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Title: Can any material superconduct at room temperature and ambient pressure
Plain: The best superconductor at normal pressure works up to about 151 K, roughly minus 120 degrees Celsius; whether any material can reach room temperature without huge pressure is unknown.
Precise: Determine whether any thermodynamically stable or long-lived metastable material has $T_c \ge 300\ \mathrm{K}$ at ambient pressure. The ambient-pressure record is 151 K in pressure-quenched HgBa2Ca2Cu3O8+d (2026). An answer is a reproduced zero-resistance and Meissner measurement above 300 K at 1 bar, or a proof that a defined class of realistic materials cannot exceed a stated $T_c$ below 300 K.
Settled by: Independent replication of resistive and magnetic transitions above 300 K at ambient pressure.
Kind: well-posed
Answer type: yes-no
References: (empty)
Literature status: open
Status note: Pressure quench of $\mathrm{HgBa2Ca2Cu3O8}+d$ raised the ambient-pressure record from $133\,\mathrm{K}$ to $151\,\mathrm{K}$ (2026); claims of room-temperature superconductivity in nitrogen-doped lutetium hydride (2023) and LK-99 (2023) were not reproduced.
Posed since: (empty)