Surface OH Groups of Commercial Si₃N₄ Powders Evaluated by Diffuse Reflectance Infrared Fourier Transform Spectroscopy

Abstract

Surface OH groups of seven as-received Si₃N₄ powders produced by three different manufacturing processes: diimide precipitation, carbothermal reduction and silicon nitridation with different nitridation media were analyzed by FTIR measurement using a diffused reflectance accessory (DRIFT). The powder produced by the carbothermal reduction process using N₂ gas as the nitriding media shows the highest OH intensity and the powder produced by the direct nitridation of silicon using a mixture of N₂ + H₂ as nitriding media and washed by acid shows the least. The results are in agreement with the values of H₂O molecules desorbed below 1300°C measured by temperature programmed desorption mass spectroscopy (TPDMS).