Superconducting wire composites (MgB2, REBCO and Bi-2223 tapes) MgB2, REBCO, BSCCO

spore: profile
id: superconducting-composites
spore_version: 0.2
family: magnet-and-superconducting-alloys
name: Superconducting wire composites (MgB2, REBCO and Bi-2223 tapes)
abbreviation: MgB2, REBCO, BSCCO
role: Composite superconducting wire and tape for high-field and power magnets (NbTi and Nb3Sn have their own profiles)
category: metals
type: magnet-alloys
summary: |
  Three families of superconducting composites are profiled together: magnesium diboride (MgB2) powder-in-tube wire, rare-earth barium copper oxide (REBCO) coated-conductor tape, and bismuth strontium calcium copper oxide (Bi-2223, DI-BSCCO) silver-sheathed tape. MgB2 has a critical temperature of 39 K, REBCO about 93 K and Bi-2223 about 108 K, so the last two can be cooled with liquid nitrogen at 77 K while MgB2 needs cooling to about 20 K or below. Each family is a composite of a brittle or powdered superconductor in a metal matrix, and the current a wire carries depends on its temperature, its field and the strain it is under. The figures below keep each one with its own composition, temperature and field, since the sources differ.
best_for: 'Magnets and cables at 20 K to 77 K where liquid helium is not wanted: Bi-2223 and REBCO tapes carry about 170 to 200 A at 77 K in self-field, and a Sumitomo review and an academic comparison both report the 77 K case'
weakest_at: 'Brittleness and strain: REBCO and Bi-2223 lose critical current under bending and tension, and no corrosion or space-environment test was found for the REBCO or Bi-2223 wire itself'
identity:
  formula: MgB2 powder in a metal sheath (magnesium diboride, MgB2); REBCO, rare-earth barium copper oxide such as YBa2Cu3O7-x on a metal substrate; Bi-2223 (Bi2Sr2Ca2Cu3O10) powder in a silver or silver-gold sheath
  source: wikipedia-mgb2
  where: 'Wikipedia MgB2 infobox (formula MgB2, hexagonal P6/mmm); Wikipedia YBCO (general formula YBa2Cu3O7-x); Wikipedia BSCCO (general formula Bi2Sr2Ca(n-1)CunO(2n+4+x), Bi-2223 is n = 3); Barth et al. Fig. 1 (layer stack); Sumitomo review Table 1 (silver and Ag-Au matrix). Process note from Wikipedia MgB2: ex situ sintering at 800 to 1000 degC and hot isostatic pressing at approximately 950 degC.'
  designations:
    - system: Trade name
      code: DI-BSCCO
      source: sumitomo-dibscco-review
      where: Title of Table 1, DI-BSCCO wire specifications (Bi-2223 silver-sheathed wire)
tags:
  environments: []
  stresses:
    - extreme-cold
  applications:
    - propulsion-and-tanks
properties:
  - benchmark: critical_temperature
    label: Critical temperature, MgB2
    value: 39
    unit: K
    scope: material
    conditions:
      form: MgB2 compound, bulk form as described in the article
    method: Value printed in the Wikipedia article, which calls it the highest among conventional superconductors
    status: ground
    source: wikipedia-mgb2
    where: Lead section and Superconductivity section, critical temperature 39 K
  - benchmark: upper_critical_field
    label: Upper critical field, MgB2, parallel to ab planes (as of 2008)
    value: 14
    unit: T
    scope: material
    conditions:
      orientation: parallel to the ab planes
      temperature: not stated in the article
    method: Value printed in the Wikipedia article, which says it was the figure as of 2008
    status: ground
    source: wikipedia-mgb2
    where: Superconductivity section, sentence giving about 14 T parallel to ab planes
  - benchmark: upper_critical_field
    label: Upper critical field, MgB2, perpendicular to ab planes (as of 2008)
    value: 3
    unit: T
    scope: material
    conditions:
      orientation: perpendicular to the ab planes
      temperature: not stated in the article
    method: Value printed in the Wikipedia article, which says it was the figure as of 2008
    status: ground
    source: wikipedia-mgb2
    where: Superconductivity section, sentence giving about 3 T perpendicular to ab planes
  - benchmark: density
    label: Density, MgB2
    value: 2.57
    unit: g/cm3
    scope: material
    conditions:
      basis: density in the article infobox
    method: Value printed in the Wikipedia infobox, with no measurement method given
    status: ground
    source: wikipedia-mgb2
    where: Infobox, density row
  - benchmark: melting_point
    label: Melting point, MgB2 (with decomposition)
    value: 830
    unit: °C
    scope: material
    conditions:
      basis: infobox value; the article notes decomposition
    method: Value printed in the Wikipedia infobox
    status: ground
    note: The melting point is noted together with decomposition, so treat it as an approximate upper value rather than a clean melting point.
