Enhanced quantum efficiency with magnesium doping in europium-containing silicon oxynitride phosphor

Two types of europium (Eu)-containing silicon oxynitride phosphors were prepared by the polymer-derived method via polycarbosilane and Eu acetylacetonate with/without magnesium (Mg) acetylacetonate. The influences of Mg doping on the phase structure, surface morphology, microstructure and photoluminescence property of the Eu-containing silicon oxynitride phosphor were investigated. It was found that both the phosphors had almost single crystalized particles with a β-Si3N4 like major phase and a strong emission band ranging 430-440 nm. Doping a small amount of Mg ions into the Eu-containing silicon oxynitride phosphor not only enlarged the crystalline and particle sizes, but also significantly enhanced the quantum efficiency from 34.53% to 93.81%. By comparing with the pure silicon oxynitride powder, possible mechanisms for the major emission band in the region of 430-440 nm and the shoulder emission band at around 550 nm are discussed.