METAL-SEMICONDUCTOR TRANSITION IN LIQUID M(X)SB(1-X) ALLOYS (M=NA, K,CS) - VARIATION OF ELECTRICAL-CONDUCTIVITY AND THERMODYNAMIC PROPERTIES

The electrical conductivity, sigma, and the thermodynamic activity of alkali metal, alpha(M), of liquid KxSb1-x and CsxSb1-x alloys have bee n measured for x less than or equal to 0.8 at temperatures up to 854 d egrees C. The composition has been varied in situ by coulometric titra tion. The conductivity in both systems exhibits a broad semi conductin g minimum (sigma less than or equal to 100 Ohm(-1) cm(-1)) at composit ions in between the stoichiometric compounds MSb and M(3)Sb, respectiv ely. A strong variation of the excess stability is observed within the M-Sb alloys at the 3:1 stoichiometry. The change of the electrical co nductivity from semiconducting to metallic behaviour is found to be in good agreement with the predictions of a simple quasichemical associa tion model fitted to the thermodynamic mixing quantities.