    source: wikipedia-mgb2
    where: Infobox, melting point row
  - benchmark: critical_current_density
    label: Critical current density, MgB2 stainless-steel tape at 4.2 K and 5 T
    value: 10000
    unit: A/cm2
    scope: material
    conditions:
      temperature: 4.2 K
      field: 5 T
      form: MgB2 tape with a stainless-steel sheath (powder-in-tube)
    method: Transport value printed in the abstract of a paper on MgB2 tapes and wires with stainless-steel and Cu-Ni sheaths
    status: ground
    note: Research tape from the early 2000s, not a current product. The same abstract says the Cu-Ni sheathed wire had lower Jc because of lower MgB2 packing density, and gives no number for it.
    source: arxiv-mgb2-jc
    where: Abstract, sentence beginning The tapes made of stainless steel showed transport critical current density Jc of about 10,000 A/cm2 at 4.2 K and 5 T
  - benchmark: critical_current_density
    label: Critical current density, MgB2 stainless-steel tape, zero-field extrapolation
    value: 300000
    unit: A/cm2
    scope: material
    conditions:
      field: zero, extrapolated from the Jc-B curves
      temperature: not stated in the abstract
    method: Extrapolated value printed in the abstract of the same paper
    status: calculated
    note: Extrapolated to zero field from measured curves, so it is not a measured value.
    source: arxiv-mgb2-jc
    where: Abstract, sentence on extrapolating the Jc-B curves to zero field
  - benchmark: critical_current
    label: Critical current, Hyper Tech MgB2 strand (0.83 mm), at about 31 K
    value: 102.64
    unit: A
    scope: material
    conditions:
      temperature: 30.99 K (plus or minus 1 K)
      strand: Hyper Tech Research MgB2 strand, niobium barrier, Monel sheath, copper central fill, 0.83 mm diameter
      criterion: 1 microvolt per cm electric-field criterion, 11.5 cm effective sample length
      field: not stated in the printed sentence
    method: Measured by DC transport on a short sample in a cryocooler test rig, with the critical current read off the V-I curves
    status: ground
    note: Measured near the transition temperature, not at 20 K, so it shows the strand at a warm operating point. The paper does not print the field for this value.
