Mechanical, lattice dynamical and electronic properties of CeO2 at high pressure: First-principles studies

Abstract

Abstract The elastic constants ( C ij ), bulk modulus ( B ), shear modulus ( G ) and elastic modulus ( E ) of cubic fluorite CeO 2 under high pressure have been studied using the plane-wave pseudopotential method based on density functional theory. The calculated results show that the mechanical properties ( C ij , B , G and E ) of CeO 2 increase with increasing pressure, and the phase transition of CeO 2 occurs beyond the pressure of 130 GPa. From the calculated phonon spectrum using Parlinsk–Li–Kawasoe method, we found that CeO 2 appears imaginary frequency at 140 GPa, which indicates phase transition. The energy band, density of states and charge density of CeO 2 under high pressure are calculated using GGA+ U method. It is found that the high pressure makes the electron delocalization and Ce–O covalent bonding enhanced. As pressure increases, the band gap between O2p and Ce4f states near the Fermi level increases, and CeO 2 nonmetallic nature promotes. The present research results in a better understanding of how CeO 2 responds to compression.