{"schemaVersion":"1.0","revision":"fa961ab24277a91737c3","article":{"id":"scwiki-d6","topicId":"scwiki-topic-d6","code":"D6","slug":"hydride-superconductors","title":"Hydride superconductors: pressure, evidence and recovery","summary":"Understand H3S, LaH10 and hydrogen-rich materials through structures, pressure conditions, isotope comparisons and the limits of disputed claims.","aliases":["hydrides","H3S","LaH10","LaD10","chemical precompression","LuH2","LuH2±xNy","Y3Fe4H20","carbonaceous sulfur hydride","retraction"],"evidenceTypes":["theory","experiment","prediction"],"relatedCodes":["D1","A4","A6","B1","B2"],"editorialStatus":"scoped-check","contentState":"pilot","modifiedAt":"2026-10-19T16:17:36.973893+00:00","review":{"checkedAt":"2026-10-20","scope":"Selected primary structure, transport and magnetometry passages; final LaH10 isotope and pressure methods; both retraction notices in full; bounded printed-parameter and isotope calculations. Follow-up: Ming final selected transport, magnetization, colour, synthesis and composition limits; final PDFpp4–7 visually inspected and arXivv3 abstract compared.","limitations":["Full scientific acceptance, raw-data and independent reproducibility assessment remain open.","Ashcroft proposals checked at abstract level; Einaga and Somayazulu detailed checks use identified author versions, not final-methods comparison.","Numerical checks do not reproduce structure searches, DFPT, anharmonic phonons or Eliashberg solutions.","2026 recovery result is not ambient-pressure superconductivity; supplementary methods and raw-data review remain open.","Ming negative-result windows are probe-specific and sampled; no continuous pressure exclusion, exact H/N composition or raw-data reproduction is established."]},"provenance":{"repository":"JackZH26/jzis-superconductivity","commit":"0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf","path":"D_material_families/D6_hydrides.md","sha256":"b5a8aa93b211383ef8a435e968858295adef9f5b2f89fe842e66112baeff3ae6","sourceId":"file-7fa327f5deb92987"},"sourceMap":[{"startLine":1,"endLine":71,"targetSections":["scope","mathematical-assumptions","experimental-criteria","limits-and-disputes","discovery-implications","related-topics"],"decision":"edited-with-scoped-evidence","note":"Pinned source preserved; original versions, withdrawn claims and recovery limits made explicit."}],"references":[{"id":"source-6fbecff48a8989e8","doi":"10.1103/PhysRevLett.21.1748","title":"Metallic Hydrogen: A High-Temperature Superconductor?","year":1968,"url":"https://doi.org/10.1103/PhysRevLett.21.1748","publicationStatus":"journal-article","verification":{"scope":"publisher-abstract-check","checkedAt":"2026-10-18","evidenceUrl":"https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.21.1748","note":"Published 23 December 1968. Abstract only; theoretical proposal, not experimental realization."}},{"id":"source-ba29a1eb0f9df263","doi":"10.1103/PhysRevLett.92.187002","title":"Hydrogen Dominant Metallic Alloys: High Temperature Superconductors?","year":2004,"url":"https://doi.org/10.1103/PhysRevLett.92.187002","publicationStatus":"journal-article","verification":{"scope":"publisher-abstract-check","checkedAt":"2026-10-18","evidenceUrl":"https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.92.187002","note":"Published 6 May 2004. Abstract only; chemical precompression is a proposal, not an ambient-pressure guarantee."}},{"id":"source-2b01ce847be6bc20","doi":"10.1038/srep06968","title":"Pressure-induced metallization of dense (H2S)2H2 with high-Tc superconductivity","year":2014,"url":"https://doi.org/10.1038/srep06968","publicationStatus":"journal-article","verification":{"scope":"selected-published-methods-equation-check","checkedAt":"2026-10-18","evidenceUrl":"https://www.nature.com/articles/srep06968.pdf","note":"Published 10 November 2014. Selected pp. 1–6: structure search, Table 1 and methods. Printed modified-McMillan estimates independently calculated; no DFPT or search reproduced."}},{"id":"source-8b901b9c6008c434","doi":"10.1038/nature14964","title":"Conventional superconductivity at 203 kelvin at high pressures in the sulfur hydride system","year":2015,"url":"https://doi.org/10.1038/nature14964","publicationStatus":"journal-article","verification":{"scope":"selected-author-text-and-published-caption-check","checkedAt":"2026-10-18","evidenceUrl":"https://arxiv.org/pdf/1506.08190v1","note":"Published 17 August 2015. Author v1 of 26 June 2015: selected pp. 3/5 and Fig. 4 pp. 11–12, visually checked; publisher abstract and extended captions also checked. Magnetization raw data and background subtraction not independently reproduced."}},{"id":"source-e7837a18f3252cb9","doi":"10.1038/nphys3760","title":"Crystal structure of the superconducting phase of sulfur hydride","year":2016,"url":"https://doi.org/10.1038/nphys3760","publicationStatus":"journal-article","verification":{"scope":"selected-author-structure-check","checkedAt":"2026-10-18","evidenceUrl":"https://arxiv.org/pdf/1509.03156v1","note":"Author v1 of 10 September 2015, selected pp. 1–3: sulfur sublattice, mixed sulfur phase and deuteride 173 GPa simultaneous transport/XRD. Final published full text not compared; hydrogen positions not directly resolved."}},{"id":"source-77b774e18b0f50c7","doi":"10.1103/PhysRevLett.122.027001","title":"Evidence for Superconductivity above 260 K in Lanthanum Superhydride at Megabar Pressures","year":2019,"url":"https://doi.org/10.1103/PhysRevLett.122.027001","publicationStatus":"journal-article","verification":{"scope":"publisher-abstract-and-selected-author-v3-methods-check","checkedAt":"2026-10-18","evidenceUrl":"https://arxiv.org/pdf/1808.07695v3","note":"Journal published 14 January 2019; detailed scope is author v3 of 29 August 2018 pp. 3–7. Four-probe versus pseudo-four-probe, pressure drift, about 20 microohm minimum and sample geometry. Final journal methods not compared; intrinsic resistivity not determined."}},{"id":"source-1e6e868a12cdd34f","doi":"10.1038/s41586-019-1201-8","title":"Superconductivity at 250 K in lanthanum hydride under high pressures","year":2019,"url":"https://doi.org/10.1038/s41586-019-1201-8","publicationStatus":"journal-article","verification":{"scope":"selected-published-methods-figures-check","checkedAt":"2026-10-18","evidenceUrl":"https://public.magnet.fsu.edu/AToth/NSF%20publication%20access/2019/05%20Newly%20Entered%20Pubs%20May%202019/2019%20cited/2019_Superconductivity%20at%20250%20K%20in%20lanthanum%20hydride%20under%20high%20pressures.pdf","note":"Published online 22 May 2019. Selected printed pp. 528–529, Fig. 4p.531, Methods and deuteride assignment; PDF p. 2 visually checked. Final 249/180 K comparison replaces early 250/168 K; rounded ratio 0.468 differs from stated 0.46. Measured 9 T versus extrapolated 95–136 T; no SQUID measurement."}},{"id":"source-1bec081a84267ffb","doi":"10.1103/PhysRevLett.114.157004","title":"High-Pressure Hydrogen Sulfide from First Principles: A Strongly Anharmonic Phonon-Mediated Superconductor","year":2015,"url":"https://doi.org/10.1103/PhysRevLett.114.157004","publicationStatus":"journal-article","verification":{"scope":"selected-author-equations-table-check","checkedAt":"2026-10-18","evidenceUrl":"https://api.repository.cam.ac.uk/server/api/core/bitstreams/5cc3e771-c6c8-423c-bea3-7faa5ba6a44f/content","note":"Author accepted manuscript dated 26 March 2015, selectedpp. 1–4 and Table II visually checked. Publisher identity confirmed. No SSCHA, phonon or full Eliashberg solver reproduced; early experimental 190/90 K comparison not promoted to later benchmark."}},{"id":"source-d04f7965dca4d5a5","doi":"10.1038/s41586-020-2801-z","title":"RETRACTED ARTICLE: Room-temperature superconductivity in a carbonaceous sulfur hydride","year":2020,"url":"https://doi.org/10.1038/s41586-020-2801-z","publicationStatus":"journal-article","verification":{"scope":"retraction-notice-identity-check","checkedAt":"2026-10-18","evidenceUrl":"https://www.nature.com/articles/s41586-022-05294-9.pdf","note":"Original article identity checked against the corrected retraction notice; original experimental claim is not accepted as a benchmark."},"retraction":{"noticeDoi":"10.1038/s41586-022-05294-9","retractedAt":"2022-09-26","evidenceUrl":"https://doi.org/10.1038/s41586-022-05294-9"}},{"id":"source-754d75026e52d9ac","doi":"10.1038/s41586-022-05294-9","title":"Retraction Note: Room-temperature superconductivity in a carbonaceous sulfur hydride","year":2022,"url":"https://doi.org/10.1038/s41586-022-05294-9","publicationStatus":"journal-article","verification":{"scope":"complete-retraction-notice-text-check","checkedAt":"2026-10-18","evidenceUrl":"https://www.nature.com/articles/s41586-022-05294-9.pdf","note":"Published 26 September 2022. Corrected notice read in full; concerns about non-standard user-defined background subtraction. All authors disagreed with retraction."}},{"id":"source-a7b93ad4f4896402","doi":"10.1038/s41586-023-05742-0","title":"RETRACTED ARTICLE: Evidence of near-ambient superconductivity in a N-doped lutetium hydride","year":2023,"url":"https://doi.org/10.1038/s41586-023-05742-0","publicationStatus":"journal-article","verification":{"scope":"retraction-notice-identity-check","checkedAt":"2026-10-18","evidenceUrl":"https://www.nature.com/articles/s41586-023-06774-2.pdf","note":"Original article identity checked against its retraction notice; original experimental claim is not accepted as a benchmark."},"retraction":{"noticeDoi":"10.1038/s41586-023-06774-2","retractedAt":"2023-11-07","evidenceUrl":"https://doi.org/10.1038/s41586-023-06774-2"}},{"id":"source-98bc73a5e1c86c78","doi":"10.1038/s41586-023-06774-2","title":"Retraction Note: Evidence of near-ambient superconductivity in a N-doped lutetium hydride","year":2023,"url":"https://doi.org/10.1038/s41586-023-06774-2","publicationStatus":"journal-article","verification":{"scope":"complete-retraction-notice-text-check","checkedAt":"2026-10-18","evidenceUrl":"https://www.nature.com/articles/s41586-023-06774-2.pdf","note":"Published 7 November 2023. Notice read in full: eight authors requested retraction over provenance, measurements and processing; additional resistivity concerns. No independent misconduct finding inferred."