scholarly journals Characterization of the High-Pressure and High-Temperature Phase Diagram and Equation of State of Chromium

2021 ◽  
Author(s):  
Simone Anzellini ◽  
Daniel Errandonea ◽  
Leonid Burakovsky ◽  
John E. Proctor ◽  
Christine M. Beavers
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Equation Of State ◽  
Density Functional ◽  
Equations Of State ◽  
Melting Curve ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Thermal Equation ◽  
Pressure Derivative

Abstract The high-pressure and high-temperature melting curve of chromium has been investigated both experimentally (in situ), using a laser-heated diamond-anvil cell technique coupled with synchrotron powder X-ray diffraction, and theoretically, using ab initio density-functional theory simulations. In the pressure–temperature range covered experimentally (up to 90 GPa and 4500 K, respectively) only the solid body-centred-cubic and liquid phases of chromium have been observed. Experiments and computer calculations give melting curves in agreement with each other, that can be described by a Simon–Glatzel equation Tm(P) = 2136K(1+P/25.9) 0.41. In addition, a quasi-hydrostatic equation of state at ambient temperature has been experimentally characterized up to 131 GPa and compared with the present simulations. Both methods give very similar third-order Birch-Murnaghan equations of state with a bulk modulus of 182-185 GPa and its pressure derivative of 4.74-5.15. According to the present calculations, the obtained melting curve and equation of state are valid at least up to 815 GPa, being the melting temperature at this pressure 9310 K. Finally, from the obtained results, it was possible to determine a thermal equation of state of chromium valid up to 65 GPa and 2100 K.

scholarly journals Equation of state and high-pressure/high-temperature phase diagram of magnesium

2014 ◽  
Vol 90 (13) ◽  
Author(s):  
G. W. Stinton ◽  
S. G. MacLeod ◽  
H. Cynn ◽  
D. Errandonea ◽  
W. J. Evans ◽  
...  
Keyword(s):  
Phase Diagram ◽  
High Pressure ◽  
High Temperature ◽  
Equation Of State ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
High Pressure High Temperature ◽  
Temperature Phase Diagram

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.

High pressure–high temperature phase diagram of InSe

2004 ◽  
Vol 24 (1) ◽  
pp. 111-116 ◽  
Author(s):  
G. Ferlat ◽  
D. Martínez-García ◽  
A. San Miguel ◽  
A. Aouizerat ◽  
V. Muñoz-Sanjosé
Keyword(s):  
Phase Diagram ◽  
High Pressure ◽  
High Temperature ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
High Pressure High Temperature ◽  
Temperature Phase Diagram

Notizen: Einkristall-Daten der Hochdruck-Hochtemperaturphase von CaSi2 / Structural Refinement of the High Pressure-High Temperature Phase of CaSi2

1982 ◽  
Vol 37 (11) ◽  
pp. 1487-1488 ◽  
Author(s):  
Jürgen Evers ◽  
Gilbert Oehlinger ◽  
Armin Weiss
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Single Crystals ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Structural Refinement ◽  
Interatomic Distances ◽  
High Pressure High Temperature

The high pressure-high temperature phase of CaSi2 is a representative of the α-ThSi2 type of structure. Single crystals grown at 40 kbar and 1000 °C enabled a structural refinement which leads to interatomic distances Si-Si: 229.9(1) pm (1 × ) and 240.0(1) pm (2 × ), Ca-Si: 309.4(4) pm (4 x ) and 323.9(4) pm (8 × ), Ca-Ca: 400.3(3) pm (4 × ) and 428.3(3) pm (4 × ).

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