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.

Super jelly springs back from a squashing


Nature, Published online: 06 December 2021; doi:10.1038/d41586-021-03586-0

This fabricated gel doesn’t crack under pressure.
6 Dec 2021 at 12:00am
Understand the real reasons reproducibility reform fails
by Nicole C. Nelson


Nature, Published online: 06 December 2021; doi:10.1038/d41586-021-03617-w

Lack of rigour is often blamed on pressure to publish. But ethnographers can find out what truly keeps science from upping its game.
6 Dec 2021 at 12:00am

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Parallel genomic responses to historical climate change and high elevation in East Asian songbirds [Evolution]
by Yalin Cheng, Matthew J. Miller, Dezhi Zhang, Ying Xiong, Yan Hao, Chenxi Jia, Tianlong Cai, Shou-Hsien Li, Ulf S. Johansson, Yang Liu, Yongbin Chang, Gang Song, Yanhua Qu, Fumin Lei
Parallel evolution can be expected among closely related taxa exposed to similar selective pressures. However, parallelism is typically stronger at the phenotypic level, while genetic solutions to achieve these phenotypic similarities may differ. For polygenic traits, the availability of standing genetic variation (i.e., heterozygosity) may influence such genetic nonparallelism. Here,...
6 Dec 2021 at 10:45pm
Pedestrian dynamics at the running of the bulls evidence an inaccessible region in the fundamental diagram [Applied Physical Sciences]
by Daniel R. Parisi, Alan G. Sartorio, Joaquin R. Colonnello, Angel Garcimartin, Luis A. Pugnaloni, Iker Zuriguel
We characterize the dynamics of runners in the famous “Running of the Bulls” Festival by computing the individual and global velocities and densities, as well as the crowd pressure. In contrast with all previously studied pedestrian systems, we unveil a unique regime in which speed increases with density that can...
6 Dec 2021 at 10:45pm
Non-Fermi liquid behavior below the Neel temperature in the frustrated heavy fermion magnet UAu2 [Physics]
by Christopher D. O’Neill, Julian L. Schmehr, Harry D. J. Keen, Luke Pritchard Cairns, Dmitry A. Sokolov, Andreas Hermann, Didier Wermeille, Pascal Manuel, Frank Kruger, Andrew D. Huxley
The term Fermi liquid is almost synonymous with the metallic state. The association is known to break down at quantum critical points (QCPs), but these require precise values of tuning parameters, such as pressure and applied magnetic field, to exactly suppress a continuous phase transition temperature to the absolute zero....
6 Dec 2021 at 6:14pm
Environmental modifications of atomic properties: The ground and 1s2p excited states of compressed helium
by N. C. Pyper
The Journal of Chemical Physics, Volume 155, Issue 21, December 2021.
Atoms remaining as recognizably distinct constituents of bulk condensed phases can have properties modified from those of the isolated species. Dense helium bubbles at high pressures are a common form of radiation damage degrading the mechanical and electrical properties of host materials. Detailed knowledge is critical for predicting their long term performance. Modifications of the ground and first singlet excited states of confined compressed helium are investigated using an entirely non-empirical theory based on the results of ab initio self-consistent field calculations with corrections for the effects of electron correlation. For finite sized portions representing bulk condensed fcc and bcc phases of helium atoms, Hartree–Fock wavefunctions, energies, and charge distributions were computed as a function of different atomic densities using two models. The first model for the first excited state localizes the excitation on the central atom; in the second model, this is partially delocalized over the closest atomic neighbors. Total energies for the finite size portions are derived by adding the inter-atomic dispersive attractions and a density functional description of the short-range inter-atomic correlation energy. The experimental energy of the first allowed electronic transition increases with density being larger than in an isolated atom. The intra-atomic correlation energy does not contribute to this energy shift. The calculated energy shifts agree well with experiment for both bulk solid and liquid helium. The 2p orbital is increasingly compressed by density enhancement, thus generating the energy shifts. Consequently, calculations of the inelastic electron scattering cross sections are substantially incorrect if the compression of the final 1s2p state is not included. The character of the excitations is examined, and it is argued that these are of Frenkel rather than the Wannier type.
1 Dec 2021 at 11:52am
On the role of intermolecular vibrational motions for ice polymorphs. III. Mode characteristics associated with negative thermal expansion
by Hideki Tanaka
The Journal of Chemical Physics, Volume 155, Issue 21, December 2021.
