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.

scholarly journals Elastic Behaviour of Diborides Under High Pressure

2009 ◽  
Vol 1 (2) ◽  
pp. 275-280
Author(s):  
Seema Gupta ◽  
S. C. Goyal
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Statistical Model ◽  
Bulk Modulus ◽  
Electron Gas ◽  
Elastic Behaviour ◽  
Pressure Derivative ◽  
First Order ◽  
Elastic Data ◽  
Quantum Statistical

The present study deals with the elastic behaviour of diborides (BeB2, MgB2 and NbB2) under high pressure with the help of equation of state (EOS) using the elastic data reported by Islam et al. It is concluded that EOS, which are based either on quantum statistical model or  pseduopotential model, only are capable of explaining high pressure behaviour of the solids under study.  Moreover the value of first order pressure derivative of bulk modulus at infinite pressure (Kinfinity) is greater than 5/3 and thus the diborides under study do not behave as Thomas-Fermi electron gas under high compression. Keywords: Equation of state; High Pressure; Diborides. © 2009 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v1i2.1189 

scholarly journals High-pressure diffraction studies of molecular organic solids. A personal view

2007 ◽  
Vol 64 (1) ◽  
pp. 218-231 ◽  
Author(s):  
Elena V. Boldyreva
Keyword(s):  
High Pressure ◽  
Solid State ◽  
High Pressures ◽  
Experimental Studies ◽  
Personal View ◽  
Organic Solids ◽  
High Pressure Studies

This paper discusses the trends in the experimental studies of molecular organic solids at high pressures by diffraction techniques. Crystallization of liquids, crystallization from solutions and solid-state transformations are considered. Special attention is paid to the high-pressure studies of pharmaceuticals and of biomimetics.

Compressibility of the high-pressure polymorph of AlOOH to 17 GPa

2009 ◽  
Vol 73 (3) ◽  
pp. 479-485 ◽  
Author(s):  
A. Suzuki
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Neutron Diffraction ◽  
Bulk Modulus ◽  
Diffraction Study ◽  
Neutron Diffraction Study ◽  
X Ray Diffraction ◽  
Pressure Derivative ◽  
X Ray ◽  
A Value

AbstractThe equation of state of δ-AlOOH was investigated using powder X-ray diffraction up to 17 GPa. Measurement of the volume at 300 K gave a value of the bulk modulus of K0 = 124(2) GPa, whereas its pressure derivative was K’ = 13.5(7). The b axis of the unit cell is more compressible than the a and c axes – in agreement with a neutron diffraction study at high pressure by Sano-Furukawa et al. (2008). Measurements presented here show that δ-AlOOH has a compressibility 200% higher than in the previously reported equation of state by Vanpeteghem et al. (2002).

scholarly journals Delamination in Tibet: Deriving constraints from the density of eclogite

2021 ◽  
Author(s):  
Zhilin Ye ◽  
Dawei Fan ◽  
Bo Li ◽  
Qizhe Tang ◽  
Jingui Xu ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Equation Of State ◽  
Lower Crust ◽  
Gravitational Instability ◽  
Volume Data ◽  
Thermal Equation ◽  
Pressure Derivative ◽  
Temperature Conditions ◽  
Slab Breakoff

Abstract. Tibet, which is characterized by collisional orogens, has undergone the process of delamination or convective removal. The lower crust and mantle lithosphere appear to have been removed through delamination during orogenic development. Numerical and analog experiments demonstrate that the metamorphic eclogitized oceanic subduction slab or lower crust may promote gravitational instability due to its increased density. The eclogitized oceanic subduction slab or crustal root is believed to be denser than the underlying mantle and tends to sink. However, the density of eclogite under high-pressure and high-temperature conditions and density differences from the surrounding mantle is not preciously constrained. Here, we offer new insights into the derivation of eclogite density with a single experiment to constrain delamination in Tibet. Using in situ synchrotron X-ray diffraction combined with diamond anvil cell, experiments focused on minerals (garnet, omphacite, and epidote) of eclogite are conducted under simultaneous high-pressure and high-temperature conditions, which avoids systematic errors. Fitting the pressure-temperature-volume data with the third-order Birch-Murnaghan equation of state, the thermal equation of state (EoS) parameters, including the bulk modulus (KT0), its pressure derivative (KT0′), the temperature derivative ((KT/T)P), and the thermal expansion coefficient (α0), are derived. The densities of rock-forming minerals and eclogite are modeled along with the geotherms of two types of delamination. The delamination processes of subduction slab breakoff and the removal of the eclogitized lower crust in Tibet are discussed. The Tibetan eclogite which containing 40–60 vol. % garnet and 37–64 % degrees of eclogitization can promote the delamination of slab break-off in Tibet. Our results indicate that eclogite is a major controlling factor in the initiation of delamination. A high abundance of garnet, a high Fe-content, and a high degree of eclogitization are more conducive to instigating the delamination.

Equation of state and some other properties of rock-salt AlN

2018 ◽  
Vol 6 (1) ◽  
pp. 49
Author(s):  
Salah Daoud ◽  
Rabie Mezouar ◽  
Abdelfateh Benmakhlouf
Keyword(s):  
Heat Capacity ◽  
High Pressure ◽  
Equation Of State ◽  
Bulk Modulus ◽  
Temperature Dependence ◽  
Rock Salt ◽  
Thermophysical Properties ◽  
Constant Pressure ◽  
Isothermal Bulk Modulus ◽  
Pressure Derivative

The object of the present work is to study the equation of state (EOS) and the temperature dependence of the vibrational constant pressure heat capacity, the adiabatic bulk modulus Bs and the pressure derivative of the isothermal bulk modulus of cubic rock-salt Aluminum nitride under high pressure up to 100 GPa. In addition, the isothermal bulk modulus and the Debye temperature θD versus pressure at 1800 K are presented. Some structural and thermophysical properties used here are taken from our previous paper published in J. Electron. Mater. (2018) DOI: 10.1007/s11664-018-6169-x. The results obtained are analyzed and compared with other data of the literature.  

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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