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Du J, Jiang Q, Zhang Z, Zhao W, Chen L, Huo Z, Song H, Tian F, Duan D, Cui T. First-principles study of high-pressure structural phase transition and superconductivity of YBeH8. J Chem Phys 2024; 160:094116. [PMID: 38445840 DOI: 10.1063/5.0195828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 02/16/2024] [Indexed: 03/07/2024] Open
Abstract
The theory-led prediction of LaBeH8, which has a high superconducting critical temperature (Tc) above liquid nitrogen under a pressure level below 1 Mbar, has been experimentally confirmed. YBeH8, which has a structural configuration similar to that of LaBeH8, has also been predicted to be a high-temperature superconductor at high pressure. In this study, we focus on the structural phase transition and superconductivity of YBeH8 under pressure by using first-principles calculations. Except for the known face-centered cubic phase of Fm3̄m, we found a monoclinic phase with P1̄ symmetry. Moreover, the P1̄ phase transforms to the Fm3̄m phase at ∼200 GPa with zero-point energy corrections. Interestingly, the P1̄ phase undergoes a complex electronic phase transition from semiconductor to metal and then to superconducting states with a low Tc of 40 K at 200 GPa. The Fm3̄m phase exhibits a high Tc of 201 K at 200 GPa, and its Tc does not change significantly with pressure. When we combine the method using two coupling constants, λopt and λac, with first-principles calculations, λopt is mainly supplied by the Be-H alloy backbone, which accounts for about 85% of total λ and makes the greatest contribution to the high Tc. These insights not only contribute to a deeper understanding of the superconducting behavior of this ternary hydride but may also guide the experimental synthesis of hydrogen-rich compounds.
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Affiliation(s)
- Jianhui Du
- 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, People's Republic of China
| | - Qiwen Jiang
- 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, People's Republic of China
| | - Zihan Zhang
- 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, People's Republic of China
| | - Wendi Zhao
- 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, People's Republic of China
| | - Ling Chen
- 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, People's Republic of China
| | - ZiHao Huo
- 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, People's Republic of China
| | - Hao Song
- Institute of High Pressure Physics, School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
| | - Fubo Tian
- 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, People's Republic of China
| | - Defang Duan
- 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, People's Republic of China
| | - Tian Cui
- 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, People's Republic of China
- Institute of High Pressure Physics, School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
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2
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Yuan W, Yang X, Li S, Feng C, Chen B, Chang Y, Li D. A systematic study on the phase diagram and superconductivity of ternary clathrate Ca-Sc-H at high pressures. Phys Chem Chem Phys 2024; 26:3408-3414. [PMID: 38204403 DOI: 10.1039/d3cp05086f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2024]
Abstract
This work explores potential high-temperature superconductor materials in hydrogen-rich systems. Here, the crystal structure stabilities of ternary Ca-Sc-H systems under high-pressure (P = 100-250 GPa) and their superconductivities are investigated using the particle swarm optimization methodology combined with first-principles calculations. For the predicted candidate structures of Ca-Sc-H systems, the pressure-dependent phase diagram and thermodynamic convex hull were investigated across a wide range of compositions; the electronic properties of all the predicted phases were analyzed in detail to study the bonding behavior of these stable phases. We identified the crystal structures of four thermodynamically stable compounds: R3̄m-CaScH6, Immm-CaSc2H9,C2/m-Ca2ScH10, and R3̄m-CaScH12. Among them, R3̄m-CaScH12 was predicted to have the highest Tc value (i.e., 173 K) at 200 GPa. The discovery of this previously unreported pressure-induced decomposition of Ca-Sc-H systems will pave the way for investigations on the nature of hydrogen-metal interactions.
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Affiliation(s)
- Wenjie Yuan
- School of Science, Chongqing University of Posts and Telecommunications, Chongqing, China.
| | - Xu Yang
- School of Science, Chongqing University of Posts and Telecommunications, Chongqing, China.
| | - Shichang Li
- School of Science, Chongqing University of Posts and Telecommunications, Chongqing, China.
| | - Chunbao Feng
- School of Science, Chongqing University of Posts and Telecommunications, Chongqing, China.
| | - Bole Chen
- School of Science, Chongqing University of Posts and Telecommunications, Chongqing, China.
| | - Ying Chang
- School of Science, Chongqing University of Posts and Telecommunications, Chongqing, China.
| | - Dengfeng Li
- School of Science, Chongqing University of Posts and Telecommunications, Chongqing, China.
