Identification of Two Luminescence Sites of Sr2SiO4:Eu2+ and (Sr,Ba)2SiO4:Eu2+ Phosphors

Abstract

Europium activated strontium orthosilicate Sr2SiO4:Eu2+ phosphors were prepared by a solid state reaction method using flux. Two emissions bands of blueish-green at 490 nm (SI) and of yellow at 560 nm (SII) were observed. The two emission bands are assigned to the 4f-5d transition of Eu2+ ions in two different cation sites in α'-Sr2SiO4 orthorhombic lattices. The relative intensities of two emission bands and the efficient yellow-emission strongly depend on the fluxes used for the preparation process and the Eu2+ concentration in the Sr2SiO4:Eu2+ phosphors. The emission intensity of Eu2+ was also increased especially for the SII site, by incorporating Ba2+ into the lattice (BaxSr2-xSiO4).