Low-temperature phase transitions in some quaternary solid solutions of IV-VI semiconductors

Abstract

Samples of PbS x Se y Te 1- x- y , Pb 1- x Sn x Te 1- y Se y and Pb 1- x Sn x Te 1- y S y quaternary solid solutions were investigated in the 4–200 K temperature range using electrical and X-ray methods. The regions where low-temperature phase transitions take place were established. It is shown that phase transitions in these solid solutions are associated with off-center S and Sn ions. The dependence of the phase transition temperature on the composition of solid solutions can be qualitatively described taking into account the influence of substitutional disorder on ordering and tunneling of off-center ions.