The production of nitride thin films and nanocrystalline composites via a sol-gel methodology

Metal nitrides are of great interest for the development of new engineering and catalytic applications based on their hardness, chemical and thermal stability. The development of sol-gel production methods for these materials, capable of producing films, powders and monoliths will broaden the range of nitride products possible and yield an important step forward in the general processing of this class of material. The work presented in this thesis details the synthesis of titanium nitride and carbonitride thin films via sol-gel techniques using primary amines or stoichiometric amounts of ammonia as crosslinking agents. The results using primary amines were found to be the most promising, especially when deposited onto silica substrates. The characterisation and formation of nanocrystalline powders, produced by the ammonolysis of tetrakis(dimethylamino)titanium are also discussed, detailing their suitability for applications requiring ultra-hard composite materials. Finally a novel synthetic route which produced rigid gels made from the precursor amides tetrakis(diethylamino)titanium, tetrakis(diethylamino)hafnium or tetrakis(diethylamino)zirconium and stoichiometric amounts of ammonia in THF will be discussed. The potential to produce monolithic metal nitride gels suitable for supercritical extraction of the solvent, enabling the ‘dried’ product to be heated with a reduced risk of sintering, is also proposed.