process in all the Pr-doped transparent ceramics. Higher doping concentration was found to be beneficial for the suppression of the slow components in the scintillation response and therefore acceleration of the scintillation decay and light yield increase up to certain level. These effects are mainly due to competition of Pr3+ ions with the antisite defects for charge carrier capture in the scintillation process which is also supported by the trends observed in the TSL measurements.
80 show abstract
0022-2313 * * 29815463
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): D.P. Singh, A.K. Misra, A.S. Achalkumar, C.V. Yelamaggad, M. Depriester


In this paper, we present the preparation of nano-soft composites of ZnS and ZnS:Mn2+ quantum dots (QDs) with star shaped hekates mesogens (HMs) derived from tris(N-salicylideneaniline) core. The photophysical studies of the neat HMs and it's composites with QDs have been carried out as a function of temperature. The blue emission of HMs is found to be enhanced and red shifted in the presence of ZnS QDs. An induced yellow emission at 575 nm has been observed in HM-ZnS:Mn2+ QDs composite which is attributed to the 4



T


1


to 6



A


1


transition between the sp electrons of ZnS and d electrons of Mn2+ in the ZnS:Mn2+ QDs. The change in photophysical properties of HMs is analogous to the adscititious electron–proton interactions in hydrogen bonded environment after the dispersion of QDs. The large shift in N-H stretching and induction of a new S-H stretching band at

2734




cm



1



in the composites reveal the occurrence of intermolecular interactions between the HMs and QDs. Moreover, the presence of QDs significantly changes the molecular orientation of the HMs as adduced by polarized optical microscopy. Tunability of the blue emission of HMs due to QDs dispersion depends on the degree of intermolecular interactions in the Guest-Host system. This study depicts its possible applications in the quantum dots based tunable photoluminescent displays.


Graphical abstract





81 show abstract
0022-2313 * * 29815464
Publication date: June 2019

Source: Journal of Luminescence, Volume 210
Author(s): M. Fhoula, M. Dammak


Na2ZnP2O7 pyrophosphates doped with different concentrations of Sm3+ were synthesized successfully via a solid-state reaction process. A vibrational Raman-IR spectroscopic and diffraction analysis has been performed. The Na2ZnP2O7:Sm3+ powders were crystallized in a tetragonal lattice with P42/mnm space group. The photoluminescence (PL) emission and PL excitation (PLE) spectra were studied as a function of Sm3+ concentration. The optimal Sm3+ doping concentration in Na2ZnP2O7 host matrix is determined to be 1 mol%. In order to enhance the luminescent intensity of these phosphors, the compensator charge Li+ and K+ ions were introduced in the Na2ZnP2O7 host. Furthermore, the luminescence of Na2ZnP2O7:Sm3+ indicates good thermal stability at high temperatures. The chromaticity diagram of the Commission International de l′Eclairage (CIE) was investigated, indicating a bright orange-red emission. Hence, the obtained results indicate that the as-prepared phosphor can be a potential candidate for application in Light Emitting Diodes (LEDs).

Graphical abstract






82 show abstract
0022-2313 * * 29815465
Publication date: Available online 21 March 2019

Source: Journal of Luminescence
Author(s): Shono Sakurai, Toshihiro Nakamura



We prepared Ti-doped MgSiF6·6H2O powder through a chemical synthesis method and observed Ti-related near-infrared (NIR) photoluminescence (PL), resulting from the dehydration due to vacuum evacuation. The NIR PL characteristics have unusual features: its emission intensity nonlinearly increases with the excitation laser power and a slow (



1 s) increase of the emission intensity is observed under the continuous irradiation of the excitation laser light. These results indicate that the NIR PL band is activated by a heating effect due to the laser irradiation.

