Structure and photoluminescence properties of Ce 3+-doped novel silicon-oxynitride Ba 4− zMzSi 8O 20−3 xN 2 x ( M=Mg, Ca, Sr)

Abstract

Structural and photoluminescence properties of undoped and Ce 3+-doped novel silicon-oxynitride phosphors of Ba 4− z M z Si 8O 20−3 x N 2 x ( M=Mg, Sr, Ca) are reported. Single-phase solid solutions of Ba 4− z M z Si 8O 20−3 x N 2 x oxynitride were synthesized by partial substitutions of 3O 2−→2N 3− and Ba→ M ( M=Mg, Ca, Sr) in orthorhombic Ba 2Si 4O 10. The influences of the type of alkaline earth ions of M, the Ce 3+ concentration on the photoluminescence properties and thermal quenching behaviors of Ba 3 MSi 8O 20−3 x N 2 x ( M=Mg, Ca, Sr, x=0.5) were investigated. Under excitation at about 330 nm, Ba 3 MSi 8O 20−3 x N 2 x :Ce 3+ ( x=0.5) exhibits efficient blue emission centered at 400–450 nm in the range of 350–650 nm owing to the 5 d→4 f transition of Ce 3+. The emission band of Ce 3+ shifts to long wavelength by increasing the ionic size of M due to the modification of the crystal field, as well as the Ce 3+ concentrations due to the Stokes shift and energy transfer or reabsorption of Ce 3+ ions. Among the silicon-oxynitride phosphors of Ba 3 MSi 8O 18.5N:Ce 3+, M=Sr 0.6Ca 0.4 possesses the best thermal stability probably related to its high onset of the absorption edge of Ce 3+.