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UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-22 1:23 |
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Conference: Bucharest University Faculty of Physics 2024 Meeting
Section: Solid State Physics and Materials Science
Title:
Computational and experimental studies of metallic hydrides
Authors:
Maria-Iulia ZAI (1,2), George Alexandru NEMNEȘ (2,3), Lucian ION (2), Ștefan ANTOHE (2,4), Victor LECA (1)
*
Affiliation:
1) Extreme Light Infrastructure-Nuclear Physics (ELI-NP), „Horia Hulubei” National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH), 30 Reactorului Street, 077125 Măgurele, Romania
2) Faculty of Physics, University of Bucharest, 077125 Măgurele, Romania
3) „Horia Hulubei” National Institute for R&D in Physics and Nuclear Engineering (IFIN-HH), 30 Reactorului Street, 077125 Măgurele, Romania
4) Academy of Romanian Scientists (AOSR), Ilfov Street 3, 050045 Bucharest, Romania
E-mail
iulia.zai@eli-np.ro
Keywords:
Density Functional Theory; chromium hydride; palladium hydride; superconductivity; ELK code; SIESTA code; phonon density of states.
Abstract:
Metallic hydrides (Me-Hx) have a long history of drawing significant interest from the scientific community for their potential as room-temperature superconductors. Due to a controllable composition of heavy and light elements, they are also attractive for the fabrication of high-power laser targets. One such promising candidate is palladium hydride (Pd-H), which can readily embed significant amounts of hydrogen in the metallic interstitial sites even at ambient pressure and at room temperature. In the present work, computational methods were used to perform structural studies and identification of the physical properties of several stoichiometries of the Pd-H and Cr-H systems, using Density Functional Theory (DFT). This ab initio approach allowed us to examine how the hydrogen embedded in metallic interstitial sites gives rise to superconductivity from the ensuing electron-phonon coupling. To this end, the formation enthalpy of the candidate hydrides presented herein, studied as a function of stoichiometry and pressure, was investigated using an efficient structure prediction software (CALYPSO). Their physical properties were then determined using an all electron linearized augmented plane wave code (ELK), which also served to predict their critical temperatures (TC). We were able to computationally determine that a majority of the studied hydrides feature hydrogen-filled interstitial sites within their closely-packed metal lattices and our electron-phonon coupling calculations showed that they are phonon-mediated superconductors. Ultimately, we compared our computational results with experimental ones derived from hydride films deposited via RF sputtering, including epitaxial PdH thin films, which were for the first time obtained using a physical deposition method.
References:
[1] S.S. Setayandeh, C.J. Webb, E. MacA Gray, Prog. Solid State Chem. 60 (2020) 100285.
[2] R. Vocaturo, et al., Journal of Applied Physics 131 (2022) 033903.
[3] T. Kawae, Tatsuya, et al., J. Phys. Soc. Jpn. 89 (2020): 051004.
Acknowledgement:
The authors would like to acknowledge the support received from the Extreme Light Infrastructure - Nuclear Physics (ELI-NP) Phase II, a project co-financed by the Romanian Government and the European Union through the European Regional Development Fund - the Competitiveness Operational Programme (1/07.07.2026, COP, ID 1334).
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