The synthesis of ultrafine titanium nitride in an r.f. plasma

Abstract

The ultrafine titanium nitride particles with a statistical median size of about 10 nm were prepared by passing pure titanium powder (<25 μm) through a radio-frequency (r.f.) argon-nitrogen plasma. The effects of the [N₂]/[Ti] molar ratio of the reactant on the nature of the products were investigated by chemical analysis, X-ray diffraction and electron microscopy. The conversion efficiency was close to 100%. The colour of the product was black, which is attributed to the particle size ranging from 5 to 150 nm. Most of the crystallites were single crystal and showed clear-cut habits of cubic phase. The chemical composition and lattice parameter of the products changed with the [N₂]/[Ti] ratio. The thermodynamics of the process were also considered. These results provide evidence to suggest that new materials can be produced by an r.f. plasma process, in particular, the ultrafine refractory nitrides.