PREPARATION OF TUNGSTEN SULFIDES BY SOL-GEL PROCESSING

Tungsten sulfides were synthesized by reaction of different tungsten a lkoxides and hydrogen sulfide in toluene. The reaction was performed i ll toluene solution at room temperature. Tungsten ethoxide yielded a b rown black gel, while tungsten dichloride ethoxide produced a brown-bl ack colloidal powder. The W/S at% ratios were 1:2.7 and 1:1.4 in the e el and powder, respectively. Both sol-gel products were amorphous mate rials. The gel appeared to be highly viscous liquid formed from spheri cal colloidal particles connected into a three-dimensional network. Ho wever. the powder consisted of loose colloidal particles whose radii w ere in the range 0.5 to 1 mu m. (C) 1997 Elsevier Science B.V.