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 (a_sp) 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.