Effects of synthesis methods and different concentrations of Eu3+ ions on the emission properties of Sr2 SiO4 phosphors

Abstract

Sr_2-x SiO₄ -xEu (x = 0.01, 0.02, 0.035, and 0.05) phosphors were synthesized at 1000-1,300°C for 2 h in two different processes, the solid-state reaction (SSR) method and a two-step (TS) method, and these results revealed three important findings. The secondary Sr₃ SiO₅ phase was observed in 1,300° C-TS-synthesized Sr_2-x SiO₄ -xEu powder, but no raw materials or secondary phases were observed in the SSR-prepared Sr_2-x SiO₄ -xEu powders. The concentration quenching effect of Eu³⁺ ions was really observed in TS-prepared Sr_2-x SiO₄ -xEu phosphors, which was not observed in SSR-prepared Sr_2-x SiO₄ -xEu phosphors. High emission intensity of charge transition state (CT) band was observed in the photoluminescence excitation spectra, for that the 265 and 393 nm were used as the excitation wavelengths of Sr_2-x SiO₄ -xEu phosphors. Sr_2-x SiO₄ -xEu phosphors under different synthesis processes and excitation wavelengths would have different main emission peaks in the photoluminescence emission spectra. In this study, we also well discussed and explored the relationships of photoluminescence properties with the dipole transitions (electric or magnetic) of Eu³⁺ ions and the different coordination structures of Sr⁺² ions.

Keywords: Sr2-xSiO4-xEu phosphors; charge transition state; concentration quenching effect; different synthesis processes.