EHPRG: The European High Pressure Research Group

## Welcome

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.

## Upcoming EHPRG Meeting

The 59th European High Pressure Research Group Meeting on High Pressure Science and Technology (EHPRG2022) will be held in Uppsala, Sweden, from 5th to 8th September 2022.
Meeting sessions will be held virtually. The 59th EHPRG intends to be a large scope conference, in line with the rapid increase of high pressure activities in all areas of Physics, Chemistry, Food Science, Geosciences, Material Research, and Biosciences.

The Joint 28th AIRAPT and 60th EHPRG International Conference on High Pressure Science and Technology (AIRAPT-2023), originally scheduled for July 2021, will be held in Edinburgh, UK, from July 23-28, 2023.
The Conference will be held at the Edinburgh International Conference Centre (EICC) and it will be a face-to-face conference only.
Immediately prior to AIRAPT/EHPRG, from the 19th to 23rd of July 2023, a Summer School will take place, also based in Edinburgh, with accommodation provided in University Halls of Residence. The School is aimed at young researchers, and experimentalists wanting a grounding in theory and vice versa.

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

Fluid migration in low-permeability faults driven by decoupling of fault slip and opening
by Frédéric Cappa

Nature Geoscience, Published online: 11 August 2022; doi:10.1038/s41561-022-00993-4

Decoupled fault slip and opening, leading to rapid fluid pressurization after initial failure, drives high-pressure fluid migration in low-permeability faults, according to modelling and in situ observations from a borehole fluid-injection experiment.
11 Aug 2022 at 12:00am
Non-isoplethic measurement on the solid–liquid–vapor equilibrium of binary mixtures at cryogenic temperatures
by Shaelyn M. Raposa
The Journal of Chemical Physics, Volume 157, Issue 6, August 2022.
We measured the solid–liquid–vapor (SLV) equilibrium of binary mixtures during experiments that alternated between cooling the mixture and injecting the more-volatile component into the sample chamber; thus, the composition of the mixture changed (non-isoplethic) throughout the experiment. Four binary mixtures were used in the experiments to represent mixtures with miscible solid phases (N2/CO) and barely miscible solid solutions (N2/C2H6), as well as mixtures with intermediate solid miscibility (N2/CH4 and CO/CH4). We measured new SLV pressure data for the binary mixtures, except for N2/CH4, which are also available in the literature for verification in this work. While these mixtures are of great interest in planetary science and cryogenics, the resulting pressure data are also needed for modeling purposes. We found the results for N2/CH4 to be consistent with the literature. The resulting new SLV curve for CO/CH4 shows similarities to N2/CH4. Both have two density inversion points (bracketing the temperature range where the solid floats). This result is important for places such as Pluto, Triton, and Titan, where these mixtures exist in vapor, liquid, and solid phases. Based on our experiments, the presence of a eutectic is unlikely for the N2/CH4 and CO/CH4 systems. An azeotrope with or without a peritectic is likely, but further investigations are needed to confirm. The N2/CO system does not have a density inversion point, as the ice always sinks in its liquid. For N2/C2H6, new SLV pressure data were measured near each triple point of the pure components.
12 Aug 2022 at 1:48pm
Pressure-annealed high-density amorphous ice made from vitrified water droplets: A systematic calorimetry study on water’s second glass transition
by Johannes Bachler
The Journal of Chemical Physics, Volume 157, Issue 6, August 2022.
In previous work, water’s second glass transition was investigated based on an amorphous sample made from crystalline ice [Amann-Winkel et al., Proc. Natl. Acad. Sci. U. S. A. 110, 17720 (2013)]. In the present work, we investigate water’s second glass transition based on the genuine glassy state of high-density water as prepared from micron-sized liquid water droplets, avoiding crystallinity at all stages. All the calorimetric features of water’s second glass transition observed in the previous work are also observed here on the genuine glassy samples. This suggests that the glass transition indeed thermodynamically links amorphous ices continuously with deeply supercooled water. We proceed to extend the earlier study by investigating the effect of preparation history on the calorimetric glass transition temperature. The best samples prepared here feature both a lower glass transition temperature Tg,2 and a higher polyamorphic transition temperature Tons, thereby extending the range of thermal stability in which the deeply supercooled liquid can be observed by about 4 K. Just before the polyamorphic transition, we observe a spike-like increase of heat capacity that we interpret in terms of nucleation of low-density water. Without this spike, the width of water’s second glass transition is 15 K, and the Δcp amounts to 3 ± 1 J K−1 mol−1, making the case for the high-density liquid being a strong liquid. We suggest that samples annealed at 1.9 GPa to 175 K and decompressed at 140 K to ≥0.10 GPa are free from such nuclei and represent the most ideal high-density amorphous glasses.
11 Aug 2022 at 12:39pm
Different temperature- and pressure-effects on the water-mediated interactions between hydrophobic, hydrophilic, and hydrophobic–hydrophilic nanoscale surfaces
by Justin Engstler
The Journal of Chemical Physics, Volume 157, Issue 6, August 2022.
Water-mediated interactions (WMIs) are responsible for diverse processes in aqueous solutions, including protein folding and nanoparticle aggregation. WMI may be affected by changes in temperature and pressure, and hence, they can alter chemical/physical processes that occur in aqueous environments. Traditionally, attention has been focused on hydrophobic interactions while, in comparison, the role of hydrophilic and hybrid (hydrophobic–hydrophilic) interactions have been mostly overlooked. Here, we study the role of T and P on the WMI between nanoscale (i) hydrophobic–hydrophobic, (ii) hydrophilic–hydrophilic, and (iii) hydrophilic–hydrophobic pairs of (hydroxylated/non-hydroxylated) graphene-based surfaces. We find that hydrophobic, hydrophilic, and hybrid interactions are all sensitive to P. However, while hydrophobic interactions [case (i)] are considerably sensitive to T-variations, hydrophilic [case (ii)] and hybrid interactions [case (iii)] are practically T-independent. An analysis of the entropic and enthalpic contributions to the potential of mean force for cases (i)–(iii) is also presented. Our results are important in understanding T- and P-induced protein denaturation and the interactions of biomolecules in solution, including protein aggregation and phase separation processes. From the computational point of view, the results presented here are relevant in the design of implicit water models for the study of molecular and colloidal/nanoparticle systems at different thermodynamic conditions.
8 Aug 2022 at 1:08pm
Viscous to Inertial Transition in Dense Granular Suspension
by Franco Tapia, Mie Ichihara, Olivier Pouliquen, and Élisabeth Guazzelli
Author(s): Franco Tapia, Mie Ichihara, Olivier Pouliquen, and Élisabeth Guazzelli

