The photoluminescence of SrAl 2O 4:Sm phosphors

Abstract

A red emitting SrAl 2O 4:Sm phosphor powder was synthesized by the solid-state method. The phosphor showed Sm 3+ emission when fired in a reducing atmosphere at 1200 °C. The intraion emission spectra of Sm 3+ ( G 5 / 2 4 ⇒ H 5 / 2 4 ) indicates S m 3 + + h υ ⇒ S m 2 + + ℏ VB reaction to occur with intense emission lines located at 562, 596 and 643 nm. Results indicate that fluxing agents such as LiF and B 2O 3 play an important role in the photoluminescence (PL) emission intensity of SrAl 2O 4 powders. Also an increased content of the hexagonal phase in the SrAl 2O 4 powder boosts the PL intensity. The emission intensity becomes stronger as the firing temperature increases from 600 to 1200 °C. SrAl 2O 4:Sm shows the maximum PL intensity at 10 wt% of B 2O 3 addition. The B 2O 3 addition affects the spacing of the ( 2 ¯ 1 1 ) planes but not the (2 2 0) and (2 1 1) planes. This derives from B 3+ ion replacing the Al 3+ ion in the ( 2 ¯ 1 1 ) plane and causing shrinkage of the crystal lattice, which induces crystal defects and hence produces a stronger PL intensity.