Effect of RE3+ electronegativities on luminescence property of Ba5Si8O21:Eu2+ persistent phosphor

A series of Ba5Si8O21: 0.02Eu(2+),0.09RE(3+) persistent phosphors were synthesized by the solid-state reaction method. The measurement results of photoluminescence (PL), phosphorescence and thermoluminescence (TL) were analysed and discussed. The XRD results showed that samples codoped with different RE3+ were Ba5Si8O21 single pure phase. Under the excitation, all samples exhibited a broad Eu2+ characteristic emission, and the La3+ co-doped sample emitted the brightest photoluminescence even though its persistent luminescence property was the worst because of the weakest electronegativity. However, Nd3+ electronegativity was suitable, thus after activation, the Ba5Si8O21:Eu2+,Nd3+ sample had the best persistent luminescence performance with the highest phosphorescence intensity and the persistent luminescence decay time beyond 8 h. The Nd3+ co-doped sample also had the largest thermoluminescence integral area which proved effectively it had longer persistent luminescence time. The luminescence mechanism was also proposed to study the photoluminescence and persistent luminescence process. These results showed that RE3+ electronegativities were distinctly important for persistent phosphors and choosing suitable electronegativity codopant was conducive to enhancing the phosphorescent performance.