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Tao YL, Liu QJ, Fan DH, Liu FS, Liu ZT. Emerging superconductivity rules in rare-earth and alkaline-earth metal hydrides. iScience 2024; 27:110542. [PMID: 39184437 PMCID: PMC11342274 DOI: 10.1016/j.isci.2024.110542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 07/03/2024] [Accepted: 07/16/2024] [Indexed: 08/27/2024] Open
Abstract
Hydrides of alkaline-earth and rare-earth metals have garnered significant interest in high-temperature superconductor research due to their excellent electron-phonon coupling and high T c upon pressurization. This study explores the electronic structures and electron-phonon coupling of metal hydrides XHn (n = 4,6), where X includes Ca, Mg, Sc, and Y. The involvement of d-orbital electrons alters the Fermi surface, leading to saddle-point nesting and a charge density wave (CDW) phase transition, which opens the superconducting gap. For instance, in YH6, the exchange coupling between Y-4d and H-1s holes in the phonon softening region results in T c values up to 230 K. The study suggests that factors, such as the origin of the CDW order, hydrogen concentration, and d-orbital contributions are crucial to superconductivity. This work proposes a new rule for high T c superconductors, emphasizing the importance of double gaps and electron-phonon interactions at exchange coupling sites, and predicts potential high-quality superconductors among rare-earth hydrides.
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Affiliation(s)
- Ya-Le Tao
- Bond and Band Engineering Group, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
| | - Qi-Jun Liu
- Bond and Band Engineering Group, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
| | - Dai-He Fan
- Bond and Band Engineering Group, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
| | - Fu-Sheng Liu
- Bond and Band Engineering Group, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
| | - Zheng-Tang Liu
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, People’s Republic of China
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Marqueño T, Kuzovnikov MA, Osmond I, Dalladay-Simpson P, Hermann A, Howie RT, Peña-Alvarez M. High pressure study of sodium trihydride. Front Chem 2024; 11:1306495. [PMID: 38264124 PMCID: PMC10803492 DOI: 10.3389/fchem.2023.1306495] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 12/19/2023] [Indexed: 01/25/2024] Open
Abstract
The reactivity between NaH and H2 has been investigated through a series of high-temperature experiments up to pressures of 78 GPa in diamond anvil cells combined with first principles calculations. Powder X-ray diffraction measurements show that heating NaH in an excess of H2 to temperatures around 2000 K above 27 GPa yields sodium trihydride (NaH3), which adopts an orthorhombic structure (space group Cmcm). Raman spectroscopy measurements indicate that NaH3 hosts quasi-molecular hydrogen (H 2 δ - ) within a NaH lattice, with the H 2 δ - stretching mode downshifted compared to pure H2 (Δν ∼-120 cm-1 at 50 GPa). NaH3 is stable under room temperature compression to at least 78 GPa, and exhibits remarkable P-T stability, decomposing at pressures below 18 GPa. Contrary to previous experimental and theoretical studies, heating NaH (or NaH3) in excess H2 between 27 and 75 GPa does not promote further hydrogenation to form sodium polyhydrides other than NaH3.
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Affiliation(s)
- Tomas Marqueño
- Centre for Science at Extreme Conditions (CSEC), The School of Physics and Astronomy, The University of Edinburgh, Edinburgh, United Kingdom
| | - Mikhail A. Kuzovnikov
- Centre for Science at Extreme Conditions (CSEC), The School of Physics and Astronomy, The University of Edinburgh, Edinburgh, United Kingdom
| | - Israel Osmond
- Centre for Science at Extreme Conditions (CSEC), The School of Physics and Astronomy, The University of Edinburgh, Edinburgh, United Kingdom
| | | | - Andreas Hermann
- Centre for Science at Extreme Conditions (CSEC), The School of Physics and Astronomy, The University of Edinburgh, Edinburgh, United Kingdom
| | - Ross T. Howie
- Centre for Science at Extreme Conditions (CSEC), The School of Physics and Astronomy, The University of Edinburgh, Edinburgh, United Kingdom
- Center for High Pressure Science and Technology Advanced Research, Shanghai, China
| | - Miriam Peña-Alvarez
- Centre for Science at Extreme Conditions (CSEC), The School of Physics and Astronomy, The University of Edinburgh, Edinburgh, United Kingdom
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Wang Q, Li H, Wei J, Zhong T, Zhu L, Zhang X, Liu H, Zhang S. Hardness and superconductivity in tetragonal LiB4 and NaB4. J Chem Phys 2023; 159:234707. [PMID: 38126624 DOI: 10.1063/5.0180248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Accepted: 11/22/2023] [Indexed: 12/23/2023] Open
Abstract
Boron-based compounds have triggered substantial attention due to their multifunctional properties, incorporating excellent hardness and superconductivity. While tetragonal metal borides LiB4 and NaB4 with BaAl4-type structure and striking clathrate boron motif have been induced under compression, there is still a lack of deep understanding of their potential properties at ambient pressure. We herein conduct a comprehensive study on I4/mmm-structured LiB4 and NaB4 under ambient pressure via first-principles calculations. Remarkably, both LiB4 and NaB4 are found to possess high Vickers hardness of 39 GPa, which is ascribed to the robust boron framework with strong covalency. Furthermore, their high hardness values together with distinguished stability make them highly potential superhard materials. Meanwhile, electron-phonon coupling analysis reveals that both LiB4 and NaB4 are conventional phonon-mediated superconductors, with critical temperatures of 6 and 8 K at 1 atmosphere pressure (atm), respectively, mainly arising from the coupling of B 2p electronic states and the low-frequency phonon modes associated with Li-, Na-, and B-derived vibrations. This work provides valuable insights into the mechanical and superconducting behaviors of metal borides and will boost further studies of emergent borides with multiple functionalities.
