Bi3+ photoluminescence in Y1-xBixCa3(GaO)3(BO3)4 and energy transfer to Eu3+ and Tb3+ in co-doped phosphors.

Abstract

Bi3+ possesses outer shell lone pair electrons, and, thus the so-involved photoluminescence (PL) is sensitive to the surrounding coordination. Besides, the similarity in the structural chemistry between Bi3+ and rare earth (RE) ions inspires us to investigate the Bi3+-PL performance in RE3+-containing hosts. Herein, Y1-xBixCa3(GaO)3(BO3)4 (0.01 ≤ x ≤ 0.15) compounds were prepared by a high temperature solid state reaction method. The successful cationic doping and phase purity were confirmed by powder X-ray diffraction analysis. This series of phosphors exhibit the very strong absorption of Bi3+ 1S0 → 3P1 at 272 nm along with the intense blue emission with a maximum at 399 nm and a full width at half maximum (FWHM) of 59 nm. They retained 78.86% of the emission intensity at 150 °C, with reference to that at room temperature. Moreover, Bi3+ could also behave as a sensitizer to enhance the emission efficiency of RE3+ and thus to realize color-tunable phosphors. The energy transfer was proved in the co-doped phosphors Y0.95-yBi0.05EuyCa3(GaO)3(BO3)4 (0.05 ≤ y ≤ 0.6) and Y0.95-zBi0.05TbzCa3(GaO)3(BO3)4 (0.05 ≤ z ≤ 0.6), and color-tunable emissions from blue to red, or from blue to green were realized in these two series of phosphors.