Photoluminescence properties of CaBi2Ta2O9:RE3+ (RE=Sm, Tb, and Tm) phosphors

Sm3+, Tb3+, and Tm3+ doped CaBi2Ta2O9 (CBTO) with the layered perovskite structure were synthesized by the solid-state reaction method. The photoluminescence properties, structure, morphology and color coordinates of the phosphors were explored in detail. CBTO:RE3+ (RE=Sm, Tb, and Tm) can emit light of three colors, reddish orange, green and blue. Under near ultraviolet (NUV) excitation, CBTO:Sm3+ show an intense reddish orange emission transition of 4 G5/2→6H7/2 at 602 nm, the novel green emission of CBTO:Tb3+ and blue emission of CBTO:Tm3+ peak at 544 and 458 nm. The study provides a comprehensive understanding of the variation in the luminescent properties of CBTO with doping concentration, and the mechanism of concentration quenching in CBTO:Sm3+ phosphors is revealed, and the critical distance of CBTO:Sm3+ is calculated to be 2.72 nm. CBTO:RE3+ (RE=Sm, Tb, and Tm) with NUV LED chip can realize white light.