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Affiliation(s)
- Qianyi Wang
- Key Laboratory of UV-Emitting Materials and Technology of Ministry of Education, School of Physics, Northeast Normal University, Changchun 130024, China
| | - Honggang Li
- Key Laboratory of UV-Emitting Materials and Technology of Ministry of Education, School of Physics, Northeast Normal University, Changchun 130024, China
| | - Jiahui Wei
- Key Laboratory of UV-Emitting Materials and Technology of Ministry of Education, School of Physics, Northeast Normal University, Changchun 130024, China
| | - Ting Zhong
- Key Laboratory of UV-Emitting Materials and Technology of Ministry of Education, School of Physics, Northeast Normal University, Changchun 130024, China
| | - Li Zhu
- Department of Physics, Rutgers University, Newark, New Jersey 07102, USA
| | - Xinxin Zhang
- College of Science, Shenyang University of Chemical Technology, Shenyang 110142, China
| | - Hanyu Liu
- Key Laboratory of Material Simulation Methods and Software of Ministry of Education and State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Shoutao Zhang
- Key Laboratory of UV-Emitting Materials and Technology of Ministry of Education, School of Physics, Northeast Normal University, Changchun 130024, China
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Wang B, Hilleke KP, Hajinazar S, Frapper G, Zurek E. Structurally Constrained Evolutionary Algorithm for the Discovery and Design of Metastable Phases. J Chem Theory Comput 2023; 19:7960-7971. [PMID: 37856841 DOI: 10.1021/acs.jctc.3c00594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
Metastable materials are abundant in nature and technology, showcasing remarkable properties that inspire innovative materials design. However, traditional crystal structure prediction methods, which rely solely on energetic factors to determine a structure's fitness, are not suitable for predicting the vast number of potentially synthesizable phases that represent a local minimum corresponding to a state in thermodynamic equilibrium. Here, we present a new approach for the prediction of metastable phases with specific structural features and interface this method with the XtalOpt evolutionary algorithm. Our method relies on structural features that include the local crystalline order (e.g, the coordination number or chemical environment), and symmetry (e.g, Bravais lattice and space group) to filter the breeding pool of an evolutionary crystal structure search. The effectiveness of this approach is benchmarked on three known metastable systems: XeN8, with a two-dimensional polymeric nitrogen sublattice, brookite TiO2, and a high pressure BaH4 phase, which was recently characterized. Additionally, a newly predicted metastable melaminate salt, P1̅ WC3N6, was found to possess an energy that is lower than that of two phases proposed in a recent computational study. The method presented here could help in identifying the structures of compounds that have already been synthesized, and in developing new synthesis targets with desired properties.
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Affiliation(s)
- Busheng Wang
- Department of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260-3000, United States
| | - Katerina P Hilleke
- Department of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260-3000, United States
| | - Samad Hajinazar
- Department of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260-3000, United States
| | - Gilles Frapper
- Applied Quantum Chemistry Group, E4 Team, IC2MP UMR 7285, Université de Poitiers, CNRS, Poitiers 86073, France
| | - Eva Zurek
- Department of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260-3000, United States
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Tao YL, Zeng W, Gao J, Liu ZT, Jiao Z, Liu QJ. Composition and structural characteristics of compressed alkaline earth metal hydrides. Phys Chem Chem Phys 2023; 25:26225-26235. [PMID: 37740369 DOI: 10.1039/d3cp03134a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/24/2023]
Abstract
The metallization of alkaline earth metal hydrides offers a way to achieve near-room temperature superconductivity. In order to explore the metallization mechanism of these hydrides under pressure, a detailed understanding of the property changes of alkaline earth metal hydrides is required. Based on first-principles calculations, we have systematically investigated the dihydrides (XH2, X = Be, Mg, Ca, Sr, Ba) and tetrahydrides (XH4, X = Mg, Ca, Sr, Ba) of alkaline earth metals, respectively. By applying external pressure, we show that the structures of these alkaline earth metal hydrides undergo a series of phase transitions. Moreover, we investigate how the size of the bandgap decreases and eventually closes and reveal the role of electronegativity of metal elements in the critical pressure of hydride metallization. Remarkably, the hydrogen units (H6 or H8) formed in XH4 can accelerate the metallization process. The increase of the energy level difference in hydrogen units promotes the electroacoustic coupling effect, which is conducive to realization of high superconducting transition temperature (Tc). Our theoretical findings identify MgH4-I4/mmm as having potential to be a high-temperature superconductor and provide unusual ideas for the search of unknown high-temperature superconducting materials.
