The thermodynamics of several elements at high pressure

Karbasi, Ali; Saxena, Surendra K.; Hrubiak, Rostislav

doi:10.1016/j.calphad.2010.11.007

Cited by 38 publications

(18 citation statements)

References 130 publications

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“…The exotic highpressure behavior of Li and Na also falls outside the scope of this review (Rousseau et al, 2011). Further, we will not cover works on the equation of state, e.g., as discussed by Karbasi, Saxena, and Hrubiak (2011) for several stable metallic elements.…”

Section: Appendix I: Pesudomorphic Epitaxymentioning

confidence: 99%

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Lattice instabilities in metallic elements

et al. 2012

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Most metallic elements have a crystal structure that is either body-centered cubic (bcc), facecentered close packed, or hexagonal close packed. If the bcc lattice is the thermodynamically most stable structure, the close-packed structures usually are dynamically unstable, i.e., have elastic constants violating the Born stability conditions or, more generally, have phonons with imaginary frequencies. Conversely, the bcc lattice tends to be dynamically unstable if the equilibrium structure is close packed. This striking regularity essentially went unnoticed until ab initio total-energy calculations in the 1990s became accurate enough to model dynamical properties of solids in hypothetical lattice structures. After a review of stability criteria, thermodynamic functions in the vicinity of an instability, Bain paths, and how instabilities may arise or disappear when pressure, temperature, and/or chemical composition is varied are discussed. The role of dynamical instabilities in the ideal strength of solids and in metallurgical phase diagrams is then considered, and comments are made on amorphization, melting, and low-dimensional systems. The review concludes with extensive references to theoretical work on the stability properties of metallic elements.

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Section: Appendix I: Pesudomorphic Epitaxymentioning

confidence: 99%

“…The equation of state VðP; TÞ for stable structures of several metallic elements has been discussed by, e.g., Karbasi, Saxena, and Hrubiak (2011).…”

Section: Pressure Effects a General Aspectsmentioning

confidence: 99%

Lattice instabilities in metallic elements

et al. 2012

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“…Nevertheless, it has been shown that HT-BM3-EOS is prone to giving spurious effects or anomalous predictions (i.e., negative thermal expansion) at very HP-HT conditions [63,113]. This has led different authors to develop alternative formulations (more or less empirical) to describe the P-V-T relations of minerals up to planetary interior conditions [4,63,78,[113][114][115][116][117][118][119]. Even though negative thermal expansion is obviously possible from a physical point of view as different minerals and compounds display a volume decrease with T not just in the low-P range [25,120], this phenomenon is systematically predicted by the HT-BM3-EOS at very HP-HT conditions.…”

Section: Phase Equilibrium Calculation At Hp-ht: Modelling High-pressmentioning

confidence: 99%

First Principles Thermodynamics of Minerals at HP–HT Conditions: MgO as a Prototypical Material

Belmonte

2017

Minerals

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Ab initio thermodynamic properties, equation of state and phase stability of periclase (MgO, B1-type structure) have been investigated in a broad P-T range (0-160 GPa; 0-3000 K) in order to set a model reference system for phase equilibria simulations under deep Earth conditions. Phonon dispersion calculations performed on large supercells using the finite displacement method and in the framework of quasi-harmonic approximation highlight the performance of the Becke three-parameter Lee-Yang-Parr (B3LYP) hybrid density functional in predicting accurate thermodynamic functions (heat capacity, entropy, thermal expansivity, isothermal bulk modulus) and phase reaction boundaries at high pressure and temperature. A first principles Mie-Grüneisen equation of state based on lattice vibrations directly provides a physically-consistent description of thermal pressure and P-V-T relations without any need to rely on empirical parameters or other phenomenological formalisms that could give spurious anomalies or uncontrolled extrapolations at HP-HT. The post-spinel phase transformation, Mg 2 SiO 4 (ringwoodite) = MgO (periclase) + MgSiO 3 (bridgmanite), is taken as a computational example to illustrate how first principles theory combined with the use of hybrid functionals is able to provide sound results on the Clapeyron slope, density change and P-T location of equilibrium mineral reactions relevant to mantle dynamics.

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“…Mo has been the subject of first-principles theoretical studies to explore various properties such as the crystal structure, melting and elasticity at extreme conditions [22][23][24][25][26][27] . It also serves as a test case to understand the general behavior of transition elements at high levels of compression 23,28,29 . The crystal structure is the most fundamental property of a solid material and controls its physical and chemical behavior.…”

Section: Introductionmentioning

confidence: 99%

X-ray diffraction of molybdenum under ramp compression to 1 TPa

et al. 2016

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Molybdenum (Mo) is a transition metal with a wide range of technical applications. There has long been strong interest in its high-pressure behavior and it is often used as standard for high-pressure experiments. Combining powder x-ray diffraction and dynamic ramp compression, structural and equation of state data were collected for solid Mo to 1 TPa (10 Mbar). Diffraction results are consistent with Mo remaining in the body-centered cubic structure into the TPa regime. Stress-density data show that Mo under ramp loading is less compressible than the room-temperature isotherm but more compressible than the single-shock Hugoniot.

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The thermodynamics of several elements at high pressure

Cited by 38 publications

References 130 publications

Lattice instabilities in metallic elements

Lattice instabilities in metallic elements

First Principles Thermodynamics of Minerals at HP–HT Conditions: MgO as a Prototypical Material

X-ray diffraction of molybdenum under ramp compression to 1 TPa

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