A novel pressure-induced phase transition in CaZrO3

Abstract

High pressure synchrotron X-ray diffraction measurements on CaZrO₃ were carried out in a diamond anvil cell up to 50.1 GPa at room temperature. It was found that the orthorhombic phase can be stable up to 30 GPa. A new pressure-induced phase transition was observed in CaZrO₃ beyond 30 GPa. The high pressure structure of CaZrO₃ was determined to be a monoclinic phase which is distinct from the high pressure structures that were previously reported for other perovskite oxides. Upon release of pressure, the high pressure phase transforms into the initial orthorhombic phase. A fit of the compression data to the third-order Birch–Murnaghan equation of state yields a bulk modulus K₀ of 193(14) GPa. We propose that the unique distorted structure probably plays a crucial role in the high pressure behavior of CaZrO₃. Especially, the distinct phase transformation may be related to the rotation or tilting of the ZrO₆ octahedra.