A novel reaction between physically separated solid reactants

Abstract

Ternary oxides were converted to ternary sulfides by a metathesis reaction with a sulfur source such as diyttrium trisulfide. Reactions took place between two physically separated solid reactants under vacuum in a sealed silica tube. Preparation of the alkali-metal niobium disulfides ANbS₂(A = Li, Na, K, Rb or Cs) has been attempted with isolation of quality crystals of the materials Li_xNbS₂[a= 3.3412(2) and c= 12.876(1)Å] and Na_0.41NbS₂[a= 3.3424(8) and c= 14.664(4)Å] in the space group P6₃/mmc. Also considered has been the metathesis reaction of sodium metavanadate, alkaline-earth metal titanates and selected Group 6 ternary oxides with diyttrium trisulfide. The mechanism of these matathesis reactions has been studied, and in the course of these investigations the reduced hexagonal LiNbO₂[a= 2.9070(6) and c= 10.457(3)Å] was characterised. Formation of binary nitrides and carbides has been possible by replacing the sulfur source, Y₂S₃, with a source of nitrogen (e.g. YN) or carbon (e.g. TiC).