Cuprate superconductors are complex copper-oxide compounds whose layered crystal structures contain copper and oxygen. Their discovery transformed superconductivity research because they can become superconducting at temperatures substantially higher than those of many conventional metallic superconductors. They remain difficult to explain completely within the simplest theories of superconductivity.
The properties of a cuprate depend on its chemical composition, carrier concentration, crystal structure and preparation. Many cuprates are brittle ceramics, and the temperature at which resistance disappears can vary with doping and processing. Their high transition temperatures make them attractive for specialized applications, but engineering useful devices remains demanding.
A mercury-barium-calcium-copper oxide cuprate, often called Hg1223, was the subject of a 2026 peer-reviewed pressure-quenching study reporting a 151 K transition at ambient pressure. That is warmer than the previous long-standing ambient-pressure record, but still far below the roughly 293 K temperature of an ordinary room.
For any cuprate record, check whether the stated temperature was measured at ambient pressure, whether it is an onset or a confirmed zero-resistance transition, and whether magnetic and structural data support the claim. Laboratory sample size and reproducibility also matter when judging practical significance.