A NOVEL REACTION BETWEEN PHYSICALLY SEPARATED SOLID REACTANTS

Ternary oxides were converted to ternary sulfides by a metathesis reac tion with a sulfur source such as diyttrium trisulfide. Reactions took place between two physically separated solid reactants under vacuum i n a sealed silica tube. Preparation of the alkali-metal niobium disulf ides ANbS(2) (A = Li, Na, K, Rb or Cs) has been attempted with isolati on of quality crystals of the materials LixNbS2 [a = 3.3412(2) and c = 12.876(1) Angstrom] and Na0.41NbS2 [a = 3.3424(8) and c = 14.664(4) A ngstrom] in the space group P6(3)/mmc. Also considered has been the me tathesis reaction of sodium metavanadate, alkaline-earth metal titanat es and selected Group 6 ternary oxides with diyttrium trisulfide. The mechanism of these metathesis reactions has been studied, and in the c ourse of these investigations the reduced hexagonal LiNbO2 [a = 2.9070 (6) and c = 10.457(3) Angstrom] was characterised. Formation of binary nitrides and carbides has been possible by replacing the sulfur sourc e. Y2S3, with a source of nitrogen (e.g. YN) or carbon (e.g. TiC).