EHPRG

Welcome to the official website of the European High Pressure Research Group (EHPRG).

EHPRG is non-profitable academic association established in 1963 which is devoted to science and technology of matter under high pressure. It organizes an annual meeting which brings together hundreds of scientists of various fields, mainly physics, chemistry, Earth and planetary sciences, bio- and food science and technology.

The reasonable size of the group, low conference fees, and a friendly relationship between the attendants have made EHPRG meetings a major event in the European high-pressure community for more than half a century.

Selection of high-pressure related titles from top scientific journals.

Why we need a new economics of water as a common good
by Johan Rockström


Nature, Published online: 22 March 2023; doi:10.1038/d41586-023-00800-z

Anthropogenic pressures and climate change are altering water flows worldwide. Better understanding, new economic thinking and an international governance framework are needed to stave off catastrophe.
22 Mar 2023 at 12:00am
Collision-induced three-body polarizability of helium
by J. Lang
The Journal of Chemical Physics, Volume 158, Issue 11, March 2023.
We present the first-principles determination of the three-body polarizability and the third dielectric virial coefficient of helium. Coupled-cluster and full configuration interaction methods were used to perform electronic structure calculations. The mean absolute relative uncertainty of the trace of the polarizability tensor, resulting from the incompleteness of the orbital basis set, was found to be 4.7%. Additional uncertainty due to the approximate treatment of triple and the neglect of higher excitations was estimated at 5.7%. An analytic function was developed to describe the short-range behavior of the polarizability and its asymptotics in all fragmentation channels. We calculated the third dielectric virial coefficient and its uncertainty using the classical and semiclassical Feynman–Hibbs approaches. The results of our calculations were compared with experimental data and with recent Path-Integral Monte Carlo (PIMC) calculations [Garberoglio et al., J. Chem. Phys. 155, 234103 (2021)] employing the so-called superposition approximation of the three-body polarizability. For temperatures above 200 K, we observed a significant discrepancy between the classical results obtained using superposition approximation and the ab initio computed polarizability. For temperatures from 10 K up to 200 K, the differences between PIMC and semiclassical calculations are several times smaller than the uncertainties of our results. Except at low temperatures, our results agree very well with the available experimental data but have much smaller uncertainties. The data reported in this work eliminate the main accuracy bottleneck in the optical pressure standard [Gaiser et al., Ann. Phys. 534, 2200336 (2022)] and facilitate further progress in the field of quantum metrology.
15 Mar 2023 at 11:05am
Molecular rotations trigger a glass-to-plastic fcc heterogeneous crystallization in high-pressure water
by Małgorzata J. Zimoń
The Journal of Chemical Physics, Volume 158, Issue 11, March 2023.
We report a molecular dynamics study of the heterogeneous crystallization of high-pressure glassy water using (plastic) ice VII as a substrate. We focus on the thermodynamic conditions P ∈ [6–8] GPa and T ∈ [100–500] K, at which (plastic) ice VII and glassy water are supposed to coexist in several (exo)planets and icy moons. We find that (plastic) ice VII undergoes a martensitic phase transition to a (plastic) fcc crystal. Depending on the molecular rotational lifetime τ, we identify three rotational regimes: for τ > 20 ps, crystallization does not occur; for τ ∼ 15 ps, we observe a very sluggish crystallization and the formation of a considerable amount of icosahedral environments trapped in a highly defective crystal or in the residual glassy matrix; and for τ < 10 ps, crystallization takes place smoothly, resulting in an almost defect-free plastic fcc solid. The presence of icosahedral environments at intermediate τ is of particular interest as it shows that such a geometry, otherwise ephemeral at lower pressures, is, indeed, present in water. We justify the presence of icosahedral structures based on geometrical arguments. Our results represent the first study of heterogeneous crystallization occurring at thermodynamic conditions of relevance for planetary science and unveil the role of molecular rotations in achieving it. Our findings (i) show that the stability of plastic ice VII, widely reported in the literature, should be reconsidered in favor of plastic fcc, (ii) provide a rationale for the role of molecular rotations in achieving heterogeneous crystallization, and (iii) represent the first evidence of long-living icosahedral structures in water. Therefore, our work pushes forward our understanding of the properties of water.
15 Mar 2023 at 11:05am
Frictional Weakening of Vibrated Granular Flows
by Abram H. Clark, Emily E. Brodsky, H. John Nasrin, and Stephanie E. Taylor
Author(s): Abram H. Clark, Emily E. Brodsky, H. John Nasrin, and Stephanie E. Taylor


We computationally study the frictional properties of sheared granular media subjected to harmonic vibration applied at the boundary. Such vibrations are thought to play an important role in weakening flows, yet the independent effects of amplitude, frequency, and pressure on the process have remain…


[Phys. Rev. Lett. 130, 118201] Published Mon Mar 13, 2023
13 Mar 2023 at 11:00am
Synthesis of superconducting hcp-$\mathrm{Zr}{\mathrm{H}}_{3}$ under high hydrogen pressure
by Mikhail A. Kuzovnikov, Vladimir E. Antonov, Valery I. Kulakov, Vitaly D. Muzalevsky, Nikita S. Orlov, Andrey V. Palnichenko, and Yury M. Shulga
Author(s): Mikhail A. Kuzovnikov, Vladimir E. Antonov, Valery I. Kulakov, Vitaly D. Muzalevsky, Nikita S. Orlov, Andrey V. Palnichenko, and Yury M. Shulga