Granular suspensions present a transition from a Newtonian rheology in the Stokes limit to a Bagnoldian rheology when inertia is increased. A custom rheometer that can be run in a pressure- or a volume-imposed mode is used to examine this transition in the dense regime close to jamming. By varying s…

[Phys. Rev. Lett. 129, 078001] Published Mon Aug 08, 2022
8 Aug 2022 at 12:00pm
Ab initio study of Li-Mg-B superconductors
by Gyanu P. Kafle, Charlsey R. Tomassetti, Igor I. Mazin, Aleksey N. Kolmogorov, and Elena R. Margine
Author(s): Gyanu P. Kafle, Charlsey R. Tomassetti, Igor I. Mazin, Aleksey N. Kolmogorov, and Elena R. Margine

LiB, a predicted layered compound analogous to the ${\mathrm{MgB}}_{2}$ superconductor, has been recently synthesized via cold compression and quenched to ambient pressure, yet its superconducting properties have not been measured. According to prior isotropic superconductivity calculations, the cri…

[Phys. Rev. Materials 6, 084801] Published Tue Aug 09, 2022
9 Aug 2022 at 12:00pm
Superconductivity of ${\mathrm{MoBe}}_{22}$ and ${\mathrm{WBe}}_{22}$ at ambient- and under applied-pressure conditions
by T. Shiroka, T. Shang, M. Juckel, M. Krnel, M. König, U. Burkhardt, P. Koželj, R. Gupta, Yu. Prots, and E. Svanidze
Author(s): T. Shiroka, T. Shang, M. Juckel, M. Krnel, M. König, U. Burkhardt, P. Koželj, R. Gupta, Yu. Prots, and E. Svanidze

${\mathrm{MoBe}}_{22}$ and ${\mathrm{WBe}}_{22}$ compounds belong to the binary $X{\mathrm{Be}}_{22}$ $(X=4d$ or 5$d$ metal) family of superconductors, whose critical temperature depends strongly on $X$. Despite the multiphase nature of these samples, it is possible to investigate the superconductin…

[Phys. Rev. Materials 6, 064804] Published Mon Jun 27, 2022
27 Jun 2022 at 12:00pm
Pressure dependence of rotational dynamics in barocaloric ammonium sulfate
by Bernet E. Meijer, Guanqun Cai, Franz Demmel, Helen C. Walker, and Anthony E. Phillips
Author(s): Bernet E. Meijer, Guanqun Cai, Franz Demmel, Helen C. Walker, and Anthony E. Phillips

