scholarly journals Stability field of phase Egg, AlSiO3OH at high pressure and high temperature: possible water reservoir in mantle transition zone

2017 ◽  
Vol 112 (1) ◽  
pp. 31-35 ◽  
Author(s):  
Ko FUKUYAMA ◽  
Eiji OHTANI ◽  
Yuki SHIBAZAKI ◽  
Hiroyuki KAGI ◽  
Akio SUZUKI
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Transition Zone ◽  
Water Reservoir ◽  
Stability Field ◽  
Mantle Transition Zone

scholarly journals High-pressure phase of brucite stable at Earth’s mantle transition zone and lower mantle conditions

2016 ◽  
Vol 113 (49) ◽  
pp. 13971-13976 ◽  
Author(s):  
Andreas Hermann ◽  
Mainak Mookherjee
Keyword(s):  
High Pressure ◽  
Transition Zone ◽  
Lower Mantle ◽  
Direct Detection ◽  
Geophysical Methods ◽  
High Pressure Phase ◽  
Mantle Transition Zone ◽  
Earth’S Mantle ◽  
3D Network ◽  
Pressure Phase

We investigate the high-pressure phase diagram of the hydrous mineral brucite, Mg(OH)2, using structure search algorithms and ab initio simulations. We predict a high-pressure phase stable at pressure and temperature conditions found in cold subducting slabs in Earth’s mantle transition zone and lower mantle. This prediction implies that brucite can play a much more important role in water transport and storage in Earth’s interior than hitherto thought. The predicted high-pressure phase, stable in calculations between 20 and 35 GPa and up to 800 K, features MgO6 octahedral units arranged in the anatase–TiO2 structure. Our findings suggest that brucite will transform from a layered to a compact 3D network structure before eventual decomposition into periclase and ice. We show that the high-pressure phase has unique spectroscopic fingerprints that should allow for straightforward detection in experiments. The phase also has distinct elastic properties that might make its direct detection in the deep Earth possible with geophysical methods.

scholarly journals High-pressure experiments provide insights into the Mantle Transition Zone history of chromitite in Tibetan ophiolites

2017 ◽  
Vol 463 ◽  
pp. 151-158 ◽  
Author(s):  
Yanfei Zhang ◽  
Zhenmin Jin ◽  
William L. Griffin ◽  
Chao Wang ◽  
Yao Wu
Keyword(s):  
High Pressure ◽  
Transition Zone ◽  
Mantle Transition Zone ◽  
History Of

scholarly journals In situ study of the high pressure high-temperature stability field of TaN and of the compressibilities of ϑ-TaN and TaON

2013 ◽  
Vol 33 (3) ◽  
pp. 633-641 ◽  
Author(s):  
A. Friedrich ◽  
W. Morgenroth ◽  
L. Bayarjargal ◽  
E. A. Juarez-Arellano ◽  
B. Winkler ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Temperature Stability ◽  
Stability Field ◽  
High Temperature Stability ◽  
In Situ Study ◽  
High Pressure High Temperature

Microstructural Study of Diamond Deformed Under High Pressure and Temperature

1985 ◽  
Vol 43 ◽  
pp. 230-231
Author(s):  
E. F. Koch
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Lattice Structure ◽  
Diamond Particle ◽  
Polycrystalline Diamond ◽  
Sintering Process ◽  
Ion Milling ◽  
Sintered Compact ◽  
Transmission Electron ◽  
High Pressure Sintering

Because of the extremely rigid lattice structure of diamond, generating new dislocations or moving existing dislocations in diamond by applying mechanical stress at ambient temperature is very difficult. Analysis of portions of diamonds deformed under bending stress at elevated temperature has shown that diamond deforms plastically under suitable conditions and that its primary slip systems are on the ﹛111﹜ planes. Plastic deformation in diamond is more commonly observed during the high temperature - high pressure sintering process used to make diamond compacts. The pressure and temperature conditions in the sintering presses are sufficiently high that many diamond grains in the sintered compact show deformed microtructures.In this report commercially available polycrystalline diamond discs for rock cutting applications were analyzed to study the deformation substructures in the diamond grains using transmission electron microscopy. An individual diamond particle can be plastically deformed in a high pressure apparatus at high temperature, but it is nearly impossible to prepare such a particle for TEM observation, since any medium in which the diamond is mounted wears away faster than the diamond during ion milling and the diamond is lost.

Theoretical modeling of the regular olivine intergrowths in the mimetic paramorphosis after ringwoodite and wadsleyite

2018 ◽  
pp. 3-12
Author(s):  
B. B. Shkursky
Keyword(s):  
Transition Zone ◽  
Theoretical Modeling ◽  
Mantle Transition Zone ◽  
Misorientation Angles

Theoretical modeling of regular olivine grains misorientations in mimetic paramorphoses after ringwoodite and wadsleyite, the formation of which during the ascension of matter from the Mantle Transition Zone is expected, has been carried out. The coordinates of the misorientation axes and the misorientation angles, characterizing 10 operations of alignment in the pair intergrowths of olivine grains, eight of which are twins, are calculated. Possible conditions for the formation of mimetic paramorphoses predicted here, and the chances of their persistence are discussed. The calculated orientations are compared with the known twinning laws of olivine.

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