    source: nasa-mgb2-cryocooler
    where: Results section, critical current table row giving Ic = 102.64 A at T = 30.99 K
  - benchmark: filling_factor
    label: Filling factor, Hyper Tech MgB2 strand
    value: 0.123
    unit: '-'
    scope: material
    conditions:
      strand: Hyper Tech Research MgB2 strand, 0.83 mm diameter, continuous tube forming and filling process
    method: Value printed in the strand description list, defined by the paper as the volume fraction of superconductor to total wire volume
    status: ground
    source: nasa-mgb2-cryocooler
    where: Strand characteristics list, filling factor 0.123
  - benchmark: critical_temperature
    label: Critical temperature, Bi-2223
    value: 108
    unit: K
    scope: material
    conditions:
      compound: Bi-2223, n = 3 member of the Bi2Sr2Ca(n-1)CunO(2n+4+x) series
    method: Approximate value printed in the Wikipedia article
    status: ground
    source: wikipedia-bscco
    where: Critical temperature sentence, Bi-2223 has Tc about 108 K
  - benchmark: critical_temperature
    label: Critical temperature, Bi-2212
    value: 96
    unit: K
    scope: material
    conditions:
      compound: Bi-2212, n = 2, the most commonly studied member of the series
    method: Approximate value printed in the Wikipedia article
    status: ground
    source: wikipedia-bscco
    where: Critical temperature sentence, Bi-2212 has Tc about 96 K
  - benchmark: critical_current
    label: Critical current, DI-BSCCO Bi-2223 tape at 77.3 K, self-field (range over wire types)
    value: 170
    value_high: 200
    bound: range
    unit: A
    scope: material
    conditions:
      temperature: 77.3 K
      field: self-field
      form: Ag-sheathed Bi-2223 tapes, DI-BSCCO types H, G, HT-SS, HT-CA and HT-NX
      width: 4.3 mm for type H, average width as printed for each type
    method: Ic row of the DI-BSCCO product specification table in a Sumitomo Electric technical review
    status: ground
    note: The table prints four values in one cell and does not map each one to a type in the extracted text, so the row is kept as a range.
    source: sumitomo-dibscco-review
    where: Table 1 (DI-BSCCO wire specifications), row Ic at 77.3 K, self-field
  - benchmark: irreversible_stress_limit
    label: Tensile stress for 95 percent Ic retention at 77.3 K, Bi-2223 types H to HT-NX (typical)
    value: 130
    value_high: 400
    bound: range
    unit: MPa
    scope: material
    conditions:
      temperature: 77.3 K
      retention: 95 percent of Ic retained
      form: DI-BSCCO type H (130 MPa) to type HT-NX (400 MPa)
    method: Typical value printed in the product specification table, marked with an asterisk in the table
    status: ground
    source: sumitomo-dibscco-review
    where: Table 1, row tensile stress at 77.3 K with 95 percent Ic retained
  - benchmark: bending_diameter
    label: Bending diameter for 95 percent Ic retention at 77.3 K, Bi-2223 types H to HT-NX (typical)
    value: 40
    value_high: 80
    bound: range
    unit: mm
    scope: material
    conditions:
      temperature: 77.3 K
      retention: 95 percent of Ic retained, bending in both directions
      form: DI-BSCCO type HT-NX (40 mm) to type H (80 mm)
    method: Typical value printed in the product specification table, marked with an asterisk in the table
    status: ground
    source: sumitomo-dibscco-review
    where: Table 1, row bending diameter at 77.3 K with 95 percent Ic retained
  - benchmark: engineering_current_density
    label: Engineering current density at 77 K, self-field, SuperPower REBCO tape (4.00 mm)
    value: 225
    unit: A/mm2
    scope: material
    conditions:
      temperature: 77 K
      field: self-field
      tape: SuperPower REBCO tape, 4.00 mm wide, 101 um thick, Hastelloy substrate 50 um, 2 x 20 um electroplated copper
    method: Engineering current density printed in Table 1 of the paper, measured on the tape as received
    status: ground
