Hole concentration and thermoelectric figure of merit for Pb1-xSnxTe : Te solid solutions

The maximum densities of holes generated by cation vacancies, as well as th ermoelectric parameters of (Pb1-xSnx)(1-y)Te-y solid solutions with tin con tent x in the range from 0.4 to 0.6, were investigated. It is shown that ea ch vacancy produces four holes in the valence band and that only for small x can the concept of doubly charged vacancy be used. The maximum thermoelec tric figure of merit Z is (1.0-1.1) x 10(-3) K-1 at T = 800-850 K. The rela tively high value of Z achieved without doping is due to the high electrica l conductivity provided, first, by the small effective mass of holes and, s econd, by the high electrical activity of the vacancies. (C) 2000 MAIK "Nau ka/Interperiodica".