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Wu J, Zhu B, Ding C, Pei C, Wang Q, Sun J, Qi Y. Superconducting ternary hydrides in Ca-U-H under high pressure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2024; 36:165703. [PMID: 38194718 DOI: 10.1088/1361-648x/ad1ca7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Accepted: 01/09/2024] [Indexed: 01/11/2024]
Abstract
The research on hydrogen-rich ternary compounds attract tremendous attention for it paves new route to room-temperature superconductivity at lower pressures. Here, we study the crystal structures, electronic structures, and superconducting properties of the ternary Ca-U-H system, combining crystal structure predictions withab-initiocalculations under high pressure. We found four dynamically stable structures with hydrogen clathrate cages: CaUH12-Cmmm, CaUH12-Fd-3m, Ca2UH18-P-3m1, and CaU3H32-Pm-3m. Among them, the Ca2UH18-P-3m1 and CaU3H32-Pm-3mare likely to be synthesized below 1 megabar. Thefelectrons in U atoms make dominant contribution to the electronic density of states around the Fermi energy. The electron-phonon interaction calculations reveal that phonon softening in the mid-frequency region can enhance the electron-phonon coupling significantly. TheTcvalue of Ca2UH18-P-3m1 is estimated to be 57.5-65.8 K at 100 GPa. Our studies demonstrate that introducing actinides into alkaline-earth metal hydrides provides possibility in designing novel superconducting ternary hydrides.
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Affiliation(s)
- Juefei Wu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Bangshuai Zhu
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Chi Ding
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - Cuiying Pei
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Qi Wang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, People's Republic of China
| | - Jian Sun
- National Laboratory of Solid State Microstructures, School of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People's Republic of China
| | - Yanpeng Qi
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, People's Republic of China
- ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, People's Republic of China
- Shanghai Key Laboratory of High-resolution Electron Microscopy, ShanghaiTech University, Shanghai 201210, People's Republic of China
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4
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Xu M, Duan D, Du M, Zhao W, An D, Song H, Cui T. Phase diagrams and superconductivity of ternary Ca-Al-H compounds under high pressure. Phys Chem Chem Phys 2023; 25:32534-32540. [PMID: 37997767 DOI: 10.1039/d3cp03952h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
The search for high-temperature superconductors in hydrides under high pressure has always been a research hotspot. Hydrogen-based superconductors offer an avenue to achieve the long-sought goal of superconductivity at room temperature. Here we systematically explored the high-pressure phase diagram, electronic properties, lattice dynamics and superconductivity of the ternary Ca-Al-H system using ab initio methods. At 80 GPa, CaAlH5 transforms from Cmcm to P21/m phase. Both of Cmcm-CaAlH5 and Pnnm-CaAl2H8 are semiconductors. At 200 GPa, P4/mmm-CaAlH7 and a metastable compound Immm-Ca2AlH12 were found. Furthermore, P4/mmm-CaAlH7 shows obvious softening of the high frequency vibration modes, which improves the strength of electron-phonon coupling. Therefore, a superconducting transition temperature Tc of 71 K is generated in P4/mmm-CaAlH7 at 50 GPa. In addition, the thermodynamic metastable Immm-Ca2AlH12 exhibits a superconducting transition temperature of 118 K at 250 GPa. These results are very useful for the experimental searching of new high-Tc superconductors in ternary hydrides. Our work may provide an opportunity to search for high Tc superconductors at lower pressure.
