Special Issue "High-Pressure Materials"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Smart Materials".

Deadline for manuscript submissions: 30 April 2020.

Special Issue Editor

Prof. Shanti Deemyad
E-Mail Website
Guest Editor
Department of Physics and Astronomy, University of Utah, Salt Lake City, UT, United States
Interests: dense quantum matter; high pressure methods; electronic and crystal structures under pressure

Special Issue Information

Dear Colleagues,

This Special Issue on “High-Pressure Materials” will focus on high pressure effects on the structural and electronic properties of matter.

Advances in high pressure experimental and computational techniques now allow discovering and exploring new regimes in the material phase space. In recent years, using high pressure methods, many new states of matter have been observed in laboratory and many more have been predicted theoretically and have been confirmed experimentally. Dynamic and static methods are reaching regimes in which compressions exceed those within planetary cores and pressure and temperature conditions that complement what might naturally occur.

Pressure changes the fundamental interactions at the electron level, therefore, application of high pressure is a powerful tool for altering the chemical character of materials. The change in chemical reactivity and nature of chemical bonds can not only alter the band and crystal structure and basic electronic properties, but also can lead to the emergence of a variety of interesting quantum states. These include topological states, unconventional superconducting states and formation of electrides. The time evolution and dynamics of phase transitions is another research area with much potential.

This Special Issue will explore the forefront of high pressure research theory and experiments to gain an in-depth insight into the fundamental interactions in materials and explore new possibilities in condensed matter.

Prof. Shanti Deemyad
Guest Editor

Manuscript Submission Information

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Keywords

  • high pressure effects in electronic and structures of matter

Published Papers (4 papers)