83 show abstract
0022-2313 * * 29815466
Publication date: Available online 20 March 2019

Source: Journal of Luminescence
Author(s): Su Zhang, Lingling Lv, Hongjie Wang, Chongyang Zhu, Ran Pang, Jing Feng, Da Li, Guanyu Liu, Lihong Jiang, Chengyu Li



The 0.8CaWO4-0.2EuMO4 (M = Nb, Ta) solid solution and Eu3+, Ta5+ and Nb5+ single doped CaWO4 were prepared by a high-temperature solid state reaction technique. Experiments show that the addition of Nb5+ and Ta5+ can increase the red luminescence of Eu3+ in CaWO4. In this paper, the composition and structure of solid solution were analyzed by X ray diffraction (XRD), Fourier transform infrared spectrum and Raman spectrum analysis. The luminescence properties of the solid solution were studied by means of stable photoluminescent spectra, diffuse reflectance spectra (DRS), fluorescent decay curves and variable temperature spectra. By combining structural analysis, J-O theoretical calculation and experimental results, we believe that the significant improvement of the emission efficiency comes from the decrease of non-radiation relaxation rate.


Graphical abstract

CaWO4 is an important luminescent material with excellent physical and chemical properties. It is found if CaWO4 and EuMO4 (M = Nb, Ta) form a solid solution with scheelite structure, the emission intensity of Eu3+ will be 2 or 3 times of that in CaWO4. The structure and the luminescent properties are studied deeply.



84 show abstract
0022-2313 * * 29815467
Publication date: Available online 20 March 2019

Source: Journal of Luminescence
Author(s): Nilo F. Cano, T.K. Gundu Rao, Carlos D. Gonzales-Lorenzo, Jorge S. Ayala-Arenas, Shigueo Watanabe



MgCaSi2O6 polycrystal was synthesized by the devitrification method. The dosimetric characteristics by TL of this prepared polycrystal was investigated. This material exhibits TL peaks at 115, 160, 210, 260 and 280 °C. The dosimetric peak occurs at 260 °C with a well defined glow curve structure. This peak shows a linear dose response. Electron paramagnetic resonance (EPR) studies have been carried out to identify the defect centers responsible for the TL peaks. Two defect centers in the region of g = 2.0 are found. One of the centers (center I) with a g factor equal to 2.0085 is identified as O− -ion and relates with the observed high temperature 250 and 300 °C TL peaks. Additional defect centers with g = 2.0012 (center II) and 1.982 (center III) are due to F+-centers (electron trapped at an oxygen vacancy). Center II and III correlate with the TL peaks at 160 °C and 106 °C, respectively.

85 show abstract
0022-2313 * * 29815468
Publication date: Available online 19 March 2019

Source: Journal of Luminescence
Author(s): Prerana K.M. Lokhande, Dinesh S. Patil, Nagaiyan Sekar



Four novel D-π-A extended styryl colorants containing carbazole unit were designed and modified synthetically to evaluate the effect of various acceptors on ICT (intramolecular charge transfer) characteristics and to investigate the effect of incorporation of an additional π-bond along with the assistance of electron withdrawing chlorine group in the conjugation. Dye 4d with rhodanine-3-acetic acid and 4c with 2-(benzothiazol-2-yl) cyanomethylene showed the longer absorption and emission maxima than 4a and 4b in the polar solvents. The studied dyes exhibited positive solvatochromism and large Stokes shift due to twisted geometry. ICT characteristics of dyes were confirmed with the help of different solvent polarity plots to afford the validation of ICT character. The order of ε
max (molar absorption coefficient) was found as, 4c > 4d > 4b > 4a. All the studied dyes demonstrated good fluorescence molecular rotor (FMR) properties. Dyes 4c and 4d showed better sensitivity towards the viscosity with x = 0.33 and x = 0.30 respectively. The experimental and the computational studies were opted to study the NLO (Non-linear optical) characters of the dyes. Smallest band gap in 4c and 4d amongst all the four dyes was evident from the higher values of “linear polarizability (α

0
)”, “first order hyperpolarizability (β) “and “second order hyperpolarizability (γ)”. These dyes have showed better NLO properties than urea. DFT calculations [(B3LYP/6-31 + G(d)] and [CAM-B3LYP/6-31 + G(d)] were employed to understand the structural and electronic behaviour of 4a-4d which also have supported the experimental results. Thus, from the observed results of the solvatochromic and computational method, reported new carbazole styryls were found to be a good candidate of FMR and NLO material.