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Affiliation(s)
- Ming Xu
- Institute of High Pressure Physics, School of Physical Science and Technology, Ningbo University, Ningbo 315211, China.
| | - Defang Duan
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Mingyang Du
- Institute of High Pressure Physics, School of Physical Science and Technology, Ningbo University, Ningbo 315211, China.
| | - Wendi Zhao
- Institute of High Pressure Physics, School of Physical Science and Technology, Ningbo University, Ningbo 315211, China.
| | - Decheng An
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Hao Song
- Institute of High Pressure Physics, School of Physical Science and Technology, Ningbo University, Ningbo 315211, China.
| | - Tian Cui
- Institute of High Pressure Physics, School of Physical Science and Technology, Ningbo University, Ningbo 315211, China.
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
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5
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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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6
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Hilleke KP, Zurek E. Rational Design of Superconducting Metal Hydrides via Chemical Pressure Tuning**. Angew Chem Int Ed Engl 2022; 61:e202207589. [DOI: 10.1002/anie.202207589] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Indexed: 11/11/2022]
Affiliation(s)
- Katerina P. Hilleke
- Department of Chemistry State University of New York at Buffalo Buffalo NY 14260-3000 USA
| | - Eva Zurek
- Department of Chemistry State University of New York at Buffalo Buffalo NY 14260-3000 USA
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7
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Hilleke K, Zurek E. Rational Design of Superconducting Metal Hydrides via Chemical Pressure Tuning. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202207589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Katerina Hilleke
- State University of New York at Buffalo: University at Buffalo Department of Chemistry 359 Natural Sciences ComplexUniversity at Buffalo, North Campus 14260-3000 Buffalo UNITED STATES
| | - Eva Zurek
- University at Buffalo, State University of New York Department of Chemistry 331 Natural Sciences Complex 14260 Buffalo UNITED STATES
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8
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Yang K, Sun H, Chen H, Chen L, Li B, Lu W. Stable structures and superconducting properties of Ca-La-H compounds under pressure. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:355401. [PMID: 35714608 DOI: 10.1088/1361-648x/ac79ed] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 06/17/2022] [Indexed: 06/15/2023]
Abstract
The calcium hydrides and lanthanum hydrides under high pressures have been reported to have good superconducting properties with high-TC. In this work, the structures and superconductivities of Ca-La-H ternary hydrides have been studied by genetic algorithm and density functional theory calculations. Our results show that at the pressure range of 100-300 GPa, the most stable structure of CaLaH12has aCmmmsymmetry, in which there is a H24hydrogen cage. It can be expected to have high possibility to be synthesized due to its large stability. Furthermore, the predictedTCof theCmmm-CaLaH12structure is about 140 K at 150 GPa, and when the pressure decreases to 30 GPa, the CaLaH12structure with aC2/msymmetry has a predictedTCof about 49 K. The CaLaH12is suggested to be a stable good superconductor with large stability and performs well at relatively low pressures.
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Affiliation(s)
- KaiPing Yang
- College of Physics, Qingdao University, Qingdao, Shandong 266071, People's Republic of China
| | - HuiJuan Sun
- College of Physics, Qingdao University, Qingdao, Shandong 266071, People's Republic of China
| | - HaiLiang Chen
- College of Physics, Qingdao University, Qingdao, Shandong 266071, People's Republic of China
| | - LingYan Chen
- College of Physics, Qingdao University, Qingdao, Shandong 266071, People's Republic of China
| | - BingYu Li
- College of Physics, Qingdao University, Qingdao, Shandong 266071, People's Republic of China
| | - WenCai Lu
- College of Physics, Qingdao University, Qingdao, Shandong 266071, People's Republic of China
- Institute of Theoretical Chemistry, Jilin University, Changchun, Jilin 130021, People's Republic of China
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9
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Charraud JB, Geneste G, Torrent M, Maillet JB. Machine learning accelerated random structure searching: Application to yttrium superhydrides. J Chem Phys 2022; 156:204102. [DOI: 10.1063/5.0085173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The search for new superhydrides, promising materials for both hydrogen storage and high temperature superconductivity, made great progress, thanks to atomistic simulations and Crystal Structure Prediction (CSP) algorithms. When they are combined with Density Functional Theory (DFT), these methods are highly reliable and often match a great part of the experimental results. However, systems of increasing complexity (number of atoms and chemical species) become rapidly challenging as the number of minima to explore grows exponentially with the number of degrees of freedom in the