}},{"id":"source-151c87f0eda0236f","doi":"10.1038/s41586-023-06162-w","title":"Absence of near-ambient superconductivity in LuH2±xNy","year":2023,"url":"https://doi.org/10.1038/s41586-023-06162-w","publicationStatus":"journal-article","verification":{"scope":"selected-final-probe-windows-and-version-comparison","checkedAt":"2026-10-20","evidenceUrl":"https://www.nature.com/articles/s41586-023-06162-w.pdf","note":"Published 11 May 2023; version of record 26 July 2023, Nature 620, 72–77. Selected final text and PDF pages 4–7 (Figs. 3–5 and Methods) checked. Fig. 4b: transport from 2 to 350 K at discrete pressures spanning 0.4–40.1 GPa. Fig. 5a,b: magnetization from 100 to 320 K at 1.0 and 2.1 GPa, 60 Oe, with cell background subtraction. Transport, magnetization and optical measurements use NaCl, Daphne 7373 and KBr respectively. Methods specify room-temperature ruby calibration, platinum contacts and synthesis at 2 GPa, 300–350 °C for 10 hours. EDS cannot measure hydrogen. The arXiv v3 abstract (2 June 2023; https://arxiv.org/abs/2303.08759v3) retains the narrower 1–6 GPa and 10 K scope; the final record is used here. Raw source data and independent replication remain unreviewed."}},{"id":"source-f9dfe34f7dffd9d2","doi":"10.1038/s41467-026-74232-4","title":"Ambient pressure recovery of the structurally unconventional hydride Y3Fe4H20","year":2026,"url":"https://doi.org/10.1038/s41467-026-74232-4","publicationStatus":"journal-article","verification":{"scope":"selected-published-recovery-and-magnetometry-check","checkedAt":"2026-10-18","evidenceUrl":"https://www.nature.com/articles/s41467-026-74232-4.pdf","note":"Published 20 June 2026. Selected abstract p. 1, structure/DFPT discussion p. 4 and SQUID paragraph p. 5: recovered material survives tens of hours; no superconductivity down to 3 K in run 4. Full supplementary methods and raw data remain open."}}],"claims":[{"id":"scwiki-d6-claim-scope-1","sectionId":"scope","statement":"Hydrogen-rich superconductors connect light nuclei, strong electron–phonon coupling and pressure-dependent chemistry. Ashcroft's metallic-hydrogen proposal and later hydrogen-dominant-alloy proposal motivate this route; neither established a recoverable ambient-pressure superconductor. H₃S and LaH₁₀ are important high-pressure experimental systems. Their formulae, pressure scales and sample histories must accompany any quoted transition temperature.","evidenceType":"theory","sourceIds":["source-6fbecff48a8989e8","source-ba29a1eb0f9df263","source-8b901b9c6008c434","source-1e6e868a12cdd34f"],"conditions":"Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.","verificationScope":"Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance."},{"id":"scwiki-d6-claim-scope-2","sectionId":"scope","statement":"“Chemical precompression” describes a design idea, not a guarantee of low operating pressure. A predicted metallic structure, a synthesized hydride and a superconducting phase are different achievements. Distinguish the starting H₂S reagent from its proposed H₃S product, and a clathrate-like hydrogen framework from directly measured hydrogen positions. The sulfur-hydride diffraction study supports the sulfur sublattice and coexistence with sulfur; its measured patterns cannot by themselves distinguish hydrogen arrangements with the same sulfur periodicity.","evidenceType":"theory","sourceIds":["source-ba29a1eb0f9df263","source-2b01ce847be6bc20","source-e7837a18f3252cb9"],"conditions":"Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.","verificationScope":"Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance."},{"id":"scwiki-d6-claim-mathematical-assumptions-1","sectionId":"mathematical-assumptions","statement":"For a specified structure, a commonly used modified-McMillan estimate is $T_c=(\\omega_{\\log}/1.2)\\exp[-1.04(1+\\lambda)/(\\lambda-\\mu^*(1+0.62\\lambda))]$, with $\\omega_{\\log}$ expressed in kelvin here. Duan's harmonic calculations give $\\lambda=2.07$, $\\omega_{\\log}=1125.1$ K for R3m at 130 GPa and $\\lambda=2.19$, $\\omega_{\\log}=1334.6$ K for Im$\\bar{3}$m at 200 GPa. Substitution with $\\mu^*=0.13$ and 0.10 gives approximately 155–166 K and 191–204 K, respectively. This reproduces the printed estimate convention, without additional strong-coupling or spectral-shape factors; it does not reproduce the underlying density-functional perturbation calculation.","evidenceType":"theory","sourceIds":["source-2b01ce847be6bc20"],"conditions":"Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.","verificationScope":"Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance."},{"id":"scwiki-d6-claim-mathematical-assumptions-2","sectionId":"mathematical-assumptions","statement":"Hydrogen motion can invalidate a harmonic treatment. Errea and colleagues calculated a change from $\\lambda=2.64$ to 1.84 for H₃S at 200 GPa when including anharmonicity. Their full isotropic Migdal–Eliashberg calculation with $\\mu^*=0.16$ changed the calculated transition from 250 to 194 K. That table is not obtained by simply substituting parameters into the preceding approximate formula. Zero-point contributions also alter the calculated decomposition landscape: both $3\\mathrm{H_2S}\\rightarrow2\\mathrm{H_3S}+\\mathrm{S}$ and $5\\mathrm{H_2S}\\rightarrow3\\mathrm{H_3S}+\\mathrm{HS_2}$ conserve atoms, but atom balance alone does not establish stability or a reaction pathway.","evidenceType":"theory","sourceIds":["source-1bec081a84267ffb"],"conditions":"Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.","verificationScope":"Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance."},{"id":"scwiki-d6-claim-mathematical-assumptions-3","sectionId":"mathematical-assumptions","statement":"An isotope comparison uses $\\alpha=\\ln(T_{c,\\mathrm H}/T_{c,\\mathrm D})/\\ln2$ only after checking structure, pressure and transition criteria. The final LaH₁₀ paper compares approximately 249 K and 180 K for fcc hydride and deuteride near 150 GPa; its Fig. 4 specifies 151 and 152 GPa. These rounded values give 0.468, while the paper states 0.46. The early author's 250/168 K comparison gives 0.573 and must not be silently substituted for the final result. Phase mixtures and different deuteride structures further limit interpretation.","evidenceType":"theory","sourceIds":["source-1e6e868a12cdd34f"],"conditions":"Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.","verificationScope":"Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance."},{"id":"scwiki-d6-claim-experimental-criteria-1","sectionId":"experimental-criteria","statement":"For sulfur hydride, the 2015 report combined resistance, field response, isotope substitution and magnetization. Its author-version Fig. 4a reports a zero-field-cooled magnetic onset of 203(1) K at 155 GPa, with a 20 Oe field-cooled comparison. The plotted transport comparison is a different pressure, 145 GPa, and must not be treated as the identical specimen condition. Background subtraction and diamond-anvil-cell contributions require scrutiny; this scoped reading does not independently reproduce raw magnetization. The later simultaneous diffraction/transport experiment on deuteride at 173 GPa provides structural context, not a direct measurement of every hydrogen coordinate.","evidenceType":"experiment","sourceIds":["source-8b901b9c6008c434","source-e7837a18f3252cb9"],"conditions":"Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.","verificationScope":"Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance."},{"id":"scwiki-d6-claim-experimental-criteria-2","sectionId":"experimental-criteria","statement":"The two early lanthanum-superhydride studies have different evidence scopes. Somayazulu's author v3 describes a large resistance drop around 260 K, with room-temperature pressure changing from 188 to 196 GPa across a thermal cycle; pressure at the actual transition was not measured in that run. The lowest four-probe resistance was about 20 μΩ, while pseudo-four-probe measurements carried contact-resistance limitations. This should not be rewritten as an independently established zero-resistance or magnetic-shielding result. The final journal abstract was checked, but the selected detailed methods here come from the identified author version.","evidenceType":"experiment","sourceIds":["source-77b774e18b0f50c7"],"conditions":"Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.","verificationScope":"Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance."},{"id":"scwiki-d6-claim-experimental-criteria-3","sectionId":"experimental-criteria","statement":"Drozdov's final 2019 LaH₁₀ paper reports zero resistance, isotope dependence and field suppression, with a maximum near 250–252 K around 170 GPa. Its transition criterion is the onset of deviation from normal metallic resistance. Measurements to 9 T support an extrapolated zero-temperature upper critical field of approximately 95–136 T; they are not direct measurements at 136 T. The authors explicitly state that their tiny samples were below the available SQUID sensitivity. Their H₂/D₂ vibron pressure estimates were often 10–30 GPa lower than diamond-edge estimates around 150 GPa, so pressure calibrations cannot be freely interchanged.","evidenceType":"experiment","sourceIds":["source-1e6e868a12cdd34f"],"conditions":"Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.","verificationScope":"Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance."},{"id":"scwiki-d6-claim-limits-and-disputes-1","sectionId":"limits-and-disputes","statement":"The 2020 carbonaceous-sulfur-hydride article was retracted on 26 September 2022. The corrected notice identifies concerns about non-standard, user-defined magnetic-background subtraction; all authors disagreed with the retraction. The 2023 nitrogen-doped lutetium-hydride article was retracted on 7 November 2023 following concerns including sample provenance, measurements and processing. These original papers remain linked as historical claims, accompanied by their notices. Their claimed temperatures are not usable experimental benchmarks in this catalogue. A retraction notice is not a substitute for an independent misconduct finding.","evidenceType":"experiment","sourceIds":["source-d04f7965dca4d5a5","source-754d75026e52d9ac","source-a7b93ad4f4896402","source-98bc73a5e1c86c78"],"conditions":"Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.","verificationScope":"Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance."},{"id":"scwiki-d6-claim-limits-and-disputes-2","sectionId":"limits-and-disputes","statement":"Ming's independent LuH₂±xNᵧ study found no superconductivity in its transport measurements down to 2 K at sampled pressures spanning 0.4–40.1 GPa. Samples were synthesized at 2 GPa and 300–350 °C for 10 hours. This preparation and finite measurement window do not exclude every possible Lu–N–H composition or an unmeasured pressure interval.