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.

Highly stable fullerene-based porous molecular crystals with open metal sites
by C. Grazia Bezzu


Nature Materials, Published online: 13 May 2019; doi:10.1038/s41563-019-0361-0

Porous molecular crystals are easy to fabricate but thought to have limited stability as they are bound by non-covalent interactions. Here, a porous crystal composed of C60 and phthalocyanine is demonstrated with stability to heat, acid, base and high pressures.
13 May 2019 at 12:00am
Widespread nitrous oxide undersaturation in farm waterbodies creates an unexpected greenhouse gas sink [Earth, Atmospheric, and Planetary Sciences]
by Jackie R. Webb, Nicole M. Hayes, Gavin L. Simpson, Peter R. Leavitt, Helen M. Baulch, Kerri Finlay
Nitrogen pollution and global eutrophication are predicted to increase nitrous oxide (N2O) emissions from freshwater ecosystems. Surface waters within agricultural landscapes experience the full impact of these pressures and can contribute substantially to total landscape N2O emissions. However, N2O measurements to date have focused on flowing waters. Small artificial waterbodies...
14 May 2019 at 8:07pm
Optical properties of high-pressure fluid hydrogen across molecular dissociation [Physics]
by Giovanni Rillo, Miguel A. Morales, David M. Ceperley, Carlo Pierleoni
Optical properties of compressed fluid hydrogen in the region where dissociation and metallization is observed are computed by ab initio methods and compared with recent experimental results. We confirm that at T > 3,000 K, both processes are continuous, while at T
14 May 2019 at 8:07pm
Unraveling the metastability of the SI and SII carbon monoxide hydrate with a combined DFT-neutron diffraction investigation
by Claire Pétuya
The Journal of Chemical Physics, Volume 150, Issue 18, May 2019.
Clathrate hydrates are crystalline compounds consisting of water molecules forming cages (so-called “host”) inside of which “guest” molecules are encapsulated depending on the thermodynamic conditions of formation (systems stable at low temperature and high pressure). These icelike systems are naturally abundant on Earth and are generally expected to exist on icy celestial bodies. Carbon monoxide hydrate might be considered an important component of the carbon cycle in the solar system since CO gas is one of the predominant forms of carbon. Intriguing fundamental properties have also been reported: the CO hydrate initially forms in the sI structure (kinetically favored) and transforms into the sII structure (thermodynamically stable). Understanding and predicting the gas hydrate structural stability then become essential. The aim of this work is, thereby, to study the structural and energetic properties of the CO hydrate using density functional theory (DFT) calculations together with neutron diffraction measurements. In addition to the comparison of DFT-derived structural properties with those from experimental neutron diffraction, the originality of this work lies in the DFT-derived energy calculations performed on a complete unit cell (sI and sII) and not only by considering guest molecules confined in an isolated water cage (as usually performed for extracting the binding energies). Interestingly, an excellent agreement (within less than 1% error) is found between the measured and DFT-derived unit cell parameters by considering the Perdew-Burke-Ernzerhof (denoted PBE) functional. Moreover, a strategy is proposed for evaluating the hydrate structural stability on the basis of potential energy analysis of the total nonbonding energies (i.e., binding energy and water substructure nonbonding energy). It is found that the sII structure is the thermodynamically stable hydrate phase. In addition, increasing the CO content in the large cages has a stabilizing effect on the sII structure, while it destabilizes the sI structure. Such findings are in agreement with the recent experimental results evidencing the structural metastability of the CO hydrate.
14 May 2019 at 3:52am
Rotational Echoes as a Tool for Investigating Ultrafast Collisional Dynamics of Molecules
by H. Zhang, B. Lavorel, F. Billard, J.-M. Hartmann, E. Hertz, O. Faucher, Junyang Ma, Jian Wu, Erez Gershnabel, Yehiam Prior, and Ilya Sh. Averbukh
Author(s): H. Zhang, B. Lavorel, F. Billard, J.-M. Hartmann, E. Hertz, O. Faucher, Junyang Ma, Jian Wu, Erez Gershnabel, Yehiam Prior, and Ilya Sh. Averbukh


We show that recently discovered rotational echoes of molecules provide an efficient tool for studying collisional molecular dynamics in high-pressure gases. Our study demonstrates that rotational echoes enable the observation of extremely fast collisional dissipation, at timescales of the order of ...


