High-Pressure-Induced Phase Transition in 2,5-Diketopiperazine: The Anisotropic Compression of N–H···O Hydrogen-Bonded Tapes

2018 ◽  
Vol 122 (22) ◽  
pp. 11747-11753 ◽  
Author(s):  
Yuxiang Dai ◽  
Yang Qi
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Hydrogen Bonded

The influence of pressure on the infrared spectra of hydrogen bonded solids. II. Bihalide salts

1976 ◽  
Vol 29 (3) ◽  
pp. 479 ◽  
Author(s):  
SD Hamann ◽  
M Linton
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Hydrogen Bonds ◽  
High Pressure Phase Transition ◽  
Infrared Measurements ◽  
Normal Hydrogen ◽  
Combination Bands ◽  
Pressure Phase ◽  
Made In ◽  
Hydrogen Bonded

Infrared measurements have been made of the influence of pressures between 0 and 40 kbar on the asymmetrical stretching frequencies v3 and bending frequencies v2 of the hydrogen-bonded ions FHF- and ClHCl- in the solid salts NaHF2, KHF2, NH4HF2, (CH3)4NHCl2 and (C2H5)4NHCl2 at 25�C. The behaviour of the symmetrical stretching frequency v1 for FHF- in KHF2 has been deduced indirectly from the shifts of combination bands. Contrary to the behaviour of compounds with weaker, 'normal', hydrogen bonds, the v3 bands shift to higher frequencies and the v2 bands shift to lower frequencies with increasing pressure. The vl band of KHF2 shifts to higher frequencies. These trends are all in agreement with predictions made in Part I for a simple model of hydrogen bonds. A new high-pressure phase transition has been found to occur in NaHF2 at about 40 kbar.

scholarly journals The phase transition of hydrogen-bonded ferroelectric PbHPO4under high pressure

2005 ◽  
Vol 61 (a1) ◽  
pp. c462-c462
Author(s):  
Y. Nakamoto ◽  
T. Kagayama ◽  
K. Shimizu ◽  
K. Deguchi ◽  
T. Yamanaka
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Hydrogen Bonded

scholarly journals Orpiment under compression: metavalent bonding at high pressure

2020 ◽  
Vol 22 (6) ◽  
pp. 3352-3369 ◽  
Author(s):  
Vanesa Paula Cuenca-Gotor ◽  
Juan Ángel Sans ◽  
Oscar Gomis ◽  
Andres Mujica ◽  
Silvana Radescu ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Strong Change ◽  
Isostructural Phase Transition

Orpiment (α-As2S3) under compression reports a strong change in the coordination of As atoms at 25 GPa, which can be ascribed to an isostructural phase transition. These changes are consistent with the formation of metavalent bonds in orpiment.

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.

scholarly journals Pressure-Induced Structural Phase Transition and Metallization in Ga2Se3 up to 40.2 GPa under Non-Hydrostatic and Hydrostatic Environments

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 746
Author(s):  
Meiling Hong ◽  
Lidong Dai ◽  
Haiying Hu ◽  
Xinyu Zhang
Keyword(s):  
Phase Transition ◽  
Electrical Conductivity ◽  
High Pressure ◽  
Phase Transformation ◽  
Transport Properties ◽  
Electrical Transport ◽  
Structural Phase ◽  
Structure Evolution ◽  
Systematic Research ◽  
Electrical Transport Properties

A series of investigations on the structural, vibrational, and electrical transport characterizations for Ga2Se3 were conducted up to 40.2 GPa under different hydrostatic environments by virtue of Raman scattering, electrical conductivity, high-resolution transmission electron microscopy, and atomic force microscopy. Upon compression, Ga2Se3 underwent a phase transformation from the zinc-blende to NaCl-type structure at 10.6 GPa under non-hydrostatic conditions, which was manifested by the disappearance of an A mode and the noticeable discontinuities in the pressure-dependent Raman full width at half maximum (FWHMs) and electrical conductivity. Further increasing the pressure to 18.8 GPa, the semiconductor-to-metal phase transition occurred in Ga2Se3, which was evidenced by the high-pressure variable-temperature electrical conductivity measurements. However, the higher structural transition pressure point of 13.2 GPa was detected for Ga2Se3 under hydrostatic conditions, which was possibly related to the protective influence of the pressure medium. Upon decompression, the phase transformation and metallization were found to be reversible but existed in the large pressure hysteresis effect under different hydrostatic environments. Systematic research on the high-pressure structural and electrical transport properties for Ga2Se3 would be helpful to further explore the crystal structure evolution and electrical transport properties for other A2B3-type compounds.

High-pressure structural phase transition and metallization in Ga2S3 under non-hydrostatic and hydrostatic conditions up to 36.4 GPa

2021 ◽  
Author(s):  
Linfei Yang ◽  
Jianjun Jiang ◽  
Lidong Dai ◽  
Haiying Hu ◽  
Meiling Hong ◽  
...  
Keyword(s):  
Phase Transition ◽  
Raman Spectroscopy ◽  
High Pressure ◽  
Structural Properties ◽  
Structural Phase Transition ◽  
First Principles ◽  
Theoretical Calculations ◽  
Structural Phase

The vibrational, electrical and structural properties of Ga2S3 were explored by Raman spectroscopy, EC measurements, HRTEM and First-principles theoretical calculations under different pressure environments up to 36.4 GPa.

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