In situ X-ray observation of phase transitions in ZnF2 under high pressure and high temperature

High-pressure and high-temperature behavior of ZnF2 with the rutile-type structure was investigated using an energy-dispersive-type X-ray diffraction method. Two high-pressure phases were found in the range up to 15 GPa and 400 ∘C. The CaCl2-type phase with an orthorhombic cell (space group: Pnnm) was clearly observed at 5.4 GPa and 400 ∘C. Further phase transition was induced above 10 GPa at room temperature. The single phase of the high-pressure phase was obtained at 15.3 GPa and 350 ∘C. The high-pressure phase was found to have the PdF2-type structure with a cubic cell (space group: Pa-3). The single phase was observed above 4 GPa in a pressure-release process at room temperature, and completely reverted to a mixture of the rutile-type phase and the α- PbO2-type phase at ambient condition. The high-pressure behavior of ZnF2 was similar to that of MgF2.