ELECTRICAL RESISTIVITIES IN SINGLE-CRYSTALS OF TICX AND VCX

TiC//x and VC//x have wide non-stoichiometric composition ranges which come only from the carbon vacancies. High purity single crystals with controlled compositions were prepared, and their electrical resistivities at 4. 2 and 298 K were measured as a function of composition. In the case of TiC//x whose carbon vancancies are disordered in the lattice, the dependence of the residual resistivity on the composition was interpreted by applying Nordheim's rule to the vacancy scattering and by considering the change in carrier density due to the introduction of vacancies. In addition, the difference in the resistivity between 4. 2 and 298 K was discussed. In the case of VC//x whose carbon vacancies are ordered, the dependence of the resistivity on the composition ranges of the ordered phases was examined in detail.