It is shown that the band-inversion phenomenon proposed by Dimmock, Melngailis, and Strauss should influence the electrical properties of ${\mathrm{Pb}}_{0.77}$${\mathrm{Sn}}_{0.23}$Se. On the basis of a simple model, it is demonstrated that this influence should be pronounced for materials of low carrier concentration. This expectation is confirmed by our experimental studies of the electrical resistivity and Hall coefficient as a function of temperature, carrier concentration, and carrier type. In addition, an analysis of the data indicates that the effective mass of free carriers changes considerably with temperature as a result of the small and widely varying band gaps involved in the inversion phenomenon. Finally, there is no definitive experimental evidence of the multiple-band effects which have been reported for other materials of this type.

• Received 15 June 1970

DOI:https://doi.org/10.1103/PhysRevB.3.4299