Synthesis and Sm2+/Sm3+ doping effects on photoluminescence properties of Sr4Al14O25

Complete and partial samarium reduction was achieved under strong reducing atmosphere by solid-state and combustion synthesis of Sr3.96Sm0.04Al14O25. Dependence of different fluxing agents on the formation of various strontium aluminates was examined. The samples were investigated by X-ray powder diffraction, temperature dependent luminescence decay and photoluminescence measurements. Excitation with UV radiation resulted in sharp and well resolved emission lines of samarium ions. Distinct temperature behavior for Sm2+ and Sm3+ were detected in the range of 100–500 K. Estimated emission thermal quenching values (TQ1/2) for divalent samarium were approximately 270 K while for trivalent state around 660 K. Measured luminescence decay values of Sm2+ are substantially lower than for Sm3+,≈1.7 and ≈2.7 ms, respectively. The spectral feature of Sm2+ emission spectrum indicates that dopant occupies low symmetry site in Sr4Al14O25 compound.