Synthesis and luminescence enhancement of CaLa0.6(MoO4)1.9:Eu3+ red-emitting phosphors by Bi3+ doping for white LEDs

A series of novel CaLax(MoO4)1.5x+1:Eu3+ and CaLa0.6(MoO4)1.9:Eu3+,Bi3+ phosphors were synthesized through the combustion method. This study investigated the morphology, phase structure, and photoluminescence properties. All the as-prepared samples have a tetragonal structure and compatible with standard CaMoO4, belonging to the I41/a space group. The CaLa0.6(MoO4)1.9:Eu3+ (hereafter referred to as CLMO:Eu3+) phosphor possessed the strongest red emission intensity within CaLax(MoO4)1.5x+1:Eu3+ phosphors under the 393 ​nm near-ultraviolet light excited. Furthermore, the CLMO:Eu3+ phosphor showed the highest emission peak at 618 ​nm among emission peaks, which was attributed to the 5D0→7F2 transition of Eu3+. When Eu3+ was doped with 13 ​mol%, the synthesized sample had strongest red emission intensity. Moreover, Bi3+ was added into the CLMO:13%Eu3+ phosphor to improve the red color emission intensity due to the sensitization of Bi3+ to Eu3+, the maximum luminescence intensity was reached when the Bi3+ concentration was 4 ​mol%. The color purity of CLMO:13%Eu3+,4%Bi3+ phosphor reached 94.3% the emission intensity at 150 ​°C was 73.3% of that at 25 ​°C, and the activation energy of thermal quenching was 0.27 ​eV. All results indicated that the prepared phosphors could be applied as a potential red component of the w-LEDs excited by near-ultraviolet InGaN chips.