LiM(M=Ca,Sr,Ba)BO_3∶Tb~(3+)材料光谱特性研究

采用固相法制备了绿色LiM(M=Ca,Sr,Ba)BO3:Tb3+发光材料.测量结果显示材料均可被紫外(350～410 nm)光激发,发射绿光.研究了Tb3+浓度对材料发射光谱的影响,结果显示,随Tb3+浓度的增大,发射光谱峰位未发生变化,但其强度呈现出先增大后减小的趋势,即:存在浓度猝灭效应.加入电荷补偿剂Li+,Na+和K+提高了LiM(M=Ca,Sr,Ba)BO3:Tb抖材料的发射强度.

Spectra Characteristics of LiM(M=Ca,Sr,Ba)BO3:Tb3+ Phosphor

LiM(M=Ca, Sr, Ba)BO3∶Tb3+ phosphors were synthesized by solid state reaction. The starting materials CaCO3, SrCO3, BaCO3, H3BO3, Li2CO3, Na2CO3, K2CO3 and Tb4O7 (99.99% in mass) in appropriate stoichiometric ratio were mixed in the alumina crucible, then the mixed powders were calcined at 700 ℃ for 2 h, and LiCaBO3∶Tb3+, LiSrBO3∶Tb3+ and LiBaBO3∶Tb3+ phosphors were obtained. The emission and excitation spectra were measured by a Shimadzu RF-540 ultraviolet spectrophotometer. All the photoluminescence properties of these phosphors were measured at room temperature. The emission spectra of LiM(M=Ca, Sr, Ba)BO3∶Tb3+ phosphors show several bands, and the main emission peaks correspond to the 5D4→7F6(486, 486, 488 nm), 5D4→7F5(544, 544, 544 nm), 5D4→7F4(590, 595, 593 nm) and 5D4→7F3(620, 620, 616 nm) typical transitions of Tb3+, and the typical transitions of Tb3+ happens to split because of the effects of LiM(M=Ca, Sr, Ba)BO3 crystals field. The excitation spectra for the 544 nm green emission of LiM(M=Ca, Sr, Ba)BO3∶Tb3+ phosphors illuminate that these kinds of phosphors can be effectively excited by ultraviolet (350-410 nm) light, and emit green light, therefore, they are promising phosphors for white light emitting diodes. Effects of activation and charge compensation on the luminescence intensities of LiM(M=Ca, Sr, Ba)BO3∶Tb3+ phosphors were studied, and the results show that the intensities were obviously effected.