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 57th European High Pressure Research Group Meeting on High Pressure Science and Technology (EHPRG-2019) will be held in Prague, Czech Republic, from 1st to 6th September 2019. The 57th EHPRG Meeting will be chaired by Jiří Prchal (Charles University, Prague, Czech Republic).

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

Sleep-wake cycles drive daily dynamics of synaptic phosphorylation
by Brüning, F., Noya, S. B., Bange, T., Koutsouli, S., Rudolph, J. D., Tyagarajan, S. K., Cox, J., Mann, M., Brown, S. A., Robles, M. S.

The circadian clock drives daily changes of physiology, including sleep-wake cycles, through regulation of transcription, protein abundance, and function. Circadian phosphorylation controls cellular processes in peripheral organs, but little is known about its role in brain function and synaptic activity. We applied advanced quantitative phosphoproteomics to mouse forebrain synaptoneurosomes isolated across 24 hours, accurately quantifying almost 8000 phosphopeptides. Half of the synaptic phosphoproteins, including numerous kinases, had large-amplitude rhythms peaking at rest-activity and activity-rest transitions. Bioinformatic analyses revealed global temporal control of synaptic function through phosphorylation, including synaptic transmission, cytoskeleton reorganization, and excitatory/inhibitory balance. Sleep deprivation abolished 98% of all phosphorylation cycles in synaptoneurosomes, indicating that sleep-wake cycles rather than circadian signals are main drivers of synaptic phosphorylation, responding to both sleep and wake pressures.

10 Oct 2019 at 7:40pm
Epsilon iron as a spin-smectic state [Applied Physical Sciences]
by Blair W. Lebert, Tommaso Gorni, Michele Casula, Stefan Klotz, Francois Baudelet, James M. Ablett, Thomas C. Hansen, Amelie Juhin, Alain Polian, Pascal Munsch, Gilles Le Marchand, Zailan Zhang, Jean–Pascal Rueff, Matteo d’Astuto
Using X-ray emission spectroscopy, we find appreciable local magnetic moments until 30 GPa to 40 GPa in the high-pressure phase of iron; however, no magnetic order is detected with neutron powder diffraction down to 1.8 K, contrary to previous predictions. Our first-principles calculations reveal a “spin-smectic” state lower in energy...
8 Oct 2019 at 6:01pm
Resonance enhanced two-photon cavity ring-down spectroscopy of vibrational overtone bands: A proposal
by Kevin K. Lehmann
The Journal of Chemical Physics, Volume 151, Issue 14, October 2019.
This paper presents an analysis of near-resonant, rovibrational two-photon spectroscopy and the use of cavity ring-down spectroscopy for its detection. Expressions are derived for the photon absorption rate of a three-level system, correct to all orders and the simpler expressions that result from various approximations. The analysis includes the angular momentum projection degeneracies and linear or circular polarization of the exciting field. Expressions are derived for the rate of two-photon power loss for light inside a resonant cavity. Explicit calculations are made for excitation of the ν3 mode of 12C16O2 for which the two-photon excitation spectrum is dominated by a single v3 = 0 → 2, Q(16) line at [math] cm−1. This transition has an intermediate v3 = 0 → 1, P(16) one-photon transition that is off resonance by 0.093 cm−1 (2.8 GHz). At 1 Torr total pressure, the Q(16) two-photon transition is calculated to have a cross section of 2.99 × 10−38 cm4 s per CO2 molecule in the J = 16 state or 2.24 × 10−39 cm4 s per CO2 molecule at 300 K. The analysis of the sensitivity limits for 2-photon cavity ring-down spectroscopy predicts a theoretical detection limit of 32 ppq (10−15) Hz−1/2 for 12C16O2, higher sensitivity than has been realized using one-photon absorption. The analysis predicts that most polyatomic molecules will have sparse, Doppler-free two-photon absorption spectra, which will dramatically increase the selectivity of trace gas detection of samples with multiple components with overlapping absorption bands. This is demonstrated by the predicted mid-IR two-photon absorption spectrum of butadiene using theoretical spectroscopic constants.
10 Oct 2019 at 4:38am
Interfacial free energy of a liquid-solid interface: Its change with curvature
by P. Montero de Hijes
The Journal of Chemical Physics, Volume 151, Issue 14, October 2019.
We analyze the changes in the interfacial free energy between a spherical solid cluster and a fluid due to the change of the radius of the solid. Interfacial free energies from nucleation studies using the seeding technique for four different systems, being hard spheres, Lennard-Jones, and two models of water (mW and TIP4P/ICE), were plotted as a function of the inverse of the radius of the solid cluster. In all cases, the interfacial free energy was a linear function of the inverse of the radius of the solid cluster and this is consistent with Tolman’s equation. This linear behavior is shown not only in isotherms but also along isobars. The effect of curvature on the interfacial free energy is more pronounced in water, followed by hard spheres, and smaller for Lennard-Jones particles. We show that it is possible to estimate nucleation rates of Lennard-Jones particles at different pressures by using information from simple NpT simulations and taking into account the variation of the interfacial free energy with the radius of the solid cluster. Neglecting the effects of the radius on the interfacial free energy (capillarity approximation) leads to incorrect values of the nucleation rate. For the Lennard-Jones system, the homogeneous nucleation curve is not parallel to the melting curve as was found for water in previous work. This is due to the increase in the interfacial free energy along the coexistence curve as the pressure increases. This work presents a simple and relatively straightforward way to approximately estimate nucleation rates.
8 Oct 2019 at 4:45am
The role of nuclear quantum effects in the relative stability of hexagonal and cubic ice
by Samuel J. Buxton
The Journal of Chemical Physics, Volume 151, Issue 14, October 2019.
At atmospheric pressure, hexagonal ice (Ih) is thermodynamically stable relative to cubic ice (Ic), although the magnitude and underlying physical origin of this stability difference are not well defined. Pure Ic crystals are not accessible experimentally, and hence computer simulations have often been used to interrogate the relative stabilities of Ih and Ic; however, these simulations are dominated by molecular interaction models that ignore the intramolecular flexibility of individual water molecules, do not describe intermolecular hydrogen-bonding with sufficient accuracy, or ignore the role of nuclear quantum effects (NQEs) such as zero-point energy. Here, we show that when comparing the relative stability of Ih and Ic using a flexible, anharmonic molecular interaction model, while also accurately accounting for NQEs, a new picture emerges: Ih is stabilized relative to Ic as a result of subtle differences in the intramolecular geometries and intermolecular interactions of water molecules which are modulated by NQEs. Our simulations hence suggest that NQEs are a major contributor to the stabilization of Ih under terrestrial conditions and thus contribute to the well-known hexagonal (sixfold) symmetry of ice crystals.
8 Oct 2019 at 4:43am
Contrasting Pressure-Induced Metallization Processes in Layered Perovskites, $α$-${\mathrm{Sr}}_{2}M{\mathrm{O}}_{4}$ ($M=\mathrm{V}$, Cr)
by Touru Yamauchi, Taku Shimazu, Daisuke Nishio-Hamane, and Hiroya Sakurai
Author(s): Touru Yamauchi, Taku Shimazu, Daisuke Nishio-Hamane, and Hiroya Sakurai

