Enhanced photoluminescent properties and crystalline morphology of LiBaPo₄: Tm³⁺ phosphor through microwave sintering method

An investigation of the photoluminescent properties and crystalline morphology of blue emitting LiBa_1-xPO4:xTm³⁺ phosphors with various concentrations (x = 0.005-0.030) of Tm³⁺ ions were synthesized by microwave sintering. For comparison, the LiBa_1-xPO4:xTm³⁺ powders sintered at the same sintering condition but in a conventional furnace were also investigated. LiBaPO₄ without second phase was formed no matter which furnace was used. More uniform grain size distributions are obtained by microwave sintering. When the concentration of Tm³⁺ ion was x = 0.015, the luminescence intensity reached a maximum value, and then decreased with the increases of the Tm³⁺ concentration due to concentration quenching effect. The microwave sintering significantly enhanced the emission intensity of LiBa_1-xPO4:xTm³⁺ phosphors. Additionally, the d-d interaction is the key mechanism of concentration quenching for LiBaPO₄:Tm³⁺. The chromaticity (x, y) for all LiBa_1-xPO4:xTm³⁺ phosphors are located at (0.16, 0.05), which will be classified as a blue region.