Structural characteristics of HfO[formula omitted] under extreme conditions

Abstract

Pressure induced structural change of HfO2 was extensively studied up to 10 GPa with diffraction technique using synchrotron X-ray radiation. The experiment drew attention as ambiguities still exist over the monoclinic to orthorhombic evolution of HfO2 at high pressure condition. Rietveld refinement of the diffraction patterns leads to determination of the detailed structure of HfO2 at different pressures. The space group of its first orthorhombic phase is confirmed. Density functional calculations were carried out to understand the pressure induced phase transition. High temperature study of this material was also performed up to 1373 K (1100 0C) using synchrotron X-ray source for studying suitability of the material in high temperature applications and precise thermal expansion coefficients are reported.