Tracing nitridation reaction toward efficient production of oxynitride glasses as hosts for bright luminescence centers

Europium-doped oxynitride glass powder (Sr-Si-Al-O-N) was synthesized by a sol-gel method followed by ammonolysis to investigate the effect of the ammonolysis conditions on the structure and properties of the glass powder.In particular, the effect of the ammonia gas flow rate during nitridation was studied.The effective nitrogen concentration (N eff ) in the obtained powder, analyzed by X-ray fluorescence, increased with an increase in the flow rate, and the results of X-ray photoemission, nuclear magnetic resonance, and Fourier transform infrared (FT-IR) spectroscopy measurements indicated that the population of Si-N bonds increased with an increase in N eff .However, the presence of hydrogen-terminated structures, such as -NH n , in the powder with high N eff was confirmed by FT-IR measurements.The presence of hydrogen-terminated structures, such as -Si-NH n , and the thermal stability of these hydrogen-related structures were further investigated by thermal analyses, including thermal desorption measurements, which suggested that hydrogen-terminated structures can be easily formed during the nitridation of the gel and that the formation of hydrogen-terminated structures inhibits the polymerization of the glass structures.