Electric resistivity, magnetic susceptibility, and x-ray diffraction measurements under high pressure are performed in both $α$-${\mathrm{Sr}}_{2}{\mathrm{VO}}_{4}$ and $α$-${\mathrm{Sr}}_{2}{\mathrm{CrO}}_{4}$, which are carefully prepared with regard to their stoichiometry. These measurements reve...

[Phys. Rev. Lett. 123, 156601] Published Wed Oct 09, 2019
9 Oct 2019 at 12:00pm
Pressure-Induced Hydrogen-Hydrogen Interaction in Metallic FeH Revealed by NMR
by Thomas Meier, Florian Trybel, Saiana Khandarkhaeva, Gerd Steinle-Neumann, Stella Chariton, Timofey Fedotenko, Sylvain Petitgirard, Michael Hanfland, Konstantin Glazyrin, Natalia Dubrovinskaia, and Leonid Dubrovinsky
Author(s): Thomas Meier, Florian Trybel, Saiana Khandarkhaeva, Gerd Steinle-Neumann, Stella Chariton, Timofey Fedotenko, Sylvain Petitgirard, Michael Hanfland, Konstantin Glazyrin, Natalia Dubrovinskaia, and Leonid Dubrovinsky

Nuclear magnetic resonance experiments reveal how the electronic properties of hydrogen in iron hydride change under extreme pressure, a step toward understanding the onset of high-temperature superconductivity in metal hydrides.

[Phys. Rev. X 9, 031008] Published Wed Jul 17, 2019
17 Jul 2019 at 12:00pm
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
Effect of Ge substitution on magnetic properties in the itinerant chiral magnet MnSi
by Seno Aji, Hidesato Ishida, Daisuke Okuyama, Kazuhiro Nawa, Tao Hong, and Taku J. Sato
Author(s): Seno Aji, Hidesato Ishida, Daisuke Okuyama, Kazuhiro Nawa, Tao Hong, and Taku J. Sato

