Thermally stable photoluminescence and long persistent luminescence of Ca₃Ga₄O₉:Tb³⁺/Zn²⁺

A green long persistent luminescence (LPL) phosphor Ca₃Ga₄O₉:Tb³⁺/Zn²⁺ was prepared. Ca₃Ga₄O₉ matrix exhibits blue self-activated LPL due to the creation of intrinsic traps. When Tb³⁺ is doped, the photoluminescence (PL) and LPL colors change from blue to green with their intensities significantly enhanced. The doping of Zn²⁺ evidently improves the PL and LPL performances of the Ca₃Ga₄O₉ matrix and Ca₃Ga₄O₉:Tb³⁺. The thermoluminescence (TL) spectra show that a successive trap distribution is formed by multiple intrinsic traps with different depths in the Ca₃Ga₄O₉ matrix, and the incorporation of Tb³⁺ and Zn²⁺ effectively increases the densities of these intrinsic traps. The existence of a successive trap distribution makes the Ca₃Ga₄O₉:Tb³⁺/Zn²⁺ phosphor exhibit thermally stable PL and LPL. It is indicated that this phosphor shows great promise for the application such as high-temperature LPL phosphor.