simulation cell. An efficient sampling strategy preserving a sustainable computational cost then remains to be found. We propose such a strategy based on an active-learning process where machine learning potentials and DFT simulations are jointly used, opening the way to the discovery of complex structures. As a proof of concept, this method is applied to the exploration of tin crystal structures under various pressures. We showed that the α phase, not included in the learning process, is correctly retrieved, despite its singular nature of bonding. Moreover, all the expected phases are correctly predicted under pressure (20 and 100 GPa), suggesting the high transferability of our approach. The method has then been applied to the search of yttrium superhydrides (YH x) crystal structures under pressure. The YH6 structure of space group Im-3m is successfully retrieved. However, the exploration of more complex systems leads to the appearance of a large number of structures. The selection of the relevant ones to be included in the active learning process is performed through the analysis of atomic environments and the clustering algorithm. Finally, a metric involving a distance based on x-ray spectra is introduced, which guides the structural search toward experimentally relevant structures. The global process (active-learning and new selection methods) is finally considered to explore more complex and unknown YH x phases, unreachable by former CSP algorithms. New complex phases are found, demonstrating the ability of our approach to push back the exponential wall of complexity related to CSP.
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Affiliation(s)
| | - G. Geneste
- CEA-DAM, DIF, F-91297 Arpajon Cedex, France
- Université Paris-Saclay, CEA, LMCE, 91680, Bruyères-le-Châtel, France
| | - M. Torrent
- CEA-DAM, DIF, F-91297 Arpajon Cedex, France
- Université Paris-Saclay, CEA, LMCE, 91680, Bruyères-le-Châtel, France
| | - J.-B. Maillet
- CEA-DAM, DIF, F-91297 Arpajon Cedex, France
- Université Paris-Saclay, CEA, LMCE, 91680, Bruyères-le-Châtel, France
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Exploring the Effect of the Number of Hydrogen Atoms on the Properties of Lanthanide Hydrides by DMFT. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12073498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Lanthanide hydrogen-rich materials have long been considered as one of the candidates with high-temperature superconducting properties in condensed matter physics, and have been a popular topic of research. Attempts to investigate the effects of different compositions of lanthanide hydrogen-rich materials are ongoing, with predictions and experimental studies in recent years showing that substances such as LaH10, CeH9, and LaH16 exhibit extremely high superconducting temperatures between 150–250 GPa. In particular, researchers have noted that, in those materials, a rise in the f orbit character at the Fermi level combined with the presence of hydrogen vibration modes at the same low energy scale will lead to an increase in the superconducting transition temperature. Here, we further elaborate on the effect of the ratios of lanthanide to hydrogen in these substances with the aim of bringing more clarity to the study of superhydrides in these extreme cases by comparing a variety of lanthanide hydrogen-rich materials with different ratios using the dynamical mean-field theory (DMFT) method, and provide ideas for later structural predictions and material property studies.
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11
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Zhang Z, Cui T, Hutcheon MJ, Shipley AM, Song H, Du M, Kresin VZ, Duan D, Pickard CJ, Yao Y. Design Principles for High-Temperature Superconductors with a Hydrogen-Based Alloy Backbone at Moderate Pressure. PHYSICAL REVIEW LETTERS 2022; 128:047001. [PMID: 35148145 DOI: 10.1103/physrevlett.128.047001] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 09/28/2021] [Accepted: 12/24/2021] [Indexed: 05/25/2023]
Abstract
Hydrogen-based superconductors provide a route to the long-sought goal of room-temperature superconductivity, but the high pressures required to metallize these materials limit their immediate application. For example, carbonaceous sulfur hydride, the first room-temperature superconductor made in a laboratory, can reach a critical temperature (T_{c}) of 288 K only at the extreme pressure of 267 GPa. The next recognized challenge is the realization of room-temperature superconductivity at significantly lower pressures. Here, we propose a strategy for the rational design of high-temperature superconductors at low pressures by alloying small-radius elements and hydrogen to form ternary H-based superconductors with alloy backbones. We identify a "fluorite-type" backbone in compositions of the form AXH_{8}, which exhibit high-temperature superconductivity at moderate pressures compared with other reported hydrogen-based superconductors. The Fm3[over ¯]m phase of LaBeH_{8}, with a fluorite-type H-Be alloy backbone, is predicted to be thermodynamically stable above 98 GPa, and dynamically stable down to 20 GPa with a high T_{c}∼185 K. This is substantially lower than the synthesis pressure required by the geometrically similar clathrate hydride LaH_{10} (170 GPa). Our approach paves the way for finding high-T_{c} ternary H-based superconductors at conditions close to ambient pressures.
