| Autor: |
Hong, Qi-Jun, Ushakov, Sergey V., Kapush, Denys, Benmore, Chris J., Weber, Richard J. K., van de Walle, Axel, Navrotsky, Alexandra |
| Jazyk: |
angličtina |
| Rok vydání: |
2018 |
| Popis: |
Structure and thermodynamics of pure cubic ZrO₂ and HfO₂ were studied computationally and experimentally from their tetragonal to cubic transition temperatures (2311 and 2530 °C) to their melting points (2710 and 2800 °C). Computations were performed using automated ab initio molecular dynamics techniques. High temperature synchrotron X-ray diffraction on laser heated aerodynamically levitated samples provided experimental data on volume change during tetragonal-to-cubic phase transformation (0.55 ± 0.09% for ZrO₂ and 0.87 ± 0.08% for HfO₂), density and thermal expansion. Fusion enthalpies were measured using drop and catch calorimetry on laser heated levitated samples as 55 ± 7 kJ/mol for ZrO₂ and 61 ± 10 kJ/mol for HfO₂, compared with 54 ± 2 and 52 ± 2 kJ/mol from computation. Volumetric thermal expansion for cubic ZrO₂ and HfO₂ are similar and reach (4 ± 1)·10^(−5)/K from experiment and (5 ± 1)·10^(−5)/K from computation. An agreement with experiment renders confidence in values obtained exclusively from computation: namely heat capacity of cubic HfO₂ and ZrO₂, volume change on melting, and thermal expansion of the liquid to 3127 °C. Computed oxygen diffusion coefficients indicate that above 2400 °C pure ZrO₂ is an excellent oxygen conductor, perhaps even better than YSZ. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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