scholarly journals On the electronic structure and equation of state in high pressure studies of solids

2003 ◽  
Vol 26 (1) ◽  
pp. 175-181 ◽  
Author(s):  
B. K. Godwal ◽  
P. Modak ◽  
R. S. Rao
Keyword(s):  
High Pressure ◽  
Electronic Structure ◽  
Equation Of State ◽  
High Pressure Studies

High-pressure studies of MgTe using first-principle electronic-structure calculations

1999 ◽  
Vol 60 (17) ◽  
pp. 11846-11847 ◽  
Author(s):  
Chhanda Basu Chaudhuri ◽  
G. Pari ◽  
Abhijit Mookerjee ◽  
A. K. Bhattacharyya
Keyword(s):  
High Pressure ◽  
Electronic Structure ◽  
Electronic Structure Calculations ◽  
First Principle ◽  
High Pressure Studies ◽  
Structure Calculations

scholarly journals Local-Basis-Function Equation of State for Ice VII–X to 450 GPa at 300 K

Minerals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 92 ◽  
Author(s):  
J. Michael Brown ◽  
Baptiste Journaux
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Alternative Hypothesis ◽  
Experimental Studies ◽  
Current Method ◽  
Helmholtz Energy ◽  
Proton Mobility ◽  
Pressure Derivative ◽  
Local Basis ◽  
High Pressure Studies

Helmholtz energy of ice VII–X is determined in a pressure regime extending to 450 GPa at 300 K using local-basis-functions in the form of b-splines. The new representation for the equation of state is embedded in a physics-based inverse theory framework of parameter estimation. Selected pressures as a function of volume from 14 prior experimental studies and two theoretical studies constrain the behavior of Helmholtz energy. Separately measured bulk moduli, not used to construct the representation, are accurately replicated below about 20 GPa and above 60 GPa. In the intermediate range of pressure, the experimentally determined moduli are larger and have greater scatter than values predicted using the Helmholtz representation. Although systematic error in the determination of elastic moduli is possible and likely, the alternative hypothesis is a slow relaxation time associated with changes in proton mobility or the ice VII to X transition. A correlation is observed between anomalies in the pressure derivative of the predicted bulk modulus and previously suggested higher-order phase transitions. Improved determinations of elastic properties at high pressure would allow refinement of the current equation of state. More generally, the current method of data assimilation is broadly applicable to other materials in high-pressure studies and for investigations of planetary interiors.

scholarly journals Local-Basis-Function Equation of State for Ice VII-X to 450 GPa at 300 K

2019 ◽  
Author(s):  
J. Michael Brown ◽  
Baptiste Journaux
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Alternative Hypothesis ◽  
Experimental Studies ◽  
Current Method ◽  
Helmholtz Energy ◽  
Proton Mobility ◽  
Pressure Derivative ◽  
Local Basis ◽  
High Pressure Studies

Helmholtz energy of ice VII-X is determined in a pressure regime extending to 450 GPa at 300 K using local basis functions in the form of b splines. The new representation for the equation of state is embedded in a physics-based inverse theory framework of parameter estimation. Selected pressures as a function of volume from 14 prior experimental studies and two theoretical studies constrain the behavior of Helmholtz energy. Separately measured bulk moduli, not used to construct the representation, are accurately replicated below about 20 GPa and above 60 GPa. In the intermediate range of pressure, the experimentally determined moduli are larger and have greater scatter than values predicted using the Helmholtz representation. Although systematic experimental error in the experimental elastic moduli is possible and likely, the alternative hypothesis is a slow relaxation time associated with changes in proton mobility or the ice VII to X transition. A correlation is observed between anomalies in the pressure derivative of the predicted bulk modulus and previously suggested higher-order phase transitions. Improved determinations of elastic properties at high pressure would allow refinement of the current equation of state. More generally, the current method of data assimilation is broadly applicable to other materials in high-pressure studies.

Equation of state of polycrystalline Ni50Al50

1997 ◽  
Vol 12 (11) ◽  
pp. 3106-3108 ◽  
Author(s):  
J. W. Otto ◽  
J. K. Vassiliou ◽  
G. Frommeyer
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Bulk Modulus ◽  
Diamond Anvil Cell ◽  
Inert Gas ◽  
X Ray Diffraction ◽  
Pressure Derivative ◽  
X Ray ◽  
High Pressure Studies ◽  
Diamond Anvil

Polycrystalline Ni50Al50 suitable for high pressure studies was prepared by grinding and subsequent annealing of an inert-gas atomized alloy. The equation of state was determined by energy-dispersive x-ray diffraction in a diamond anvil cell to 25 GPa. The bulk modulus Bo and the pressure derivative of the bulk modulus B′o were found to be Bo = 156 ± 3 GPa and B′o = 4.0 ± 0.5.

Equation of state and electronic structure of solid CaO under high pressure

1986 ◽  
Vol 115 (6) ◽  
pp. 287-291 ◽  
Author(s):  
Juichiro Hama ◽  
Masaaki Watanabe
Keyword(s):  
High Pressure ◽  
Electronic Structure ◽  
Equation Of State

Powder processing of ductile materials for high pressure studies: application to intermetallic alloys

1997 ◽  
Vol 499 ◽  
Author(s):  
J. W. Otto ◽  
G. Frommeyer ◽  
J. K. Vassiliou
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Mechanical Alloying ◽  
Powder Processing ◽  
Gas Atomization ◽  
Intermetallic Alloys ◽  
Pressure Work ◽  
Ductile Materials ◽  
High Pressure Studies ◽  
Good Agreement

ABSTRACTDuctile materials are difficult to powderize for use in high pressure work. The potential of different techniques (gas-atomization, mechanical alloying, ball milling and subsequent annealing) for preparing suitable powders of some aluminides is investigated. Compression of Ti46Al54 and NiAl prepared by these methods yields equation of state parameters in good agreement with determinations by other methods.

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