Low-pressure ice forms, such as hexagonal and cubic ice, expand on cooling below temperature 60 K. This negative thermal expansivity has been explored in terms of phonon frequency modulation with varying volume and attributed to the negative Grüneisen parameters unique mostly to tetrahedrally coordinated substances. However, an underlying mechanism for the negative Grüneisen parameters has not been known except some schematic analyses. We investigate in this study the characteristics of the intermolecular vibrational modes whose Grüneisen parameters are negative by examining the individual vibrational modes rigorously. It is found that the low frequency modes below 100 cm−1, which we explicitly show are mostly bending motions of three hydrogen-bonded molecules, necessarily accompany elongation of the hydrogen bond length at peak amplitudes compared with that at the equilibrium position in executing the vibrational motions. The elongation gives rise to a decrease in the repulsive interaction while an increase in the Coulombic one. The decrease in the repulsive interaction is relaxed substantially by expansion due to its steep slope against molecular separation compared with the sluggish increase in the Coulombic one, and therefore, the negative Grüneisen parameters are obtainable. This scenario is tested against some variants of cubic ice with various water potential models. It is demonstrated that four interaction-site models are suitable to describe the intermolecular vibrations and the thermal expansivity because of the moderate tendency to favor the tetrahedral coordination.
2 Dec 2021 at 11:41am
Dynamics and phase behavior of two-dimensional size-asymmetric binary mixtures of core-softened colloids
by Luis A. Padilla
The Journal of Chemical Physics, Volume 155, Issue 21, December 2021.
The self-assembly of binary colloidal mixtures provides a bottom-up approach to create novel functional materials. To elucidate the effect of composition, temperature, and pressure on the self-assembly behavior of size-asymmetric mixtures, we performed extensive dynamics simulations of a simple model of polymer-grafted colloids. We have used a core-softened interaction potential and extended it to represent attractive interactions between unlike colloids and repulsions between like colloids. Our study focused on size-asymmetric mixtures where the ratio between the sizes of the colloidal cores was fixed at [math]. We have performed extensive simulations in the isothermal–isobaric and canonical (NVT) ensembles to elucidate the phase behavior and dynamics of mixtures with different stoichiometric ratios. Our simulation results uncovered a rich phase behavior, including the formation of hierarchical structures with many potential applications. For compositions where small colloids are the majority, sublattice melting occurs for a wide range of densities. Under these conditions, large colloids form a well-defined lattice, whereas small colloids can diffuse through the system. As the temperature is decreased, the small colloids localize, akin to a metal–insulator transition, with the small colloids playing a role similar to electrons. Our results are summarized in terms of phase diagrams.
1 Dec 2021 at 11:51am
Osmotic pressure and swelling behavior of ionic microcapsules
by Mohammed O. Alziyadi
The Journal of Chemical Physics, Volume 155, Issue 21, December 2021.
Ionic microcapsules are hollow shells of hydrogel, typically 10–1000 nm in radius, composed of cross-linked polymer networks that become charged and swollen in a good solvent. The ability of microcapsules to swell/deswell in response to changes in external stimuli (e.g., temperature, pH, and ionic strength) suits them to applications, such as drug delivery, biosensing, and catalysis. The equilibrium swelling behavior of ionic microcapsules is determined by a balance of electrostatic and elastic forces. The electrostatic component of the osmotic pressure of a microcapsule—the difference in the pressure between the inside and outside of the particle—plays a vital role in determining the swelling behavior. Within the spherical cell model, we derive exact expressions for the radial pressure profile and for the electrostatic and gel components of the osmotic pressure of a microcapsule, which we compute via Poisson–Boltzmann theory and molecular dynamics simulation. For the gel component, we use the Flory–Rehner theory of polymer networks. By combining the electrostatic and gel components of the osmotic pressure, we compute the equilibrium size of ionic microcapsules as a function of particle concentration, shell thickness, and valence. We predict concentration-driven deswelling at relatively low concentrations at which steric interactions between particles are weak and demonstrate that this response can be attributed to crowding-induced redistribution of counterions. Our approach may help to guide the design and applications of smart stimuli-responsive colloidal particles.
1 Dec 2021 at 11:52am
Role of rare earth sites and vacancies in the anomalous compression of modulated scheelite tungstates ${RE}_{2}$(${\mathrm{WO}}_{4}{)}_{3}$
by Nanci Prado Sabalisck, Gerardo Gil-de-Cos, Cristina González-Silgo, Candelaria Guzmán-Afonso, Víctor Lavín, Javier López-Solano, Isabel Teresa Martín-Mateos, Lourdes Mestres, Andrés Mujica, David Santamaría-Pérez, Manuel Eulalio Torres, and Xavier Vendrell
Author(s): Nanci Prado Sabalisck, Gerardo Gil-de-Cos, Cristina González-Silgo, Candelaria Guzmán-Afonso, Víctor Lavín, Javier López-Solano, Isabel Teresa Martín-Mateos, Lourdes Mestres, Andrés Mujica, David Santamaría-Pérez, Manuel Eulalio Torres, and Xavier Vendrell


