Isostructural phase transition-induced bulk modulus multiplication in dopant-stabilized ZrO2 solid solution*

Abstract

The electrical transport properties and structures of Y2O3/ZrO2 solid solution have been studied under high pressure up to 23.2 GPa by means of in situ impedance spectroscopy and x-ray diffraction (XRD) measurements. In the impedance spectra, it can be found that the pressure-dependent resistance of Y2O3/ZrO2 presents two different change trends before and after 13.3 GPa, but the crystal symmetry still remains stable in the cubic structure revealed by the XRD measurement and Rietveld refinement. The pressure dependence of the lattice constant and unit cell volume shows that the Y2O3/ZrO2 solid solution undergoes an isostructural phase transition at 13.1 GPa, which is responsible for the abnormal change in resistance. By fitting the volume data with the Birch–Murnaghan equation of state, we found that the bulk modulus B 0 of the Y2O3/ZrO2 solid solution increases by 131.9% from 125.2 GPa to 290.3 GPa due to the pressure-induced isostructural phase transition.