Wikipedia

Carbonaceous sulfur hydride

Carbonaceous sulfur hydride (CSH) is a potential superconductor that was announced in October 2020 by the lab of Ranga Dias at the University of Rochester, in a Nature paper that was later retracted.[1] It was reported to have a superconducting transition temperature of 15 °C (59 °F) at a pressure of 267 gigapascals (GPa), which would have made it the highest-temperature superconductor discovered.[2] The paper faced criticism due to its non-standard data analysis calling into question its conclusions,[3][4][5][6][7] and in September 2022 it was retracted by Nature.[8] In July 2023 a second paper by the authors was retracted from Physical Review Letters due to suspected data fabrication, and in September 2023 a third paper by the authors about N-doped lutetium hydride was retracted from Nature.[9]

Carbonaceous sulfur hydride
Identifiers
Properties
CH8S
Molar mass 52.14 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

CSH is an uncharacterized ternary polyhydride compound of carbon, sulfur and hydrogen with a chemical formula that is thought to be CH8S. Measurements under extreme pressure are difficult, and in particular the elements are too light for an X-ray determination of crystal structure (X-ray crystallography).[1]

Background

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Main article: Room-temperature superconductor

Prior to 1911, all known electrical conductors exhibited electrical resistance, due to collisions of the charge carrier with atoms in the material. Researchers discovered that in certain materials at low temperatures, the charge carriers interact with phonons in the material and form Cooper pairs, as described by BCS theory. This process results in the formation of a superconductor, with zero electrical resistance. During the transition to the superconducting state, the magnetic field lines are expelled from the interior of the material, which allows for the possibility of magnetic levitation. The effect has historically been known to occur at only low temperatures, but researchers have spent decades attempting to find a material that could operate at room temperature.[10]

Synthesis

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The material is a ternary polyhydride compound of carbon, sulfur and hydrogen with a chemical formula that is thought to be CSH8. As of October 2020, the material's molecular structure remains uncharacterized, as extreme pressures and the light elements used are unsuitable for most measurements, such as X-ray determination.[1]

The material was reportedly synthesized by compressing methane (CH4), hydrogen sulfide (H2S) and hydrogen (H2) in a diamond anvil cell and illuminating with a 532 nm green laser.[1] A starting compound of carbon and sulfur is synthesized with a 1:1 molar ratio, formed into balls less than five microns in diameter, and placed into a diamond anvil cell. Hydrogen gas is then added and the system is compressed to 4.0 GPa and illuminated with a 532-nm laser for several hours. It was reported that the crystal is not stable under 10 GPa and can be destroyed if left at room temperature overnight.[1] Other researchers were skeptical that such materials could serve as room temperature superconductors, as the absence of van Hove singularities or similar peaks in the electronic density of states of more than 3000 candidate phases rules out conventional superconductivity.[11]

Claims of superconductivity

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Superconductivity for sulfur hydrides without carbon was first reported in 2015.[12]

On 14 October 2020, a paper by Elliot Snider, et al. from the Dias lab was published, claiming that carbonaceous sulfur hydride was a room-temperature superconductor.[1] Two years later, the paper was retracted.[13][14] The claims in the paper included a superconducting state at temperatures as high as 15 °C (59 °F),[15][16] almost 30 °C (54 °F) higher than the existing record holder for high-temperature superconductivity.[2][17] This state was claimed to be observable only at the very high pressure of 267 GPa (38.7 million psi), a million times the pressure in a typical car tire.[16] The report was published in Nature and received significant media coverage.[17][18][19][20][21][10][22]

Criticism and retraction

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The validity of these results was called into question[3] by Jorge E. Hirsch[4] as well as others.[7][5] Unavailability of the data prompted an editor's note on the original paper.[1] additional criticism focused on the measurements of AC susceptibility[6] [23] used to test the superconductivity as the more definitive Meissner effect was too hard to observe at the scale of the experiments.

