Thermal expansion and heat capacity of cuprous chloride at low temperatures

The linear thermal expansion of a polycrystalline sample has been measured in the ranges 1.5<T<34K, 55<T<90K, and at room temperature; and its heat capacity in the range 1.3<T<16K. Expansion is strongly negative at low temperatures, with Gruneisen parameters gamma 0 th =-2.4+or-0.4 and gamma min th =-2.71; gamma infinity th =0.75+or-0.15. Debye temperatures are Theta 0 C =179+or-0.6K, Theta min C =119K, Theta infinity C =285+or-10K. The elastic and piezoelectric measurements of Hanson et al. (1974) are used to calculate Theta el =182.2+or-2K, gamma el =-1.19+or-0.2. When CuCl is compared with other crystals of zincblende structure, gamma 0 th and Theta infinity C / Theta 0 C correlate well with increasing ionicity, but no such trend is observed for the depth of the minima in gamma th (T) and Theta C (T).