roomtsc

Record transition temperatures

The target is superconductivity at about 300 K and one atmosphere. The highest reproduced transition temperature at one atmosphere is less than half of that, and the highest reproduced at any pressure needs about 170 GPa, roughly 1.7 million atmospheres. The article on the room-temperature superconductor explains why the gap is hard to close, and the history tells how the record moved.

Where it stands

HighestTcMaterialPressureStanding
Stable phase at one atmosphere133 to 138 KHgBa2Ca2Cu3O8+δ1 atm133 K in the pure compound, about 135 K when optimized, reproduced widely since 1993. 138 K with part of the mercury replaced by thallium, 1995. Schilling et al., Nature 363, 56 (1993)
Kept at one atmosphere after a pressure quench151 K onsetHgBa2Ca2Cu3O8+δ1 atm, after a quench from 10 to 30 GPaOne group, 2026. Zero resistance not reported. Deng et al., PNAS 123, e2536178123 (2026)
Reproduced at any pressure250 KLaH10170 GPaReproduced in Beijing (2020) and Jilin (2025). Drozdov et al., Nature 569, 528 (2019)
Claimed at any pressure298 K onsetLaSc2H24260 GPaPreprint. No magnetization, susceptibility or isotope data. A second group did not obtain the phase in seven attempts. Song et al., arXiv:2510.01273 (2025)
050100150200250300192019401960198020002020Tc (K)La-Ba-Cu-O: 35 K, 1986YBa2Cu3O7: 93 K, 1987Tl-2223: 125 K, 1988Hg-1223: 133 K, 1993Hg-1223 with partial Tl substitution: 138 K, 1995Hg-1223, 31 GPa (onset): 164 K, 1994H3S, 155 GPa: 203 K, 2015LaH10, 170 GPa: 250 K, 2019Hg-1223 after pressure quench, ambient pressure, metastable (onset): 151 K, 2026, not independently reproducedLaSc2H24, 260 GPa (onset): 298 K, 2025, not independently reproducedAny pressure: 250 KLaH₁₀ at 170 GPaAmbient pressure: 138 KHg cuprates, since 1993LaSc₂H₂₄, not reproducedquenched Hg-1223,one groupYBa₂Cu₃O₇H₃SHg-1223 at 31 GPaNb₃GeAmbient pressureAny pressuresingle group, not reproducedSingle group, not reproduced
Highest accepted transition temperature by year, at ambient pressure and at any pressure. Open markers are results from a single group that have not been independently reproduced. Retracted claims are not plotted.

The record by year

Each row is the year a new highest value was reported, by the criterion its authors used. Several are resistive onsets.

Stable phases at ambient pressure
YearMaterialTcSource
1911Hg4.2 K[1]
1913Pb7.2 K[2]
1930Nb9.2 K[2]
1941NbNAbout 15 K[3]
1954Nb3Sn18 K[4]
1973Nb3Ge22.3 K[4]
1986La-Ba-Cu-O35 K[5]
1987YBa2Cu3O793 K[6]
1988Tl-2223125 K[7]
1993Hg-1223133 K[8]
1995Hg-1223 with partial Tl substitution138 K[9]
At any pressure, where higher than the ambient record
YearMaterialTcSource
1994Hg-1223, 31 GPa (onset)164 K[10]
2015H3S, 155 GPa203 K[11]
2019LaH10, 170 GPa250 K[12]
Reported by one group and not reproduced
YearMaterialTcSource
2026Hg-1223 after pressure quench, ambient pressure, metastable (onset)151 K[13]
2025LaSc2H24, 260 GPa (onset)298 K[14]

References

  1. D. van Delft and P. Kes. The discovery of superconductivity. Phys. Today 63(9), 38 (2010).
  2. G. W. Webb, F. Marsiglio and J. E. Hirsch. Superconductivity in the elements, alloys and simple compounds. Physica C 514, 17 (2015).
  3. P. J. Lee (ed.). Brief history of superconductivity. Web page of the Applied Superconductivity Center, National High Magnetic Field Laboratory; excerpted from Engineering Superconductivity (Wiley-Interscience, New York) (2001).
  4. G. R. Stewart. Superconductivity in the A15 structure. Physica C 514, 28 (2015).
  5. J. G. Bednorz and K. A. Müller. Possible high Tc superconductivity in the Ba-La-Cu-O system. Z. Phys. B 64, 189 (1986).
  6. M. K. Wu et al. Superconductivity at 93 K in a new mixed-phase Y-Ba-Cu-O compound system at ambient pressure. Phys. Rev. Lett. 58, 908 (1987).
  7. S. S. P. Parkin et al. Bulk superconductivity at 125 K in Tl₂Ca₂Ba₂Cu₃Oₓ. Phys. Rev. Lett. 60, 2539 (1988).
  8. A. Schilling et al. Superconductivity above 130 K in the Hg-Ba-Ca-Cu-O system. Nature 363, 56 (1993).
  9. P. Dai et al. Synthesis and neutron powder diffraction study of the superconductor HgBa₂Ca₂Cu₃O₈₊δ by Tl substitution. Physica C 243, 201 (1995).
  10. L. Gao et al. Superconductivity up to 164 K in HgBa₂Caₘ₋₁CuₘO₂ₘ₊₂₊δ (m = 1, 2, and 3) under quasihydrostatic pressures. Phys. Rev. B 50, 4260 (1994).
  11. A. P. Drozdov et al. Conventional superconductivity at 203 kelvin at high pressures in the sulfur hydride system. Nature 525, 73 (2015).
  12. A. P. Drozdov et al. Superconductivity at 250 K in lanthanum hydride under high pressures. Nature 569, 528 (2019).
  13. L. Deng et al. Ambient-pressure 151-K superconductivity in HgBa₂Ca₂Cu₃O₈₊δ via pressure quench. Proc. Natl. Acad. Sci. U.S.A. 123, e2536178123 (2026).
  14. Y. Song et al. Room-temperature superconductivity at 298 K in ternary La-Sc-H system at high-pressure conditions. arXiv:2510.01273 (2025).