Scheelite to fergusonite phase transition inYLiF4at high pressures

2002 ◽  
Vol 65 (10) ◽  
Author(s):  
A. Grzechnik ◽  
K. Syassen ◽  
I. Loa ◽  
M. Hanfland ◽  
J. Y. Gesland
Keyword(s):  
Phase Transition ◽  
High Pressures

scholarly journals Crystal and electronic structure engineering of tin monoxide by external pressure

2021 ◽  
Author(s):  
Kun Li ◽  
Junjie Wang ◽  
Vladislav A. Blatov ◽  
Yutong Gong ◽  
Naoto Umezawa ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Band Gap ◽  
High Pressures ◽  
Low Pressure ◽  
Widespread Application ◽  
Space Group ◽  
Tin Monoxide ◽  
High Possibility ◽  
Pressure Phase

AbstractAlthough tin monoxide (SnO) is an interesting compound due to its p-type conductivity, a widespread application of SnO has been limited by its narrow band gap of 0.7 eV. In this work, we theoretically investigate the structural and electronic properties of several SnO phases under high pressures through employing van der Waals (vdW) functionals. Our calculations reveal that a metastable SnO (β-SnO), which possesses space group P21/c and a wide band gap of 1.9 eV, is more stable than α-SnO at pressures higher than 80 GPa. Moreover, a stable (space group P2/c) and a metastable (space group Pnma) phases of SnO appear at pressures higher than 120 GPa. Energy and topological analyses show that P2/c-SnO has a high possibility to directly transform to β-SnO at around 120 GPa. Our work also reveals that β-SnO is a necessary intermediate state between high-pressure phase Pnma-SnO and low-pressure phase α-SnO for the phase transition path Pnma-SnO →β-SnO → α-SnO. Two phase transition analyses indicate that there is a high possibility to synthesize β-SnO under high-pressure conditions and have it remain stable under normal pressure. Finally, our study reveals that the conductive property of β-SnO can be engineered in a low-pressure range (0–9 GPa) through a semiconductor-to-metal transition, while maintaining transparency in the visible light range.

Neutron scattering study of the phase transition in 1,3 cyclohexanedione crystals at ambient and high pressures

1996 ◽  
Vol 196 (1) ◽  
pp. 39-47
Author(s):  
L. Bobrowicz ◽  
A. Katrusiak ◽  
W. Nawrocik ◽  
J. Wasicki ◽  
I. Natkaniec
Keyword(s):  
Phase Transition ◽  
Neutron Scattering ◽  
High Pressures ◽  
Scattering Study ◽  
Neutron Scattering Study

scholarly journals Theoretical and Experimental Evidence for a Post-Cotunnite Phase Transition in Hafnia at High Pressures

2018 ◽  
Vol 40 (6) ◽  
pp. 374-383 ◽  
Author(s):  
Yahya Al-Khatatbeh ◽  
Khaldoun Tarawneh ◽  
Hussein Al-Taani ◽  
Kanani K. M. Lee
Keyword(s):  
Phase Transition ◽  
Experimental Evidence ◽  
High Pressures

Phase transition and superconductivity in ReS2, ReSe2 and ReTe2

2018 ◽  
Vol 20 (46) ◽  
pp. 29472-29479 ◽  
Author(s):  
Jurong Zhang ◽  
Ermiao Sun ◽  
Xiaolei Feng ◽  
Hanyu Liu ◽  
Simon A. T. Redfern ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
High Pressures ◽  
Trigonal Prism ◽  
Coordination Environment

Five energetically stable phases of P1̄′, P63/mmc, I41/amd, I4/mmm and I4/mmm′ were predicted in the ReX2 family of compounds at high pressures. The coordination environment of a Re atom changes from a ReX6 octahedron or a trigonal prism to a ReX8 cuboid coordination with increasing pressure. The high-pressure metallic phases of ReX2 exhibit superconductivity.

