Thermophysical properties of liquid ternary chalcogenides
Vasyl Sklyarchuk, Yuriy Plevachuk
Electrical conductivity, s(T) and Seebeck coefficient, S(T), measurements were performed for ternary CuTlSe2, CuAsSe2, and TlAsSe2 alloys in a wide temperature range (from 600 K to 1800 K) under ambient pressures of argon gas (up to 50 MPa). An exponential s(T) dependence observed for the above-listed systems points to the occurrence of a metal – nonmetal transition. Contrary to theoretical expectations, the parameters of an electron energy spectrum determined separately from s(T) and S(T) measurements (and indicated by the superscript) do not coincide. It was found that: (i) the metallisation temperature TS < Ts; (ii) the activation energy, Es(0), does not coincide withES(0); (iii) a condition Es(0) > ES(0) in the vicinity of the semiconductor – metal transition occurs. A metal – nonmetal high-temperature transition is interpreted in the frame of a transformation mechanism of the energy spectrum of the liquid semiconductors. This mechanism suggests the existence of an energy gap in charge transfer processes.