Theoretical investigation of high-pressure phase stability and potential superconductivity of Ce–S–H ternary hydrides

The discovery of high-temperature superconductivity in lanthanide- and sulfur-hydrides has attracted substantial interest recently. Here, we systematically investigate the high-pressure phase stability and superconducting properties of Ce-S-H ternary hydrides using first-principles calculations coupled with swarm-intelligence-based structure prediction methods. Our calculations reveal that all considered compositions (CeSH₂, CeSH₃, CeSH₆, CeSH₈, CeSH₉ and CeSH₁₀) exhibit thermodynamic and dynamic stability within the pressure range of 50-300 GPa. The hydrogen configurations in these compounds feature diverse motifs, including isolated H atoms, molecular "H₂" and "H₃" units, and H-S covalent networks, as validated by electron localization function (ELF) and Bader charge analysis. Notably, electron-phonon coupling (EPC) calculations identify <i>Cm</i>-CeSH₉ and <i>Cc</i>-CeSH₁₀ as promising superconductors, with transition temperatures (<i>T</i>_c) of 73.3 K at 150 GPa and 95.7 K at 300 GPa, respectively. These findings highlight the potential of Ce-S-H systems as high-<i>T</i>_c candidates under high-pressure conditions.