Graphical abstract






86 show abstract
0022-2313 * * 29815469
Publication date: Available online 19 March 2019

Source: Journal of Luminescence
Author(s): Lu Yao, Yongjin Li, Dekang Xu, Hao Lin, Yan Peng, Shenghong Yang, Yueli Zhang



Lanthanide luminescence nano-thermometers, with great potential applications in photo-thermal therapy for temperature detecting and controlling, have aroused wide interest recently. Enhancing the sensitivity and accuracy of temperature sensing property of those nano-thermometers are of great importance. In the present paper, NaGdF4 upconversion nanoparticles with high doping Bi ions concentration were investigated. With as high as 60% Bi ions doping concentration, no impurity phase was observed in the products and no morphological change occurred. Enhanced upconversion luminescence and thermal sensing properties were obtained, due to the tailoring of crystal field and increasing asymmetry of host matrix. Judd-Ofelt calculation was performed to testify the increasing lattice asymmetry, which was consistent with experimental results. This work provides guidance of tuning thermal-sensing properties of optical nano-thermometer, which are of great significance in bio-sensing field.


Graphical abstract

By doping 60% Bi ions into β-NaGdF4: Yb, Er UCNPs,

Δ
E

is enhanced and hence the thermal sensitivity.



87 show abstract
0022-2313 * * 29815470
Publication date: Available online 19 March 2019

Source: Journal of Luminescence
Author(s): M. Malinowski, M. Kaczkan



Optical absorption, excitation and emission spectra of Eu3+ ions in stoichiometric KEu(PO3)4 and KEuxY1-x(PO3)4 crystals were investigated. Strong, red emissions of Eu3+ centered at 617 and 700 nm originates mainly from the 5D0 →7F2+7F4 transitions respectively. Judd-Ofelt intensity parameters for f-f transitions were derived from the emission spectra and also from the integrated absorption spectra. These parameters were used to calculate the radiative transition rates (AR), lifetimes (τR) and branching ratios β for 5D0 excited state of Eu3+. The calculated values of τR and β were compared with the measured values for 5D0 level. The 5D0 fluorescence decay time in pure KEu(PO3)4 was exponential and quite long, of 3.93 ms. The stimulated emission cross-sections σ were also evaluated for the 5D0 → 7FJ transitions for the first time in this system.

88 show abstract
0022-2313 * * 29815471
Publication date: Available online 16 March 2019

Source: Journal of Luminescence
Author(s): P. Manasa, T. Srihari, Ch Basavapoornima, A.S. Joshi, C.K. Jayasankar



Nb2O5 phosphate glasses (PNbKA: P2O5+Nb2O5+K2O + Al2O3) doped with different Nd3+ concentrations employed via melt-quenching method and their physical, thermal and spectroscopic properties were investigated. The Judd-Ofelt (JO) intensity parameters (Ωλ, λ = 2,4 and 6) and radiative properties have been evaluated for 1.0 mol % Nd3+ (PNbKANd1.0) absorption spectrum. Strong NIR emission has been observed for the 4F3/2 → 4I11/2 transition at 1.056 μm for PNbKANd glasses by the λ
exc of 808 nm laser. Lifetime for PNbKANd1.0 glass was found to be relatively quite longer (240 μs) for the 4F3/2 level of Nd3+ ion. The stimulated emission cross-section, quantum efficiency, gain bandwidth, figure of merit and saturation intensity have been found to be 3.69 × 10−20 cm2, 88.56 × 10−25 cm2s, 88%, 0.99 × 10−27 cm3 and 2.12 × 108 W/m2, respectively, for PNbKANd1.0 glass. The results specifies that the PNbKANd1.0 glass might be useful for laser gain media at 1.056 μm region.


