PREPARATION AND PROPERTIES OF UNIFORM COATED COLLOIDAL PARTICLES .8. TITANIUM NITRIDE ON SILICA

Spherical silica particles, dispersed in ethanol/water solutions, were first coated with titania by hydrolysis of added titanium isopropoxid e. The coating thickness could be readily adjusted by the ratio of tit anium alkoxide concentration to the amount of silica. The coated cores prepared as above were then treated with ammonia in a temperature-pro grammed reaction to produce a shell of titanium nitride. After nitrida tion, the powders of the high specific surface area showed electrical conductivity, which depended on the thickness of the coatings.