Synthesis and photoluminescence enhancement of the LiLa(MoO ₄ ) ₂ :Sm ³⁺ red phosphors by co‐doping with Bi ³⁺

The LiLa(MoO4 )2 :Sm3+ and LiLa(MoO4 )2 :Sm3+ ,Bi3+ phosphors were prepared using the citric-acid-fueled combustion method and the influence of concentrations of Bi3+ dopant on LiLa(MoO4 )2 :Sm3+ red luminescence was investigated. The LiLa(MoO4 )2 :Sm3+ and LiLa(MoO4 )2 :Sm3+ ,Bi3+ samples matched well with the scheelite structure and I41 /a space group and did not detect structural changes. Under an excitation of 403 nm, the prepared LiLa(MoO4 )2 :Sm3+ ,Bi3+ phosphor was excited and produced orange-red emission. When compared with the LiLa(MoO4 )2 :Sm3+ phosphor, the LiLa(MoO4 )2 :Sm3+ ,Bi3+ phosphor exhibited enhanced fluorescence intensity because the Bi3+ dopant ions are doped as a sensitizer. The optimal doping concentrations of Sm3+ and Bi3+ were 5 and 1 mol%, respectively. Furthermore, the energy transfer from Bi3+ to Sm3+ is effective (3 P1 → 4 K11/2 ). Subsequently, the electrons in an unstable excited state were transferred to a stable ground state (4 G5/2 → 6 H5/2 , 6 H7/2 , 6 H9/2 ). The Commission Internationale de L'Eclairage (CIE) chromaticity coordinates of the optimized LiLa(MoO4 )2 :Sm3+ ,Bi3+ phosphor were situated in the orange-red region. The luminescence of the LiLa(MoO4 )2 :Sm3+ ,Bi3+ phosphor generated under near-ultraviolet (UV) irradiation could be used to produce a warm white light, indicating its possible applications in white light-emitting diodes.