Issue 39, 2023

Coexistence of superconductivity and electride states in Ca2H with an antifluorite-type motif under compression

Abstract

Hydrogen-abundant compounds, as highly potential candidates of near- or room-temperature superconductors, have recently attracted substantial attention. It is noted that metal-rich hydrides may exhibit unique electride feature, together with potential superconductivity, which indicates that they could be regarded as electride superconductor (ESC) hydrides. Herein, we performed the first-principles structure searches of calcium-rich hydrides for designing ESC hydrides. Strikingly, unprecedented calcium-based hydride Ca2H with robust stability and excellent metallicity is identified under compression, where it possesses the zero-dimensional distribution feature of interstitial electrons serving as interstitial quasiatoms (ISQs), mainly originating from the donation of calcium atoms. Interestingly, cubic Fm[3 with combining macron]m Ca2H, with antifluorite-type configuration, consists of a host Ca sublattice and guests H and ISQs confined in the center of Ca8 cubes. Furthermore, Ca2H is predicted to have a superconducting critical temperature Tc of 6 K at 100 GPa and exhibit significantly enhanced superconductivity up to 11 K when dynamically stabilized to 30 GPa, which is predominantly attributed to the remarkable softening of low-frequency acoustic phonon modes involving Ca-dominated vibrations, accompanied by the strong coupling with Ca 3d states near the Fermi energy. Additionally, the yielded electride Na2H via substituting Ca with Na in Ca2H is found to have a notably high Tc of 46 K at 30 GPa. Our current work improved the understanding of structures and properties of electrides, as well as paving the way for exploring emergent ESCs in hydride systems.

Graphical abstract: Coexistence of superconductivity and electride states in Ca2H with an antifluorite-type motif under compression

  • This article is part of the themed collection: #MyFirstJMCA

Supplementary files

Article information

Article type
Paper
Submitted
26 7月 2023
Accepted
09 9月 2023
First published
10 9月 2023

J. Mater. Chem. A, 2023,11, 21345-21353

Coexistence of superconductivity and electride states in Ca2H with an antifluorite-type motif under compression

Q. Wang, S. Zhang, H. Li, H. Wang, G. Liu, J. Ma, H. Xu, H. Liu and Y. Ma, J. Mater. Chem. A, 2023, 11, 21345 DOI: 10.1039/D3TA04418A

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