Solid-state cooling using barocaloric materials is a promising avenue for ecofriendly, inexpensive, and highly efficient cooling. To design barocaloric compounds ready for deployment, it is essential to understand their thermodynamic behavior under working conditions. To this end, we have studied th…

[Phys. Rev. B 106, 064302] Published Mon Aug 15, 2022
15 Aug 2022 at 12:00pm
Ab initio investigation of the magnetic and ferroelectric properties of ${\mathrm{BaCuF}}_{4}$ under hydrostatic pressure
by David Vincent, Xavier Rocquefelte, and Andres Saúl
Author(s): David Vincent, Xavier Rocquefelte, and Andres Saúl

We present a first-principles investigation of the magnetic and ferroelectric properties of ${\mathrm{BaCuF}}_{4}$. Our calculations indicate that the magnetic topology is one-dimensional, with a Néel temperature smaller than 1 K, if existing. We also show that applying high-pressure values up to 40…

[Phys. Rev. B 106, 064421] Published Mon Aug 15, 2022
15 Aug 2022 at 12:00pm
Anomalous bond softening mediated by strain-induced Friedel-like oscillations in a ${\mathrm{BC}}_{2}\mathrm{N}$ superlattice
by Tengfei Xu, Zhaorui Liu, Dominik Legut, and Ruifeng Zhang
Author(s): Tengfei Xu, Zhaorui Liu, Dominik Legut, and Ruifeng Zhang

The crystal structure of ${\mathrm{BC}}_{2}\mathrm{N}$ and the origin of its superhardness remain under constant debate, hindering its development. Herein, by evaluating the x-ray diffraction pattern, the thermodynamic stability at normal and high pressures of a series of ${\mathrm{BC}}_{2}\mathrm{N… [Phys. Rev. B 106, L060101] Published Mon Aug 15, 2022 15 Aug 2022 at 12:00pm Pressure-induced metallization in the absence of a structural transition in the layered ferromagnetic insulator${\mathrm{Cr}}_{2}{\mathrm{Ge}}_{2}{\mathrm{Te}}_{6}$by Weizhao Cai, Luo Yan, Su Kong Chong, Jingui Xu, Dongzhou Zhang, Vikram V. Deshpande, Liujiang Zhou, and Shanti Deemyad Author(s): Weizhao Cai, Luo Yan, Su Kong Chong, Jingui Xu, Dongzhou Zhang, Vikram V. Deshpande, Liujiang Zhou, and Shanti Deemyad We report the crystallographic and electrical transport properties of single crystals of the ferromagnetic two-dimensional (2D) material${\mathrm{Cr}}_{2}{\mathrm{Ge}}_{2}{\mathrm{Te}}_{6}$under high pressure. In contrast to previous studies, our high-pressure single-crystal x-ray diffraction unde… [Phys. Rev. B 106, 085116] Published Tue Aug 09, 2022 9 Aug 2022 at 12:00pm Crystal structure solution of a high-pressure polymorph of scintillating${\mathrm{MgMoO}}_{4}$and its electronic structure by J. Ruiz-Fuertes, A. Friedrich, N. Garg, V. Monteseguro, K. Radacki, D. Errandonea, E. Cavalli, P. Rodríguez-Hernández, and A. Muñoz Author(s): J. Ruiz-Fuertes, A. Friedrich, N. Garg, V. Monteseguro, K. Radacki, D. Errandonea, E. Cavalli, P. Rodríguez-Hernández, and A. Muñoz The structure of the potentially scintillating high-pressure phase of$β\text{−}{\mathrm{MgMoO}}_{4}$($γ\text{−}{\mathrm{MgMoO}}_{4}\$) has been solved by means of high-pressure single-crystal x-ray diffraction. The phase transition occurs above 1.5 GPa and involves an increase of the Mo coordinatio…

[Phys. Rev. B 106, 064101] Published Mon Aug 08, 2022
8 Aug 2022 at 12:00pm
Progress and prospects for cuprate high temperature superconductors under pressure
by Alexander C. Mark
Volume 42, Issue 2, June 2022, Page 137-199
.

19 Apr 2022 at 1:55pm
High pressure neutron diffraction on WAND2 with a Paris-Edinburgh press
by M-E. Donnelly
Volume 42, Issue 2, June 2022, Page 213-225
.

19 Apr 2022 at 1:41pm
Review: inactivation of very heat-resistant spores of Bacilus sporothermodurans by high pressure treatment combined with others treatments