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As an excellent host material, rare earth-doped glasses have gotten extensive attention. Herein, a novel Eu3+-doped P2O5-Gd2O3-Ga2O3-NaF-ZnO glasses with excellent optical properties have been prepared. The structure and spectroscopic features of title glasses showed that the densities of glasses increased monotonically with an increase in Eu2O3 contents, and these glasses were made up of metaphosphate, pyrophosphate, and orthophosphate units. From the resultant spectra, five emission peaks were clearly found in the emission spectra of Eu3+-doped glasses excited at 392 nm light, and the intensity of the emission spectra exhibited a trend of growing initially and then declining. The glass doped with 2 mol.% Eu2O3 had the highest emission intensity, the luminescence intensity at 150 °C remained at 80.57% of the initial intensity at 27 °C, and the CIE and lifetime were (0.6480, 0.3412) and 2.16 ms, respectively. The excellent optical properties suggest that this phosphate glass has potential application in display devices. [ABSTRACT FROM AUTHOR]

Y1.94MAl4SiO12:0.06Ce3+ (M = Ba, Sr, Ca, Mg) phosphors were successfully prepared through a classic solid‐state reaction method. The crystal structures, photoluminescence spectra, quantum yields, and thermal stabilities of the phosphors were investigated in detail. The results indicate that all Y1.94MAl4SiO12:0.06Ce3+ phosphors maintain the crystal structure of garnets. The emission peaks of Y1.94MAl4SiO12:0.06Ce3+ (M = Ba, Sr, Ca, Mg) phosphors are located at 537, 538, 554, and 565 nm, respectively. A red‐shift trend of emission peak is observed with decreasing M radius, which can be ascribed to the increase in the crystal‐field splitting in the Ce3+ 5d level owing to the co‐doping of M2+−Si4+. Under 460 nm excitation, the luminescence quantum yields and thermal stabilities of the Y1.94MAl4SiO12:0.06Ce3+ phosphors decreased with the decrease of M radius. The IQE of the Y1.94BaAl4SiO12:0.06Ce3+ phosphor is 92.89%, and the resistance to thermal quenching is improved to be 93.32% at 150°C. In addition, the color shifts of Y1.94MAl4SiO12: 0.06Ce3+ phosphors with increasing temperature are all tiny, which also demonstrates good resistance to thermal quenching of luminescence. The linear shrinkage of Y1.94MAl4SiO12:0.06Ce3+ phosphors is significantly improved compared with that of YAG: Ce3+, which is expected to generate Y1.94MAl4SiO12:0.06Ce3+ transparent/translucent ceramics and fabricate high‐powder w‐LEDs for high‐quality solid‐state lighting in the future. [ABSTRACT FROM AUTHOR]

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 Gd 2 Ce 2 O 7 : 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 Gd 2 Ce 2 O 7 host. Furthermore, potential temperature sensing properties are also evaluated according to the fluorescence intensity ratio of 2H 11/2 and 4S 3/2 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. [ABSTRACT FROM AUTHOR]

The poor thermal stability of current commercial white light emitting diodes (WLED) fabricated using a blue chip, a yellow YAG:Ce 3+ phosphor (YAG) and resins, restricts their application in fields where long service time and high power lighting systems are required. Incorporating YAG into glass offers a possible way to resolve the problem by removing the organic resins in LED encapsulation. In the present study, YAG glass-ceramics with bismuth borate glass matrices were prepared using a rapid melt quenching technique. The YAG erosion mechanism was investigated for the first time in various glass matrix compositions at different co-sintering temperatures. The results demonstrate that neither B 2 O 3 nor Bi 2 O 3 individually erodes YAG particles, but the mixtures of B 2 O 3 and Bi 2 O 3 binary glass systems react with YAG and dissolve it almost completely or generate YAl 3 (BO 3 ) 4 (abbreviated as YAB), and they even erode as-produced YAB again under certain conditions. The production of YAB particles increases with the increase of the n Bi /n B ratio at a lower temperature (680 °C), while it first increases and then decreases at a higher temperature (800 °C). The maximum production of YAB can be obtained at the co-sintering temperature of 680 °C with an n Bi /n B ratio of 55:45 or at 760 °C with an n Bi /n B ratio of 35:65. The intermediate Bi 4 B 2 O 9 phase is found during the transformation of YAG into YAB. A simple but efficient approach is proposed to prevent YAG erosion and increase the luminous properties of YAG glass ceramics to a great extent by simply adding Ca 2+ into bismuth borate glass matrices. The degree of YAG erosion decreases with increasing Ca 2+ concentration until an impurity phase appears when the Ca 2+ concentration exceeds 20 mol%. The combination of good white light emission and suitable quantum efficiency as well as higher thermal stability makes the as-prepared YAG glass-ceramics equipped with a blue chip a possible alternative to commercial WLED. [ABSTRACT FROM AUTHOR]