As of 2022, no other lab had been able to reproduce the result, and the criticisms of the data analysis in the paper had not been addressed. On February 15, 2022, Nature added a cautionary Editor's Note to the article,[1] and on 26 September 26, 2022, retracted the article entirely.[1][8] By the end of 2023 two other papers from the lab had been retracted from Physical Review Letters and Nature, due to suspicions of data fabrication.[24][9] At this point other publications by the lab were scrutinized more closely and as of March 2024 a total of nine of their papers had been retracted.[25]

References

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  1. ^ a b c d e f g h i Snider, Elliot; Dasenbrock-Gammon, Nathan; McBride, Raymond; Debessai, Mathew; Vindana, Hiranya; Vencatasamy, Kevin; Lawler, Keith V.; Salamat, Ashkan; Dias, Ranga P. (15 October 2020). "RETRACTED ARTICLE: Room-temperature superconductivity in a carbonaceous sulfur hydride". Nature. 586 (7829): 373–377. Bibcode:2020Natur.586..373S. doi:10.1038/s41586-020-2801-z. OSTI 1673473. PMID 33057222. S2CID 222823227. (Retracted, see doi:10.1038/s41586-022-05294-9, PMID 36163290)
  2. ^ a b "Material sets superconducting record". Chemical & Engineering News. Retrieved 2020-10-17.
  3. ^ a b "Breakthrough or bust? Claim of room-temperature superconductivity draws fire". Retrieved 2021-10-26.
  4. ^ a b Hirsch, J. E.; Marsiglio, F. (August 2021). "Unusual width of the superconducting transition in a hydride". Nature. 596 (7873): E9–E10. arXiv:2010.10307. Bibcode:2021Natur.596E...9H. doi:10.1038/s41586-021-03595-z. ISSN 1476-4687. PMID 34433940. S2CID 237306217.
  5. ^ a b Eremets, M. I.; Minkov, V. S.; Drozdov, A. P.; Kong, P. P.; Ksenofontov, V.; Shylin, S. I.; Bud’ko, S. L.; Prozorov, R.; Balakirev, F. F.; Sun, Dan; Mozaffari, S. (2022-03-25). "High-Temperature Superconductivity in Hydrides: Experimental Evidence and Details". Journal of Superconductivity and Novel Magnetism. 35 (4): 965–977. arXiv:2201.05137. doi:10.1007/s10948-022-06148-1. ISSN 1557-1939. S2CID 245906117.
  6. ^ a b Hirsch, J. E. (2021-09-26). "On the ac magnetic susceptibility of a room temperature superconductor: anatomy of a probable scientific fraud". Physica C: Superconductivity and Its Applications: 1353964. arXiv:2110.12854. doi:10.1016/j.physc.2021.1353964. ISSN 0921-4534. S2CID 239194714.
  7. ^ a b Dogan, Mehmet; Cohen, Marvin L. (2021-04-15). "Anomalous behavior in high-pressure carbonaceous sulfur hydride". Physica C: Superconductivity and Its Applications. 583: 1353851. arXiv:2012.10771. Bibcode:2021PhyC..58353851D. doi:10.1016/j.physc.2021.1353851. ISSN 0921-4534. S2CID 229340504.
  8. ^ a b Castelvecchi, Davide (2022-09-27). "Stunning room-temperature-superconductor claim is retracted". Nature. doi:10.1038/d41586-022-03066-z. PMID 36171305. S2CID 252597663.
  9. ^ a b Dasenbrock-Gammon, Nathan; Snider, Elliot; McBride, Raymond; Pasan, Hiranya; Durkee, Dylan; Khalvashi-Sutter, Nugzari; Munasinghe, Sasanka; Dissanayake, Sachith E.; Lawler, Keith V.; Salamat, Ashkan; Dias, Ranga P. (March 2023). "RETRACTED ARTICLE: Evidence of near-ambient superconductivity in a N-doped lutetium hydride". Nature. 615 (7951): 244–250. Bibcode:2023Natur.615..244D. doi:10.1038/s41586-023-05742-0. ISSN 1476-4687. PMID 36890373. (Retracted, see doi:10.1038/s41586-023-06774-2, PMID 37935926)