\n\n| Probe in the final paper | Measurement window and preparation | What the result does not establish |\n|---|---|---|\n| Resistance, Fig. 4b | 2–350 K; sampled 0.4–40.1 GPa; NaCl medium | 2 K is a measurement floor, not a transition temperature |\n| Magnetization, Fig. 5a,b | 100–320 K; 1.0 and 2.1 GPa; 60 Oe; Daphne 7373 medium | This is not the full transport window; subtracting the cell background leaves a weak positive signal |\n| Optical colour, Fig. 4a | Up to 41 GPa; KBr medium | A blue-to-pink colour change is not a superconductivity measurement |\n\nThe methods specify room-temperature ruby pressure calibration and four-probe van der Pauw resistance with platinum electrodes. EDS detects nitrogen but cannot detect hydrogen here; it does not fix both x and y. The pressure range is a sampled envelope, not continuous coverage. The [arXiv v3 abstract](https://arxiv.org/abs/2303.08759v3), dated 2 June 2023, still describes 1–6 GPa and a 10 K floor; this catalogue uses the expanded final-paper transport window.","evidenceType":"experiment","sourceIds":["source-151c87f0eda0236f"],"conditions":"Ming final paper, Nature 620, 72–77; specified synthesis. Transport: Fig. 4b, 2–350 K, discrete pressures 0.4–40.1 GPa, NaCl medium. Magnetization: Fig. 5a,b, 100–320 K, 1.0/2.1 GPa, 60 Oe, Daphne 7373 medium. Optical measurements use KBr. Room-temperature ruby calibration; no universal composition exclusion.","verificationScope":"Selected final text, Fig3–5/captions and Methods; arXivv3 abstract/history comparison. No source-data reanalysis, continuous pressure sampling, composition determination or independent replication.","sourceRelationship":"mixed-source-and-local-derivation","derivationNote":"Primary paper supports the stated probe-specific observations and preparation. The prohibition on extending finite negative evidence to all compositions or unsampled intervals is editorial inference, not a newly measured exclusion bound. The arXivv3 abstract is an alternate version, not a replacement for the final record."},{"id":"scwiki-d6-claim-discovery-implications-1","sectionId":"discovery-implications","statement":"A credible search must connect composition and structure to dynamical and thermodynamic stability, finite-temperature and nuclear-quantum effects, synthesis access and multiple superconductivity probes. A finite structure search can miss larger cells; absence of imaginary harmonic frequencies is a local dynamical check, not proof of global stability. Preserve decompression history, mixed phases, pressure standards and unsuccessful samples instead of ranking formulae by isolated temperature claims.","evidenceType":"theory","sourceIds":["source-2b01ce847be6bc20","source-e7837a18f3252cb9","source-1bec081a84267ffb"],"conditions":"Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.","verificationScope":"Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance."},{"id":"scwiki-d6-claim-discovery-implications-2","sectionId":"discovery-implications","statement":"A June 2026 study recovered Y₃Fe₄H₂₀ at ambient pressure after synthesis above about 60 GPa, with survival on the scale of tens of hours. This is useful progress in hydride recovery, but its reported SQUID test found no superconductivity down to 3 K in the tested recovered sample. Hydrogen positions were supported by structure searches, and the sample was small and not pure. Recovery, long-term stability and ambient-pressure superconductivity remain distinct questions. Full raw-data, convergence and cross-laboratory assessment remain open for this article.","evidenceType":"experiment","sourceIds":["source-f9dfe34f7dffd9d2"],"conditions":"Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.","verificationScope":"Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance."}],"corrections":[{"id":"scwiki-d6-correction-1","description":"Retained final LaH10 249/180K isotope comparison and identified early-version differences; explicitly linked two retraction notices and excluded withdrawn Tc benchmarks.","sourceId":"source-1e6e868a12cdd34f","scope":"Public article and metadata; pinned source bytes unchanged."}],"equationChecks":[{"targetSectionId":"mathematical-assumptions","tex":"T_c=\\omega_{\\log}\\exp[-1.04(1+\\lambda)/(\\lambda-\\mu^*(1+0.62\\lambda))]/1.2","check":"Four printed-parameter estimates and bounded monotonic Coulomb suppression."},{"targetSectionId":"mathematical-assumptions","tex":"\\alpha=\\ln(T_{c,H}/T_{c,D})/\\ln2","check":"Final rounded0.468, early-version0.573, theory0.352 distinguished; atom balances verified separately."}],"materialCases":[{"id":"scwiki-d6-material-1","formula":"H3S","sample":"Sulfur hydride, author Fig. 4a, 155 GPa","recordType":"experiment","reportedTemperatureK":203,"tcK":203,"temperatureKind":"transition","temperatureNote":"Reported 203(1) K onset; raw background subtraction not independently reproduced.","criterion":"zfc-magnetic-onset","pressureRegime":"high","pressureGPa":{"min":155,"max":155},"equilibrium":"unknown","probe":"ZFC/FC magnetization; 20 Oe FC comparison","sourceId":"source-8b901b9c6008c434","aliases":["hydride","hydrides"]},{"id":"scwiki-d6-material-2","formula":"LaH10","sample":"Final 2019 pressure-dome maximum, near 170 GPa","recordType":"experiment","reportedTemperatureK":250,"tcK":250,"temperatureKind":"transition","temperatureNote":"Approximate maximum 250–252 K; onset of departure from normal metallic resistance.","criterion":"resistance-onset-deviation","pressureRegime":"high","pressureGPa":{"min":170,"max":170},"equilibrium":"unknown","probe":"Zero resistance, isotope and measured field suppression; no SQUID measurement","sourceId":"source-1e6e868a12cdd34f","aliases":["hydride","hydrides"]},{"id":"scwiki-d6-material-3","formula":"LaD10","sample":"fcc sample 17, isotope Fig. 4, 152 GPa","recordType":"experiment","reportedTemperatureK":180,"tcK":180,"temperatureKind":"transition","temperatureNote":"Final isotope comparison; not early 168 K assignment.","criterion":"resistance-onset-deviation","pressureRegime":"high","pressureGPa":{"min":152,"max":152},"equilibrium":"unknown","probe":"Resistance; diffraction-assigned fcc phase with mixture limitations","sourceId":"source-1e6e868a12cdd34f","aliases":["hydride","hydrides"]},{"id":"scwiki-d6-material-4","formula":"LuH2±xNy","sample":"Ming final Fig. 4b transport; synthesized at 2 GPa, 300–350 °C for 10 hours; NaCl pressure medium","recordType":"experiment","reportedTemperatureK":2,"tcK":null,"temperatureKind":"measurement","temperatureNote":"2 K lower measurement limit, not Tc. Tested pressures span 0.4–40.1 GPa; range endpoints do not imply continuous coverage. Fig. 5 magnetic measurements have a separate 100–320 K, 1.0/2.1 GPa window. No universal composition exclusion.","criterion":"negative-search-lower-limit","pressureRegime":"high","pressureGPa":{"min":0.4,"max":40.1},"equilibrium":"unknown","probe":"Four-probe van der Pauw resistance with platinum electrodes; room-temperature ruby pressure calibration","sourceId":"source-151c87f0eda0236f","aliases":["hydride","hydrides"]},{"id":"scwiki-d6-material-5","formula":"Y3Fe4H20","sample":"Recovered run 4 sample, small and not pure","recordType":"experiment","reportedTemperatureK":3,"tcK":null,"temperatureKind":"measurement","temperatureNote":"Lower measurement limit, not Tc; ambient recovery lasted tens of hours.","criterion":"negative-squid-lower-limit","pressureRegime":"ambient","pressureGPa":null,"equilibrium":"metastable","probe":"SQUID test found no superconductivity down to 3 K","sourceId":"source-f9dfe34f7dffd9d2","aliases":["hydride","hydrides"]},{"id":"scwiki-d6-material-6","formula":"H3S","sample":"Im-3m harmonic model, mu*=0.10","recordType":"prediction","reportedTemperatureK":204,"tcK":null,"temperatureKind":"transition","temperatureNote":"Rounded printed prediction for mu*=0.10; not a measured transition. Independent substitution gives about 203.65 K.","criterion":"modified-mcmillan-prediction","pressureRegime":"high","pressureGPa":{"min":200,"max":200},"equilibrium":"unknown","probe":"Harmonic DFPT parameters; bounded algebra independently checked","sourceId":"source-2b01ce847be6bc20","aliases":["hydride","hydrides"]}],"body":"## Scope\n\nHydrogen-rich superconductors connect light nuclei, strong electron–phonon coupling and pressure-dependent chemistry. Ashcroft's metallic-hydrogen proposal and later hydrogen-dominant-alloy proposal motivate this route; neither established a recoverable ambient-pressure superconductor. H₃S and LaH₁₀ are important high-pressure experimental systems. Their formulae, pressure scales and sample histories must accompany any quoted transition temperature. [R1](#ref-source-6fbecff48a8989e8) [R2](#ref-source-ba29a1eb0f9df263) [R4](#ref-source-8b901b9c6008c434) [R7](#ref-source-1e6e868a12cdd34f)\n\n“Chemical precompression” describes a design idea, not a guarantee of low operating pressure. A predicted metallic structure, a synthesized hydride and a superconducting phase are different achievements. Distinguish the starting H₂S reagent from its proposed H₃S product, and a clathrate-like hydrogen framework from directly measured hydrogen positions. The sulfur-hydride diffraction study supports the sulfur sublattice and coexistence with sulfur; its measured patterns cannot by themselves distinguish hydrogen arrangements with the same sulfur periodicity. [R2](#ref-source-ba29a1eb0f9df263) [R3](#ref-source-2b01ce847be6bc20) [R5](#ref-source-e7837a18f3252cb9)\n\n## Mathematical assumptions\n\nFor a specified structure, a commonly used modified-McMillan estimate is $T_c=(\\omega_{\\log}/1.2)\\exp[-1.04(1+\\lambda)/(\\lambda-\\mu^*(1+0.62\\lambda))]$, with $\\omega_{\\log}$ expressed in kelvin here. Duan's harmonic calculations give $\\lambda=2.07$, $\\omega_{\\log}=1125.1$ K for R3m at 130 GPa and $\\lambda=2.19$, $\\omega_{\\log}=1334.6$ K for Im$\\bar{3}$m at 200 GPa. Substitution with $\\mu^*=0.13$ and 0.10 gives approximately 155–166 K and 191–204 K, respectively. This reproduces the printed estimate convention, without additional strong-coupling or spectral-shape factors; it does not reproduce the underlying density-functional perturbation calculation. [R3](#ref-source-2b01ce847be6bc20)\n\nHydrogen motion can invalidate a harmonic treatment. Errea and colleagues calculated a change from $\\lambda=2.64$ to 1.84 for H₃S at 200 GPa when including anharmonicity. Their full isotropic Migdal–Eliashberg calculation with $\\mu^*=0.16$ changed the calculated transition from 250 to 194 K. That table is not