Graphical abstract






89 show abstract
0022-2313 * * 29815472
Publication date: Available online 9 March 2019

Source: Journal of Luminescence
Author(s): Arnab Kumar Dey, Bibek Samanta, Preetam Bhaumik, Sumanta Manna, Anupam Halder, Tamal Kanti Ghosh, Tapan Kumar Paria, Uttam Kumar Ghorai



In white LED fabrication, an appropriate combination of blue LED with yellow phosphor is the most convenient technique till date. But, deficiency in yellow emission with sufficient red counterpart of the phosphor is the main difficulty in this technique. Herein we report Yb3+/Ho3+ co-doped BaWO4 nanophosphor with a significant thermal and chemical stability synthesized by a low-temperature hydrothermal process with red (655 nm) and green (538 nm) double color up-conversion (UC) under 980 nm near-infrared (NIR) excitation, resulting in yellow emission. The synthesized samples were characterized by X-Ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), UV–Vis–NIR Spectroscopy and Transmission Electron Microscopy (TEM) techniques. The dependence of emission behavior on various concentrations of activator ion (Ho3+) in BaWO4: Yb3+:Ho3+ phosphors were studied in detail. Temperature dependent emission spectra revealed that the phosphor possesses stable emission up to 200 °C and luminescence intensity drop of only 11.5% of the initial luminescence intensity was observed at 150 °C. Therefore, the luminescence behavior and the temperature stability of the phosphor suggest an effective pathway in the optoelectronic application, especially in LED fabrication.


Graphical abstract






90 show abstract
0022-2313 * * 29815473
Publication date: Available online 6 March 2019

Source: Journal of Luminescence
Author(s): Jong Won Chung, Jin Young Park, Hyun Kyoung Yang



Hexagonal crystal structured NaBiF4:Eu3+ nanophosphors have successfully been synthesized by an ultra-fast approach at various concentrations of NH4F. The crystal structure, grain size, morphology, and luminescence properties were analyzed with the aid of X-ray diffraction, field-emission scanning electron microscopy, and photoluminescence measurements. The experimental results showed that the concentration of NH4F is crucial in controlling the crystal structure, morphology, and luminescence properties. It exhibited the pure hexagonal structure and uniform morphology when the concentration of NH4F was above 0.05 mol. For the emission spectra, NaBiF4:Eu3+ nanophosphors exhibited the highest intensities at 615 nm by 5D0 → 7F2 transitions of Eu3+ ion. The calculated CIE coordinates were shifted to the yellow region when the concentration of NH4F increased. These results hint that the NaBiF4:Eu3+ nanophosphors may be good candidates for their potential use in the fabrication of WLEDs.


Graphical abstract






91 show abstract
0022-2313 * * 29815474
Publication date: Available online 5 March 2019

Source: Journal of Luminescence
Author(s): Hyung-Joo Lee, Hong-Gun Kim, Lee-Ku Kwac



The effects of using a rough GaP layer to improve the light efficiency of 860-nm GaAs vertical-cavity surface-emitting laser were investigated. The light efficiency was significant increased by enlargement of current flow path caused from use of GaP layer grown on the top distributed Bragg reflector (DBR) of VCSEL. Furthermore, it was found that improved light efficiency significantly could be further increased by optimizing the surface morphology of the p-GaP layer fabricated in limited surface lighting area of VCSEL. Various surface morphologies could be obtained easily by controlling the RF power of an ICP dry etching. The highest output power of 34 mW was obtained from the VCSEL with a rough GaP layer fabricated at a RF power of 40 W introduced with BCl3 gas, showing a noticeable increase of ∼113% than a conventional one (16 mW). This result clearly insists that light efficiency of 860-nm GaAs based VCSEL could be increased effectively by using the rough GaP layer.

