|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Computational Materials Discovery and Optimization: From 2D to Bulk Materials
||Computational Exploration of Rare-earth Zirconate Pyrochlores for Thermal Barrier Coatings: Accurate Prediction of Thermal Conductivities and Thermal Expansion Coefficients from First-principles Calculations
||Guoqiang Lan, Jun Song
|On-Site Speaker (Planned)
Rare-earth zirconate pyrochlores (RE2Zr2O7) are considered as promising candidate materials for the thermal barrier coating. To facilitate material exploration, the ability to predict thermal conductivities and coefficients of expansion (CTEs) of RE2Zr2O7 is of critical importance. In this study, we investigated several RE2Zr2O7 employing density functional theory and quasi harmonic approximation. Through the relaxation time approximation (RTA) with Debye model, their thermal conductivities were predicted, showing good agreement with experimental measurements. The low thermal conductivities of RE2Zr2O7 were shown to largely come from the interference between the lowing lying optical phonon branches and acoustic branches. However these low-lying optical phonon branches that become imaginary as the volume expands, preventing correct characterization of thermal expansion behaviors. These branches were shown to correspond to RE-cation rattling vibrational modes. We proposed a tailored quasi-harmonic (QH) approximation to predict the CTEs of RE2Zr2O7. The predictions also agreed well with available experimental data.
||Planned: A print-only volume