Anomalies in the isotherms of the thermoelectric properties of Bi-Sb solid solutions

The goal of the present work is a detailed study of the thermoelectric property-composition dependences of polycrystalline Bi-Sb solid solutions in the range of 0-15 at.% Sb. The Seebeck coefficient, electrical conductivity, Hall coefficient, and magnetoresistance were measured in the temperature range 77-300 K. In the isotherms of these properties, distinct extrema were observed in the certain concentration ranges. The presence of the concentration anomalies is attributed to 1) the transition from the dilute impurity range to the impurity continuum and possible self-organization processes accompanying this transition; 2) the reconstruction of the energy band structure under increasing Sb concentration. It was established that the maximum values of the figure of merit Z reached in the semiconductor region for the studied polycrystals, practically correspond to the values of Z observed in single crystals in the direction perpendicular to a trigonal axis. The obtained results should be taken into account when developing new thermoelectric materials based on Bi-Sb solid solutions