    source: arxiv-rebco-barth
    where: Table 1, row Jeng (77 K, self-field), SuperPower column
  - benchmark: engineering_current_density
    label: Engineering current density at 77 K, self-field, SuNAM REBCO tape (4.00 mm)
    value: 445
    unit: A/mm2
    scope: material
    conditions:
      temperature: 77 K
      field: self-field
      tape: SuNAM REBCO tape, 4.00 mm wide, 110 um thick, Hastelloy substrate 60 um, 2 x 18 um electroplated copper
    method: Engineering current density printed in Table 1 of the paper, measured on the tape as received
    status: ground
    source: arxiv-rebco-barth
    where: Table 1, row Jeng (77 K, self-field), SuNAM column
  - benchmark: engineering_current_density
    label: Engineering current density at 77 K, self-field, Fujikura REBCO tape (3.05 mm)
    value: 350
    unit: A/mm2
    scope: material
    conditions:
      temperature: 77 K
      field: self-field
      tape: Fujikura REBCO tape, 3.05 mm wide, 161 um thick, Hastelloy substrate 75 um, 75 um laminated copper
    method: Engineering current density printed in Table 1 of the paper, measured on the tape as received
    status: ground
    source: arxiv-rebco-barth
    where: Table 1, row Jeng (77 K, self-field), Fujikura column
  - benchmark: engineering_current_density
    label: Engineering current density at 77 K, self-field, SuperOx REBCO tape (4.04 mm)
    value: 305
    unit: A/mm2
    scope: material
    conditions:
      temperature: 77 K
      field: self-field
      tape: SuperOx REBCO tape, 4.04 mm wide, 112 um thick, Hastelloy substrate 60 um, 2 x 20 um electroplated copper
    method: Engineering current density printed in Table 1 of the paper, measured on the tape as received
    status: ground
    source: arxiv-rebco-barth
    where: Table 1, row Jeng (77 K, self-field), SuperOx column
  - benchmark: engineering_current_density
    label: Engineering current density at 77 K, self-field, Bruker HTS REBCO tape (4.10 mm)
    value: 87
    unit: A/mm2
    scope: material
    conditions:
      temperature: 77 K
      field: self-field
      tape: Bruker HTS REBCO tape, 4.10 mm wide, 153 um thick, stainless-steel substrate 100 um, 2 x 15 um electroplated copper
    method: Engineering current density printed in Table 1 of the paper, measured on the tape as received
    status: ground
    source: arxiv-rebco-barth
    where: Table 1, row Jeng (77 K, self-field), Bruker HTS column
  - benchmark: engineering_current_density
    label: Engineering current density at 4.2 K and 19 T (parallel field), SuperPower REBCO tape
    value: 3.9
    unit: kA/mm2
    scope: material
    conditions:
      temperature: 4.2 K
      field: 19 T, parallel
      tape: SuperPower REBCO tape, 4.00 mm wide
    method: Value printed in Table 1; marked with an asterisk, so extrapolated from the measured data by the authors' scaling relations
    status: calculated
    note: Extrapolated value, not measured directly in the paper. The 77 K self-field figure for the same tape is 225 A/mm2.
    source: arxiv-rebco-barth
    where: Table 1, row Jeng (4.2 K, 19 T parallel), SuperPower column
  - benchmark: engineering_current_density
    label: Engineering current density at 4.2 K and 19 T (parallel field), SuNAM REBCO tape
    value: 2
    unit: kA/mm2
    scope: material
    conditions:
      temperature: 4.2 K
      field: 19 T, parallel
      tape: SuNAM REBCO tape, 4.00 mm wide
    method: Value printed in Table 1 without an asterisk, so measured
    status: ground
    source: arxiv-rebco-barth
    where: Table 1, row Jeng (4.2 K, 19 T parallel), SuNAM column
  - benchmark: critical_temperature
    label: Critical temperature, YBCO (YBa2Cu3O7)
    value: 93
    unit: K
    scope: material
    conditions:
      compound: YBa2Cu3O7 (YBCO, one of the REBCO family)
    method: Value printed in the Wikipedia article
    status: ground
    note: The article also gives 95 K for the highest-temperature composition, which is not used here.