  10. ^ a b Wood, Charlie (14 October 2020). "Room-Temperature Superconductivity Achieved for the First Time". Quanta Magazine. Retrieved 2020-10-16.
  11. ^ Gubler, Moritz; Flores-Livas, José A.; Kozhevnikov, Anton; Goedecker, Stefan (2022-01-06). "Missing theoretical evidence for conventional room-temperature superconductivity in low-enthalpy structures of carbonaceous sulfur hydrides". Physical Review Materials. 6 (1): 014801. arXiv:2109.10019. Bibcode:2022PhRvM...6a4801G. doi:10.1103/PhysRevMaterials.6.014801. ISSN 2475-9953. S2CID 237581517.
  12. ^ Cartlidge, Edwin (2015). "Superconductivity record sparks wave of follow-up physics". Nature. 524 (7565): 277. Bibcode:2015Natur.524..277C. doi:10.1038/nature.2015.18191. PMID 26289188. S2CID 2294273.
  13. ^ Eric Hand (26 September 2022). "'Something is seriously wrong': Room-temperature superconductivity study retracted". Science. After doubts grew, blockbuster Nature paper is withdrawn over objections of study team
  14. ^ Snider, Elliot; Dasenbrock-Gammon, Nathan; McBride, Raymond; Debessai, Mathew; Vindana, Hiranya; Vencatasamy, Kevin; Lawler, Keith V.; Salamat, Ashkan; Dias, Ranga P. (2022). "Retraction Note: Room-temperature superconductivity in a carbonaceous sulfur hydride". Nature. 610 (7933): 804. Bibcode:2022Natur.610..804S. doi:10.1038/s41586-022-05294-9. PMID 36163290. S2CID 252544156.
  15. ^ Johnston, Hamish (14 October 2020). "Superconductivity endures to 15 °C in high-pressure material". Physics World. Retrieved 15 October 2020.
  16. ^ a b Rincon, Paul (2020-10-15). "Superconductors: Material raises hope of energy revolution". BBC News. Retrieved 2020-10-16.
  17. ^ a b Service, Robert F. (2020-10-16). "At last, room temperature superconductivity achieved". Science. 370 (6514): 273–274. Bibcode:2020Sci...370..273S. doi:10.1126/science.370.6514.273. ISSN 0036-8075. PMID 33060340. S2CID 222841128.
  18. ^ Castelvecchi, Davide (15 October 2020). "First room-temperature superconductor excites — and baffles — scientists". Nature. 586 (7829): 349. Bibcode:2020Natur.586..349C. doi:10.1038/d41586-020-02895-0. PMID 33057238. S2CID 222838731.
  19. ^ Conover, Emily (2020-10-14). "The first room-temperature superconductor has finally been found". Science News. Retrieved 2020-10-16.
  20. ^ Delbert, Caroline (2020-10-15). "In a Monumental First, Scientists Discover a Room-Temperature Superconductor". Popular Mechanics. Retrieved 2020-10-16.
  21. ^ Chang, Kenneth (2020-10-14). "Finally, the First Room-Temperature Superconductor". The New York Times. ISSN 0362-4331. Retrieved 2020-10-16.
  22. ^ Rochester, University of (2020-10-14). ""Holy Grail" Sought for More Than a Century: Researchers Synthesize Room Temperature Superconducting Material". SciTechDaily. Retrieved 2020-10-16.
  23. ^ van der Marel, D.; Hirsch, J. E. (2022). "Room-temperature superconductivity – or not ? Comment on Nature 586, 373 (2020) by E. Snider et al". International Journal of Modern Physics B. 37 (4): 2375001. arXiv:2201.07686. doi:10.1142/S0217979223750012. S2CID 252324362.
  24. ^ Caren, Rachel (2023-07-23). "Professor faces second paper retraction due to alleged data manipulation". Campus Times. Retrieved 2024-04-02.
  25. ^ "Retraction Watch database: Dias, Ranga P". Retraction Watch. Retrieved 2024-04-01.
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