Synthesis of transition metal nitride powders and coatings using alkanolamine chelated precursors

A new synthesis approach has been developed in which transition metal nitride powders and coatings are synthesized from alkanolamine complexed precursors. In this technique, a transition metal chloride is dissolved in an aprotic polar solvent such as acetonitrile, then reacted with either monoethanolamine or triethanolamine to form a highly viscous solution which settles out of the solvent phase. The monoethanolamine-chelated precursor can be hydrolyzed by the addition of excess water, followed by refluxing for several hours to form a colloidal precipitate. However, the precursors generated after chelation with triethanolamine are much more resistant to hydrolysis and can be easily diluted with water or methanol, forming a semi-viscous liquid, which can be used directly to dip coat various substrates. In both cases, the powder generated by hydrolysis or the coating obtained by dipping a substrate in the polymeric liquid precursor will transform to the corresponding nitride when heat-treated in ammonia. The approach has been successfully used to synthesize a number of transition metal nitride powders as well as several different transition metal nitride coatings on silicon and stainless steel substrates.