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Prediction of the structural stability and superconducting properties of RbSc2 hydrides under high pressure

Wenhui Zhang* and Hui Wang†

  • Key Laboratory for Photonic and Electronic Bandgap Materials (Ministry of Education), School of Physics and Electronic Engineering, Harbin Normal University, Harbin 150025, China

  • *Contact author: wenhui5643@163.com
  • †Contact author: wh@fysik.cn
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Phys. Rev. Research 8, 013278 – Published 12 March, 2026

DOI: https://doi.org/10.1103/5fmy-qlr7

Abstract

Ternary hydrides, owing to their chemical diversity and structural tunability, are considered important candidate systems for the exploration of high-temperature superconductivity. In this work, we performed systematic structure searches and superconductivity calculations on the RbSc2Hx ternary system over pressures ranging from 150 to 300 GPa. Our results reveal that RbSc2H16 adopts a highly symmetric cubic structure with space group Fd-3m, which is both dynamically and thermodynamically stable down to 150 GPa, featuring a hydrogen-based cage framework. Upon increasing hydrogen content, RbSc2H17 forms a fully occupied cage structure with enhanced H-H interactions and strengthened Sc-H hybridization. Electron localization function, crystal orbital Hamilton population, and Bader charge analysis collectively indicate that the bonding is dominated by strong H-H covalent interactions, supported by ionic contributions from Sc-H bonds. Electronic structure calculations show pronounced metallicity with Sc-3d and H-1s hybridization dominating near the Fermi level, facilitating strong electron-phonon coupling. The superconducting critical temperatures estimated using the Allen-Dynes modified McMillan formula reach 140 K for RbSc2H16 at 150 GPa and 190.7 K for RbSc2H17 at 200 GPa, underscoring the crucial role of hydrogen occupancy in optimizing superconducting behavior. The results indicate that variations in hydrogen content have a noticeable effect on the stability and superconducting characteristics of the RbSc2Hx system.

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Phys. Rev. Research 8, 013278– Published 12 March, 2026
  • Received 24 October 2025
  • Accepted 14 February 2026
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