High-Temperature Superconductivity in a Th–H System under Pressure Conditions

New stable phase thorium decahydride Fm3̅m-ThH₁₀, a high-temperature superconductor with T_C up to 241 K (−32 °C), critical field H_C up to 71 T, and superconducting gap Δ₀ of 52 meV at 80–100 GPa, is predicted by evolutionary algorithm USPEX. Another phase, P2₁/c-ThH₇, is found to be a superconductor with T_C of 62 K. Analysis of the superconducting state was performed within Eliashberg formalism, and H_C(T), Δ­(T), and T_C(P) functions with a jump in the specific heat at critical temperature were calculated. Several other new thorium hydrides were predicted to be stable under pressure, including ThH₃, Th₃H₁₀, ThH₄, and ThH₆. Thorium (which has s²d² electronic configuration) forms high-T_C polyhydrides similar to those formed by s²d¹ metals (Y–La–Ac). Thorium belongs to the Mg–Ca–Sc–Y–La–Ac family of elements forming high-T_C superconducting hydrides.