Theory and Practice – Thermodynamics, Equations of State, Elasticity, and Phase Transitions of Minerals at High Pressures and Temperatures

Oganov, Artem R.

doi:10.1016/b978-044452748-6.00033-x

Cited by 8 publications

(12 citation statements)

References 106 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our theoretical study at the lower temperature side shows a better agreement, but at the higher temperature side, slight disagreement may be ascribed to the non-inclusion of the harmonic interactions are using in present report, which justify the incorporation of (VWI) is essential. The Complete lattice dynamical, thermodynamical property and density of state curve of MgOtheoretically reported has agreed with different reported data [15][16][17][18][19][20][21][22][23][24][25][26]. The authors and more researchers have already used the present model and successfully reported the value of alkali halides and semiconductor materials [31][32][33][34][35][36][37].To sum up, we can say that the contributions of VWI and TBI are essential for the description of the lattice dynamics and thermodynamical study of MgO.…”

Section: Resultssupporting

confidence: 88%

“…The lattice dynamical calculations for alkaline-earth oxides MgO based on 11 parameters. Orientation dependent ultrasonic velocities is reported theoretically in table-3 by using the experimental data [19,20]. The uncertainty in the thermal expansion for MgO is seen that using the phonon theory do not converge for T>2000 K, whereas those by [30] show convergence up > 3000 K has been observed at high temperature but it does not affect the result.…”

Section: Resultsmentioning

confidence: 99%

“…The Internal energy, entropy, free energy heat capacity and dispersion relation curve at temperature 500K has shown in Fig.2-6with the available theoretical and experimental result which has shown parallel to the present calculated results . Ref [19] Ref [20] V S1…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Thermophysical and Ultrasonic Properties on Magnesium Oxide

Srivastava¹,

Singh²

2019

IJRTE

View full text Add to dashboard Cite

In present manuscript phonon dynamics of alkaline-earth oxides, MgO by including the three-body interconnections in the framework of ‘van der Waals three-body force shell model’ (VTBFSM) is based on my thorough theoretical study of the relevant research papers on this topic. The studies of lattice energy and other properties made by Huggins and Sakamoto [1] .The instigate work of Kellerman [2] for lattice dynamics of the alkali halides has provided attentive theoretically as well as experimentally. The thermal properties, densities of states (DOS), structure analysis, direction-dependent ultrasonic velocities and Debye velocity of magnesium oxide have been evaluated in present investigation. However, a considerable improvement in computational results has been obtained by the use of the present model and successfully predicted the lattice dynamic of MgO for the study of bulk thermo-elastic properties. The results of this investigation are discussed successfully with available experimental data

show abstract

Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Thermophysical and Ultrasonic Properties on Magnesium Oxide

Srivastava¹,

Singh²

2019

IJRTE

View full text Add to dashboard Cite

show abstract

“…The isentropic bulk modulus K s ( r ) is calculated as a function of the isothermal bulk modulus K T ( r ), which is related to ρ using the third order Vinet EOS (Oganov, 2007; Vinet et al, 1989):

K_{S} ((), r) = K_{T} ((), r) ([], 1 + α ((), r) γ ((), r) T ((), r))

K_{T} = K_{0} x^{- 2 / 3} ([], 1 + ((), 1 + θ x^{1 / 3}) ((), 1 - x^{1 / 3})) \exp ([], θ ((), 1 - x^{1 / 3}))

where α , γ , and T are the thermal expansivity, the Gruneisen parameter, and the temperature, respectively. Equation accounts for the effect of thermal expansion on the bulk modulus.…”

Section: Methodsmentioning

confidence: 99%

“…The isentropic bulk modulus K s (r) is calculated as a function of the isothermal bulk modulus K T (r), which is related to ρ using the third order Vinet EOS (Oganov, 2007;Vinet et al, 1989):…”

