A study assessment of the thermodynamic properties of MgO and CaO at PREM pressures up to the outer core’s limits of the Earth

Using the PBEsol function of the GGA approximation of the DFT method included in the CASTEP program, the optimization of the geometric structure of MgO and CaO was calculated to observe the possible phase transformation of their crystal structures in a pressure range from 0 to 140 GPa. The evolution...

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Published inNeuroQuantology Vol. 21; no. 7; p. 624
Main Authors Achouri, Abderrahim, Tlili, Salah, Kaddour, Abdelmadjid, Benatallah Nassiba, Mohammed Said Nedjimi, Medjahed Driss Meddah, Medjadji Nassira
Format Journal Article
LanguageEnglish
Published Bornova Izmir NeuroQuantology 01.01.2023
Subjects
Calcium oxide
Debye temperature
Earth core
Earth crust
Earth surface
Elastic properties
Entropy
Free energy
Heat
Internal energy
Lime
Magnesium
Magnesium oxide
Mathematical analysis
Mathematics
Parameters
Phase transitions
Specific heat
Superconductors (materials)
Temperature
Thermodynamic properties
Thermodynamics
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Summary:Using the PBEsol function of the GGA approximation of the DFT method included in the CASTEP program, the optimization of the geometric structure of MgO and CaO was calculated to observe the possible phase transformation of their crystal structures in a pressure range from 0 to 140 GPa. The evolution of the Debye temperature with pressure changes was also examined after calculating the elastic properties. We were therefore able to study the changes in heat capacity, internal energy, entropy, and Gibbs energy as a function of pressure and temperature. Moreover, we were able to compare the values of these parameters for these two oxides, particularly within this field of study, which extends from the surface of the earth's crust to the confines of its outer core. We found that the results were in excellent agreement with previous studies. The MgO stabilizes in phase B1, while the dioxide transforms at a pressure of 59.2 GPa from this phase to phase B2. The agreement is also clear for the Debye temperature of both oxides, and the values of both the heat capacity with constant volume and the entropy at 300 K for magnesium oxide. While we were not able to compare the results of our calculation for both internal and free energy of oxides and the tow thermodynamic parameters for calcium oxide with the results of previous studies because they are not available.
ISSN:1303-5150
DOI:10.48047/nq.2023.21.7.nq23055