We have investigated the effect of Ge substitution on the magnetic ordering in the B20 itinerant chiral magnet MnSi prepared by melting and annealing under ambient pressure. From a metallurgical survey, the solubility limit of Ge was found to be $x=0.144(5)$ with annealing temperature ${T}_{\mathrm{... [Phys. Rev. Materials 3, 104408] Published Mon Oct 14, 2019 14 Oct 2019 at 12:00pm Physical properties of$R{\mathrm{Bi}}_{2}(R=\mathrm{La},\mathrm{Ce})$under pressure by Li Xiang, Elena Gati, Kathryn Neilson, Sergey L. Bud'ko, and Paul C. Canfield Author(s): Li Xiang, Elena Gati, Kathryn Neilson, Sergey L. Bud'ko, and Paul C. Canfield We present a study of electrical transport properties of$R{\mathrm{Bi}}_{2}(R=\mathrm{La},\mathrm{Ce})$under hydrostatic pressure up to$∼2.5$GPa. These measurements are complemented by thermodynamic measurements of the specific heat on${\mathrm{CeBi}}_{2}$at different pressures up to 2.55 G... [Phys. Rev. Materials 3, 095006] Published Tue Sep 24, 2019 24 Sep 2019 at 12:00pm Theoretical assessment of the structure and stability of the$λ$phase of nitrogen by Watit Sontising and Gregory J. O. Beran Author(s): Watit Sontising and Gregory J. O. Beran The$λ$phase of nitrogen was reported in 2016 and is one of more than a dozen high-pressure solid nitrogen forms that have been discovered. However, its crystal structure could not be solved unambiguously from powder diffraction alone; rather the reported structure was determined by combining exper... [Phys. Rev. Materials 3, 095002] Published Fri Sep 13, 2019 13 Sep 2019 at 12:00pm Evidence for pressure-induced polarization rotation, octahedral tilting, and reentrant ferroelectric phase in tetragonal$(\mathrm{P}{\mathrm{b}}_{0.5}\mathrm{B}{\mathrm{i}}_{0.5})(\mathrm{T}{\mathrm{i}}_{0.5}\mathrm{F}{\mathrm{e}}_{0.5}){\mathrm{O}}_{3}$by Pragya Singh, Chandan Upadhyay, Zuzana Konôpková, Hanns-Peter Liermann, and Dhananjai Pandey Author(s): Pragya Singh, Chandan Upadhyay, Zuzana Konôpková, Hanns-Peter Liermann, and Dhananjai Pandey Pressure-induced phase transition in the technologically important tetragonal phase of${\mathrm{PbTiO}}_{3}$has been quite controversial with two entirely different propositions: (1) morphotropic phase boundary-like structural transition with concomitant rotation of the ferroelectric polarization ... [Phys. Rev. Materials 3, 094405] Published Wed Sep 11, 2019 11 Sep 2019 at 12:00pm Suppression of the antiferromagnetic metallic state in the pressurized$\mathrm{MnB}{\mathrm{i}}_{2}\mathrm{T}{\mathrm{e}}_{4}$single crystal by K. Y. Chen, B. S. Wang, J.-Q. Yan, D. S. Parker, J.-S. Zhou, Y. Uwatoko, and J.-G. Cheng Author(s): K. Y. Chen, B. S. Wang, J.-Q. Yan, D. S. Parker, J.-S. Zhou, Y. Uwatoko, and J.-G. Cheng We study the effect of hydrostatic pressure on the electrical transport, magnetic, and structural properties of$\mathrm{MnB}{\mathrm{i}}_{2}\mathrm{T}{\mathrm{e}}_{4}$by measuring its resistivity, Hall effect, and x-ray diffraction under pressures up to 12.8 GPa supplemented by the first-principle... [Phys. Rev. Materials 3, 094201] Published Tue Sep 03, 2019 3 Sep 2019 at 12:00pm Predicted lithium oxide compounds and superconducting low-pressure${\mathrm{LiO}}_{4}$by Xiao Dong, Jingyu Hou, Jun Kong, Haixu Cui, Yan-Ling Li, Artem R. Oganov, Kuo Li, Haiyan Zheng, Xiang-Feng Zhou, and Hui-Tian Wang Author(s): Xiao Dong, Jingyu Hou, Jun Kong, Haixu Cui, Yan-Ling Li, Artem R. Oganov, Kuo Li, Haiyan Zheng, Xiang-Feng Zhou, and Hui-Tian Wang We study the stability of Li-O compounds as a function of pressure, with rich phase diagram, diverse properties, and fundamental chemical interest in mind. Using the ab initio evolutionary algorithm USPEX, we predict the stability of compounds${\mathrm{LiO}}_{4}, {\mathrm{Li}}_{5}{\mathrm{O}}_{3}$,... [Phys. Rev. B 100, 144104] Published Mon Oct 14, 2019 14 Oct 2019 at 12:00pm Unusual pressure-induced metallic state in the correlated narrow band-gap semiconductor FeSi by G. R. Hearne, P. Musyimi, S. Bhattacharjee, M. K. Forthaus, and M. M. Abd-Elmeguid Author(s): G. R. Hearne, P. Musyimi, S. Bhattacharjee, M. K. Forthaus, and M. M. Abd-Elmeguid The extent of electron correlations in FeSi and Fe-3d/Si-3p hybridization embeds a narrow gap in the resultant quasiparticle peak at the Fermi level. Here, the authors investigate the effect of compression tuning of this electronic fine structure and demonstrate its sensitivity to lattice heterogeneities, e.g., those resulting from extrinsic lattice strains. Pressurization tunes the mobility edge relative to the Fermi level until an unusual metallic state ensues beyond about 15 GPa, which does not involve any structural instability of the original B20-type cubic structure. [Phys. Rev. B 100, 155118] Published Thu Oct 10, 2019 10 Oct 2019 at 12:00pm Crystalline phase transitions and vibrational spectra of silicon up to multiterapascal pressures by R. Paul, S. X. Hu, and V. V. Karasiev Author(s): R. Paul, S. X. Hu, and V. V. Karasiev A composite high-pressure phase diagram for silicon has been predicted for up to 4 TPa. This diagram has been built using a combination of evolutionary algorithm-based structure searches, electronic density functional theory, lattice dynamics of perfect crystals, and anharmonic corrections for the s... [Phys. Rev. B 100, 144101] Published Wed Oct 09, 2019 9 Oct 2019 at 12:00pm Superconducting order parameter and bosonic mode in hydrogen-substituted${\mathrm{NdFeAsO}}_{0.6}{\mathrm{H}}_{0.36}\$ revealed by multiple-Andreev-reflection spectroscopy
by T. E. Kuzmicheva, S. A. Kuzmichev, and N. D. Zhigadlo
Author(s): T. E. Kuzmicheva, S. A. Kuzmichev, and N. D. Zhigadlo

Synthesized under high pressure, hydrogen-substituted NdFeAsO0.6H0.36 (with a critical temperature of 48 K) possibly demonstrates a double-dome superconducting state in its phase diagram, thus foreshadowing extraordinary physics as compared with other iron-based oxypnictides. Ballistic Andreev transport in superconductor–normal metal–superconductor junctions provides direct information about the superconducting order parameter at any temperatures up to Tc, and specific boson emission. The authors discuss here the characteristics found of the multiple-band superconducting state, the boson energy, and their nature.

[Phys. Rev. B 100, 144504] Published Wed Oct 09, 2019
9 Oct 2019 at 12:00pm
Development of a technique for high pressure neutron diffraction at 40 GPa with a Paris-Edinburgh press
by T. Hattori
Volume 39, Issue 3, September 2019, Page 417-425
.

4 Jun 2019 at 6:21am
Modified Bridgman anvils for high pressure synthesis and neutron scattering
by Bianca Haberl
Volume 39, Issue 3, September 2019, Page 426-437
.

17 Jun 2019 at 8:18am
Ultrahigh pressure equation of state of tantalum to 310 GPa
by Kaleb C. Burrage
Volume 39, Issue 3, September 2019, Page 489-498
.

11 Jul 2019 at 8:28am
In-situ X-ray diffraction study on β-CrOOH at high pressure and high-temperature
by Chikara Shito
Volume 39, Issue 3, September 2019, Page 499-508
.

17 Jul 2019 at 2:46pm
Effects of high hydrostatic pressure on β-glucan content, swelling power, starch damage, and pasting properties of high-β-glucan barley flour
by Shigeaki Ueno
Volume 39, Issue 3, September 2019, Page 509-524
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29 Mar 2019 at 1:58pm
The usage of high hydrostatic pressure (HHP) to control food-borne pathogens in hummus
by Barbara Sokołowska
Volume 39, Issue 3, September 2019, Page 525-532
.

24 Jun 2019 at 12:09pm
High pressure influence on the Diels–Alder reaction volume in the solid phase at pressure up to 7000 bar and in solution
by Dmitry A. Kornilov
.

8 Oct 2019 at 10:58am
The application of manganin wire pressure gauges in a large volume press under high-temperature conditions
by Ren Dongsheng
.

8 Oct 2019 at 10:58am
Hydrostaticity of pressure-transmitting media for high pressure infrared spectroscopy
by A. Celeste
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20 Sep 2019 at 11:59am
Enhancing the pressure limitation in large-volume Bridgman-anvil cell used for in situ neutron diffraction
by Qiwei Hu
.

19 Sep 2019 at 1:28pm
High hydrostatic pressure processing of beetroot juice: effects on nutritional, sensory and microbiological quality
by Marta Ubeira-Iglesias
.

19 Sep 2019 at 1:24pm
Lattice distortion-induced sluggish phase transition in CoCrFeNixAl1-x (x = 0.5, 0.75) high-entropy alloys at high pressures
by Lei Liu
.

16 Aug 2019 at 12:07pm