To investigate the modification effect of the B2O3 component on tellurite glass, a series of glasses with a composition of xB2O3-(80-x)TeO2-10ZnO-10Na2O (x=0, 10, 20, 30, 40, 50, 60, 70, 80) and an additional amount of 0.5% Er2O3 (in molar) were prepared. The refractive index, the absorption edge of the host, the J-O parameters of Er3+, the fluorescent decay time, the bandwidth, and the quantum efficiency for the 4I13/2→4I15/2 transition were obtained theoretically and experimentally. These results indicated that the introduction of B2O3 modified the performance of the tellurite glass. For example, with increasing content of B2O3, the refractive index of the host decreases from 1.9 to 1.5, the absorption edge of the host shifted toward the blue regime, the intensity parameter Ω6 changed from 1.08×10-20 (for the pure tellurite glass) to 1.98×10-20 cm2 (for the pure borate glass), the bandwidth of the 4I13/2→4I15/2 transition increased, and the quantum efficiency of the 4I13/2→4I15/2 transition decreased.
Eu3+-doped Gd2Mo3O9 was prepared by solid-state reaction method using Na2CO3 as flux and characterized by powder X-ray diffractometry. According to X-ray diffraction, this material belonged to a tetragonal system with space group I41/a. The effects of flux content and sintering temperature on the luminescent properties were investigated with the emission and excitation spectra. The results showed that flux content and sintering temperature had effects on the luminescent properties, the optimized flux content and the best temperature was 3% and 800 ℃, respectively. The excitation and emission spectra also showed that this phosphor could be effectively excited by C-T band (280 nm), ultraviolet light 395 nm and blue light 465 nm. The wavelengths at 395 and 465 nm were nicely fitting in with the widely applied output wavelengths of ultraviolet or blue LED chips. Integrated emission intensity of Gd2Mo3O9∶Eu was twice higher than that of Y2O2S∶Eu3+ under 395 nm excitation. The Eu3+ doped Gd2Mo3O9 phosphor may be a better candidate in solid-state lighting applications.
A novel red emitting phosphor Gd2(MoO4)3:Eu3+ was prepared by solid reaction, using Gd2O3, Eu2O3 and WO3 as starting materi- als and NH4F as flux. The effects of flux content and Eu3+ concentration on the crystal structure, morphology and luminescent properties were investigated using XRD, SEM and fluorescent spectrum measurement. The XRD patterns showed that the resultants had the monoclinic structure. With the increase in flux amount, their crystallization significantly improved. The SEM images indicated that the mean size of the phosphor particles was around 2 μm, and agglomeration of the phosphor particles appeared while introducing higher flux amount. The exci- tation spectra exhibited more intense f-f transitions originating from ground state 7F0 to upper states 5L6 and 5D2 than the charge transfer band. The concentration quenching of Eu3+ emission indicated that energy transfer from Eu3+ to molybdate host existed even at lower Eu3+ concen- tration.