obtained by simply substituting parameters into the preceding approximate formula. Zero-point contributions also alter the calculated decomposition landscape: both $3\\mathrm{H_2S}\\rightarrow2\\mathrm{H_3S}+\\mathrm{S}$ and $5\\mathrm{H_2S}\\rightarrow3\\mathrm{H_3S}+\\mathrm{HS_2}$ conserve atoms, but atom balance alone does not establish stability or a reaction pathway. [R8](#ref-source-1bec081a84267ffb)\n\nAn isotope comparison uses $\\alpha=\\ln(T_{c,\\mathrm H}/T_{c,\\mathrm D})/\\ln2$ only after checking structure, pressure and transition criteria. The final LaH₁₀ paper compares approximately 249 K and 180 K for fcc hydride and deuteride near 150 GPa; its Fig. 4 specifies 151 and 152 GPa. These rounded values give 0.468, while the paper states 0.46. The early author's 250/168 K comparison gives 0.573 and must not be silently substituted for the final result. Phase mixtures and different deuteride structures further limit interpretation. [R7](#ref-source-1e6e868a12cdd34f)\n\n## Experimental criteria\n\nFor sulfur hydride, the 2015 report combined resistance, field response, isotope substitution and magnetization. Its author-version Fig. 4a reports a zero-field-cooled magnetic onset of 203(1) K at 155 GPa, with a 20 Oe field-cooled comparison. The plotted transport comparison is a different pressure, 145 GPa, and must not be treated as the identical specimen condition. Background subtraction and diamond-anvil-cell contributions require scrutiny; this scoped reading does not independently reproduce raw magnetization. The later simultaneous diffraction/transport experiment on deuteride at 173 GPa provides structural context, not a direct measurement of every hydrogen coordinate. [R4](#ref-source-8b901b9c6008c434) [R5](#ref-source-e7837a18f3252cb9)\n\nThe two early lanthanum-superhydride studies have different evidence scopes. Somayazulu's author v3 describes a large resistance drop around 260 K, with room-temperature pressure changing from 188 to 196 GPa across a thermal cycle; pressure at the actual transition was not measured in that run. The lowest four-probe resistance was about 20 μΩ, while pseudo-four-probe measurements carried contact-resistance limitations. This should not be rewritten as an independently established zero-resistance or magnetic-shielding result. The final journal abstract was checked, but the selected detailed methods here come from the identified author version. [R6](#ref-source-77b774e18b0f50c7)\n\nDrozdov's final 2019 LaH₁₀ paper reports zero resistance, isotope dependence and field suppression, with a maximum near 250–252 K around 170 GPa. Its transition criterion is the onset of deviation from normal metallic resistance. Measurements to 9 T support an extrapolated zero-temperature upper critical field of approximately 95–136 T; they are not direct measurements at 136 T. The authors explicitly state that their tiny samples were below the available SQUID sensitivity. Their H₂/D₂ vibron pressure estimates were often 10–30 GPa lower than diamond-edge estimates around 150 GPa, so pressure calibrations cannot be freely interchanged. [R7](#ref-source-1e6e868a12cdd34f)\n\n## Limits and disputes\n\nThe 2020 carbonaceous-sulfur-hydride article was retracted on 26 September 2022. The corrected notice identifies concerns about non-standard, user-defined magnetic-background subtraction; all authors disagreed with the retraction. The 2023 nitrogen-doped lutetium-hydride article was retracted on 7 November 2023 following concerns including sample provenance, measurements and processing. These original papers remain linked as historical claims, accompanied by their notices. Their claimed temperatures are not usable experimental benchmarks in this catalogue. A retraction notice is not a substitute for an independent misconduct finding. [R9](#ref-source-d04f7965dca4d5a5) [R10](#ref-source-754d75026e52d9ac) [R11](#ref-source-a7b93ad4f4896402) [R12](#ref-source-98bc73a5e1c86c78)\n\nMing's independent LuH₂±xNᵧ study found no superconductivity in its transport measurements down to 2 K at sampled pressures spanning 0.4–40.1 GPa. Samples were synthesized at 2 GPa and 300–350 °C for 10 hours. This preparation and finite measurement window do not exclude every possible Lu–N–H composition or an unmeasured pressure interval.\n\n| Probe in the final paper | Measurement window and preparation | What the result does not establish |\n|---|---|---|\n| Resistance, Fig. 4b | 2–350 K; sampled 0.4–40.1 GPa; NaCl medium | 2 K is a measurement floor, not a transition temperature |\n| Magnetization, Fig. 5a,b | 100–320 K; 1.0 and 2.1 GPa; 60 Oe; Daphne 7373 medium | This is not the full transport window; subtracting the cell background leaves a weak positive signal |\n| Optical colour, Fig. 4a | Up to 41 GPa; KBr medium | A blue-to-pink colour change is not a superconductivity measurement |\n\nThe methods specify room-temperature ruby pressure calibration and four-probe van der Pauw resistance with platinum electrodes. EDS detects nitrogen but cannot detect hydrogen here; it does not fix both x and y. The pressure range is a sampled envelope, not continuous coverage. The [arXiv v3 abstract](https://arxiv.org/abs/2303.08759v3), dated 2 June 2023, still describes 1–6 GPa and a 10 K floor; this catalogue uses the expanded final-paper transport window. [R13](#ref-source-151c87f0eda0236f)\n\n## Discovery implications\n\nA credible search must connect composition and structure to dynamical and thermodynamic stability, finite-temperature and nuclear-quantum effects, synthesis access and multiple superconductivity probes. A finite structure search can miss larger cells; absence of imaginary harmonic frequencies is a local dynamical check, not proof of global stability. Preserve decompression history, mixed phases, pressure standards and unsuccessful samples instead of ranking formulae by isolated temperature claims. [R3](#ref-source-2b01ce847be6bc20) [R5](#ref-source-e7837a18f3252cb9) [R8](#ref-source-1bec081a84267ffb)\n\nA June 2026 study recovered Y₃Fe₄H₂₀ at ambient pressure after synthesis above about 60 GPa, with survival on the scale of tens of hours. This is useful progress in hydride recovery, but its reported SQUID test found no superconductivity down to 3 K in the tested recovered sample. Hydrogen positions were supported by structure searches, and the sample was small and not pure. Recovery, long-term stability and ambient-pressure superconductivity remain distinct questions. Full raw-data, convergence and cross-laboratory assessment remain open for this article. [R14](#ref-source-f9dfe34f7dffd9d2)\n\n## Related topics\n\nContinue with [isotope effects](/scwiki/isotope-effect), [Eliashberg theory](/scwiki/eliashberg-strong-coupling), [critical fields](/scwiki/critical-fields) and [elemental superconductors](/scwiki/elemental-superconductors).","revision":"7346f5cb0fd101401073","sections":[{"id":"scope","title":"Scope","markdown":"## Scope\n\nHydrogen-rich superconductors connect light nuclei, strong electron–phonon coupling and pressure-dependent chemistry. Ashcroft's metallic-hydrogen proposal and later hydrogen-dominant-alloy proposal motivate this route; neither established a recoverable ambient-pressure superconductor. H₃S and LaH₁₀ are important high-pressure experimental systems. Their formulae, pressure scales and sample histories must accompany any quoted transition temperature. [R1](#ref-source-6fbecff48a8989e8) [R2](#ref-source-ba29a1eb0f9df263) [R4](#ref-source-8b901b9c6008c434) [R7](#ref-source-1e6e868a12cdd34f)\n\n“Chemical precompression” describes a design idea, not a guarantee of low operating pressure. A predicted metallic structure, a synthesized hydride and a superconducting phase are different achievements. Distinguish the starting H₂S reagent from its proposed H₃S product, and a clathrate-like hydrogen framework from directly measured hydrogen positions. The sulfur-hydride diffraction study supports the sulfur sublattice and coexistence with sulfur; its measured patterns cannot by themselves distinguish hydrogen arrangements with the same sulfur periodicity. [R2](#ref-source-ba29a1eb0f9df263) [R3](#ref-source-2b01ce847be6bc20) [R5](#ref-source-e7837a18f3252cb9)"},{"id":"mathematical-assumptions","title":"Mathematical assumptions","markdown":"## Mathematical assumptions\n\nFor a specified structure, a commonly used modified-McMillan estimate is $T_c=(\\omega_{\\log}/1.2)\\exp[-1.04(1+\\lambda)/(\\lambda-\\mu^*(1+0.62\\lambda))]$, with $\\omega_{\\log}$ expressed in kelvin here. Duan's harmonic calculations give $\\lambda=2.07$, $\\omega_{\\log}=1125.1$ K for R3m at 130 GPa and $\\lambda=2.19$, $\\omega_{\\log}=1334.6$ K for Im$\\bar{3}$m at 200 GPa. Substitution with $\\mu^*=0.13$ and 0.10 gives approximately 155–166 K and 191–204 K, respectively. This reproduces the printed estimate convention, without additional strong-coupling or spectral-shape factors; it does not reproduce the underlying density-functional perturbation calculation. [R3](#ref-source-2b01ce847be6bc20)\n\nHydrogen motion can invalidate a harmonic treatment. Errea and colleagues calculated a change from $\\lambda=2.64$ to 1.84 for H₃S at 200 GPa when including anharmonicity. Their full isotropic Migdal–Eliashberg calculation with $\\mu^*=0.16$ changed the calculated transition from 250 to 194 K. That table is not obtained by simply substituting parameters into the preceding approximate formula. Zero-point contributions also alter the calculated decomposition landscape: both $3\\mathrm{H_2S}\\rightarrow2\\mathrm{H_3S}+\\mathrm{S}$ and $5\\mathrm{H_2S}\\rightarrow3\\mathrm{H_3S}+\\mathrm{HS_2}$ conserve atoms, but atom balance alone does not establish stability or a reaction pathway. [R8](#ref-source-1bec081a84267ffb)\n\nAn isotope comparison uses $\\alpha=\\ln(T_{c,\\mathrm H}/T_{c,\\mathrm D})/\\ln2$ only after checking structure, pressure and transition criteria. The final LaH₁₀ paper compares approximately 249 K and 180 K for fcc hydride and deuteride near 150 GPa; its Fig. 4 specifies 151 and 152 GPa. These rounded values give 0.468, while the paper states 0.46. The early author's 250/168 K comparison gives 0.573 and must not be silently substituted for the final result. Phase mixtures and different deuteride structures further limit interpretation. [R7](#ref-source-1e6e868a12cdd34f)"},{"id":"experimental-criteria","title":"Experimental criteria","markdown":"## Experimental criteria\n\nFor sulfur hydride, the 2015 report combined resistance, field response, isotope substitution and magnetization. Its