Studies of molecular mixtures containing hydrogen sulfide (H₂S) could open up new routes towards hydrogen-rich high-temperature superconductors under pressure. H₂S and ammonia (NH₃) form hydrogen-bonded molecular mixtures at ambient conditions, but their phase behavior and propensity towards mixing under pressure is not well understood. Here, we show stable phases in the H₂S–NH₃ system under extreme pressure conditions to 4 Mbar from first-principles crystal structure prediction methods. We identify four stable compositions, two of which, (H₂S) (NH₃) and (H₂S) (NH₃)₄, are stable in a sequence of structures to the Mbar regime. A re-entrant stabilization of (H₂S) (NH₃)₄ above 300 GPa is driven by a marked reversal of sulfur-hydrogen chemistry. Several stable phases exhibit metallic character. Electron–phonon coupling calculations predict superconducting temperatures up to 50 K, in the Cmma phase of (H₂S) (NH₃) at 150 GPa. The present findings shed light on how sulfur hydride bonding and superconductivity are affected in molecular mixtures. They also suggest a reservoir for hydrogen sulfide in the upper mantle regions of icy planets in a potentially metallic mixture, which could have implications for their magnetic field formation.

对含有硫化氢 (H ₂ S) 的分子混合物的研究可以为在压力下制备富氢高温超导体开辟新途径。H ₂ S 和氨 (NH ₃ ) 在环境条件下形成氢键分子混合物，但它们的相行为和在压力下混合的倾向尚不清楚。在这里，我们通过第一性原理晶体结构预测方法展示了在至 4 Mbar 的极端压力条件下H ₂ S–NH ₃系统中的稳定相。我们确定了四种稳定的成分，其中两种是 (H ₂ S) (NH ₃ ) 和 (H ₂ S) (NH ₃ ) ₄, 在 Mbar 制度的一系列结构中是稳定的。_{(H 2} S) (NH ₃ ) ₄在 300 GPa 以上的重入稳定是由硫氢化学的显着逆转驱动的。几个稳定相表现出金属特性。电子-声子耦合计算预测超导温度高达 50 K，在(H ₂ S) (NH _{3 ) 的}Cmma相中，压力为 150 GPa。目前的发现阐明了硫氢化物键合和超导性在分子混合物中是如何受到影响的。他们还提出，在冰冷行星的上地幔区域存在潜在金属混合物中的硫化氢储层，这可能对它们的磁场形成产生影响。