Zirconium trihydride and, for comparison, trideuteride with hexagonal close-packed (hcp) metal lattices were synthesized at a hydrogen/deuterium pressure of 9 GPa and a temperature of 873 K using toroid-type high-pressure chambers. After a rapid cooling (quenching) to 100 K and lowering the pressure…


[Phys. Rev. Materials 7, 024803] Published Mon Feb 13, 2023
13 Feb 2023 at 11:00am
Ferrimagnetic coupling between cobalt and light rare-earth samarium induced by dense hydrogenation of ${\mathrm{SmCo}}_{5}$ permanent magnet under high pressures
by Naoki Ishimatsu, Kentaro Ishimoto, Kouji Sakaki, Yumiko Nakamura, Naomi Kawamura, Saori I. Kawaguchi, Naohisa Hirao, and Satoshi Nakano
Author(s): Naoki Ishimatsu, Kentaro Ishimoto, Kouji Sakaki, Yumiko Nakamura, Naomi Kawamura, Saori I. Kawaguchi, Naohisa Hirao, and Satoshi Nakano


X-ray magnetic circular dichroism, x-ray powder diffraction and first-principles calculations revealed that dense hydrogenation of a Gd-doped ${\mathrm{SmCo}}_{5}{\mathrm{H}}_{x}$ compound $({\mathrm{Sm}}_{0.92}{\mathrm{Gd}}_{0.08}{\mathrm{Co}}_{5}{\mathrm{H}}_{x})$, ranging up to $x≈13.5$, flips th…


[Phys. Rev. Materials 7, 024401] Published Fri Feb 03, 2023
3 Feb 2023 at 11:00am
First-principles theory of the pressure-induced invar effect in FeNi alloys
by Amanda Ehn, Björn Alling, and Igor A. Abrikosov
Author(s): Amanda Ehn, Björn Alling, and Igor A. Abrikosov


Beside the classic Fe64Ni36 Invar alloy, which shows an anomalously low thermal expansion at ambient pressure, Fe-Ni alloys with a higher nickel composition can be driven to Invar behavior by pressure. The authors investigate the pressure induced Invar effect theoretically and demonstrate that it can be explained by a magnetic transition from a ferromagnetic state at high volume to a complex noncollinear state upon compression. They relate the Invar effect to the increasing contribution of magnetic entropy with pressure.


[Phys. Rev. B 107, 104422] Published Tue Mar 21, 2023
21 Mar 2023 at 11:00am
Interplay of structure and magnetism in ${\mathrm{LuFe}}_{4}{\mathrm{Ge}}_{2}$ tuned by hydrostatic pressure
by M. O. Ajeesh, P. Materne, R. D. dos Reis, K. Weber, S. Dengre, R. Sarkar, R. Khasanov, I. Kraft, A. M. León, W. Bi, J. Zhao, E. E. Alp, S. Medvedev, V. Ksenofontov, H. Rosner, H.-H. Klauss, C. Geibel, and M. Nicklas
Author(s): M. O. Ajeesh, P. Materne, R. D. dos Reis, K. Weber, S. Dengre, R. Sarkar, R. Khasanov, I. Kraft, A. M. León, W. Bi, J. Zhao, E. E. Alp, S. Medvedev, V. Ksenofontov, H. Rosner, H.-H. Klauss, C. Geibel, and M. Nicklas


Competing ground states often lead to the emergence of novel unconventional phases. The presence of magnetic frustration in such materials brings about additional complexity. Here, the authors present a comprehensive study on the ground-state properties of LuFe4Ge2, a ternary intermetallic compound with magnetic frustration and quasi-one-dimensional structure, elucidating the interplay of structure and magnetism. In contrast to the well-studied two-dimensional iron pnictides with competing exchange interactions, LuFe4Ge2 exhibits quasi-one-dimensional chains of geometrically frustrated Fe tetrahedra. It displays a magnetostructural transition at ambient pressure with a change in symmetry from tetragonal to orthorhombic, similar to that in the iron-pnictides, which evolves in an unexpected way under the application of hydrostatic pressure. In that way the intermetallic LuFe4Ge2 material family offers a new perspective on the entanglement of crystal structure and magnetism.


[Phys. Rev. B 107, 125136] Published Thu Mar 16, 2023
16 Mar 2023 at 11:00am
Investigation of null-matrix alloy gaskets for a diamond-anvil-cell on high pressure neutron diffraction experiments
by Shinichi Machida
Volume 42, Issue 4, December 2022, Page 303-317
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11 Nov 2022 at 6:06am
Sound velocity anomalies of limestone at high pressure and implications for the mantle wedge
by Fengxia Sun
Volume 42, Issue 4, December 2022, Page 336-348
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12 Nov 2022 at 1:16pm
Effect of pressure of vanadium nitride using XRD and DFT
by Lun Xiong
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21 Mar 2023 at 6:28am
Modeling the inactivation of Aspergillus niger spores in a model parenteral emulsion by high hydrostatic pressure and its effect on the emulsion droplet size
by Maricarmen Iñiguez-Moreno
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3 Mar 2023 at 10:15am
New uniaxial pressure cell used in a study of magnetization of the Heusler Ni2MnSn-based alloy
by J. Kamarád
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2 Feb 2023 at 2:46am
Development of an explicit pressure explicit saturation (EPES) method for modelling dissociation processes of methane hydrate
by Giovanni Luzi
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27 Dec 2022 at 4:10am