author-version Fig. 4a reports a zero-field-cooled magnetic onset of 203(1) K at 155 GPa, with a 20 Oe field-cooled comparison. The plotted transport comparison is a different pressure, 145 GPa, and must not be treated as the identical specimen condition. Background subtraction and diamond-anvil-cell contributions require scrutiny; this scoped reading does not independently reproduce raw magnetization. The later simultaneous diffraction/transport experiment on deuteride at 173 GPa provides structural context, not a direct measurement of every hydrogen coordinate. [R4](#ref-source-8b901b9c6008c434) [R5](#ref-source-e7837a18f3252cb9)\n\nThe two early lanthanum-superhydride studies have different evidence scopes. Somayazulu's author v3 describes a large resistance drop around 260 K, with room-temperature pressure changing from 188 to 196 GPa across a thermal cycle; pressure at the actual transition was not measured in that run. The lowest four-probe resistance was about 20 μΩ, while pseudo-four-probe measurements carried contact-resistance limitations. This should not be rewritten as an independently established zero-resistance or magnetic-shielding result. The final journal abstract was checked, but the selected detailed methods here come from the identified author version. [R6](#ref-source-77b774e18b0f50c7)\n\nDrozdov's final 2019 LaH₁₀ paper reports zero resistance, isotope dependence and field suppression, with a maximum near 250–252 K around 170 GPa. Its transition criterion is the onset of deviation from normal metallic resistance. Measurements to 9 T support an extrapolated zero-temperature upper critical field of approximately 95–136 T; they are not direct measurements at 136 T. The authors explicitly state that their tiny samples were below the available SQUID sensitivity. Their H₂/D₂ vibron pressure estimates were often 10–30 GPa lower than diamond-edge estimates around 150 GPa, so pressure calibrations cannot be freely interchanged. [R7](#ref-source-1e6e868a12cdd34f)"},{"id":"limits-and-disputes","title":"Limits and disputes","markdown":"## Limits and disputes\n\nThe 2020 carbonaceous-sulfur-hydride article was retracted on 26 September 2022. The corrected notice identifies concerns about non-standard, user-defined magnetic-background subtraction; all authors disagreed with the retraction. The 2023 nitrogen-doped lutetium-hydride article was retracted on 7 November 2023 following concerns including sample provenance, measurements and processing. These original papers remain linked as historical claims, accompanied by their notices. Their claimed temperatures are not usable experimental benchmarks in this catalogue. A retraction notice is not a substitute for an independent misconduct finding. [R9](#ref-source-d04f7965dca4d5a5) [R10](#ref-source-754d75026e52d9ac) [R11](#ref-source-a7b93ad4f4896402) [R12](#ref-source-98bc73a5e1c86c78)\n\nMing's independent LuH₂±xNᵧ study found no superconductivity in its transport measurements down to 2 K at sampled pressures spanning 0.4–40.1 GPa. Samples were synthesized at 2 GPa and 300–350 °C for 10 hours. This preparation and finite measurement window do not exclude every possible Lu–N–H composition or an unmeasured pressure interval.\n\n| Probe in the final paper | Measurement window and preparation | What the result does not establish |\n|---|---|---|\n| Resistance, Fig. 4b | 2–350 K; sampled 0.4–40.1 GPa; NaCl medium | 2 K is a measurement floor, not a transition temperature |\n| Magnetization, Fig. 5a,b | 100–320 K; 1.0 and 2.1 GPa; 60 Oe; Daphne 7373 medium | This is not the full transport window; subtracting the cell background leaves a weak positive signal |\n| Optical colour, Fig. 4a | Up to 41 GPa; KBr medium | A blue-to-pink colour change is not a superconductivity measurement |\n\nThe methods specify room-temperature ruby pressure calibration and four-probe van der Pauw resistance with platinum electrodes. EDS detects nitrogen but cannot detect hydrogen here; it does not fix both x and y. The pressure range is a sampled envelope, not continuous coverage. The [arXiv v3 abstract](https://arxiv.org/abs/2303.08759v3), dated 2 June 2023, still describes 1–6 GPa and a 10 K floor; this catalogue uses the expanded final-paper transport window. [R13](#ref-source-151c87f0eda0236f)"},{"id":"discovery-implications","title":"Discovery implications","markdown":"## Discovery implications\n\nA credible search must connect composition and structure to dynamical and thermodynamic stability, finite-temperature and nuclear-quantum effects, synthesis access and multiple superconductivity probes. A finite structure search can miss larger cells; absence of imaginary harmonic frequencies is a local dynamical check, not proof of global stability. Preserve decompression history, mixed phases, pressure standards and unsuccessful samples instead of ranking formulae by isolated temperature claims. [R3](#ref-source-2b01ce847be6bc20) [R5](#ref-source-e7837a18f3252cb9) [R8](#ref-source-1bec081a84267ffb)\n\nA June 2026 study recovered Y₃Fe₄H₂₀ at ambient pressure after synthesis above about 60 GPa, with survival on the scale of tens of hours. This is useful progress in hydride recovery, but its reported SQUID test found no superconductivity down to 3 K in the tested recovered sample. Hydrogen positions were supported by structure searches, and the sample was small and not pure. Recovery, long-term stability and ambient-pressure superconductivity remain distinct questions. Full raw-data, convergence and cross-laboratory assessment remain open for this article. [R14](#ref-source-f9dfe34f7dffd9d2)"},{"id":"related-topics","title":"Related topics","markdown":"## Related topics\n\nContinue with [isotope effects](/scwiki/isotope-effect), [Eliashberg theory](/scwiki/eliashberg-strong-coupling), [critical fields](/scwiki/critical-fields) and [elemental superconductors](/scwiki/elemental-superconductors)."},{"id":"material-cases","title":"Material cases","markdown":"## Material cases\n\nValues describe individual reports, not a ranking. Unknown means the checked source did not supply the field at this review scope.\n\n| Material and sample | Reported temperature | Criterion | Probe | Pressure | State | Evidence |\n|---|---|---|---|---|---|---|\n| H3S (aliases: hydride, hydrides); Sulfur hydride, author Fig. 4a, 155 GPa | 203 K; Reported 203(1) K onset; raw background subtraction not independently reproduced. | transition; zfc-magnetic-onset | ZFC/FC magnetization; 20 Oe FC comparison | high; 155 to 155 GPa | unknown | experiment; [source](#ref-source-8b901b9c6008c434) |\n| LaH10 (aliases: hydride, hydrides); Final 2019 pressure-dome maximum, near 170 GPa | 250 K; Approximate maximum 250–252 K; onset of departure from normal metallic resistance. | transition; resistance-onset-deviation | Zero resistance, isotope and measured field suppression; no SQUID measurement | high; 170 to 170 GPa | unknown | experiment; [source](#ref-source-1e6e868a12cdd34f) |\n| LaD10 (aliases: hydride, hydrides); fcc sample 17, isotope Fig. 4, 152 GPa | 180 K; Final isotope comparison; not early 168 K assignment. | transition; resistance-onset-deviation | Resistance; diffraction-assigned fcc phase with mixture limitations | high; 152 to 152 GPa | unknown | experiment; [source](#ref-source-1e6e868a12cdd34f) |\n| LuH2±xNy (aliases: hydride, hydrides); Ming final Fig. 4b transport; synthesized at 2 GPa, 300–350 °C for 10 hours; NaCl pressure medium | 2 K; 2 K lower measurement limit, not Tc. Tested pressures span 0.4–40.1 GPa; range endpoints do not imply continuous coverage. Fig. 5 magnetic measurements have a separate 100–320 K, 1.0/2.1 GPa window. No universal composition exclusion. | measurement; negative-search-lower-limit | Four-probe van der Pauw resistance with platinum electrodes; room-temperature ruby pressure calibration | high; 0.4 to 40.1 GPa | unknown | experiment; [source](#ref-source-151c87f0eda0236f) |\n| Y3Fe4H20 (aliases: hydride, hydrides); Recovered run 4 sample, small and not pure | 3 K; Lower measurement limit, not Tc; ambient recovery lasted tens of hours. | measurement; negative-squid-lower-limit | SQUID test found no superconductivity down to 3 K | ambient; unknown GPa | metastable | experiment; [source](#ref-source-f9dfe34f7dffd9d2) |\n| H3S (aliases: hydride, hydrides); Im-3m harmonic model, mu*=0.10 | 204 K; Rounded printed prediction for mu*=0.10; not a measured transition. Independent substitution gives about 203.65 K. | transition; modified-mcmillan-prediction | Harmonic DFPT parameters; bounded algebra independently checked | high; 200 to 200 GPa | unknown | prediction; [source](#ref-source-2b01ce847be6bc20) |"}],"markdown":"# Hydride superconductors: pressure, evidence and recovery\n\nUnderstand H3S, LaH10 and hydrogen-rich materials through structures, pressure conditions, isotope comparisons and the limits of disputed claims.\n\n## Scope\n\nHydrogen-rich superconductors connect light nuclei, strong electron–phonon coupling and pressure-dependent chemistry. Ashcroft's metallic-hydrogen proposal and later hydrogen-dominant-alloy proposal motivate this route; neither established a recoverable ambient-pressure superconductor. H₃S and LaH₁₀ are important high-pressure experimental systems. Their formulae, pressure scales and sample histories must accompany any quoted transition temperature. [R1](#ref-source-6fbecff48a8989e8) [R2](#ref-source-ba29a1eb0f9df263) [R4](#ref-source-8b901b9c6008c434) [R7](#ref-source-1e6e868a12cdd34f)\n\n“Chemical precompression” describes a design idea, not a guarantee of low operating pressure. A predicted metallic structure, a synthesized hydride and a superconducting phase are different achievements. Distinguish the starting H₂S reagent from its proposed H₃S product, and a clathrate-like hydrogen framework from directly measured hydrogen positions. The sulfur-hydride diffraction study supports the sulfur sublattice and coexistence with sulfur; its measured patterns cannot by themselves distinguish hydrogen arrangements with the same sulfur periodicity. [R2](#ref-source-ba29a1eb0f9df263) [R3](#ref-source-2b01ce847be6bc20) [R5](#ref-source-e7837a18f3252cb9)\n\n## Mathematical assumptions\n\nFor a specified structure, a commonly used modified-McMillan estimate is $T_c=(\\omega_{\\log}/1.2)\\exp[-1.04(1+\\lambda)/(\\lambda-\\mu^*(1+0.62\\lambda))]$, with $\\omega_{\\log}$ expressed in kelvin here. Duan's harmonic calculations give $\\lambda=2.07$, $\\omega_{\\log}=1125.1$ K for R3m at 130 GPa and $\\lambda=2.19$, $\\omega_{\\log}=1334.6$ K for Im$\\bar{3}$m at 200 GPa. Substitution with $\\mu^*=0.13$ and 0.10 gives approximately 155–166 K and 191–204 K, respectively. This reproduces the printed estimate convention, without additional strong-coupling or spectral-shape factors; it does not reproduce the underlying density-functional perturbation calculation. [R3](#ref-source-2b01ce847be6bc20)\n\nHydrogen motion can invalidate a harmonic treatment. Errea and colleagues calculated a change from $\\lambda=2.64$ to 1.84 for H₃S at 200 GPa when including anharmonicity. Their full isotropic Migdal–Eliashberg calculation with $\\mu^*=0.16$ changed the calculated transition from 250 to 194 K. That table is not obtained by simply substituting parameters into the preceding approximate formula. Zero-point contributions also alter the calculated decomposition landscape: both $3\\mathrm{H_2S}\\rightarrow2\\mathrm{H_3S}+\\mathrm{S}$ and $5\\mathrm{H_2S}\\rightarrow3\\mathrm{H_3S}+\\mathrm{HS_2}$ conserve atoms, but atom balance alone does not establish stability or a reaction pathway. [R8](#ref-source-1bec081a84267ffb)\n\nAn isotope comparison uses $\\alpha=\\ln(T_{c,\\mathrm H}/T_{c,\\mathrm D})/\\ln2$ only after checking structure, pressure and transition criteria. The final LaH₁₀ paper compares approximately 249 K and 180 K for fcc hydride and deuteride near 150 GPa; its Fig. 4 specifies 151 and 152 GPa. These rounded values give 0.468, while the paper states 0.46. The early author's 250/168 K comparison gives 0.573 and must not be silently substituted for the final result. Phase mixtures and different deuteride structures further limit interpretation. [R7](#ref-source-1e6e868a12cdd34f)\n\n## Experimental criteria\n\nFor sulfur hydride, the 2015 report combined resistance, field response, isotope substitution and magnetization. Its author-version Fig. 4a reports a zero-field-cooled magnetic onset of 203(1) K at 155 GPa, with a 20 Oe field-cooled comparison. The plotted transport comparison is a different pressure, 145 GPa, and must not be treated as the identical specimen condition. Background subtraction and diamond-anvil-cell contributions require scrutiny; this scoped reading does not independently reproduce raw magnetization. The later simultaneous diffraction/transport experiment on deuteride at 173 GPa provides structural context, not a direct measurement of every hydrogen coordinate. [R4](#ref-source-8b901b9c6008c434) [R5](#ref-source-e7837a18f3252cb9)\n\nThe two early lanthanum-superhydride studies have different evidence scopes. Somayazulu's author v3 describes a large resistance drop around 260 K, with room-temperature pressure changing from 188 to 196 GPa across a thermal cycle; pressure at the actual transition was not measured in that run. The lowest four-probe resistance was about 20 μΩ, while pseudo-four-probe measurements carried contact-resistance limitations. This should not be rewritten as an independently established zero-resistance or magnetic-shielding result. The final journal abstract was checked, but the selected detailed methods here come from the identified author version. [R6](#ref-source-77b774e18b0f50c7)\n\nDrozdov's final 2019 LaH₁₀ paper reports zero resistance, isotope dependence and field suppression, with a maximum near 250–252 K around 170 GPa. Its transition criterion is the onset of deviation from normal metallic resistance. Measurements to 9 T support an extrapolated zero-temperature upper critical field of approximately 95–136 T; they are not direct measurements at 136 T. The authors explicitly state that their tiny samples were below the available SQUID sensitivity. Their H₂/D₂ vibron pressure estimates were often 10–30 GPa lower than diamond-edge estimates around 150 GPa, so pressure calibrations cannot be freely interchanged. [R7](#ref-source-1e6e868a12cdd34f)\n\n## Limits and disputes\n\nThe 2020 carbonaceous-sulfur-hydride article was retracted on 26 September 2022. The corrected notice identifies concerns about non-standard, user-defined magnetic-background subtraction; all authors disagreed with the retraction. The 2023 nitrogen-doped lutetium-hydride article was retracted on 7 November 2023 following concerns including sample provenance, measurements and processing. These original papers remain linked as historical claims, accompanied by their notices. Their claimed temperatures are not usable experimental benchmarks in this catalogue. A retraction notice is not a substitute for an independent misconduct finding. [R9](#ref-source-d04f7965dca4d5a5) [R10](#ref-source-754d75026e52d9ac) [R11](#ref-source-a7b93ad4f4896402) [R12](#ref-source-98bc73a5e1c86c78)\n\nMing's independent LuH₂±xNᵧ study found no superconductivity in its transport measurements down to 2 K at sampled pressures spanning 0.4–40.1 GPa. Samples were synthesized at 2 GPa and 300–350 °C for 10 hours. This preparation and finite measurement window do not exclude every possible Lu–N–H composition or an unmeasured pressure interval.\n\n| Probe in the final paper | Measurement window and preparation | What the result does not establish |\n|---|---|---|\n| Resistance, Fig. 4b | 2–350 K; sampled 0.4–40.1 GPa; NaCl medium | 2 K is a measurement floor, not a transition temperature |\n| Magnetization, Fig. 5a,b | 100–320 K; 1.0 and 2.1 GPa; 60 Oe; Daphne 7373 medium | This is not the full transport window; subtracting the cell background leaves a weak positive signal |\n| Optical colour, Fig. 4a | Up to 41 GPa; KBr medium | A blue-to-pink colour change is not a superconductivity measurement |\n\nThe methods specify room-temperature ruby pressure calibration and four-probe van der Pauw resistance with platinum electrodes. EDS detects nitrogen but cannot detect hydrogen here; it does not fix both x and y. The pressure range is a sampled envelope, not continuous coverage. The [arXiv v3 abstract](https://arxiv.org/abs/2303.08759v3), dated 2 June 2023, still describes 1–6 GPa and a 10 K floor; this catalogue uses the expanded final-paper transport window. [R13](#ref-source-151c87f0eda0236f)\n\n## Discovery implications\n\nA credible search must connect composition and structure to dynamical and thermodynamic stability, finite-temperature and nuclear-quantum effects, synthesis access and multiple superconductivity probes. A finite structure search can miss larger cells; absence of imaginary harmonic frequencies is a local dynamical check, not proof of global stability. Preserve decompression history, mixed phases, pressure standards and unsuccessful samples instead of ranking formulae by isolated temperature claims. [R3](#ref-source-2b01ce847be6bc20) [R5](#ref-source-e7837a18f3252cb9) [R8](#ref-source-1bec081a84267ffb)\n\nA June 2026 study recovered Y₃Fe₄H₂₀ at ambient pressure after synthesis above about 60 GPa, with survival on the scale of tens of hours. This is useful progress in hydride recovery, but its reported SQUID test found no superconductivity down to 3 K in the tested recovered sample. Hydrogen positions were supported by structure searches, and the sample was small and not pure. Recovery, long-term stability and ambient-pressure superconductivity remain distinct questions. Full raw-data, convergence and cross-laboratory assessment remain open for this article. [R14](#ref-source-f9dfe34f7dffd9d2)\n\n## Related topics\n\nContinue with [isotope effects](/scwiki/isotope-effect), [Eliashberg theory](/scwiki/eliashberg-strong-coupling), [critical fields](/scwiki/critical-fields) and [elemental superconductors](/scwiki/elemental-superconductors).\n\n## Material cases\n\nValues describe individual reports, not a ranking. Unknown means the checked source did not supply the field at this review scope.\n\n| Material and sample | Reported temperature | Criterion | Probe | Pressure | State | Evidence |\n|---|---|---|---|---|---|---|\n| H3S (aliases: hydride, hydrides); Sulfur hydride, author Fig. 4a, 155 GPa | 203 K; Reported 203(1) K onset; raw background subtraction not independently reproduced. | transition; zfc-magnetic-onset | ZFC/FC magnetization; 20 Oe FC comparison | high; 155 to 155 GPa | unknown | experiment; [source](#ref-source-8b901b9c6008c434) |\n| LaH10 (aliases: hydride, hydrides); Final 2019 pressure-dome maximum, near 170 GPa | 250 K; Approximate maximum 250–252 K; onset of departure from normal metallic resistance. | transition; resistance-onset-deviation | Zero resistance, isotope and measured field suppression; no SQUID measurement | high; 170 to 170 GPa | unknown | experiment; [source](#ref-source-1e6e868a12cdd34f) |\n| LaD10 (aliases: hydride, hydrides); fcc sample 17, isotope Fig. 4, 152 GPa | 180 K; Final isotope comparison; not early 168 K assignment. | transition; resistance-onset-deviation | Resistance; diffraction-assigned fcc phase with mixture limitations | high; 152 to 152 GPa | unknown | experiment; [source](#ref-source-1e6e868a12cdd34f) |\n| LuH2±xNy (aliases: hydride, hydrides); Ming final Fig. 4b transport; synthesized at 2 GPa, 300–350 °C for 10 hours; NaCl pressure medium | 2 K; 2 K lower measurement limit, not Tc. Tested pressures span 0.4–40.1 GPa; range endpoints do not imply continuous coverage. Fig. 5 magnetic measurements have a separate 100–320 K, 1.0/2.1 GPa window. No universal composition exclusion. | measurement; negative-search-lower-limit | Four-probe van der Pauw resistance with platinum electrodes; room-temperature ruby pressure calibration | high; 0.4 to 40.1 GPa | unknown | experiment; [source](#ref-source-151c87f0eda0236f) |\n| Y3Fe4H20 (aliases: hydride, hydrides); Recovered run 4 sample, small and not pure | 3 K; Lower measurement limit, not Tc; ambient recovery lasted tens of hours. | measurement; negative-squid-lower-limit | SQUID test found no superconductivity down to 3 K | ambient; unknown GPa | metastable | experiment; [source](#ref-source-f9dfe34f7dffd9d2) |\n| H3S (aliases: hydride, hydrides); Im-3m harmonic model, mu*=0.10 | 204 K; Rounded printed prediction for mu*=0.10; not a measured transition. Independent substitution gives about 203.65 K. | transition; modified-mcmillan-prediction | Harmonic DFPT parameters; bounded algebra independently checked | high; 200 to 200 GPa | unknown | prediction; [source](#ref-source-2b01ce847be6bc20) |\n\n## Sources\n\n### Ref source-6fbecff48a8989e8\n\n[R1] Metallic Hydrogen: A High-Temperature Superconductor? (1968). [DOI 10.1103/PhysRevLett.21.1748](https://doi.org/10.1103/PhysRevLett.21.1748). Publication: journal-article. Check: publisher-abstract-check. Checked: 2026-10-18. Published 23 December 1968. Abstract only; theoretical proposal, not experimental realization.