Characterization of the Nitridation Process of Boric Acid.

Boric acid B(OH)(3) has been thermally nitrided under flowing ammonia into a boron oxynitride. This reaction has been followed using various structural techniques: X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), X-ray diffraction and chemical analyses. Reaction of boric acid with ammonia began at 155 degrees C. The weight percent of nitrogen increases with the temperature of the pyrolysis process. Formation of B-N bonds is observed at 400 degrees C by infrared spectroscopy. Two boron species are observed by XPS and identified as boron linked mostly to oxygen atoms and as boron linked mostly to nitrogen atoms, denoted BOx and BNx, respectively. The intensity of the BNx signal increases with the pyrolysis temperature.