Photoluminescence properties of Tb-doped and (Zn,Tb) co-doped barium strontium titanate crystalline powders

Tb-doped and (Zn,Tb)-codoped Ba0.75Sr0.25TiO3 (BST) crystalline powders were prepared via a sol-gel process. Photoluminescence spectra of the samples were recorded at room temperature. When excited by 320 nm ultraviolet light, several emission peaks were detected, including four characteristic emission peaks of Tb3+ located at 488 nm, 543 nm, 589 nm and 624 nm. Further research indicates that the various Tb3+ doping concentrations range from 1 to 2 at. % can result in the different intensities of emission peaks depending on their positions. The intensities of emission peaks at 488 nm and 624 nm decrease with increasing the concentration of Tb3+, while the intensity of the peak at 543 nm has a relatively slow response to the variation of Tb3+ concentration. The concentration quenching phenomena were observed in all the emission peaks, and the quenching concentration of Tb is different depending on the peak position. In addition, PL emission peak intensities are enhanced by (Zn,Tb)-codoping, which is understood by a charge compensation mechanism of defects. According to CIE coordinates, green-emitting phosphors based on BST crystalline powders were obtained. The experimental results imply a potential green light application of Tb-doped and (Zn,Tb)-codoped BST materials.