THERMAL EQUATION OF STATE OF POLAR CRYSTALS .2. THREEDIMENSIONAL MODEL FOR WURTZITE STRUCTURES (ZNO)

The thermal equation of state is investigated for polar crystals (zinc blende and wurtzite structures). A finite crystal is considered with free charges to compensate the dipole moment of the crystal in equilibrium. The free energy is taken in the quasiharmonic approximation. A simple point-charge model for zinc oxide leads to the thermal expansion coefficients and pyroelectric constants, and to the elastic moduli, piezoelectric moduli and dielectric susceptibilities. © 1968 Springer-Verlag.