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Research

Open AccessArticle
Pressure-Dependent Stability of Imidazolium-Based Ionic Liquid/DNA Materials Investigated by High-Pressure Infrared Spectroscopy
Materials 2019, 12(24), 4202; https://doi.org/10.3390/ma12244202 - 13 Dec 2019
Abstract
1-Butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6])/DNA and 1-methyl-3-propylimidazolium hexafluorophosphate ([C3MIM][PF6])/DNA mixtures were prepared and characterized by high-pressure infrared spectroscopy. Under ambient pressure, the imidazolium C2–H and C4,5–H absorption bands of [C4MIM][PF6 [...] Read more.
1-Butyl-3-methylimidazolium hexafluorophosphate ([C4MIM][PF6])/DNA and 1-methyl-3-propylimidazolium hexafluorophosphate ([C3MIM][PF6])/DNA mixtures were prepared and characterized by high-pressure infrared spectroscopy. Under ambient pressure, the imidazolium C2–H and C4,5–H absorption bands of [C4MIM][PF6]/DNA mixture were red-shifted in comparison with those of pure [C4MIM][PF6]. This indicates that the C2–H and C4,5–H groups may have certain interactions with DNA that assist in the formation of the ionic liquid/DNA association. With the increase of pressure from ambient to 2.5 GPa, the C2–H and C4,5–H absorption bands of pure [C4MIM][PF6] displayed significant blue shifts. On the other hand, the imidazolium C–H absorption bands of [C4MIM][PF6]/DNA showed smaller frequency shift upon compression. This indicates that the associated [C4MIM][PF6]/DNA conformation may be stable under pressures up to 2.5 GPa. Under ambient pressure, the imidazolium C2–H and C4,5–H absorption bands of [C3MIM][PF6]/DNA mixture displayed negligible shifts in frequency compared with those of pure [C3MIM][PF6]. The pressure-dependent spectra of [C3MIM][PF6]/DNA mixture revealed spectral features similar to those of pure [C3MIM][PF6]. Our results indicate that the associated structures of [C4MIM][PF6]/DNA are more stable than those of [C3MIM][PF6]/DNA under high pressures. Full article
(This article belongs to the Special Issue High-Pressure Materials)
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Open AccessArticle
Zirconium Phase Transformation under Static High Pressure and ω-Zr Phase Stability at High Temperatures
Materials 2019, 12(14), 2244; https://doi.org/10.3390/ma12142244 - 12 Jul 2019
Abstract
High-purity Zr has been observed to undergo a phase transformation from the α-phase to the hexagonal ω-phase under high pressure generated either statically or by shock loading. The transition pressure from α-Zr to ω-Zr at 300 K is 2.10 GPa. The main aim [...] Read more.
High-purity Zr has been observed to undergo a phase transformation from the α-phase to the hexagonal ω-phase under high pressure generated either statically or by shock loading. The transition pressure from α-Zr to ω-Zr at 300 K is 2.10 GPa. The main aim of this research was to determine the conditions of α-Zr in ω-Zr transformation and the state of stresses after the high-pressure pressing and sintering of zirconium powders. Commercially acquired zirconium powders of 99.9% and 98.8% purity were used in this study. Qualitative and quantitative phase analysis of the materials was carried out using X-ray diffraction. The materials were statically pressed and sintered using a Bridgman-type toroidal apparatus at under 4.0 and 7.8 GPa. After pressing, the transformation proceeded for the zirconium powder containing 98.8% purity (with hydrides admixture) but did not occur for the high-purity zirconium powders with 99.9% purity. The zirconium powders were sintered using the HPHT (High Pressure—High Temperature) method at temperatures of 1273 K and 1473 K. The transformation proceeded for both powders. The highest contribution of the ω-Zr phase was obtained in the zirconium (98.8% purity with the hydrides contents) sintered for 1 min at a temperature of 1473 K and a pressure of 7.8. The ω-phase content was 87 wt.%. The stress measurement was performed for the pressed and sintered materials using the sin2ψ X-ray diffraction method. The higher sintering temperature resulted in a decrease of the residual stresses in the ω-Zr phase for the sintered zirconium. The higher levels of stress limited the transformation of the α-Zr phase into the ω-Zr phase. Investigated materials characterized by higher compressive macrostresses were also typical of the greater stability of the ω-Zr phase at high temperatures. Full article
(This article belongs to the Special Issue High-Pressure Materials)
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Open AccessArticle
Structural Change in Ni-Fe-Ga Magnetic Shape Memory Alloys after Severe Plastic Deformation
Materials 2019, 12(12), 1939; https://doi.org/10.3390/ma12121939 - 17 Jun 2019
Cited by 2
Abstract
Severe plastic deformation (SPD) is widely considered to be the most efficient process in obtaining ultrafine-grained bulk materials. The aim of this study is to examine the effects of the SPD process on Ni-Fe-Ga ferromagnetic shape memory alloys (FSMA). High-speed high-pressure torsion (HSHPT) [...] Read more.
Severe plastic deformation (SPD) is widely considered to be the most efficient process in obtaining ultrafine-grained bulk materials. The aim of this study is to examine the effects of the SPD process on Ni-Fe-Ga ferromagnetic shape memory alloys (FSMA). High-speed high-pressure torsion (HSHPT) was applied in the as-cast state. The exerted key parameters of deformation are described. Microstructural changes, including morphology that were the result of processing, were investigated by optical and scanning electron microscopy. Energy-dispersive X-ray spectroscopy was used to study the two-phase microstructure of the alloys. The influence of deformation on microstructural features, such as martensitic plates, intragranular γ phase precipitates, and grain boundaries’ dependence of the extent of deformation is disclosed by transmission electron microscopy. Moreover, the work brings to light the influence of deformation on the characteristics of martensitic transformation (MT). Vickers hardness measurements were carried out on disks obtained by SPD so as to correlate the hardness with the microstructure. The method represents a feasible alternative to obtain ultrafine-grained bulk Ni-Fe-Ga alloys. Full article
(This article belongs to the Special Issue High-Pressure Materials)
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Open AccessArticle
Microstructure and Mechanical Properties of Pressure-Quenched SS304 Stainless Steel
Materials 2019, 12(2), 290; https://doi.org/10.3390/ma12020290 - 17 Jan 2019
Cited by 1
Abstract
Bulk SS304 polycrystalline materials with ultrafine microstructures were prepared via a high-pressure self-heating melting and quenching method. Analyses of phase composition, grain size and microstructure were performed using metallographic analysis, X-ray diffraction, Rietveld refinement and transmission electron microscope (TEM). The effects of pressure [...] Read more.
Bulk SS304 polycrystalline materials with ultrafine microstructures were prepared via a high-pressure self-heating melting and quenching method. Analyses of phase composition, grain size and microstructure were performed using metallographic analysis, X-ray diffraction, Rietveld refinement and transmission electron microscope (TEM). The effects of pressure and cooling rate on the solidification of SS304 were analyzed. Mechanical property test results show that, compared with the as-received sample, the hardness and the yield strength of the pressure-quenched (PQ) samples were greatly increased, the ultimate tensile strength changed minimally, and the elongation rate became small, primarily due to the large density of dislocations in the sample. The high-pressure self-heating melting and quenching method is an exotic route to process a small piece of steel with moderate properties and ultrafine microstructure. Full article
(This article belongs to the Special Issue High-Pressure Materials)
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