Sound velocity of neon at high pressures and temperatures by Brillouin scattering

2019 ◽  
Vol 104 (11) ◽  
pp. 1650-1655
Author(s):  
Wei Wei ◽  
Xinyang Li ◽  
Ningyu Sun ◽  
Sergey N. Tkachev ◽  
Zhu Mao
Keyword(s):  
Phase Transition ◽  
High Pressures ◽  
Velocity Structure ◽  
Solid Phase ◽  
Brillouin Scattering ◽  
Compressional Wave ◽  
Rare Gases ◽  
Apparent Reduction ◽  
Diamond Anvil ◽  
Increasing Temperature

Abstract In this study, we have determined the combined effect of pressure and temperature on the compressional-wave velocity (VP) of Ne up to 53 GPa and 1100 K using Brillouin scattering in externally heated diamond-anvil cells. The phase transition from the supercritical fluid to solid phase was observed to cause a 10.5–11% jump in VP, and the magnitude in the VP contrast across the phase transition increases with temperature. In addition, we have observed an abnormal reduced increase rate of VP with pressure in the supercritical Ne fluid at both 800 and 1100 K before the transition to the solid phase. VP of the solid Ne exhibits a nonlinear increase with pressure at all the investigated temperatures. The elevating temperature was noted to cause an apparent reduction in VP, yet the reduction in VP caused by increasing temperature dramatically decreases at higher pressures. At 20 GPa, increasing temperature by 100 K can lower the VP of Ne by 2.4%. Yet elevating temperature by 100 K can only reduce the VP by 0.4% at 50 GPa. We further compare VP of Ne to that of other rare gases, including Ar, Kr, and Xe. At 300 K, VP of Ne shows a stronger dependence on pressure than both Kr and Xe. Moreover, increasing temperature can produce a greater reduction in VP of Ne than that of Ar below 50 GPa. Our measured VP of Ne is also useful for understanding the velocity structure of giant planets, such as Jupiter.

scholarly journals Isostructural Second-Order Phase Transition of β-Bi2O3 at High Pressures: An Experimental and Theoretical Study

2014 ◽  
Vol 118 (40) ◽  
pp. 23189-23201 ◽  
Author(s):  
A. L. J. Pereira ◽  
J. A. Sans ◽  
R. Vilaplana ◽  
O. Gomis ◽  
F. J. Manjón ◽  
...  
Keyword(s):  
Phase Transition ◽  
Order Phase Transition ◽  
High Pressures ◽  
Theoretical Study ◽  
Second Order ◽  
Second Order Phase Transition

OPTICAL PROPERTIES OF ANATASE TiO2 UNDER THE HIGH PRESSURE

2001 ◽  
Vol 15 (28n30) ◽  
pp. 3952-3955 ◽  
Author(s):  
TAKAO SEKIYA ◽  
SHINSUKE OHTA ◽  
SUSUMU KURITA
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Optical Properties ◽  
Lower Energy ◽  
Luminescence Band ◽  
High Pressures ◽  
Anatase Tio2 ◽  
Broad Luminescence Band ◽  
Pressure Phase ◽  
Energy Side

Optical absorption, luminescence and Raman spectra were measured for anatase TiO 2 under high pressures. The pressure dependence of Raman frequencies is determined. The absorption edge of anatase shifts to higher energy side with increasing pressure and the edge jumps abruptly to lower energy side on the phase transition. A broad luminescence band of anatase shifts also to higher energy side with increasing pressure. These experimental results reveal that the pressure-induced phase transition from anatase to high-pressure phase arises in the range of 4.0-4.6 GPa.

LEAD-CHALCOGENIDES UNDER PRESSURE: AB-INITIO STUDY

2013 ◽  
Vol 22 ◽  
pp. 612-618 ◽  
Author(s):  
DINESH C. GUPTA ◽  
IDRIS HAMID
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Ab Initio ◽  
Band Gap ◽  
Rock Salt ◽  
High Pressures ◽  
Ambient Pressure ◽  
High Pressure Phase ◽  
Lead Chalcogenides ◽  
Pressure Phase

ab-initio calculations using fully relativistic pseudo-potential have been performed to investigate the high pressure phase transition, elastic and electronic properties of lead-chalcogenides including the less known lead polonium. The calculated ground state parameters, for the rock-salt structure show good agreement with the experimental data. The enthalpy calculations show that these materials undergo a first-order phase transition from rock-salt to CsCl structure at 19.4, 15.5, 11.5 and 7.3 GPa for PbS, PbSe, PbTe and PbPo, respectively. Present calculations successfully predicted the location of the band gap at L-point of Brillouin zone as well as the value of the band gap in every case at ambient pressure. It is observed that unlike other lead-chalcogenides, PbPo is semi-metal at ambient pressure. The pressure variation of the energy gap indicates that these materials metalized under high pressures. For this purpose, the electronic structure of these materials has also been computed in parent as well as in high pressure phase.

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