Theoretical calculations of the high-pressure phases of ZnF2 and CdF2
Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P.R. China
Corresponding author: a email@example.com
Published online: 17 May 2006
First-principles calculations based on density functional theory were used to study the high-pressure phases of both ZnF2 and CdF2. We found that the sequence of the pressure-induced phase transitions is: Rutile (P42/mnm) ↦ CaCl2 (Pnnm) ↦ PdF2 (Pa-3) and CaF2 (Fm3m) ↦ PbCl2 (Pnma) ↦ Ni2In (P63/mmc) for ZnF2 and CdF2 respectively. In ZnF2 the behavior of the ground-state total energy, of the Gibbs free energy and of the lattice constant vs. pressure shown that the phase transition at 4 GPa from the rutile-type phase to the CaCl2-type phase is a second-order phase transition. The mechanism of the structural change was also revealed by the transition from the PbCl2-type phase to the Ni2In-type phase in CdF2. Moreover, the high-pressure behavior of divalent metal fluorides was compared and discussed.
PACS: 61.50.Ks – Crystallographic aspects of phase transformations; pressure effects / 71.15.-m – Methods of electronic structure calculations
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2006