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Affiliation(s)
- Ya-Le Tao
- Bond and Band Engineering Group, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People's Republic of China.
| | - Wei Zeng
- Teaching and Research Group of Chemistry, School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu 610075, People's Republic of China
| | - Juan Gao
- Bond and Band Engineering Group, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People's Republic of China.
| | - Zheng-Tang Liu
- State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, People's Republic of China
| | - Zhen Jiao
- Bond and Band Engineering Group, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People's Republic of China.
| | - Qi-Jun Liu
- Bond and Band Engineering Group, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People's Republic of China.
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Marqués M, Peña-Alvarez M, Martínez-Canales M, Ackland GJ. H 2 Chemical Bond in a High-Pressure Crystalline Environment. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2023; 127:15523-15532. [PMID: 37583438 PMCID: PMC10424234 DOI: 10.1021/acs.jpcc.3c02366] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Revised: 07/13/2023] [Indexed: 08/17/2023]
Abstract
We show that the hydrogen in metal superhydride compounds can adopt two distinct states-atomic and molecular. At low pressures, the maximum number of atomic hydrogens is typically equal to the valency of the cation; additional hydrogens pair to form molecules with electronic states far below the Fermi energy causing low-symmetry structures with large unit cells. At high pressures, molecules become unstable, and all hydrogens become atomic. This study uses density functional theory, adopting BaH4 as a reference compound, which is compared with other stoichiometries and other cations. Increased temperature and zero-point motion also favor high-symmetry atomic states, and picosecond-timescale breaking and remaking of the bond permutations via intermediate H3- units.
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Affiliation(s)
- Miriam Marqués
- Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, U.K
| | - Miriam Peña-Alvarez
- Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, U.K
| | - Miguel Martínez-Canales
- Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, U.K
| | - Graeme J Ackland
- Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, U.K
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7
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Peña-Alvarez M, Binns J, Marqués M, Kuzovnikov MA, Dalladay-Simpson P, Pickard CJ, Ackland GJ, Gregoryanz E, Howie RT. Chemically Assisted Precompression of Hydrogen Molecules in Alkaline-Earth Tetrahydrides. J Phys Chem Lett 2022; 13:8447-8454. [PMID: 36053162 PMCID: PMC9488899 DOI: 10.1021/acs.jpclett.2c02157] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Accepted: 08/12/2022] [Indexed: 06/15/2023]
Abstract
Through a series of high pressure diamond anvil experiments, we report the synthesis of alkaline earth (Ca, Sr, Ba) tetrahydrides, and investigate their properties through Raman spectroscopy, X-ray diffraction, and density functional theory calculations. The tetrahydrides incorporate both atomic and quasi-molecular hydrogen, and we find that the frequency of the intramolecular stretching mode of the H2δ- units downshifts from Ca to Sr and to Ba upon compression. The experimental results indicate that the larger the host cation, the longer the H2δ- bond. Analysis of the electron localization function (ELF) demonstrates that the lengthening of the H-H bond is caused by the charge transfer from the metal to H2δ- and by the steric effect of the metal host on the H-H bond. This effect is most prominent for BaH4, where the precompression of H2δ- units at 50 GPa results in bond lengths comparable to that of pure H2 above 275 GPa.
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Affiliation(s)
- Miriam Peña-Alvarez
- Centre
for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, U.K.
| | - Jack Binns
- Center
for High Pressure Science and Technology Advanced Research, Shanghai 100094, P. R. China
| | - Miriam Marqués
- Centre
for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, U.K.
| | - Mikhail A. Kuzovnikov
- Centre
for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, U.K.
| | - Philip Dalladay-Simpson
- Center
for High Pressure Science and Technology Advanced Research, Shanghai 100094, P. R. China
| | - Chris J. Pickard
- Department
of Materials Science and Metallurgy, University
of Cambridge, Cambridge CB3 0FS, U.K.
- Advanced
Institute for Materials Research, Tohoku
University, Sendai 980-8577, Japan
| | - Graeme J. Ackland
- Centre
for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, U.K.
| | - Eugene Gregoryanz
- Centre
for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, U.K.
- Center
for High Pressure Science and Technology Advanced Research, Shanghai 100094, P. R. China
- Key Laboratory
of Materials Physics, Institute of Solid
State Physics, Hefei 230031, P. R. China
| | - Ross T. Howie
- Centre
for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, Edinburgh EH9 3FD, U.K.
- Center
for High Pressure Science and Technology Advanced Research, Shanghai 100094, P. R. China
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