Tunable orange red phosphors: S2−-doped high temperature phase Ca3SiO4Cl2:Eu2+ for solid-state lighting

Abstract

S²⁻-doped high temperature phase (HTP) Ca₃SiO₄Cl₂:Eu²⁺ is synthesized by one-step solid-state reaction at 1020 °C under H₂(5%)/N₂(95%) reducing atmosphere, using CaSO₄ as the S source for sulfuration. Remarkable red shift of the emission spectra of S²⁻-doped HTP Ca₃SiO₄Cl₂:Eu²⁺ is observed, comparing with Ca₃SiO₄Cl₂:Eu²⁺. This is attributed to the crystal field splitting effect and nephelauxetic effect by S²⁻ doping. The competition of the two effects also changes the excitation spectra, showing first red then blue shift. The color chromaticity of S²⁻-doped HTP Ca₃SiO₄Cl₂:Eu²⁺ shows that it can be used as an efficient orange red phosphor for solid-state lighting.