Time: 11:00 a.m.
Place: Seminar Room IC 02-722
Ying Chen, Department of Finemechanics, and Fracture and Reliability Research Institute, Tohoku University, Sendai, Japan
A first-principles calculation of the self-diffusivity of oxygen in tetragonal ZrO2 has been attempted based on the atomistic theory of diffusion using the electronic structures, phonon vibration spectrum combing the transition state theory (TST). A local harmonic approximation (LHA) that captures the most important vibrations adjacent to the migrating atom is proposed in the present work to deal with the dynamic instability of tetragonal ZrO2 which is stable above 1478K, the absolute values of correlation factors, atom jump frequencies along a-axis and c-axis directions for a tetragonal lattice have been evaluated respectively. Together with the calculated vacancy concentration, the oxygen self-diffusion coefficients along a-axis and c-axis as the functions of temperature and oxygen partial pressure are obtained for tetragonal ZrO2, which shows that the calculated values with a partial oxygen pressure of 10-15 atm compares well with the available experimental measurements in ZrO2.