Theoretical study of Raman modes in high-pressure phases of Si, Ge, and Sn

1993 ◽  
Vol 48 (6) ◽  
pp. 3646-3653 ◽  
Author(s):  
Steven P. Lewis ◽  
Marvin L. Cohen
Keyword(s):  
High Pressure ◽  
Theoretical Study ◽  
Raman Modes

57Fe Mössbauer isomer shift of pure iron and iron oxides at high pressure—An experimental and theoretical study

2021 ◽  
Vol 154 (21) ◽  
pp. 214104
Author(s):  
Jacques K. Desmarais ◽  
Wenli Bi ◽  
Jiyong Zhao ◽  
Michael H. Hu ◽  
Esen Alp ◽  
...  
Keyword(s):  
High Pressure ◽  
Isomer Shift ◽  
Iron Oxides ◽  
Pure Iron ◽  
Theoretical Study ◽  
57Fe Mössbauer ◽  
Mössbauer Isomer Shift

Theoretical study of ground state and high-pressure phase of platinum carbide

2008 ◽  
Vol 69 (11) ◽  
pp. 2907-2910 ◽  
Author(s):  
M. Rabah ◽  
D. Rached ◽  
M. Ameri ◽  
R. Khenata ◽  
A. Zenati ◽  
...  
Keyword(s):  
High Pressure ◽  
Ground State ◽  
Theoretical Study ◽  
High Pressure Phase ◽  
Pressure Phase

Theoretical Study on the Mechanism of Direct Transformation from Graphite to Diamond at Ultra High-Pressure and High-Temperature

2014 ◽  
Vol 151 (1) ◽  
pp. 99-107 ◽  
Author(s):  
Bin Xu ◽  
Bin Tian ◽  
Mei-zhe Lv ◽  
Xiao-hong Fan ◽  
Xiao-fei Guo ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Theoretical Study ◽  
Direct Transformation ◽  
Ultra High Pressure

Theoretical study on UH4, UH8 and UH10 at high pressure

2019 ◽  
Vol 383 (8) ◽  
pp. 774-780
Author(s):  
Dong Wang ◽  
Han Zhang ◽  
Hai-Liang Chen ◽  
Jie Wu ◽  
Qing-Jun Zang ◽  
...  
Keyword(s):  
High Pressure ◽  
Theoretical Study

Raman modes of the two-dimensional tetragonal polymeric phase of C60 under high pressure

2001 ◽  
Vol 114 (20) ◽  
pp. 9099-9104 ◽  
Author(s):  
J. Arvanitidis ◽  
K. P. Meletov ◽  
K. Papagelis ◽  
S. Ves ◽  
G. A. Kourouklis ◽  
...  
Keyword(s):  
High Pressure ◽  
Two Dimensional ◽  
Raman Modes

scholarly journals First-Principles Calculations of High-Pressure Physical Properties of Ti0.5Ta0.5 Alloy

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 796
Author(s):  
Fang Yu ◽  
Yu Liu
Keyword(s):  
High Pressure ◽  
Physical Properties ◽  
First Principles ◽  
Theoretical Study ◽  
Applied Pressure ◽  
Lattice Parameter ◽  
Physical Parameters ◽  
First Principles Calculations ◽  
Analysis Method ◽  
Metallic Bond

In this paper, an in-depth theoretical study on some physical properties of Ti0.5Ta0.5 alloy with systematic symmetry under high pressure is conducted via first-principles calculations, and relevant physical parameters are calculated. The results demonstrate that the calculated parameters, including lattice parameter, elastic constants, and elastic moduli, fit well with available theoretical and experimental data when the Ti0.5Ta0.5 alloy is under T = 0 and P = 0 , indicating that the theoretical analysis method can effectively predict the physical properties of the Ti0.5Ta0.5 alloy. The microstructure and macroscopic physical properties of the alloy cannot be destroyed as the applied pressure ranges from 0 to 50GPa, but the phase transition of crystal structure may occur in the Ti0.5Ta0.5 alloy if the applied pressure continues to increase according to the TDOS curves and charge density diagram. The value of Young’s and shear modulus is maximized at P = 25   GPa . The anisotropy factors A ( 100 ) [ 001 ] and A ( 110 ) [ 001 ] are equal to 1, suggesting the Ti0.5Ta0.5 alloy is an isotropic material at 28 GPa, and the metallic bond is strengthened under high pressure. The present results provide helpful insights into the physical properties of Ti0.5Ta0.5 alloy.

scholarly journals Phase Stability and Vibrational Properties of Iron-Bearing Carbonates at High Pressure

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1142
Author(s):  
Chaoshuai Zhao ◽  
Liangxu Xu ◽  
Weibin Gui ◽  
Jin Liu
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Spin Transition ◽  
Laser Raman ◽  
Electronic Spin ◽  
Pressure Medium ◽  
Raman Modes ◽  
Sample Chamber ◽  
The Stability ◽  
Iron Bearing

The spin transition of iron can greatly affect the stability and various physical properties of iron-bearing carbonates at high pressure. Here, we reported laser Raman measurements on iron-bearing dolomite and siderite at high pressure and room temperature. Raman modes of siderite FeCO3 were investigated up to 75 GPa in the helium (He) pressure medium and up to 82 GPa in the NaCl pressure medium, respectively. We found that the electronic spin-paring transition of iron in siderite occurred sharply at 42–44 GPa, consistent with that in the neon (Ne) pressure medium in our previous study. This indicated that the improved hydrostaticity from Ne to He had minimal effects on the spin transition pressure. Remarkably, the spin crossover of siderite was broadened to 38–48 GPa in the NaCl pressure medium, due to the large deviatoric stress in the sample chamber. In addition, Raman modes of iron-bearing dolomite Ca1.02Mg0.76Fe0.20Mn0.02(CO3)2 were explored up to 58 GPa by using argon as a pressure medium. The sample underwent phase transitions from dolomite-Ⅰ to -Ⅰb phase at ~8 GPa, and then to -Ⅱ at ~15 and -Ⅲb phase at 36 GPa, while no spin transition was observed in iron-bearing dolomite up to 58 GPa. The incorporation of FeCO3 by 20 mol% appeared to marginally decrease the onset pressures of the three phase transitions aforementioned for pure dolomite. At 55–58 GPa, the ν1 mode shifted to a lower frequency at ~1186 cm−1, which was likely associated with the 3 + 1 coordination in dolomite-Ⅲb. These results shed new insights into the nature of iron-bearing carbonates at high pressure.

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