Temperature-dependent elastic stiffness constants (cijs), including both the isothermal and isoentropic ones, have been predicted for rhombohedral α-Al2O3 and monoclinic Ö-AI2O3 in terms of a quasistatic approach, i.e., a combination of volume-dependent c ijs determined by a first-principles strain versus stress method and direction-dependent thermal expansions obtained by first-principles phonon calculations. A good agreement is observed between the predictions and the available experiments for α-Al2O3, especially for the off-diagonal elastic constants. In addition, the temperature-dependent cijs predicted herein, in particular the ones for metastable Ö-Al2O3, enable the stress analysis at elevated temperatures in thermally grown oxides containing &- and θ-Al 2O3, which are crucial to understand the failure of thermal barrier coatings in gas-turbine engines.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics