High pressure

Résumé

In science and engineering the study of high pressure examines its effects on materials and the design and construction of devices, such as a diamond anvil cell, which can create high pressure. By high pressure is usually meant pressures of thousands (kilobars) or millions (megabars) of times atmospheric pressure (about 1 bar or 100,000 Pa). History and overview Percy Williams Bridgman received a Nobel Prize in 1946 for advancing this area of physics by two magnitudes of pressure (400 MPa to 40 GPa). The list of founding fathers of this field includes also the names of Harry George Drickamer, Tracy Hall, Francis P. Bundy, Leonid F. Vereschagin, and Sergey M. Stishov. It was by applying high pressure as well as high temperature to carbon that man-made diamonds were first produced alongside many other interesting discoveries. Almost any material when subjected to high pressure will compact itself into a denser form, for example, quartz (also called silica or silicon dioxide)

Source officielle

https://en.wikipedia.org/wiki/High_pressure

À propos de ce résultat

Cette page est générée automatiquement et peut contenir des informations qui ne sont pas correctes, complètes, à jour ou pertinentes par rapport à votre recherche. Il en va de même pour toutes les autres pages de ce site. Veillez à vérifier les informations auprès des sources officielles de l'EPFL.

Publications associées (100)

Publications associées

Chargement

Personnes associées (16)

Personnes associées

Chargement

Unités associées (6)

Unités associées

Chargement

Concepts associés (2)

Concepts associés

Chargement

Cours associés (47)

Cours associés

Chargement

Séances de cours associées (89)

Séances de cours associées

Chargement

Journal of Physics: Conference Series High-pressure specific heat technique to uncover novel states of quantum matter

Julio Antonio Larrea Jiménez, Henrik Moodysson Rønnow

AC-specific heat measurements remain as the foremost thermodynamic experimental method to underpin phase transitions in tiny samples. However, its performance under combined extreme conditions of high-pressure, very low temperature and intense magnetic fields needs to be broadly extended for investigation of quantum phase transition in strongly correlated electron systems. In this communication, we discuss the determination of specific heat on the quantum paramagnetic insulator SrCu2 (BO3)(2) by applying the AC-specific heat technique under extreme conditions. In order to apply this technique to insulating samples we sputtered a metallic thin film-heater and attached thermometer onto sample. Besides that, we performed full frequency scans with the aim to get quantitative specific heat data. Our results show that we can determine the sample heat capacity within 5 % of accuracy respect to an adiabatic technique. This allows to uncover low energy scales that characterize the ground state of quantum spin entanglement in SrCu2 (BO3)(2).

IOP PUBLISHING LTD2020

Chargement

Salt- and gas-filled ices under planetary conditions

Livia Eleonora Bove Kado, Umbertoluca Ranieri

In recent years, evidence has emerged that solid water can contain substantial amounts of guest species, such as small gas molecules-in gas hydrate structures-or ions-in salty ice structures-and that these 'filled' ice structures can be stable under pressures of tens of Gigapascals and temperatures of hundreds of Kelvins. The inclusion of guest species can strongly modify the density, vibrational, diffusive and conductivity properties of ice under high pressure, and promote novel exotic properties. In this review, we discuss our experimental findings and molecular dynamics simulation results on the structures formed by salt- and gas-filled ices, their unusual properties, and the unexpected dynamical phenomena observed under pressure and temperature conditions relevant for planetary interiors modelling. This article is part of the theme issue 'The physics and chemistry of ice: scaffolding across scales, from the viability of life to the formation of planets'.

ROYAL SOC2019

Chargement

We report the structural transformation of hexagonal Ba3YIr 2O9 to a cubic double perovskite form (stable in ambient conditions) under an applied pressure of 8 GPa at 1273 K. While the ambient pressure synthesized sample undergoes long-range magnetic ordering at ∼4 K, the high-pressure (HP) synthesized sample does not order down to 2 K as evidenced from our susceptibility, heat capacity, and nuclear magnetic resonance (NMR) measurements. Further, for the HP sample, our heat capacity data have the form γT+βT3 in the temperature (T) range of 2-10 K with the Sommerfeld coefficient γ=10 mJ/mol-Ir K2. The 89Y NMR shift has no T dependence in the range of 4-120 K and its spin-lattice relaxation rate varies linearly with T in the range of 8-45 K (above which it is T independent). Resistance measurements of both the samples confirm that they are semiconducting. Our data provide evidence for the formation of a 5d-based, gapless, quantum spin-liquid in the cubic (HP) phase of Ba3YIr 2O9. In this picture, the γT term in the heat capacity and the linear variation of 89Y 1/T1 arises from excitations out of a spinon Fermi surface. Our findings lend credence to the theoretical suggestion that strong spin-orbit coupling can enhance quantum fluctuations and lead to a QSL state in the double perovskite lattice. © 2013 American Physical Society.

2013

Chargement