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Title: Is there a hydride superconducting above 77 K at ambient pressure
Plain: Hydride superconductors need enormous pressure; the goal is a hydrogen-rich compound that keeps a high transition temperature, above liquid-nitrogen temperature, at normal pressure.
Precise: Determine whether any thermodynamically stable or long-lived metastable hydride has $T_c > 77\ \mathrm{K}$ at ambient pressure. An answer is a synthesized compound with zero resistance and diamagnetic shielding above 77 K at 1 bar, or a computational search with stated completeness showing none exists among a defined class.
Settled by: Synthesis and characterization of a predicted candidate with resistive and magnetic transitions above 77 K at ambient pressure.
Kind: well-posed
Answer type: yes-no
References: (empty)
Literature status: open
Status note: Calculations (2024) predicted Mg2IrH6 with $T_{c}$ above $100\,\mathrm{K}$ at ambient pressure; no superconducting sample has been reported.
Posed since: (empty)