Low temperature synthesis of barium oxynitridosilicates using BaCN2 and SiO2

Abstract

Barium oxynitridosilicates, Ba₃Si₆O₁₂N₂ and Ba₃Si₆O₉N₄, were obtained from a mixture of BaCN₂ and SiO₂ at 800 °C, which is several hundred degrees lower than the temperature required in solid state reactions using BaCO₃, SiO₂ and Si₃N₄. The low-temperature formation mechanism was investigated by thermogravimetry analysis in conjunction with gas chromatography and mass spectroscopy. The phase ratio between the oxynitridosilicates was controlled by tuning the reaction temperature, duration, and atmosphere. Almost single-phase Ba₃Si₆O₁₂N₂ was obtained by reaction at 800 °C for 15 h under a N₂ atmosphere, but the product changed to Ba₃Si₆O₉N₄ after 50 h at 800 °C or by heating at 950 °C for 15 h. The photoluminescence properties of Eu-doped products obtained at 800 °C using a mixture of BaCN₂ : Eu and SiO₂ were investigated.