Lattice-dynamic treatment of vibrational and elastic properties of cotunnite-type ZrO2 and HfO2: Comparison with ambient pressure polymorphs

The results of the joint lattice-dynamical model treatment of the vibration al and elastic properties of the cotunnite-type zirconia and hafnia are pre sented. The model is capable of reproducing the frequencies of the Raman-ac tive vibrations, and provides their symmetry assignment. Also it predicts t he position of the infrared-active bands. The model successfully describes the elastic properties of the low-pressure polymorphs, but could not reprod uce the bulk modulus of OII-ZrO2 of 332 GPa obtained from a volume-pressure dependence. The current results give an estimate of the bulk modulus of 25 4 GPa.