Oxynitride Glasses

Abstract

Research on oxynitride glasses has expanded considerably since the first systematic compositional investigations were begun some ten years ago. This review will briefly introduce that work with an emphasis on more recent developments. Also included is some discussion of the applications of oxynitride glasses in both bulk and thin film form. The literature review is selective, however, and the recently developed phosphorus oxynitride glasses are only briefly mentioned. For more detailed information on earlier work on silicon oxynitride glasses see the reviews by Jack and Loehman. For discussions of phosphorus oxynitride glasses see Marchand, Peng and Day, and Rajaram and Day.The development of bulk oxynitride glasses has been closely associated with research on Si3N4 and other nitrogen-containing ceramics. The initial discovery that large amounts of nitrogen can be incorporated in silicate glasses originated with analyses of glassy grain boundary phases in Si3N4 that was hot-pressed or sintered with different additives to promote liquid phase formation at the processing temperature. (Some applications of oxynitride glasses take advantage of that close connection to Si3N4. See Applications of Oxynitride Glasses below.) Later, systematic study of the bulk oxynitride glasses showed that nitrogen incorporation increases density, hardness, glass transition temperature and fracture toughness, and, to a certain extent, decreases the thermal expansion coefficient. Nitrogen additions also tend to lower glass solubility in aqueous solutions.