Experimental techniques have been developed for measuring the Seebeck coefficient S and electrical resistivity ρ of liquid semiconductors at high temperatures. Data have been obtained for S(T) and ρ(T) in a temperature range of 200° to 800°C and a composition range of 31 to 68 at.% of thallium. The liquids are n type for compositions with more than 66% thallium, and p type for lower thallium concentrations. At several compositions where thermal conductivity data are available, evaluation of the thermoelectric figure of merit γ(=ZT) shows ranges of relatively large values of γ(0.1 to 0.85).

Experimental data for the resistivity and Seebeck coefficient of liquid thallium-tellurium solutions have been analyzed in the light of the conventional equations for electronic structure and transport in solids. The behavior of p-type solutions can be described by the presence of deep acceptor levels which have an activation energy of 0.25db0.01 eV. The hole mobility n P in these solutions is nearly independent of composition with d In fj,p/d In T= -1.68±0.08 over a large range of T. Data are obtained about the variation of the concentration of acceptor states with composition. Preliminary information is also obtained about the energy of the band gap, and the mobility of w-type solutions. The results show that much of the observed behavior can be placed in the framework of conventional theoretical equations. We discuss some of the ways in which these equations may require significant modifications in the case of liquid semiconductors, and note how this would change our numerical results.

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