Thermal expansion of ZnTe and HgTe and heat capacity of HgTe at low temperatures

The linear coefficient of thermal expansion of ZnTe and HgTe is measured between 1.5 and 30K by means of a three-terminal capacitance dilatometer; the heat capacity of HgTe is measured in this temperature range. Values gamma 0 th =0.07+or-0.07 (ZnTe) and -1.2+or-0.2 (HgTe) are obtained for the zero-temperature limit of the Gruneisen parameter. The former value is in good agreement with gamma 0 el =0.05 calculated from the pressure derivatives of the elastic moduli. The low-temperature limiting value of the Debye temperature theta 0 th =147.5+or-2K for HgTe. The variation of gamma (T) and theta D (T) as functions of reduced temperature, T/ theta D , fit the patterns established previously for other II-VI compounds of zincblende structure.