\n### Ref source-ba29a1eb0f9df263\n\n[R2] Hydrogen Dominant Metallic Alloys: High Temperature Superconductors? (2004). [DOI 10.1103/PhysRevLett.92.187002](https://doi.org/10.1103/PhysRevLett.92.187002). Publication: journal-article. Check: publisher-abstract-check. Checked: 2026-10-18. Published 6 May 2004. Abstract only; chemical precompression is a proposal, not an ambient-pressure guarantee.\n### Ref source-2b01ce847be6bc20\n\n[R3] Pressure-induced metallization of dense (H2S)2H2 with high-Tc superconductivity (2014). [DOI 10.1038/srep06968](https://doi.org/10.1038/srep06968). Publication: journal-article. Check: selected-published-methods-equation-check. Checked: 2026-10-18. Published 10 November 2014. Selected pp. 1–6: structure search, Table 1 and methods. Printed modified-McMillan estimates independently calculated; no DFPT or search reproduced.\n### Ref source-8b901b9c6008c434\n\n[R4] Conventional superconductivity at 203 kelvin at high pressures in the sulfur hydride system (2015). [DOI 10.1038/nature14964](https://doi.org/10.1038/nature14964). Publication: journal-article. Check: selected-author-text-and-published-caption-check. Checked: 2026-10-18. Published 17 August 2015. Author v1 of 26 June 2015: selected pp. 3/5 and Fig. 4 pp. 11–12, visually checked; publisher abstract and extended captions also checked. Magnetization raw data and background subtraction not independently reproduced.\n### Ref source-e7837a18f3252cb9\n\n[R5] Crystal structure of the superconducting phase of sulfur hydride (2016). [DOI 10.1038/nphys3760](https://doi.org/10.1038/nphys3760). Publication: journal-article. Check: selected-author-structure-check. Checked: 2026-10-18. Author v1 of 10 September 2015, selected pp. 1–3: sulfur sublattice, mixed sulfur phase and deuteride 173 GPa simultaneous transport/XRD. Final published full text not compared; hydrogen positions not directly resolved.\n### Ref source-77b774e18b0f50c7\n\n[R6] Evidence for Superconductivity above 260 K in Lanthanum Superhydride at Megabar Pressures (2019). [DOI 10.1103/PhysRevLett.122.027001](https://doi.org/10.1103/PhysRevLett.122.027001). Publication: journal-article. Check: publisher-abstract-and-selected-author-v3-methods-check. Checked: 2026-10-18. Journal published 14 January 2019; detailed scope is author v3 of 29 August 2018 pp. 3–7. Four-probe versus pseudo-four-probe, pressure drift, about 20 microohm minimum and sample geometry. Final journal methods not compared; intrinsic resistivity not determined.\n### Ref source-1e6e868a12cdd34f\n\n[R7] Superconductivity at 250 K in lanthanum hydride under high pressures (2019). [DOI 10.1038/s41586-019-1201-8](https://doi.org/10.1038/s41586-019-1201-8). Publication: journal-article. Check: selected-published-methods-figures-check. Checked: 2026-10-18. Published online 22 May 2019. Selected printed pp. 528–529, Fig. 4p.531, Methods and deuteride assignment; PDF p. 2 visually checked. Final 249/180 K comparison replaces early 250/168 K; rounded ratio 0.468 differs from stated 0.46. Measured 9 T versus extrapolated 95–136 T; no SQUID measurement.\n### Ref source-1bec081a84267ffb\n\n[R8] High-Pressure Hydrogen Sulfide from First Principles: A Strongly Anharmonic Phonon-Mediated Superconductor (2015). [DOI 10.1103/PhysRevLett.114.157004](https://doi.org/10.1103/PhysRevLett.114.157004). Publication: journal-article. Check: selected-author-equations-table-check. Checked: 2026-10-18. Author accepted manuscript dated 26 March 2015, selectedpp. 1–4 and Table II visually checked. Publisher identity confirmed. No SSCHA, phonon or full Eliashberg solver reproduced; early experimental 190/90 K comparison not promoted to later benchmark.\n### Ref source-d04f7965dca4d5a5\n\n[R9] RETRACTED ARTICLE: Room-temperature superconductivity in a carbonaceous sulfur hydride (2020). [DOI 10.1038/s41586-020-2801-z](https://doi.org/10.1038/s41586-020-2801-z). Publication: journal-article. Retracted: 2022-09-26. [Retraction notice](https://doi.org/10.1038/s41586-022-05294-9). Check: retraction-notice-identity-check. Checked: 2026-10-18. Original article identity checked against the corrected retraction notice; original experimental claim is not accepted as a benchmark.\n### Ref source-754d75026e52d9ac\n\n[R10] Retraction Note: Room-temperature superconductivity in a carbonaceous sulfur hydride (2022). [DOI 10.1038/s41586-022-05294-9](https://doi.org/10.1038/s41586-022-05294-9). Publication: journal-article. Check: complete-retraction-notice-text-check. Checked: 2026-10-18. Published 26 September 2022. Corrected notice read in full; concerns about non-standard user-defined background subtraction. All authors disagreed with retraction.\n### Ref source-a7b93ad4f4896402\n\n[R11] RETRACTED ARTICLE: Evidence of near-ambient superconductivity in a N-doped lutetium hydride (2023). [DOI 10.1038/s41586-023-05742-0](https://doi.org/10.1038/s41586-023-05742-0). Publication: journal-article. Retracted: 2023-11-07. [Retraction notice](https://doi.org/10.1038/s41586-023-06774-2). Check: retraction-notice-identity-check. Checked: 2026-10-18. Original article identity checked against its retraction notice; original experimental claim is not accepted as a benchmark.\n### Ref source-98bc73a5e1c86c78\n\n[R12] Retraction Note: Evidence of near-ambient superconductivity in a N-doped lutetium hydride (2023). [DOI 10.1038/s41586-023-06774-2](https://doi.org/10.1038/s41586-023-06774-2). Publication: journal-article. Check: complete-retraction-notice-text-check. Checked: 2026-10-18. Published 7 November 2023. Notice read in full: eight authors requested retraction over provenance, measurements and processing; additional resistivity concerns. No independent misconduct finding inferred.\n### Ref source-151c87f0eda0236f\n\n[R13] Absence of near-ambient superconductivity in LuH2±xNy (2023). [DOI 10.1038/s41586-023-06162-w](https://doi.org/10.1038/s41586-023-06162-w). Publication: journal-article. Check: selected-final-probe-windows-and-version-comparison. Checked: 2026-10-20. Published 11 May 2023; version of record 26 July 2023, Nature 620, 72–77. Selected final text and PDF pages 4–7 (Figs. 3–5 and Methods) checked. Fig. 4b: transport from 2 to 350 K at discrete pressures spanning 0.4–40.1 GPa. Fig. 5a,b: magnetization from 100 to 320 K at 1.0 and 2.1 GPa, 60 Oe, with cell background subtraction. Transport, magnetization and optical measurements use NaCl, Daphne 7373 and KBr respectively. Methods specify room-temperature ruby calibration, platinum contacts and synthesis at 2 GPa, 300–350 °C for 10 hours. EDS cannot measure hydrogen. The arXiv v3 abstract (2 June 2023; https://arxiv.org/abs/2303.08759v3) retains the narrower 1–6 GPa and 10 K scope; the final record is used here. Raw source data and independent replication remain unreviewed.\n### Ref source-f9dfe34f7dffd9d2\n\n[R14] Ambient pressure recovery of the structurally unconventional hydride Y3Fe4H20 (2026). [DOI 10.1038/s41467-026-74232-4](https://doi.org/10.1038/s41467-026-74232-4). Publication: journal-article. Check: selected-published-recovery-and-magnetometry-check. Checked: 2026-10-18. Published 20 June 2026. Selected abstract p. 1, structure/DFPT discussion p. 4 and SQUID paragraph p. 5: recovered material survives tens of hours; no superconductivity down to 3 K in run 4. Full supplementary methods and raw data remain open.\n\n## Claim evidence and conditions\n\n### scwiki-d6-claim-scope-1\n\nHydrogen-rich superconductors connect light nuclei, strong electron–phonon coupling and pressure-dependent chemistry. Ashcroft's metallic-hydrogen proposal and later hydrogen-dominant-alloy proposal motivate this route; neither established a recoverable ambient-pressure superconductor. H₃S and LaH₁₀ are important high-pressure experimental systems. Their formulae, pressure scales and sample histories must accompany any quoted transition temperature.\n\nEvidence: theory. Sources: source-6fbecff48a8989e8, source-ba29a1eb0f9df263, source-8b901b9c6008c434, source-1e6e868a12cdd34f.\n\nConditions: Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.\n\nVerification scope: Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance.\n\n### scwiki-d6-claim-scope-2\n\n“Chemical precompression” describes a design idea, not a guarantee of low operating pressure. A predicted metallic structure, a synthesized hydride and a superconducting phase are different achievements. Distinguish the starting H₂S reagent from its proposed H₃S product, and a clathrate-like hydrogen framework from directly measured hydrogen positions. The sulfur-hydride diffraction study supports the sulfur sublattice and coexistence with sulfur; its measured patterns cannot by themselves distinguish hydrogen arrangements with the same sulfur periodicity.\n\nEvidence: theory. Sources: source-ba29a1eb0f9df263, source-2b01ce847be6bc20, source-e7837a18f3252cb9.\n\nConditions: Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.\n\nVerification scope: Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance.\n\n### scwiki-d6-claim-mathematical-assumptions-1\n\nFor a specified structure, a commonly used modified-McMillan estimate is $T_c=(\\omega_{\\log}/1.2)\\exp[-1.04(1+\\lambda)/(\\lambda-\\mu^*(1+0.62\\lambda))]$, with $\\omega_{\\log}$ expressed in kelvin here. Duan's harmonic calculations give $\\lambda=2.07$, $\\omega_{\\log}=1125.1$ K for R3m at 130 GPa and $\\lambda=2.19$, $\\omega_{\\log}=1334.6$ K for Im$\\bar{3}$m at 200 GPa. Substitution with $\\mu^*=0.13$ and 0.10 gives approximately 155–166 K and 191–204 K, respectively. This reproduces the printed estimate convention, without additional strong-coupling or spectral-shape factors; it does not reproduce the underlying density-functional perturbation calculation.\n\nEvidence: theory. Sources: source-2b01ce847be6bc20.\n\nConditions: Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.\n\nVerification scope: Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance.\n\n### scwiki-d6-claim-mathematical-assumptions-2\n\nHydrogen motion can invalidate a harmonic treatment. Errea and colleagues calculated a change from $\\lambda=2.64$ to 1.84 for H₃S at 200 GPa when including anharmonicity. Their full isotropic Migdal–Eliashberg calculation with $\\mu^*=0.16$ changed the calculated transition from 250 to 194 K. That table is not obtained by simply substituting parameters into the preceding approximate formula. Zero-point contributions also alter the calculated decomposition landscape: both $3\\mathrm{H_2S}\\rightarrow2\\mathrm{H_3S}+\\mathrm{S}$ and $5\\mathrm{H_2S}\\rightarrow3\\mathrm{H_3S}+\\mathrm{HS_2}$ conserve atoms, but atom balance alone does not establish stability or a reaction pathway.