On the Atomic Kinetic Energies in Ceramic Oxides

Abstract

We calculated the mean atomic kinetic energy, <Ke(X)>, of the X atom (X = Si, Ti, Hf, O) in some ceramic oxides, SiO 2 , TiO 2 and HfO 2 using the published partial vibrational density of states (PVDOS). These were simulated by means of lattice dynamics, molecular dynamics and density functional theory.The predicted values are compared to those recently obtained by electron Compton scattering (ECS), with an overall good agreement of ~4%. In accord with calculations, the ECS measurements reveal a small, but detectable, dependence of <Ke(X)> on the fine structural details of the oxide, e.g. whether it is in a crystalline or amorphous form, and whether it exhibits surface or bulk characteristics. This study illustrates the limitations and the potential of PVDOS simulations in predicting experimental atomic kinetic energies, and can be viewed as a promising approach for elucidating valuable structural and dynamical information of ceramic oxides and other materials.