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Tao X, Yang A, Quan Y, Wan B, Yang S, Zhang P. Discovery of superconductivity in technetium borides at moderate pressures. Phys Chem Chem Phys 2024; 26:16963-16971. [PMID: 38742395 DOI: 10.1039/d4cp00191e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Advances in theoretical calculations have boosted the search for high-temperature superconductors, such as sulfur hydrides and rare-earth polyhydrides. However, the required extremely high pressures for stabilizing these superconductors has handicapped further implementation. Based upon thorough structural searches, we identified a series of unprecedented superconducting technetium borides at moderate pressures, including TcB (P63/mmc) with a superconducting transition temperature of Tc = 20.2 K at ambient pressure and TcB2 (P6/mmm) with Tc = 23.1 K at 20 GPa. Superconductivity in these technetium borides mainly originates from the coupling between the low-frequency vibrations of technetium atoms and the dominant technetium-4d electrons at the Fermi level. Our work therefore presents a fresh group in the family of superconducting borides, whose diversified crystal structures suggest rich possibilities in the discovery of other superconducting transition-metal borides.
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Affiliation(s)
- Xiangru Tao
- MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, Shaanxi Province Key Laboratory of Advanced Functional Materials and Mesoscopic Physics, School of Physics, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, P.R. China.
| | - Aiqin Yang
- MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, Shaanxi Province Key Laboratory of Advanced Functional Materials and Mesoscopic Physics, School of Physics, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, P.R. China.
| | - Yundi Quan
- MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, Shaanxi Province Key Laboratory of Advanced Functional Materials and Mesoscopic Physics, School of Physics, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, P.R. China.
| | - Biao Wan
- Key Laboratory of Material Physics of Ministry of Education, School of Physics and Microelectronics, Zhengzhou University, Zhengzhou 450052, Henan, P.R. China
| | - Shuxiang Yang
- Zhejiang Laboratory, Hangzhou, Zhejiang, P.R. China.
| | - Peng Zhang
- MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, Shaanxi Province Key Laboratory of Advanced Functional Materials and Mesoscopic Physics, School of Physics, Xi'an Jiaotong University, Xi'an, Shaanxi, 710049, P.R. China.
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Chen S, Xie H, Xu D, Chen J, Cao B, Liang M, Sun Y, Gai X, Wang X, Yang M, Zhang M, Duan D, Li D, Tian F. Superconductivity of cubic MB6 (M = Na, K, Rb, Cs). J Chem Phys 2024; 160:044702. [PMID: 38258919 DOI: 10.1063/5.0179339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Accepted: 01/01/2024] [Indexed: 01/24/2024] Open
Abstract
Previous studies have shown that NaB6, KB6, and RbB6 adopting Pm3̄m are superconductors with a relatively high Tc under ambient conditions. In this paper, we conducted systematic structural and related properties research on CsB6 through a genetic evolution algorithm and total energy calculations based on density functional theory between 0 and 20 GPa. Our results reveal a cubic Pm3̄m CsB6, which is dynamically stable under the pressures we studied. We systematically calculated the formation enthalpies, electronic properties, and superconducting properties of Pm3̄m MB6 (M = Na, K, Rb, Cs). They all exhibit metallic features, and boron has high contributions to band structures, density of states, and electron-phonon coupling (EPC). The calculated results about the Helmholtz free energy difference of Pm3̄m CsB6 at 0, 10, and 20 GPa indicate that it is stable upon chemical decomposition (decomposition to simple substances Cs and B) from 0 to 400 K. The phonon density of states indicates that boron atoms occupy the high frequency area. The EPC results show that Pm3̄m CsB6 is a superconductor with Tc = 11.7 K at 0 GPa, close to NaB6 (13.1 K), KB6 (11.7 K), and RbB6 (11.3 K) at 0 GPa in our work, which indicates that boron atoms play an essential role in superconductivity: vibrations of B6 regular octagons lead to the high Tc of Pm3̄m MB6. Our work about Pm3̄m hexaborides provides a supplementary study on the borides of the group IA elements (without Fr and Li) and has an important guiding significance for the experimental synthesis of CsB6.
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Affiliation(s)
- Shi Chen
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Hui Xie
- College of Physics and Electronic Engineering, Hebei Normal University for Nationalities, Chengde 067000, China
| | - Dan Xu
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Jiajin Chen
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Bohan Cao
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Min Liang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Yibo Sun
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Xiaoqian Gai
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Xinwei Wang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Mengxin Yang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Mengrui Zhang
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Defang Duan
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Da Li
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
| | - Fubo Tian
- State Key Laboratory of Superhard Materials, College of Physics, Jilin University, Changchun 130012, China
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Du J, Li X, Peng F. Pressure-induced evolution of structures and promising superconductivity of ScB 6. Phys Chem Chem Phys 2022; 24:10079-10084. [PMID: 35416197 DOI: 10.1039/d2cp00711h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Unique multicenter bonding in boron-rich materials leads to the formation of complicated structures and intriguing properties. ScB6, as a sister compound, possibly possesses high hardness and superconducting critical temperature in this family under ambient pressure. Here, phase transitions, chemical bonding states and electronic properties of ScB6 at high pressure are uncovered using particle swarm optimization (PSO) combined with first-principles calculations. The phase sequence of P21/m → C2/m → Cmcm for ScB6 has been identified under high pressure. Interestingly, the evolution of a boron framework is from a graphene-like layer to a planar B4 ring, B6 and B7 cycle, and non-planar B8 cycle, which interconnect a graphene-like network. These phases of ScB6 are expected to be hard materials due to the excellent mechanical behaviors by the mechanical property calculations. Although the metallic features of the three phases reduce their hardness, the further electron-phonon coupling calculations indicate that the three phases of ScB6 are superconducting phases under high pressures.
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Affiliation(s)
- Junyi Du
- College of Mathematical Science, Luoyang Normal University, Luoyang 471934, China
| | - Xiaofeng Li
- College of Physics and Electronic Information & Henan Key Laboratory of Electromagnetic Transformation and Detection, Luoyang Normal University, Luoyang 471934, China.
| | - Feng Peng
- College of Physics and Electronic Information & Henan Key Laboratory of Electromagnetic Transformation and Detection, Luoyang Normal University, Luoyang 471934, China.
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