X-ray powder diffraction experiments at high pressures combining conventional sources and synchrotron radiation, together with theoretical simulations have allowed us to study the anomalous compression of the entire α-${RE}_{2}$(${\mathrm{WO}}_{4}{)}_{3}$ ($\mathit{RE}$ = La-Ho) family with modulate...


[Phys. Rev. Materials 5, 123601] Published Fri Dec 03, 2021
3 Dec 2021 at 11:00am
Robust evidence for the stabilization of the premartensite phase in Ni-Mn-In magnetic shape memory alloys by chemical pressure
by Anupam K. Singh, Sanjay Singh, B. Dutta, K. K. Dubey, Boby Joseph, R. Rawat, and Dhananjai Pandey
Author(s): Anupam K. Singh, Sanjay Singh, B. Dutta, K. K. Dubey, Boby Joseph, R. Rawat, and Dhananjai Pandey


The thermodynamic stability of the premartensite (PM) phase has been a topic of extensive investigation in shape memory alloys as it affects the main martensite phase transition and the related physical properties. In general, the PM phase is stable over a rather narrow temperature-composition range...


[Phys. Rev. Materials 5, 113607] Published Tue Nov 30, 2021
30 Nov 2021 at 11:00am
Epitaxial growth of (100)-oriented SmN directly on (100)Si substrates
by J. F. McNulty, K. Temst, M. J. Van Bael, A. Vantomme, and E.-M. Anton
Author(s): J. F. McNulty, K. Temst, M. J. Van Bael, A. Vantomme, and E.-M. Anton


We demonstrate growth of epitaxial (100)SmN thin films directly on (100)Si surfaces. By using physical vapor deposition of Sm metal in an ${\mathrm{N}}_{2}$ atmosphere we show that careful control of substrate temperature, ${\mathrm{N}}_{2}$ pressure, and postannealing steps leads to epitaxial SmN w...


[Phys. Rev. Materials 5, 113404] Published Mon Nov 29, 2021
29 Nov 2021 at 11:00am
Stable polar oxynitrides through epitaxial strain
by Li Zhu, Hiroyuki Takenaka, and R. E. Cohen
Author(s): Li Zhu, Hiroyuki Takenaka, and R. E. Cohen


We investigate energetically favorable structures of $AB{\mathrm{O}}_{2}\mathrm{N}$ oxynitrides as functions of pressure and strain via swarm-intelligence-based structure prediction methods, density functional theory (DFT) lattice dynamics and first-principles molecular dynamics. We predict several ...


[Phys. Rev. Materials 5, 114404] Published Mon Nov 15, 2021
15 Nov 2021 at 11:00am
$\mathrm{Na}\mathrm{Zn}{\mathrm{F}}_{3}$ as a low-pressure analog of $\mathrm{Mg}\mathrm{Si}{\mathrm{O}}_{3}$
by Dominik Kurzydłowski, Arkadiusz Gajek, and Zoran Mazej
Author(s): Dominik Kurzydłowski, Arkadiusz Gajek, and Zoran Mazej


Solid-state systems whose properties at high pressure (exceeding 1 GPa) mimic those of $\mathrm{Mg}\mathrm{Si}{\mathrm{O}}_{3}$ are of large importance in the study of the interior of planets. By means of density functional theory (DFT) calculations we studied the high-pressure properties of a $\mat...


