Tin telluride based thermoelectrical alloys.

The effect on the Hall hole concentration and the thermoelectric coefficient of various elemental impurities in SnTe containing excess Te and in some solid solutions based on it is investigated in the temperature interval 300-900 K. The variation of the kinetic parameters is treated on the basis of the concept of resonance states bound to cation vacancies and to the impurities determining the hole concentration. The low values of the thermoelectric coefficient in SnTe is explained by selectivity of scattering of charge carriers with more probable transition of the holes to the resonance states and vice versa. In isomorphic solid solutions based on SnTe, because of a shift in the energy position of the resonance states relative to the band edges and the Fermi level, it is possible to alter the nature of the resonance scattering and raise the thermoelectric coefficient to values which are optimal from the standpoint of obtaining maximum thermoelectric efficiency. In solid solutions of chalcogenides of group-IV elements with SnTe content about 40 mol% of the dimensionless parameter of thermoelectric efficiency ZT = 1 at temperatures above 700 K. [ABSTRACT FROM AUTHOR]