    source: wikipedia-ybco
    where: Introduction, sentence giving a transition temperature of 93 K
  - benchmark: density
    label: Density, YBCO
    value: 6.4
    unit: g/cm3
    scope: material
    conditions:
      basis: density in the article infobox
    method: Value printed in the Wikipedia infobox, with no measurement method given
    status: ground
    source: wikipedia-ybco
    where: Infobox, density row
  - benchmark: melting_point
    label: Melting point, YBCO (lower bound)
    value: 1000
    bound: lower
    unit: °C
    scope: material
    conditions:
      basis: infobox lower bound
    method: Value printed in the Wikipedia infobox as greater than 1000 degC
    status: ground
    source: wikipedia-ybco
    where: Infobox, melting point row
  - benchmark: elastic_modulus
    label: Young's modulus at 77 K, five commercial REBCO tapes (range)
    value: 149
    value_high: 186
    bound: range
    unit: GPa
    scope: material
    conditions:
      temperature: 77 K
      field: self-field
      form: five commercial REBCO coated conductors, SuperPower (lowest) to Bruker HTS (highest)
    method: Values printed in Table 2 of the paper, measured by the authors on tapes as received
    status: ground
    source: arxiv-rebco-barth
    where: Table 2, column Young's modulus E at 77 K, self-field
  - benchmark: yield_strength
    label: Yield strength Rp0.2 at 77 K, five commercial REBCO tapes (range)
    value: 694
    value_high: 957
    bound: range
    unit: MPa
    scope: material
    conditions:
      temperature: 77 K
      field: self-field
      form: five commercial REBCO coated conductors, Fujikura (lowest) to SuperOx (highest)
    method: Values printed in Table 2 of the paper, measured by the authors on tapes as received
    status: ground
    source: arxiv-rebco-barth
    where: Table 2, column yield strength Rp0.2 at 77 K, self-field
  - benchmark: irreversible_strain_limit
    label: Irreversible strain limit at 77 K, five commercial REBCO tapes (range)
    value: 0.47
    value_high: 0.72
    bound: range
    unit: '%'
    scope: material
    conditions:
      temperature: 77 K
      field: self-field
      form: five commercial REBCO coated conductors, SuperOx (lowest) to Bruker HTS (highest)
    method: Values printed in Table 2 of the paper, as the strain at which the critical current first falls irreversibly
    status: ground
    source: arxiv-rebco-barth
    where: Table 2, column irreversible strain limit at 77 K, self-field
  - benchmark: irreversible_stress_limit
    label: Irreversible stress limit at 77 K, five commercial REBCO tapes (range)
    value: 660
    value_high: 820
    bound: range
    unit: MPa
    scope: material
    conditions:
      temperature: 77 K
      field: self-field
      form: five commercial REBCO coated conductors, Bruker HTS (lowest) to SuperPower (highest)
    method: Values printed in Table 2 of the paper, read from the stress limit column
    status: ground
    source: arxiv-rebco-barth
    where: Table 2, column irreversible stress limit at 77 K, self-field
corrosion:
  - environment: Ambient laboratory air, MgB2 bulk pellets (not wire), well sintered with large grains
    headline: Well-sintered MgB2 kept its superconducting properties for several months in ambient air.
    effect: Serquis et al. say the samples with larger grains and good sintering remained stable for several months under ambient conditions. The Tc did not change. The study used bulk pellets, so this is not a wire result.
    rating: low
    conditions:
      basis: bulk pellets, ambient air, exposure times given in months in the paper
      sintering: well sintered, larger grain size, excess Mg
    source: serquis-mgb2-ageing
    where: Results and discussion on ageing, samples with excess Mg and well sintered
  - environment: Ambient laboratory air, MgB2 bulk pellets with poor grain connectivity
    headline: 'Poorly connected MgB2 degraded slowly in air: Tc held, but the superconducting fraction fell.'
    effect: In the samples with poor grain connectivity and small grains, the Tc did not change but the superconducting fraction was reduced, and the degradation was linked to a surface decomposition. XPS showed magnesium hydroxide at the surface. The paper reports this as slow degradation rather than a sudden failure.
    rating: moderate
    conditions:
      basis: bulk pellets, ambient air, grain connectivity poor
      surface_analysis: X-ray photoelectron spectroscopy
    source: serquis-mgb2-ageing
    where: Ageing results for samples D and E, and XPS discussion
  - environment: Water, MgB2 thin films (cited second-hand by Serquis et al.)
