Effects of synthesis methods and different concentrations of Eu ions on the emission properties of Sr SiO phosphors.

Sr SiO -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 Sr SiO phase was observed in 1,300° C-TS-synthesized Sr SiO -xEu powder, but no raw materials or secondary phases were observed in the SSR-prepared Sr SiO -xEu powders. The concentration quenching effect of Eu ions was really observed in TS-prepared Sr SiO -xEu phosphors, which was not observed in SSR-prepared Sr SiO -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 SiO -xEu phosphors. Sr SiO -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 Eu ions and the different coordination structures of Sr ions.