Metallic conductivity of liquid ternary Te-based alloys

Electrical conductivity sigma(T) and thermo-e. m.f. S(T) measurements were performed for ternary CuTlTe2, CuAsTe2, and TlAsTe2 alloys in a wide temper ature range (from 600 K to 1800 K). The observed exponential sigma(T) depen dence points to the occurrence of a metal-nonmetal transition. Contrary to theoretical expectations, parameters of an electron spectrum determined sep arately from sigma(T) and S(T) measurements do not coincide. It was found t hat the metallization temperature T-S < T-sigma, the activation energy E-si gma(0) does not coincide with E-S(0), and a condition E-sigma(0) > E-S(0) i n the vicinity of the metal-nonmetal transition takes place. A metal-nonmet al high-temperature transition is interpreted in the frame of a developed t ransformation mechanism of the electron spectrum of liquid semiconductors. This mechanism suggests the existence of an energy interval of charge trans fer processes.