Thermal Expansion of Silicon and Zinc Oxide (II)

Coefficients of thermal expansion α‖ c and α ⊥ c between 4 and 800°K have been measured for zinc oxide using an interferometric and a capacitance method. Thermal properties of wurtzite lattices (two coefficients of thermal expansion and a pyroelectric constant) can be described in terms of three thermal equations of state. Two mechanical and one electrical Grüneisen parameters are defined and their temperature dependence is calculated from experimental results. The high‐ and low‐temperature limits of the Grüneisen parameters are compared with results obtained in other experiments. The values predicted from a rigid ion model are discussed.