[Phys. Rev. Lett. 122, 193401] Published Fri May 17, 2019
17 May 2019 at 12:00pm
Comment on “High-Pressure Behavior of Hydrogen and Deuterium at Low Temperatures”
by Alexander F. Goncharov and Yu. A. Freiman
Author(s): Alexander F. Goncharov and Yu. A. Freiman


X.-D. Liu et al. [Phys. Rev. Lett. 119, 065301 (2017)] report on the existence of a new unique solid phase of ${\mathrm{D}}_{2}$, which makes the high-pressure low-temperature behavior distinct from ${\mathrm{H}}_{2}$. Here, based on the analysis of their Raman data and phase transition theory, we s...


[Phys. Rev. Lett. 122, 199601] Published Mon May 13, 2019
13 May 2019 at 12:00pm
Persistent Octahedral Coordination in Amorphous ${\mathrm{GeO}}_{2}$ Up to 100 GPa by $\mathrm{K}{β}^{′′}$ X-Ray Emission Spectroscopy
by G. Spiekermann, M. Harder, K. Gilmore, P. Zalden, Ch. J. Sahle, S. Petitgirard, M. Wilke, N. Biedermann, C. Weis, W. Morgenroth, J. S. Tse, E. Kulik, N. Nishiyama, H. Yavaş, and C. Sternemann
Author(s): G. Spiekermann, M. Harder, K. Gilmore, P. Zalden, Ch. J. Sahle, S. Petitgirard, M. Wilke, N. Biedermann, C. Weis, W. Morgenroth, J. S. Tse, E. Kulik, N. Nishiyama, H. Yavaş, and C. Sternemann


X-ray emission spectra reveal that under pressure conditions of Earth’s lower mantle, the compaction mechanism in amorphous germanium dioxide on the atomic scale is similar to that of its crystalline form.


[Phys. Rev. X 9, 011025] Published Wed Feb 06, 2019
6 Feb 2019 at 11:00am
Solids, liquids, and gases under high pressure
by Ho-Kwang Mao, Xiao-Jia Chen, Yang Ding, Bing Li, and Lin Wang
Author(s): Ho-Kwang Mao, Xiao-Jia Chen, Yang Ding, Bing Li, and Lin Wang


The effect of adding high pressure as a control parameter in solids, liquids, and gases expands opportunities to observe unexpected novel phenomena and understand matter in extreme environments. This review on high pressure science highlights subjects ranging from quantum criticality to Earth science. State-of-the-art experimental methods at megabar pressures are also discussed. The proliferation of pressure-induced phases illustrate promising new directions for this field of research.


[Rev. Mod. Phys. 90, 015007] Published Tue Mar 20, 2018
20 Mar 2018 at 11:00am
Colloquium: High pressure and road to room temperature superconductivity
by Lev P. Gor’kov and Vladimir Z. Kresin
Author(s): Lev P. Gor’kov and Vladimir Z. Kresin


Even after three decades of development, high-temperature superconductivity remains one of the most challenging theoretical and experimental areas in condensed matter physics. In this Colloquium some new discoveries in this area are reviewed and possible routes toward much higher transition temperatures are analyzed.


[Rev. Mod. Phys. 90, 011001] Published Tue Jan 09, 2018
9 Jan 2018 at 11:00am
Equations of state for supernovae and compact stars
by M. Oertel, M. Hempel, T. Klähn, and S. Typel
Author(s): M. Oertel, M. Hempel, T. Klähn, and S. Typel


What are the thermodynamic properties of matter at extreme densities, even exceeding nuclear matter density severely? How can we describe the composition of matter for such conditions, the resulting pressure, and the maximum mass of cold neutron stars? How is this affected by finite temperatures, as they occur in core collapse supernovae and in compact star mergers? This review addresses these points within the framework of constraints from experiments as well as astronomical observations.


[Rev. Mod. Phys. 89, 015007] Published Wed Mar 15, 2017
15 Mar 2017 at 11:00am
XMCD study of magnetism and valence state in iron-substituted strontium titanate
by Astera S. Tang, Jonathan Pelliciari, Qi Song, Qian Song, Shuai Ning, John W. Freeland, Riccardo Comin, and Caroline A. Ross
Author(s): Astera S. Tang, Jonathan Pelliciari, Qi Song, Qian Song, Shuai Ning, John W. Freeland, Riccardo Comin, and Caroline A. Ross


Room-temperature ferromagnetism was characterized for thin films of $\mathrm{SrT}{\mathrm{i}}_{0.6}\mathrm{F}{\mathrm{e}}_{0.4}{\mathrm{O}}_{3\text{−}δ}$ grown by pulsed laser deposition on $\mathrm{SrTi}{\mathrm{O}}_{3}$ and Si substrates under different oxygen pressures and after annealing under o...


