Nonstoichiometry and thermal expansion of SnTe

The influence of kinetic factors on dependences of thermal expansion coefficient (α) of SnTe crystals on temperature and deviation from stoichiometry was studied. The α(T) dependences were obtained under stationary and dynamic (without keeping samples for a long time at fixed temperatures) regimes. In the case of a stationary regime, an increase in α with increasing temperature (4.2–300 K) was registered, and anomalies in α(T) dependences were observed and attributed to phase transitions. In the case of a dynamic regime, α(T) dependences exhibited an oscillatory behavior, most pronounced in the sample with 50.4 at% Te. It is suggested that the observed behavior of α(T) dependences is connected with an oscillatory process of approaching the equilibrium in the intrinsic defect subsystem and with simultaneous occurrence of relaxation processes and temperature-phase transitions. It was established that regardless of the measurement regime, a minimum in the α isotherms is observed at ∼50.4 at% Te.