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The first-principle studies of the crystal phase transitions: Fd3m-MgAl2O4→F4-3m-MgAl2O4 |
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| Authors: | Liang Zhang Guang-Fu Ji Feng ZhaoChuan-Min Meng Dong-Qing Wei |
| Affiliation: | a Science and Technology on Shock Wave and Detonation Physics Laboratory, Institute of Fluid Physics, Chinese Academy of Engineering Physics, Mianyang 621900, China b College of Physical Science and Technology, Sichuan University, Chengdu 610065, China c College of Life Science and Biotechnology, Shanghai Jiaotong University, Shanghai 200240, China d State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China |
| Abstract: | Magnesium aluminum spinel (MgAl2O4) is a major constituent of the shallow upper mantle. It is of great geophysical importance to explore its physical properties under high pressure and temperature. The first-principle density functional theory (DFT) with the plane wave along with pseudopotential was employed to obtain the total energy for both Fd3m-MgAl2O4 and F4-3m-MgAl2O4, which was used to generate the Gibbs free energy as a function of temperature and pressure with the quasi-harmonic Debye model. It is found that the phase transition temperature from Fd3m-MgAl2O4 to F4-3m-MgAl2O4 is beyond 452.6 K in the pressure regime studied, which is consistent with the experiment. The phase transition temperature is related to pressure by a linear function, i.e. T=8.05P+452.6, which is the first equation of this kind to describe the phase transition Fd3m→F4-3m. The elastic constants, equation of states and thermodynamic properties of Fd3m-MgAl2O4 are also reported in this paper to make a complete study. |
| Keywords: | The first-principle DFT MgAl2O4 Phase transition High pressure physics Equation of states |
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