Volume changes during melting and heating of zinc and cadmium tellurides

The method of penetrating $\gamma$-radiation is used to investigate the temperature dependence of the density of condensed phases of zinc and cadmium tellurides in the vicinity of the melting point and to determine volume changes during transition from the solid to liquid state. The density of zinc telluride in the liquid phase is investigated for the first time. It is demonstrated that, during melting, the density of both investigated compounds decreases and continues to decrease linearly on heating in the liquid state. It is noted that, in accordance with Regel's classification, zinc and cadmium tellurides melt down by the semiconductor–semiconductor pattern. The volume changes of the investigated compounds during melting are analyzed using the Clausius–Clapeyron equation. The pressure coefficients of the melting temperature of these compounds are estimated, and it is noted that they are positive ($dT/dp>0$). The thermal expansion of zinc and cadmium tellurides in the solid and liquid phases is analyzed; the equation of Sirota is used to calculate the characteristic Debye temperatures from which the mean-square dynamic displacements of atoms from the equilibrium position in the structure of condensed phases are determined at the melting point of the investigated compounds.