92 show abstract
0022-2313 * * 29815475
Publication date: Available online 4 March 2019

Source: Journal of Luminescence
Author(s): Cole Grinnell, Alexander Samokhvalov


We report, for the first time, an experimental study of interaction of metal-organic framework (MOF) with dimethyl sulfoxide (DMSO). Adsorption of DMSO on aluminum MOF Basolite A100 results in formation of the stoichiometric complex [A100]2[DMSO]3. The solid-state synchronous fluorescence spectroscopy allows observation of the following major excitation/emission transitions in Basolite A100 and its adsorption complex [A100]2[DMSO]3 which are not well-resolved in “conventional” fluorescence spectra: 1) narrow resonance of the isolated BDC linker, 2) excitation across optical bandgap, and 3) excimers. In the adsorption complex [A100]2[DMSO]3, the DMSO molecules interact with the μ2-OH group of Basolite A100 and with its BDC linker through the π-π system. We present, for the first time, the new variety of the solid-state synchronous fluorescence spectroscopy, which we denote as the solid-state enhanced-resolution synchronous fluorescence (excitation) spectroscopy. The accurate measurements of small changes in the optical bandgap of the adsorption complex [A100]2[DMSO]3 and Basolite A100 are described by the solid-state enhanced-resolution synchronous fluorescence (excitation) spectroscopy.
93 show abstract
0022-2313 * * 29815476
Publication date: Available online 3 March 2019

Source: Journal of Luminescence
Author(s): Volker Lorenz, Phil Liebing, Markus Suta, Felix Engelhardt, Liane Hilfert, Sabine Busse, Sida Wang, Claudia Wickleder, Frank T. Edelmann



The synthesis and structural characterization of 1,7-bis(4-triphenylsiloxy-3-methoxy-phenyl)-1,6-heptadiene-3,5-dione (1 = Ph3SiCurcH) and 1,7-bis(4-methoxycarbonyloxy-3-methoxy-phenyl)-1,6-heptadiene-3,5-dione (2 = MeOC(O)CurcH) are reported. Compound 1 represents the first metal-organic curcumin derivative. The complexation of 1 and 2 with Cu2+ has been studied. The new copper(II) complexes (Ph3SiCurc)2Cu (3) and [MeOC(O)Curc]2Cu·4MeCN (4) have been prepared and their crystal structures determined by single-crystal X-ray diffraction. Moreover, the optical properties of the solid compound 1 have been investigated in detail. The emission spectrum shows a vibronic fine structure that has been analysed in terms of Franck-Condon factors. The excitation spectrum is broad and structureless and may be interpreted in terms of an interband transition as also confirmed by diffuse reflectance spectra. Due to the weak intermolecular interactions, an isolated molecular picture is used instead for the assignment of the transitions, which are thus characterized as S1 ↔ S0 or π* ↔ π fluorescent transitions. Despite the electric-dipole allowed nature of the transition, the quantum yield is Φ = (2.4 ± 0.3)% in agreement with other findings on curcumin derivatives.

94 show abstract
0022-2313 * * 29815477
Publication date: Available online 2 March 2019

Source: Journal of Luminescence
Author(s): Nichakan Miengmern, Amonchat Koonwong, Suwannee Sriyab, Anwaraporn Suramitr, Rungtiva P. Poo-arporn, Supa Hannongbua, Songwut Suramitr


The Schiff base of N,N′-Bis(Salicylidene)-p-Phenylenediamine (BSP) has been synthesized and characterized. The molecular structure and spectroscopic properties of the compound were experimentally characterized by elemental analysis, 1H NMR, FT-IR, UV–Visible, fluorescent spectroscopic techniques, and computationally by the density functional theory (DFT) method. The appearance of photophysical properties can be ascribed to the efficiency of the excited-state intramolecular proton transfer (ESIPT) and the twisted intramolecular charge transfer (TICT) process. Their fluorescence emission performance in solution and aggregation state showed that the compound had obvious aggregation-induced emission enhancement (AIEE) characteristics, upon addition of water in acetonitrile (80:20, v/v) solution; the quantum yield (ΦF) is increased by 0.001–0.152. Furthermore, due to the good luminescent properties, high quantum yield and the large Stokes shifts, the compound was an ideal candidate for promising applications in metal ion sensing of Cu2+ ions.