    headline: 'Water exposure of MgB2 films: the onset Tc is reported to stay the same.'
    effect: Serquis et al. summarise an earlier study (Zhai et al.) in which MgB2 films were exposed to water and the onset Tc remained unchanged through the degradation. The paper gives no rate, and the study is about films, not wire.
    rating: unknown
    conditions:
      basis: thin films in room-temperature water, as summarised in a second paper
    source: serquis-mgb2-ageing
    where: Introduction, sentence citing Zhai et al. on water exposure of MgB2 films
risks:
  hazards:
    - text: 'Stanford Advanced Materials safety data sheet for magnesium boride (MgB2, CAS 12007-25-9), version 3.0 dated 2017: classified as not a hazardous substance or mixture, with no GHS label elements.'
      ghs: []
      source: samaterials-mgb2-sds
      where: Sections 2.1 and 2.2
    - text: 'Angstrom Sciences safety data sheet for YBCO powder (last revised 2015): signal word Warning, hazard statements H302 and H332 (harmful if swallowed or inhaled).'
      ghs:
        - H302
        - H332
      source: angstrom-ybco-sds
      where: Section 2, Hazard statements
    - text: The Wikipedia infobox for YBCO lists the signal word Warning and hazard statements H302, H315, H319 and H335 (GHS07 pictogram).
      ghs:
        - H302
        - H315
        - H319
        - H335
      source: wikipedia-ybco
      where: Infobox, hazard statements row
  failure_risks:
    - mode: Irreversible loss of critical current under longitudinal strain (REBCO)
      trigger: Strain or stress above the irreversible limit, which the paper places at 0.47 to 0.72 percent strain at 77 K in self-field
      consequence: The paper reports that critical current is already reduced before the irreversible limit is reached, and that the limit differs by manufacturer, so a magnet design needs the figures of the actual tape.
      severity: high
      source: arxiv-rebco-barth
      where: Results on strain dependence and Table 2
    - mode: Loss of Ic under bending or tension (Bi-2223 tape)
      trigger: Bending below about 80 mm for type H, or tensile stress above about 130 MPa at 77.3 K (typical values)
      consequence: The table gives typical values for 95 percent Ic retention, so critical current falls outside these limits. Type HT-NX has stronger reinforcement, with 400 MPa and 40 mm as typical limits.
      severity: moderate
      source: sumitomo-dibscco-review
      where: Table 1, rows tensile stress and bending diameter at 77.3 K
    - mode: Loss of superconducting fraction in poorly connected MgB2 bulk exposed to air
      trigger: Exposure of porous, poorly sintered MgB2 to humid or ambient air for months
      consequence: The Tc holds but the superconducting fraction falls, so the material carries less current. Serquis et al. did not test wire.
      severity: low
      source: serquis-mgb2-ageing
      where: Ageing results for samples D and E
  side_effects: []
  handling:
    - text: 'Angstrom YBCO safety data sheet: avoid breathing dust (P261), wash after handling (P264), and treat the powder as a barium compound with a long-term exposure limit of 0.5 mg/m3 as Ba.'
      source: angstrom-ybco-sds
      where: Sections 2, 8 (exposure limit) and 9
    - text: Prefer well-sintered, dense MgB2. The Serquis study found that poorly connected, porous material degraded in ambient air over months, while well-sintered material stayed stable.
      source: serquis-mgb2-ageing
      where: Ageing results and conclusions
  mitigations:
    - text: Use the critical current and strain figures of the actual tape, because the irreversible strain limit differs by maker (0.47 to 0.72 percent at 77 K).