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Affiliation(s)
- Zihan Zhang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Tian Cui
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
- Institute of High Pressure Physics, School of Physical Science and Technology, Ningbo University, Ningbo 315211, China
| | - Michael J Hutcheon
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Alice M Shipley
- Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Hao Song
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Mingyang Du
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Vladimir Z Kresin
- Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720, USA
| | - Defang Duan
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Chris J Pickard
- Department of Materials Science & Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS, United Kingdom
- Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
| | - Yansun Yao
- Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
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12
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Bi T, Zurek E. Electronic Structure and Superconductivity of Compressed Metal Tetrahydrides. Chemistry 2021; 27:14858-14870. [PMID: 34469606 DOI: 10.1002/chem.202102679] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Indexed: 11/10/2022]
Abstract
Tetrahydrides crystallizing in the ThCr2 Si2 structure type have been predicted to become stable for a plethora of metals under pressure, and some have recently been synthesized. Through detailed first-principles investigations we show that the metal atoms within these I 4 / m m m symmetry MH4 compounds may be divalent, trivalent or tetravalent. The valence of the metal atom and its radius govern the bonding and electronic structure of these phases, and their evolution under pressure. The factors important for enhancing superconductivity include a large number of hydrogenic states at the Fermi level, and the presence of quasi-molecular H 2 δ - units whose bonds have been stretched and weakened (but not broken) via electron transfer from the electropositive metal, and via a Kubas-like interaction with the metal. Analysis of the microscopic mechanism of superconductivity in MgH4 , ScH4 and ZrH4 reveals that phonon modes involving a coupled libration and stretch of the H 2 δ - units leading to the formation of more complex hydrogenic motifs are important contributors towards the electron phonon coupling mechanism. In the divalent hydride MgH4 , modes associated with motions of the hydridic hydrogen atoms are also key contributors, and soften substantially at lower pressures.
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Affiliation(s)
- Tiange Bi
- Department of Chemistry, State University of New York at Buffalo, Buffalo, NY 14260-3000, USA
| | - Eva Zurek
- Department of Chemistry, State University of New York at Buffalo, Buffalo, NY 14260-3000, USA
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Stabilization and electronic topological transition of hydrogen-rich metal Li 5MoH 11 under high pressures from first-principles predictions. Sci Rep 2021; 11:4079. [PMID: 33602984 PMCID: PMC7893069 DOI: 10.1038/s41598-021-83468-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 02/01/2021] [Indexed: 11/08/2022] Open
Abstract
Regarded as doped binary hydrides, ternary hydrides have recently become the subject of investigation since they are deemed to be metallic under pressure and possibly potentially high-temperature superconductors. Herein, the candidate structure of Li5MoH11 is predicted by exploiting the evolutionary searching. Its high-pressure phase adopts a hexagonal structure with P63/mcm space group. We used first-principles calculations including the zero-point energy to investigate the structures up to 200 GPa and found that the P63cm structure transforms into the P63/mcm structure at 48 GPa. Phonon calculations confirm that the P63/mcm structure is dynamically stable. Its stability is mainly attributed to the isostructural second-order phase transition. Our calculations reveal the electronic topological transition displaying an isostructural second-order phase transition at 160 GPa as well as the topology of its Fermi surfaces. We used the projected crystal orbital Hamilton population (pCOHP) to examine the nature of the chemical bonding and demonstrated that the results obtained from the pCOHP calculation are associated with the electronic band structure and electronic localized function.
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