[Phys. Rev. Materials 3, 054408] Published Fri May 17, 2019
17 May 2019 at 12:00pm
High-pressure synthesis, crystal growth, and compression behavior of hexagonal ${\mathrm{CrN}}_{2}$ having one-dimensionally aligned nitrogen dimer
by Ken Niwa, Takurou Yamamoto, Takuya Sasaki, and Masashi Hasegawa
Author(s): Ken Niwa, Takurou Yamamoto, Takuya Sasaki, and Masashi Hasegawa


A hexagonal chromium pernitride, ${\mathrm{CrN}}_{2}$, has been successfully synthesized $via$ a direct chemical reaction between chromium and molecular nitrogen at a pressure of approximately 70 GPa. The advanced synchrotron x-ray diffraction (XRD) measurements after recovery and structural refinem...


[Phys. Rev. Materials 3, 053601] Published Wed May 01, 2019
1 May 2019 at 12:00pm
Phonon dispersion relation, high-pressure phase stability, and thermal expansion in ${\mathrm{YVO}}_{4}$
by R. Mittal, M. K. Gupta, Baltej Singh, L. Pintschovius, Yu D. Zavartsev, and S. L. Chaplot
Author(s): R. Mittal, M. K. Gupta, Baltej Singh, L. Pintschovius, Yu D. Zavartsev, and S. L. Chaplot


The orthovanadates are useful as host matrices for immobilization of radioactive wastes. The thermodynamic stability of these materials is crucial for their applications in high-pressure and high-temperature environment. It is necessary to investigate the phonons in the entire Brillouin zone, beyond...


[Phys. Rev. Materials 3, 043608] Published Fri Apr 26, 2019
26 Apr 2019 at 12:00pm
High-pressure lithium as an elemental topological semimetal
by S. F. Elatresh, Zhimou Zhou, N. W. Ashcroft, S. A. Bonev, Ji Feng, and Roald Hoffmann
Author(s): S. F. Elatresh, Zhimou Zhou, N. W. Ashcroft, S. A. Bonev, Ji Feng, and Roald Hoffmann


Topological semimetals generally contain heavy elements. Using density-functional theoretic calculations, we predict that three dense lithium polymorphs in the pressure range 200–360 GPa display nontrivial semimetallic electronic structure. Specifically, these high-pressure phases exhibit Fermi pock...


[Phys. Rev. Materials 3, 044203] Published Tue Apr 23, 2019
23 Apr 2019 at 12:00pm
Ambipolar suppression of superconductivity by ionic gating in optimally doped ${\mathrm{BaFe}}_{2}{(\mathrm{As},\mathrm{P})}_{2}$ ultrathin films
by Erik Piatti, Takafumi Hatano, Dario Daghero, Francesco Galanti, Claudio Gerbaldi, Salvatore Guastella, Chiara Portesi, Ibuki Nakamura, Ryosuke Fujimoto, Kazumasa Iida, Hiroshi Ikuta, and Renato S. Gonnelli
Author(s): Erik Piatti, Takafumi Hatano, Dario Daghero, Francesco Galanti, Claudio Gerbaldi, Salvatore Guastella, Chiara Portesi, Ibuki Nakamura, Ryosuke Fujimoto, Kazumasa Iida, Hiroshi Ikuta, and Renato S. Gonnelli


Superconductivity (SC) in the Ba-122 family of iron-based compounds can be controlled by aliovalent or isovalent substitutions, applied external pressure, and strain, the combined effects of which are sometimes studied within the same sample. Most often, the result is limited to a shift of the SC do...


[Phys. Rev. Materials 3, 044801] Published Mon Apr 15, 2019
15 Apr 2019 at 12:00pm
Pressure tuning of the electrical transport properties in the Weyl semimetal TaP
by M. Besser, R. D. dos Reis, F.-R. Fan, M. O. Ajeesh, Y. Sun, M. Schmidt, C. Felser, and M. Nicklas
Author(s): M. Besser, R. D. dos Reis, F.-R. Fan, M. O. Ajeesh, Y. Sun, M. Schmidt, C. Felser, and M. Nicklas


We investigated the pressure evolution of the electrical transport in the almost compensated Weyl semimetal TaP. In addition, we obtained information on the modifications of the Fermi-surface topology with pressure from the analysis of pronounced Shubnikov–de Haas (SdH) quantum oscillations present ...


