Elasticity and Poisson's ratio of hexagonal close-packed hydrogen at high pressures

Goncharov, Alexander F.; Gauthier, Michel; Antonangeli, Daniele; Ayrinhac, Simon; Decremps, F.; Morand, Marc; Grechnev, Alexei; Tretyak, S. M.; Freǐman, Yu. A.

doi:10.1103/physrevb.95.214104

Cited by 7 publications

(9 citation statements)

References 45 publications

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“…At 0 GPa, the mechanical stability criteria for hcp structure are featured as 39 Elastic anisotropic is a fundamental parameter for mechanical properties. For an hcp crystal, the elastic anisotropic is described by the following formulas 41 where ΔP is anisotropy for compressional wave, ΔS 1 and ΔS 2 are anisotropy for shear wave, polarized perpendicular to the basal plane and polarized in the basal plane, respectively. These three parameters characterize the anisotropy of the three main acoustic modes.…”

Section: Discussionmentioning

confidence: 99%

Mechanical and electronic properties of van der Waals layered hcp PdH2

Liu

Ahuja

et al. 2020

Sci Rep

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Mechanical and electronic properties of palladium dihydrides (pdH 2) as a function of pressure were studied by ab initio calculations based on density functional theory (Dft). the ab initio random structure searching technique was employed for screening potential pdH 2 crystal structures under high pressure. A hexagonal close packed (hcp) phase of pdH 2 with space group P6 3 mc was reported. the structure geometry and elastic constants were calculated as a function of pressure. it was found that H atoms are in the interstitial position of Pd atoms layer at 0 GPa. There is an electronic topology transition of hcp pdH 2 at 15 GPa. When pressure exceeds above 15 GPa, one hydrogen atom occupies the tetrahedral site and another hydrogen atom locates in the interstitial position. When the c/a ratio is between 1.765 to 1.875, the hcp PdH 2 is mechanically stable, and the Pd-H 2b bond is the major factor that limits the mechanical stability. the elastic constant c 44 is the first one that cannot satisfy the mechanical stability criteria under pressure. The anisotropy parameters are far from 1(one) shows that the hcp pdH 2 is a highly anisotropic structure. the electronic structure study indicates that the bonding force between Pd and H atoms along the z-axis direction increases with the increasing pressure. Also, the phonon dispersion study shows that pdH 2 is dynamic stability under pressure. the results suggest that hcp pdH 2 can be metastable in van der Waals layered structure. Metal hydride (M-H) systems have attracted a lot of attention because of their properties, such as high hydrogen-storage capacity, fast hydrogen absorption/desorption, long-term cycle life and low toxicity 1. Palladium-hydrogen (Pd-H) is used to be a system to understand the hydrogen atoms bonding with the metal host lattice in the M-H systems. The phase diagram and electronic properties of Pd-H have been used as a prototype in other M-H systems 2. Some applications of Pd-H system have been investigated. The palladium can absorb hydrogen at ambient conditions and the dissociative adsorption of H 2 molecules occurs with little or no activation energy barrier on the palladium surface. The reversible hydrogen absorption property can be used for hydrogen storage 3. Increasing the hydrogen concentration will cause volume expansion of PdH x. Based on this mechanism, a Pd based H 2 sensor was used to measure the hydrogen concentration 4. Due to the dissociative properties of H, Pd-H can be used for hydrogen-related catalytic reactions 5. The hydrogen concentration affects the superconductivity of Pd-H system. PdH x is a superconductor and the transition temperature Tc increased with the increase of H concentration x 6. For the H/Pd is 0.81, a Tc = 1.3 K was observed. At the highest concentration ratio of about 1.0, the Tc to the superconducting state higher than 8.0 K 7. Recently Syed et al. found that by rapidly cooling the hydride after loading with hydrogen at elevated temperature, the Tc has a remarkable increase to 54 K when the H/Pd is about 1 8...

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Section: Discussionmentioning

confidence: 99%

Mechanical and electronic properties of van der Waals layered hcp PdH2

Liu

Ahuja

et al. 2020

Sci Rep

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“…For transparent samples, the acoustic wave is generated by focusing the pump on a transducer coated on the pump side of the sample (as in [8] and in the examples shown in Section 3.1 and 5). The probe is focused through the sample on the other side of the transducer.…”

Section: Brillouin Detectionmentioning

confidence: 99%

“…Up to now, picosecond acoustic has been used at ambient temperature and high pressure conditions up to 150 GPa on polycrytalline samples compressed in a DAC measuring the sound velocities of Fe [7], H 2 [8], Fe-Ni alloys [9] and Fe-Si alloys [10,11]. Measurements on single crystals allowed determining the complete elastic tensor of Si up to 8 GPa [2].…”

Section: Introductionmentioning

confidence: 99%

Picosecond acoustics: a new way to access elastic properties of materials at pressure and temperature conditions of planetary interiors

et al. 2022

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Picosecond acoustics is an optical pump-probe technique allowing to access thermoelastic properties and sound velocities of a large variety of materials under extreme conditions. Coupled with diamond anvil cells and laser heating, picosecond acoustic measurements offer the possibility to probe materials over a pressure and temperature range directly pertinent for the deep planetary interiors. In this paper we highlight the capabilities and versatility of this technique by presenting some recent applications on materials of geophysical interest. All the independent components of the elastic tensor of MgO are simultaneously determined Picosecond acoustics: elastic properties under extreme conditions by measurements on single crystal at ambient conditions. Compressional sound velocity is measured at high pressure on an iron-carbon alloy and on polycrystalline argon. First laser heating test measurements performed on molybdenum at high pressure are also presented. These examples demonstrate that picosecond acoustics is a valuable alternative to already existing techniques for determining the physical properties of samples under extreme pressure and temperature conditions.

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“…Picosecond acoustics permits an in-depth resolution in transparent materials. It can be used to determine elastic inhomogeneities [28] or to probe grains in a polycristalline sample if those are large enough [29,30]. After subtraction of the base line, short time Fourier transform (STFT) is performed on the signal, with a normalization of the amplitude (Hanning window, 0.26 ns width).…”

Section: Picosecond Acousticsmentioning

confidence: 99%

Stability of lauric acid at high pressure studied by Raman spectroscopy and picosecond acoustics

et al. 2019

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Lauric acid is commonly used as a coating agent which efficiently protects against oxidation and/or coalescence a set of inorganic nanocrystals obtained by chemical process. Its stability under pressure is likely to be informative on the stability and ordering of compressed supercrystals of nanocrystals. Therefore the elastic behaviour of lauric acid submitted to high pressures up to 25 GPa is studied. This elastic behavior has been probed by two complementary in situ techniques at high pressure : Raman spectroscopy and picosecond acoustics. Comparison between pressure-induced transformations as observed with the two techniques suggests that lauric acid remains elastically stable above 2 GPa up to 25 GPa.

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Elasticity and Poisson's ratio of hexagonal close-packed hydrogen at high pressures

Cited by 7 publications

References 45 publications

Mechanical and electronic properties of van der Waals layered hcp PdH2

Mechanical and electronic properties of van der Waals layered hcp PdH2

Picosecond acoustics: a new way to access elastic properties of materials at pressure and temperature conditions of planetary interiors

Stability of lauric acid at high pressure studied by Raman spectroscopy and picosecond acoustics

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