\n\nEvidence: theory. Sources: source-1bec081a84267ffb.\n\nConditions: Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.\n\nVerification scope: Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance.\n\n### scwiki-d6-claim-mathematical-assumptions-3\n\nAn isotope comparison uses $\\alpha=\\ln(T_{c,\\mathrm H}/T_{c,\\mathrm D})/\\ln2$ only after checking structure, pressure and transition criteria. The final LaH₁₀ paper compares approximately 249 K and 180 K for fcc hydride and deuteride near 150 GPa; its Fig. 4 specifies 151 and 152 GPa. These rounded values give 0.468, while the paper states 0.46. The early author's 250/168 K comparison gives 0.573 and must not be silently substituted for the final result. Phase mixtures and different deuteride structures further limit interpretation.\n\nEvidence: theory. Sources: source-1e6e868a12cdd34f.\n\nConditions: Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.\n\nVerification scope: Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance.\n\n### scwiki-d6-claim-experimental-criteria-1\n\nFor sulfur hydride, the 2015 report combined resistance, field response, isotope substitution and magnetization. Its author-version Fig. 4a reports a zero-field-cooled magnetic onset of 203(1) K at 155 GPa, with a 20 Oe field-cooled comparison. The plotted transport comparison is a different pressure, 145 GPa, and must not be treated as the identical specimen condition. Background subtraction and diamond-anvil-cell contributions require scrutiny; this scoped reading does not independently reproduce raw magnetization. The later simultaneous diffraction/transport experiment on deuteride at 173 GPa provides structural context, not a direct measurement of every hydrogen coordinate.\n\nEvidence: experiment. Sources: source-8b901b9c6008c434, source-e7837a18f3252cb9.\n\nConditions: Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.\n\nVerification scope: Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance.\n\n### scwiki-d6-claim-experimental-criteria-2\n\nThe two early lanthanum-superhydride studies have different evidence scopes. Somayazulu's author v3 describes a large resistance drop around 260 K, with room-temperature pressure changing from 188 to 196 GPa across a thermal cycle; pressure at the actual transition was not measured in that run. The lowest four-probe resistance was about 20 μΩ, while pseudo-four-probe measurements carried contact-resistance limitations. This should not be rewritten as an independently established zero-resistance or magnetic-shielding result. The final journal abstract was checked, but the selected detailed methods here come from the identified author version.\n\nEvidence: experiment. Sources: source-77b774e18b0f50c7.\n\nConditions: Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.\n\nVerification scope: Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance.\n\n### scwiki-d6-claim-experimental-criteria-3\n\nDrozdov's final 2019 LaH₁₀ paper reports zero resistance, isotope dependence and field suppression, with a maximum near 250–252 K around 170 GPa. Its transition criterion is the onset of deviation from normal metallic resistance. Measurements to 9 T support an extrapolated zero-temperature upper critical field of approximately 95–136 T; they are not direct measurements at 136 T. The authors explicitly state that their tiny samples were below the available SQUID sensitivity. Their H₂/D₂ vibron pressure estimates were often 10–30 GPa lower than diamond-edge estimates around 150 GPa, so pressure calibrations cannot be freely interchanged.\n\nEvidence: experiment. Sources: source-1e6e868a12cdd34f.\n\nConditions: Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.\n\nVerification scope: Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance.\n\n### scwiki-d6-claim-limits-and-disputes-1\n\nThe 2020 carbonaceous-sulfur-hydride article was retracted on 26 September 2022. The corrected notice identifies concerns about non-standard, user-defined magnetic-background subtraction; all authors disagreed with the retraction. The 2023 nitrogen-doped lutetium-hydride article was retracted on 7 November 2023 following concerns including sample provenance, measurements and processing. These original papers remain linked as historical claims, accompanied by their notices. Their claimed temperatures are not usable experimental benchmarks in this catalogue. A retraction notice is not a substitute for an independent misconduct finding.\n\nEvidence: experiment. Sources: source-d04f7965dca4d5a5, source-754d75026e52d9ac, source-a7b93ad4f4896402, source-98bc73a5e1c86c78.\n\nConditions: Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.\n\nVerification scope: Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance.\n\n### scwiki-d6-claim-limits-and-disputes-2\n\nMing's independent LuH₂±xNᵧ study found no superconductivity in its transport measurements down to 2 K at sampled pressures spanning 0.4–40.1 GPa. Samples were synthesized at 2 GPa and 300–350 °C for 10 hours. This preparation and finite measurement window do not exclude every possible Lu–N–H composition or an unmeasured pressure interval.\n\n| Probe in the final paper | Measurement window and preparation | What the result does not establish |\n|---|---|---|\n| Resistance, Fig. 4b | 2–350 K; sampled 0.4–40.1 GPa; NaCl medium | 2 K is a measurement floor, not a transition temperature |\n| Magnetization, Fig. 5a,b | 100–320 K; 1.0 and 2.1 GPa; 60 Oe; Daphne 7373 medium | This is not the full transport window; subtracting the cell background leaves a weak positive signal |\n| Optical colour, Fig. 4a | Up to 41 GPa; KBr medium | A blue-to-pink colour change is not a superconductivity measurement |\n\nThe methods specify room-temperature ruby pressure calibration and four-probe van der Pauw resistance with platinum electrodes. EDS detects nitrogen but cannot detect hydrogen here; it does not fix both x and y. The pressure range is a sampled envelope, not continuous coverage. The [arXiv v3 abstract](https://arxiv.org/abs/2303.08759v3), dated 2 June 2023, still describes 1–6 GPa and a 10 K floor; this catalogue uses the expanded final-paper transport window.\n\nEvidence: experiment. Sources: source-151c87f0eda0236f.\n\nSource relationship: mixed-source-and-local-derivation. Primary paper supports the stated probe-specific observations and preparation. The prohibition on extending finite negative evidence to all compositions or unsampled intervals is editorial inference, not a newly measured exclusion bound. The arXivv3 abstract is an alternate version, not a replacement for the final record.\n\nConditions: Ming final paper, Nature 620, 72–77; specified synthesis. Transport: Fig. 4b, 2–350 K, discrete pressures 0.4–40.1 GPa, NaCl medium. Magnetization: Fig. 5a,b, 100–320 K, 1.0/2.1 GPa, 60 Oe, Daphne 7373 medium. Optical measurements use KBr. Room-temperature ruby calibration; no universal composition exclusion.\n\nVerification scope: Selected final text, Fig3–5/captions and Methods; arXivv3 abstract/history comparison. No source-data reanalysis, continuous pressure sampling, composition determination or independent replication.\n\n### scwiki-d6-claim-discovery-implications-1\n\nA credible search must connect composition and structure to dynamical and thermodynamic stability, finite-temperature and nuclear-quantum effects, synthesis access and multiple superconductivity probes. A finite structure search can miss larger cells; absence of imaginary harmonic frequencies is a local dynamical check, not proof of global stability. Preserve decompression history, mixed phases, pressure standards and unsuccessful samples instead of ranking formulae by isolated temperature claims.\n\nEvidence: theory. Sources: source-2b01ce847be6bc20, source-e7837a18f3252cb9, source-1bec081a84267ffb.\n\nConditions: Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.\n\nVerification scope: Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance.\n\n### scwiki-d6-claim-discovery-implications-2\n\nA June 2026 study recovered Y₃Fe₄H₂₀ at ambient pressure after synthesis above about 60 GPa, with survival on the scale of tens of hours. This is useful progress in hydride recovery, but its reported SQUID test found no superconductivity down to 3 K in the tested recovered sample. Hydrogen positions were supported by structure searches, and the sample was small and not pure. Recovery, long-term stability and ambient-pressure superconductivity remain distinct questions. Full raw-data, convergence and cross-laboratory assessment remain open for this article.\n\nEvidence: experiment. Sources: source-f9dfe34f7dffd9d2.\n\nConditions: Named source/version, sample, pressure calibration and probe limits; withdrawn claims are historical only.\n\nVerification scope: Selected primary passages and bounded algebra, not independent raw-data reproduction or full scientific acceptance.\n\n## Revision and review\n\nArticle ID: scwiki-d6. Revision: 7346f5cb0fd101401073. Updated: 2026-10-19T16:17:36.973893+00:00.\n\nReview scope: Selected primary structure, transport and magnetometry passages; final LaH10 isotope and pressure methods; both retraction notices in full; bounded printed-parameter and isotope calculations. Follow-up: Ming final selected transport, magnetization, colour, synthesis and composition limits; final PDFpp4–7 visually inspected and arXivv3 abstract compared.\n\n- Full scientific acceptance, raw-data and independent reproducibility assessment remain open.\n- Ashcroft proposals checked at abstract level; Einaga and Somayazulu detailed checks use identified author versions, not final-methods comparison.\n- Numerical checks do not reproduce structure searches, DFPT, anharmonic phonons or Eliashberg solutions.\n- 2026 recovery result is not ambient-pressure superconductivity; supplementary methods and raw-data review remain open.\n- Ming negative-result windows are probe-specific and sampled; no continuous pressure exclusion, exact H/N composition or raw-data reproduction is established.\n\nSource: [D_material_families/D6_hydrides.md](https://github.com/JackZH26/jzis-superconductivity/blob/0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf/D_material_families/D6_hydrides.md), commit 0a7c9d6696804ec26aa12f8eed68b55c9b3c0fcf, SHA-256 b5a8aa93b211383ef8a435e968858295adef9f5b2f89fe842e66112baeff3ae6.\n","wordCount":1126}}