[Phys. Rev. Materials 3, 044201] Published Wed Apr 10, 2019
10 Apr 2019 at 12:00pm
Probing the quantum phase transition in Mott insulator ${\mathrm{BaCoS}}_{2}$ tuned by pressure and Ni substitution
by Z. Guguchia, B. A. Frandsen, D. Santos-Cottin, S. C. Cheung, Z. Gong, Q. Sheng, K. Yamakawa, A. M. Hallas, M. N. Wilson, Y. Cai, J. Beare, R. Khasanov, R. De Renzi, G. M. Luke, S. Shamoto, A. Gauzzi, Y. Klein, and Y. J. Uemura
Author(s): Z. Guguchia, B. A. Frandsen, D. Santos-Cottin, S. C. Cheung, Z. Gong, Q. Sheng, K. Yamakawa, A. M. Hallas, M. N. Wilson, Y. Cai, J. Beare, R. Khasanov, R. De Renzi, G. M. Luke, S. Shamoto, A. Gauzzi, Y. Klein, and Y. J. Uemura


We present a muon spin relaxation study of the Mott transition in ${\mathrm{BaCoS}}_{2}$ using two independent control parameters: (i) pressure $p$ to tune the electronic bandwidth and (ii) Ni substitution $x$ on the Co site to tune the band filling. For both tuning parameters, the antiferromagnetic...


[Phys. Rev. Materials 3, 045001] Published Fri Apr 05, 2019
5 Apr 2019 at 12:00pm
Ultrahigh-pressure induced decomposition of silicon disulfide into silicon-sulfur compounds with high coordination numbers
by Yuanzheng Chen, Xiaolei Feng, Jiao Chen, Xinyong Cai, Bai Sun, Hongyan Wang, Huarong Du, Simon A. T. Redfern, Yu Xie, and Hanyu Liu
Author(s): Yuanzheng Chen, Xiaolei Feng, Jiao Chen, Xinyong Cai, Bai Sun, Hongyan Wang, Huarong Du, Simon A. T. Redfern, Yu Xie, and Hanyu Liu


Silicon disulfide, ${\mathrm{SiS}}_{2}$, is thought to occur in interstellar dust and is of fundamental interest more generally among the silicon chalcogenides as a comparator to ${\mathrm{SiO}}_{2}$, an important component of terrestrial planets. However, the high-pressure behaviors of silicon sulf...


[Phys. Rev. B 99, 184106] Published Wed May 15, 2019
15 May 2019 at 12:00pm
Superconducting nature of the Bi-II phase of elemental bismuth
by Rustem Khasanov, Miloš M. Radonjić, Hubertus Luetkens, Elvezio Morenzoni, Gediminas Simutis, Stephan Schönecker, Wilhelm H. Appelt, Andreas Östlin, Liviu Chioncel, and Alex Amato
Author(s): Rustem Khasanov, Miloš M. Radonjić, Hubertus Luetkens, Elvezio Morenzoni, Gediminas Simutis, Stephan Schönecker, Wilhelm H. Appelt, Andreas Östlin, Liviu Chioncel, and Alex Amato


The superconductivity in the Bi-II phase of elemental bismuth (transition temperature ${T}_{\mathrm{c}}≃3.92$ K at pressure $p≃2.80$ GPa) was studied experimentally by means of the muon-spin rotation as well as theoretically by using the Eliashberg theory in combination with density functional theor...


[Phys. Rev. B 99, 174506] Published Mon May 13, 2019
13 May 2019 at 12:00pm
Effect of hydrostatic pressure on ferromagnetism in two-dimensional ${\mathrm{CrI}}_{3}$
by Suchanda Mondal, Murugesan Kannan, Moumita Das, Linganan Govindaraj, Ratnadwip Singha, Biswarup Satpati, Sonachalam Arumugam, and Prabhat Mandal
Author(s): Suchanda Mondal, Murugesan Kannan, Moumita Das, Linganan Govindaraj, Ratnadwip Singha, Biswarup Satpati, Sonachalam Arumugam, and Prabhat Mandal


We have investigated the magnetic properties of the highly anisotropic layered ferromagnetic semiconductor ${\mathrm{CrI}}_{3}$ under hydrostatic pressure with the magnetic field along the easy axis of magnetization. At ambient pressure, ${\mathrm{CrI}}_{3}$ undergoes a second-order paramagnetic-to-...


[Phys. Rev. B 99, 180407(R)] Published Mon May 13, 2019
13 May 2019 at 12:00pm
Grocery bills can predict diabetes rates by neighborhood
Dietary habits are notoriously difficult to monitor. Now data scientists have analyzed sales figures from London’s biggest grocer to link eating patterns with local rates of high blood pressure, high cholesterol, and high blood sugar.
17 May 2019 at 4:45pm
Superionic ice observed at extreme pressure and temperature

17 May 2019 at 9:34pm