Prediction of ternary superconducting YCH12 using a novel solid hydrogen source under high pressure

Abstract

Various hydrogen-rich superconductors have been theoretically predicted under high pressure, such as YH₁₀ with the highest superconducting temperature T_c among the binary compounds. Following the theoretical discoveries, the subsequent experimental work has confirmed the high-T_c superconductivity in hydrogen-rich materials such as H₃S and LaH₁₀. However, most experiments use molecular hydrogen as the hydrogen source, which is difficult to seal due to the small H atoms. Besides, the possible hydrogen permeation may also affect the mechanical properties of a diamond anvil cell. Therefore, we examine ternary Y–C–H hydrides to search for a potential superconductor that can be possibly fabricated using a new solid hydrogen source adamantane (C₁₀H₁₆). Our ab initio calculations indicate that the YCH₁₂ stoichiometry among various candidates is thermodynamically stable in the pressure range of 100–300 GPa. The triclinic YCH₁₂ consisting of Y, H_n (n = 1, 3, 4, and 7) and CH₄ motifs is a superconductor with an estimated T_c ∼ 112 K at 180 GPa. Its superconductivity derives from a large electron–phonon coupling (λ = 3.80), which depends on the contribution of Y atoms and evolution of ω_log under the pressure-induced chemical–structural transformations. These results will provide a novel route to explore promising high-T_c hydride superconductors.