Section: Internal Structure Modelmentioning

confidence: 99%

Super‐Earth Internal Structures and Initial Thermal States

2020

View full text Add to dashboard Cite

The presence of a planetary magnetic field is an important ingredient for habitability. The coexistence of a solid and a liquid core can facilitate the maintenance of a compositionally driven dynamo; however, the likelihood of such a configuration in super-Earths is unknown. Recently, shock experiments and ab initio calculations have constrained the stability, equations of state, and melting properties of ultrahigh pressure core and mantle phases. Here, we investigate the internal structure of super-Earth exoplanets with a range of total masses and core mass fractions ranging from that of Mars (0.2) to Mercury (0.68), including an Earth-like bulk composition. We examine the effect of the initial core-mantle boundary temperature (T CMB ) on their internal structure and identify regimes with coexisting solid and liquid cores, and deep mantle melting. We find that the range of T CMB for which an inner core is growing increases with the total planet mass and even more with the core mass fraction. Therefore, our results suggest that super-Earths should have a crystallizing core over a large temperature range. We also find that the presence of a growing inner core is likely to be accompanied by a partially liquid lower mantle, which will likely influence planetary thermal evolution. We estimate the initial CMB temperature after super-Earth accretion by assuming an accretional heat retention efficiency similar to Earth. We find that massive super-Earths are expected to have an initial internal temperature consistent with a partially liquid core, allowing for the possibility of thermal and compositional dynamo action. Plain Language SummaryThe presence of a magnetic field in a planetary body is an important criterion for habitability, since it may reduce atmospheric loss and shield planetary surfaces from high-energy charged particles. In terrestrial planets, when an inner iron-rich core crystallizes, it releases light elements in the residual liquid outer core, which can facilitate liquid iron alloy convection and contribute to the maintenance of a magnetic field. In this study, we investigate the optimal conditions for the presence of a crystallizing core in super-Earths (i.e., large rocky exoplanets), by modeling their internal structure and using recent data on the melting properties of materials at ultrahigh pressure. We find that cores of super-Earths of large sizes have a greater likelihood to be partially molten, which may aid in maintaining a magnetic field. In addition, the lowermost mantle of massive super-Earths are likely to experience prolonged partial melting. Increasing the size of their core relative to their mantle increases even more the probability of a growing inner core. In addition, we calculate the initial heat retained during planetary formation, which confirms that large super-Earths are likely to have an initial crystallizing core.

show abstract

Ab Initio Study of Elastic Properties of High-Pressure Polymorphs of CO₂ Phases II and V

Parq

Lee

et al. 2016

J. Phys. Chem. C

View full text Add to dashboard Cite

Elastic properties of prototypical CO2 polymorphs under compression are essential to understanding the nature of their pressure-induced structural changes. Despite the fundamental importance in physical chemistry and condensed matter physics and geophysical implications for the nature of fluids in the Earth and planetary interiors, the elastic properties of these polymorphs are not fully understood because of intrinsic uncertainty and difficulties in experimental estimation of elasticity. Theoretical calculations of elastic properties of high-pressure CO2 polymorphs allow us to reveal the previously unknown details of elasticity of the diverse polymorphs under extreme compression. As a step toward getting insights into the deep carbon cycle, we carried out density-functional-theory calculations and investigated the elastic constants, bulk modulus, shear modulus, Poisson ratios and acoustic wave velocities of CO2 polymorphs: II (tetragonal, P42/mnm), β-cristobalite-like V (VCR, tetragonal, I4̅2d) and tridymite-like V (VTD, orthorhombic, P2 12121) up to approximately 40 GPa. Particularly, the elastic properties and bulk moduli of all the three CO2 phases except the elastic constants of CO2–II are the first calculation results, and the elastic constants and bulk modulus calculated for CO2–II are improved. The change in elastic properties with varying pressure shows distinct trends among CO2–II, CO2–VCR, and CO2–VTD. Despite these differences, the bulk moduli for CO2 of phases I, II, VCR and VTD exhibit a gradual increase with increasing density without major discontinuity. On the basis of the calculated elastic properties of CO2–II, CO2–VCR, and CO2–VTD and a comparison between these CO2 units and SiO2 materials, we suggest that these polymorphs may be classified into two groups: (1) a weakly connected group: CO2–II, cristobalite, and tridymite and (2) a strongly connected group: CO2–VCR, CO2–VTD, and stishovite. This classification does not depend on crystal symmetry. The bulk modulus of a CO2 solid is greater than that of a SiO2 solid of the same density, and the shear modulus of a CO2 solid is smaller than that of a SiO2 solid of the same density. The elasticity of CO2 polymorphs shown here may hold some promise for investigating the elasticity of diverse solids consisting of oxide molecules under extreme pressure.

show abstract

Theory and Practice – Thermodynamics, Equations of State, Elasticity, and Phase Transitions of Minerals at High Pressures and Temperatures

Cited by 8 publications

References 106 publications

Thermophysical and Ultrasonic Properties on Magnesium Oxide

Thermophysical and Ultrasonic Properties on Magnesium Oxide

Super‐Earth Internal Structures and Initial Thermal States

Ab Initio Study of Elastic Properties of High-Pressure Polymorphs of CO₂ Phases II and V

Contact Info

Product

Resources

About

Theory and Practice – Thermodynamics, Equations of State, Elasticity, and Phase Transitions of Minerals at High Pressures and Temperatures

Cited by 8 publications

References 106 publications

Thermophysical and Ultrasonic Properties on Magnesium Oxide

Thermophysical and Ultrasonic Properties on Magnesium Oxide

Super‐Earth Internal Structures and Initial Thermal States

Ab Initio Study of Elastic Properties of High-Pressure Polymorphs of CO2 Phases II and V

Contact Info

Product

Resources

About

Ab Initio Study of Elastic Properties of High-Pressure Polymorphs of CO₂ Phases II and V