Graphical abstract






95 show abstract
0022-2313 * * 29815478
Publication date: Available online 2 March 2019

Source: Journal of Luminescence
Author(s): N.O. Braga, D.G.S.M. Cavalcante, A.S. Gomes, E. Yoshihara, R.F. Bianchi, A.E. Job


This paper reports an interesting strategy of incorporating a photodegradable polymeric luminophore, the poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] - OC10C6-PPV (MEH-PPV), in an inert natural rubber (Hevea brasiliensisis) - C5H8 (NR) matrix for monitoring and recording the radiation dose administered to patients under phototherapy, particularly in the treatment for jaundice newborns. A time-trend spectrofluorimetric study has been carried out to characterize the luminescent changes of the MEH-PPV/NR luminophore system upon photodegradation by realistic conditions of phototherapy treatment, and the dependence between color and dose was used to determine the dose-response relationships of this color film dosimeter. Cytotoxicity tests (CHO-K1 cell line) have also been conducted on extracts of the OC10C6-PPV/C5H8 before and after photolysis. The experimental results reported here highlight the potential application of photodegradable polymer/natural rubber as a biocompatible skin-mountable patch to monitor light exposure to improve patient care in phototherapy, photodynamic, lasers and radiation therapies.

Graphical abstract






96 show abstract
0022-2313 * * 29815479
Publication date: Available online 1 March 2019

Source: Journal of Luminescence
Author(s): Lijun Gao, Cong Li, Chongzhou Wang, Jing Cui, Liming Zhou, Shaoming Fang



The rare earth complex (Eu(PBA)3) with the active functional group (OH) was prepared by p-hydroxybenzoic acid (PBA) and europium chloride in the ethanol solution. Then, the photoluminescence polyurethane (Eu(PBA)3/PU) materials were synthesized by the reaction of the functional groups on the complex with the isocyanates in the polyurethane reaction system. The content of the complex has great influence on photoluminescence performances of Eu(PBA)3/PU materials. The fluorescence intensity increases with the increase of Eu(PBA)3 content. Especially, the obtained Eu(PBA)3/PU materials possess good fluorescence emission purity and a long luminescence lifetime, which have potential applications in optical display instruments.

97 show abstract
0022-2313 * * 29815480
Publication date: Available online 28 February 2019

Source: Journal of Luminescence
Author(s): Dinesh Maity, Abhishek Mukherjee, Sushil Kumar Mandal, Partha Roy


An electron pushing group has been introduced to a Schiff-base compound, 2-((2-(quinolin-2-yl)hydrazono)methyl)phenol (HQP) to get another Schiff-base molecule, namely, 4-methyl-2-((2-(quinolin-2-yl)hydrazono)methyl)phenol (HMQP), to modulate the Zn2+ sensing properties of the probe. HQP and HMQP have been synthesized by Schiff-base condensation between 2-hydrazinylquinoline and the respective aldehyde in 1:1 ratio and characterized by standard methods. Both the compounds show their Zn2+ sensing ability but to different extents. The fluorescence intensity of HQP at ~490 nm (λex = 410 nm) increases by about 4.5 folds in the presence of one equivalent of Zn2+ ion. However, the fluorescence intensity is enhanced by around 30 folds in the presence of one equivalent of Zn2+ in case of HMQP. The fluorescence peak of HMQP at 502 nm (λex = 420 nm) is shifted to 515 nm in the presence of Zn2+ whereas same type of shifting for HQP is found to be negligible. Some theoretical calculations have been performed to look into the spectral transitions of HMQP. Fluorescence intensity enhancement is explained by PET mechanism. Limit of detection (LOD) value for HMQP has been determined to be 220.6 nM, showing its good sensitivity towards zinc. The color change of HMQP under visible light is not conclusive in the presence of different metal ions, but only Zn2+ can induce green coloration to HMQP solution under UV light, thus indicating the possibility of naked eye detection by the analyte. HMQP with one equivalent of Zn2+ displays high fluorescence intensity in the pH range of 7.0–9.0 indicating its suitability towards biological applications. The probe has been utilized to live cell imaging studies using C6 cells.

Graphical abstract

Fluorescence intensity of 4-methyl-2-((2-(quinolin-2-yl)hydrazono)methyl)phenol increases hugely in the presence of Zn2+ than that of 2-((2-(quinolin-2-yl)hydrazono)methyl)phenol, which differs by a methyl group.



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Impact factor: 2.732
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