Effect of Al/Si substitution on the structure and luminescence properties of CaSrSiO4:Ce3+ phosphors: analysis based on the polyhedra distortion

Abstract

Blue-emitting CaSrSiO₄:Ce³⁺,Li⁺ phosphors were prepared by a high temperature solid-state method, and the effect of substituting Al³⁺ for Si⁴⁺ in CaSrSiO₄:Ce³⁺,Li⁺ has been studied. Crystal structures of the as-prepared Ca_1−ySr_1−ySi_1−xAl_xO₄:yCe³⁺,yLi⁺ phosphors were resolved by the Rietveld method, which suggested that all the samples belonged to the orthorhombic symmetry (Pnma) group of α-CaSrSiO₄. The photoluminescence (PL) emission and excitation spectra, the lifetime, and the effect of Al³⁺ concentration on the PL properties were investigated in detail. The emission peaks of the CaSrSi_1−xAl_xO₄:Ce³⁺,Li⁺ (x = 0–0.10) phosphors were red-shifted from 452 to 472 nm with increasing Al/Si ratio. The red-shift of the Ce³⁺ emission is ascribed to the polyhedra distortion of the cations, originating from the variation in the neighboring [(Si,Al)O₄] polyhedra, and the detailed mechanism has been discussed.