Preparation and luminescence properties of Eu2+ -doped CASN-sinoite multiphase system for LED

A series of Eu2+-doped CASN-sinoite multiphase system with a formula of (CaAlSiN3)(1-x)-(Si2N2O)x were successfully synthesized by the high temperature solid-state method. The crystal structure and morphology of the phosphors and their photoluminescence (PL) were investigated. For the Eu2+-doped samples the PL intensity approached its maximum when the molar ratio of Si2N2O in the samples was about 0.15. With increase of the concentration of Si2N2O, the emission peak shifted from 645 to 605 nm. It was because the spectroscopic polarizability (asp) became smaller with the increase of Si/Al ratio or the adding of O atoms, which caused the change of crystal field strength. In addition, the full width at half maximum (FWHM) widened with the increase of x value, which was favor of the improvement of the color rendering index.