Synthesis and photoluminescence of Ca–(Sn,Ti)–Si–O compounds

Abstract

The phase relation of the compounds prepared in the CaO–SnO 2–SiO 2 system at 1673 K and in the CaO–TiO 2–SiO 2 system at 1573 K was investigated in order to explore new Ti 4+-activated stannate phosphors. Solid solutions of Ca(Sn 1− x Ti x )SiO 5 and Ca 3(Sn 1− y Ti y )Si 2O 9 were synthesized at x = 0–1.0 and y = 0–0.10, respectively, and their crystal structures were analyzed by powder X-ray diffraction. Photoluminescence of these solid solutions was observed in a broad range of a visible light wavelength region under ultraviolet (UV) light excitation. The peaks of the emission band of Ca(Sn 0.97Ti 0.03)SiO 5 and Ca 3(Sn 0.925Ti 0.075)Si 2O 9 were at 510 nm under excitation of 252 nm and at 534 nm under excitation of 258 nm, respectively. The absorption edges estimated by the diffuse reflectance spectra were at 300 nm (4.1 eV) for CaSnSiO 5 and at 270 nm (4.6 eV) for Ca 3SnSi 2O 9, suggesting that the excitation levels in Ca(Sn 1− x Ti x )SiO 5 were above the band gap of the host, although the levels in Ca 3(Sn 1− y Ti y )Si 2O 9 were within the band gap and near the conduction band edge.