Elasticity of single-crystal NAL phase at high pressure: A potential source of the seismic anisotropy in the lower mantle

2016 ◽  
Vol 121 (8) ◽  
pp. 5696-5707 ◽  
Author(s):  
Ye Wu ◽  
Jing Yang ◽  
Xiang Wu ◽  
Maoshuang Song ◽  
Takashi Yoshino ◽  
...  
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
Lower Mantle ◽  
Seismic Anisotropy ◽  
Potential Source ◽  
Nal Phase

Elasticity of single-crystal low water content hydrous pyrope at high-pressure and high-temperature conditions

2019 ◽  
Vol 104 (7) ◽  
pp. 1022-1031 ◽  
Author(s):  
Dawei Fan ◽  
Jingui Xu ◽  
Chang Lu ◽  
Sergey N. Tkachev ◽  
Bo Li ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Single Crystal ◽  
Upper Mantle ◽  
Room Temperature ◽  
Seismic Anisotropy ◽  
Ambient Pressure ◽  
Seismic Velocities ◽  
Shear Moduli ◽  
Derivatives Of

Abstract The elasticity of single-crystal hydrous pyrope with ~900 ppmw H2O has been derived from sound velocity and density measurements using in situ Brillouin light spectroscopy (BLS) and synchrotron X-ray diffraction (XRD) in the diamond-anvil cell (DAC) up to 18.6 GPa at room temperature and up to 700 K at ambient pressure. These experimental results are used to evaluate the effect of hydration on the single-crystal elasticity of pyrope at high pressure and high temperature (P-T) conditions to better understand its velocity profiles and anisotropies in the upper mantle. Analysis of the results shows that all of the elastic moduli increase almost linearly with increasing pressure at room temperature, and decrease linearly with increasing temperature at ambient pressure. At ambient conditions, the aggregate adiabatic bulk and shear moduli (KS0, G0) are 168.6(4) and 92.0(3) GPa, respectively. Compared to anhydrous pyrope, the presence of ~900 ppmw H2O in pyrope does not significantly affect its KS0 and G0 within their uncertainties. Using the third-order Eulerian finite-strain equation to model the elasticity data, the pressure derivatives of the bulk [(∂KS/∂P)T] and shear moduli [(∂G/∂P)T] at 300 K are derived as 4.6(1) and 1.3(1), respectively. Compared to previous BLS results of anhydrous pyrope, an addition of ~900 ppmw H2O in pyrope slightly increases the (∂KS/∂P)T, but has a negligible effect on the (∂G/∂P)T within their uncertainties. The temperature derivatives of the bulk and shear moduli at ambient pressure are (∂KS/∂T)P = –0.015(1) GPa/K and (∂G/∂T)P = –0.008(1) GPa/K, which are similar to those of anhydrous pyrope in previous BLS studies within their uncertainties. Meanwhile, our results also indicate that hydrous pyrope remains almost elastically isotropic at relevant high P-T conditions, and may have no significant contribution to seismic anisotropy in the upper mantle. In addition, we evaluated the seismic velocities (νP and νS) and the νP/νS ratio of hydrous pyrope along the upper mantle geotherm and a cold subducted slabs geotherm. It displays that hydrogen also has no significant effect on the seismic velocities and the νP/νS ratio of pyrope at the upper mantle conditions.

scholarly journals Perspective for elasticity of minerals in the Earth's top lower mantle

2020 ◽  
Author(s):  
Zhu Mao ◽  
Ningyu Sun ◽  
Wei Wei
Keyword(s):  
High Pressure ◽  
Lower Mantle ◽  
Seismic Anisotropy ◽  
Theoretical Work ◽  
Low Velocity ◽  
Mantle Composition ◽  
Temperature Conditions ◽  
Recent Advances

Abstract The elasticity of minerals under high pressure-temperature conditions is crucial for constraining mantle composition. This perspective highlights recent advances in experimental and theoretical work in determining the elasticity of minerals to resolve the origin of low-velocity layers and the seismic anisotropy in the top lower mantle.

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

scholarly journals Single Crystal Growth and Physical Properties of Pyroxene CoGeO3

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 378
Author(s):  
Li Zhao ◽  
Zhiwei Hu ◽  
Hanjie Guo ◽  
Christoph Geibel ◽  
Hong-Ji Lin ◽  
...  
Keyword(s):  
High Pressure ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Crystal Growth ◽  
Physical Properties ◽  
Single Crystal ◽  
Single Crystals ◽  
Magnetic Moments ◽  
Single Crystal Growth ◽  
The Impact

We report on the synthesis and physical properties of cm-sized CoGeO3 single crystals grown in a high pressure mirror furnace at pressures of 80 bar. Direction dependent magnetic susceptibility measurements on our single crystals reveal highly anisotropic magnetic properties that we attribute to the impact of strong single ion anisotropy appearing in this system with TN∼33.5 K. Furthermore, we observe effective magnetic moments that are exceeding the spin only values of the Co ions, which reveals the presence of sizable orbital moments in CoGeO3.

scholarly journals From Slater to Mott physics by epitaxially engineering electronic correlations in oxide interfaces

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Carla Lupo ◽  
Evan Sheridan ◽  
Edoardo Fertitta ◽  
David Dubbink ◽  
Chris J. Pickard ◽  
...  
Keyword(s):  
Phase Diagram ◽  
High Pressure ◽  
Charge Transfer ◽  
Lower Mantle ◽  
Random Structure ◽  
Titanium Oxides ◽  
Oxide Interfaces ◽  
Electronic Correlations ◽  
Epitaxial Strain ◽  
Magnetic Switching

AbstractUsing spin-assisted ab initio random structure searches, we explore an exhaustive quantum phase diagram of archetypal interfaced Mott insulators, i.e. lanthanum-iron and lanthanum-titanium oxides. In particular, we report that the charge transfer induced by the interfacial electronic reconstruction stabilises a high-spin ferrous Fe2+ state. We provide a pathway to control the strength of correlation in this electronic state by tuning the epitaxial strain, yielding a manifold of quantum electronic phases, i.e. Mott-Hubbard, charge transfer and Slater insulating states. Furthermore, we report that the electronic correlations are closely related to the structural oxygen octahedral rotations, whose control is able to stabilise the low-spin state of Fe2+ at low pressure previously observed only under the extreme high pressure conditions in the Earth’s lower mantle. Thus, we provide avenues for magnetic switching via THz radiations which have crucial implications for next generation of spintronics technologies.

scholarly journals Epitaxial lateral growth of single-crystal diamond under high pressure by a plate-to-plate MPCVD

2021 ◽  
Vol 1 (1) ◽  
pp. 143-149
Author(s):  
Wei Cao ◽  
Deng Gao ◽  
Hongyang Zhao ◽  
Zhibin Ma
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
Lateral Growth ◽  
Single Crystal Diamond

scholarly journals Magnetic Properties and Single Crystal Growth of a Spin Gapped Compound, High Pressure Phase of (VO)2P2O7.

1999 ◽  
Vol 46 (9) ◽  
pp. 1014-1019
Author(s):  
Takashi Saito ◽  
Masaki Azuma ◽  
Mikio Takano ◽  
Zenji Hiroi ◽  
Yasuo Narumi ◽  
...  
Keyword(s):  
High Pressure ◽  
Magnetic Properties ◽  
Crystal Growth ◽  
Single Crystal ◽  
Single Crystal Growth ◽  
High Pressure Phase ◽  
Pressure Phase
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