[Phys. Rev. Materials 5, 113602] Published Wed Nov 03, 2021
3 Nov 2021 at 11:00am
Pressure-induced structural phase transition and suppression of Jahn-Teller distortion in the quadruple perovskite structure
by V. S. Bhadram, B. Joseph, D. Delmonte, E. Gilioli, B. Baptiste, Y. Le Godec, R. P. S. M. Lobo, and A. Gauzzi
Author(s): V. S. Bhadram, B. Joseph, D. Delmonte, E. Gilioli, B. Baptiste, Y. Le Godec, R. P. S. M. Lobo, and A. Gauzzi


By means of in situ synchrotron x-ray diffraction and Raman spectroscopy under hydrostatic pressure, we investigate the structural stability of the quadruple perovskite $\mathrm{La}{\mathrm{Mn}}_{7}{\mathrm{O}}_{12}$. At 34 GPa, the data unveil a first-order structural phase transition from monoclin...


[Phys. Rev. Materials 5, 104411] Published Tue Oct 26, 2021
26 Oct 2021 at 12:00pm
Direct evidence of the proton-dynamics crossover in ice VII from high-pressure dielectric measurements beyond 10 GPa
by Ryo Yamane, Kazuki Komatsu, and Hiroyuki Kagi
Author(s): Ryo Yamane, Kazuki Komatsu, and Hiroyuki Kagi


We have conducted dielectric measurements of ice VII at pressures up to 12.2 GPa, and verified a dominant-dynamics change from a molecular rotation to a proton translation at approximately 10 GPa, using a newly developed high-pressure cell. Based on relaxation times of the two motions, which have a ...


[Phys. Rev. B 104, 214304] Published Wed Dec 08, 2021
8 Dec 2021 at 11:00am
Pressure-densified new rhombohedral phase of ${\mathrm{EuSn}}_{2}{\mathrm{As}}_{2}$
by Jian-Tao Wang, Changhao Wang, and Changfeng Chen
Author(s): Jian-Tao Wang, Changhao Wang, and Changfeng Chen


The magnetic topological insulator ${\mathrm{EuSn}}_{2}{\mathrm{As}}_{2}$ is known to crystallize in a ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$-type layered structure in rhombohedral symmetry at ambient conditions and undergo a structural phase transition toward a monoclinic $β$ phase under increasing p...


[Phys. Rev. B 104, L220101] Published Tue Dec 07, 2021
7 Dec 2021 at 11:00am
Doping site induced alteration of incommensurate antiferromagnetic ordering in Fe-doped MnNiGe alloys
by R. Roy, S. K. Adhikari, J. Sannigrahi, K. Mandal, S. C. Das, P. Dutta, S. Pramanick, D. Khalyavin, D. T. Adroja, and S. Chatterjee
Author(s): R. Roy, S. K. Adhikari, J. Sannigrahi, K. Mandal, S. C. Das, P. Dutta, S. Pramanick, D. Khalyavin, D. T. Adroja, and S. Chatterjee


The magnetic structure of Fe-doped MnNiGe alloys of nominal compositions ${\mathrm{MnNi}}_{0.75}{\mathrm{Fe}}_{0.25}\mathrm{Ge}$ and ${\mathrm{Mn}}_{0.85}{\mathrm{Fe}}_{0.15}\mathrm{NiGe}$ has been explored through detailed neutron powder diffraction (NPD) study in ambient and high-pressure (6 kbar)...


[Phys. Rev. B 104, 214405] Published Mon Dec 06, 2021
6 Dec 2021 at 11:00am
Valence skipping, internal doping, and site-selective Mott transition in ${\mathrm{PbCoO}}_{3}$ under pressure
by Atsushi Hariki, Kyo-Hoon Ahn, and Jan Kuneš
Author(s): Atsushi Hariki, Kyo-Hoon Ahn, and Jan Kuneš


We present a computational study of ${\mathrm{PbCoO}}_{3}$ at ambient and elevated pressure. We employ the static and dynamic treatment of local correlation in the form of density functional theory $+$ $U$ $(\mathrm{DFT}+U)$ and $+$ dynamical mean-field theory $(\mathrm{DFT}+\mathrm{DMFT})$. Our res...


[Phys. Rev. B 104, 235101] Published Wed Dec 01, 2021
1 Dec 2021 at 11:00am
Effect of hydrostatic pressure on magneto-crystalline anisotropy of Heusler Ni2MnSn-based alloy
by J. Kamarád
Volume 41, Issue 4, December 2021, Page 405-413
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11 Nov 2021 at 3:40am
Vacuum impregnation of apple assisted by high hydrostatic pressure
by Ming Gao
Volume 41, Issue 4, December 2021, Page 414-428
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7 Oct 2021 at 2:34pm

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