{
 "note": "Record transition temperatures. 'ambient' is the highest accepted Tc of an equilibrium phase at ambient pressure; 'any' is the highest accepted Tc at any pressure. Criterion is as reported (several are resistive onsets). Sources are citation keys in paper/refs.json or textbook values. The Nb, NbN, Nb3Sn and Nb3Ge rows are textbook values not checked against a primary source. A 2026 claim of 112 to 187 K in boron-doped quenched carbon (narayan2026) is not plotted.",
 "ambient": [
  {
   "year": 1911,
   "tc": 4.2,
   "material": "Hg",
   "source": "textbook"
  },
  {
   "year": 1913,
   "tc": 7.2,
   "material": "Pb",
   "source": "textbook"
  },
  {
   "year": 1930,
   "tc": 9.2,
   "material": "Nb",
   "source": "textbook"
  },
  {
   "year": 1941,
   "tc": 16,
   "material": "NbN",
   "source": "textbook"
  },
  {
   "year": 1954,
   "tc": 18.0,
   "material": "Nb3Sn",
   "source": "textbook"
  },
  {
   "year": 1973,
   "tc": 22.3,
   "material": "Nb3Ge",
   "source": "textbook"
  },
  {
   "year": 1986,
   "tc": 35,
   "material": "La-Ba-Cu-O",
   "source": "bednorz1986"
  },
  {
   "year": 1987,
   "tc": 93,
   "material": "YBa2Cu3O7",
   "source": "wu1987"
  },
  {
   "year": 1988,
   "tc": 125,
   "material": "Tl-2223",
   "source": "parkin1988"
  },
  {
   "year": 1993,
   "tc": 133,
   "material": "Hg-1223",
   "source": "schilling1993"
  },
  {
   "year": 1995,
   "tc": 138,
   "material": "Hg-1223 with partial Tl substitution",
   "source": "dai1995"
  }
 ],
 "any": [
  {
   "year": 1994,
   "tc": 164,
   "material": "Hg-1223, 31 GPa (onset)",
   "source": "gao1994"
  },
  {
   "year": 2015,
   "tc": 203,
   "material": "H3S, 155 GPa",
   "source": "drozdov2015"
  },
  {
   "year": 2019,
   "tc": 250,
   "material": "LaH10, 170 GPa",
   "source": "drozdov2019"
  }
 ],
 "unreproduced": [
  {
   "year": 2026,
   "tc": 151,
   "material": "Hg-1223 after pressure quench, ambient pressure, metastable (onset)",
   "series": "ambient",
   "source": "deng2026"
  },
  {
   "year": 2025,
   "tc": 298,
   "material": "LaSc2H24, 260 GPa (onset)",
   "series": "any",
   "source": "song2025"
  }
 ],
 "end_year": 2026
}