      source: arxiv-rebco-barth
      where: Table 2
uses:
  - application: propulsion-and-tanks
    device: Superconducting motor and generator for a turboelectric aircraft (NASA N3-X concept, laboratory test of MgB2 strand only, not flown)
    example: NASA describes fully superconducting motors and generators for turboelectric aircraft and tests a Hyper Tech MgB2 strand in a cryocooler rig. The test is a preliminary sample measurement, not a flight or a motor build.
    source: nasa-mgb2-cryocooler
    where: Introduction, paragraph on turboelectric aircraft and the N3-X concept
supply:
  - subject: Copper (stabilizer in REBCO and BSCCO tape, central core of the MgB2 strand)
    producers:
      - country: Chile
        share_percent: 23
        year: 2025
      - country: Congo (Kinshasa)
        share_percent: 13.9
        year: 2025
      - country: Peru
        share_percent: 11.7
        year: 2025
      - country: China
        share_percent: 7.8
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (Copper, used widely in wiring and cables)
        listed: true
    recycling: 'USGS: about 160,000 tons of copper was recovered from old scrap in 2025 (U.S. figures as printed).'
    substitutes:
      - 'USGS: aluminum substitutes for copper in power cable and electrical equipment; titanium and steel are used in heat exchangers.'
    source: usgs-mcs2026-copper
    where: World Mine Production table, 2025e column (world total 23,000 thousand t; shares calculated by Space Mushroom from Chile 5,300, Congo (Kinshasa) 3,200, Peru 2,700 and China 1,800); Recycling; Substitutes; list status from the USGS 2025 list page
  - subject: Rare earths (yttrium and gadolinium in REBCO)
    producers:
      - country: China
        share_percent: 69.2
        year: 2025
      - country: United States
        share_percent: 13.1
        year: 2025
      - country: Australia
        share_percent: 7.4
        year: 2025
      - country: Burma
        share_percent: 5.6
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (yttrium and gadolinium each listed)
        listed: true
    recycling: 'USGS: limited quantities of rare earths were recovered from batteries, permanent magnets and fluorescent lamps.'
    substitutes:
      - 'USGS: substitutes are available for many rare-earth applications but generally are less effective.'
    source: usgs-mcs2026-rare-earths
    where: World Mine Production and Reserves table, 2025 column (world total 390,000 t; shares calculated by Space Mushroom from China 270,000, United States 51,000, Australia 29,000 and Burma 22,000); Events, Trends and Issues (China export controls on samarium, gadolinium and yttrium, April 2025); Recycling; Substitutes
  - subject: Bismuth (in Bi-2223 tape)
    producers:
      - country: China
        share_percent: 88
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (Bismuth, used in nontoxic metals, atomic research and some medical applications)
        listed: true
    recycling: 'USGS: recycled bismuth-containing alloy scrap was estimated at up to 10 percent of U.S. apparent consumption for 2021 to 2025.'
    substitutes:
      - 'USGS: cadmium, indium, lead and tin can partially replace bismuth in low-temperature solders.'
    source: usgs-mcs2026-bismuth
    where: Events, Trends and Issues (China produced 88 percent of 16,000 t world production in 2025; China export controls in April 2025 and price record); Recycling; Substitutes; list status from the USGS 2025 list page
  - subject: Silver (sheath and cap in Bi-2223 and REBCO tape)
    producers:
      - country: Mexico
        share_percent: 24.2
        year: 2025
      - country: Peru
        share_percent: 13.8
        year: 2025
      - country: China
        share_percent: 13.1
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (Silver, used in electrical circuits, batteries, solar cells and medical instruments)
        listed: true
    recycling: 'USGS: about 1,000 tons of silver was recovered from new and old scrap in 2025, about 11 percent of apparent consumption.'
    substitutes:
      - 'USGS: the chapter gives substitutes for silver in photography and some medical and flatware uses; it names no substitute for silver in electrical conductors.'
    source: usgs-mcs2026-silver
    where: World Mine Production and Reserves table, 2025e column (world total 26,000 t; shares calculated by Space Mushroom from Mexico 6,300, Peru 3,600 and China 3,400); Recycling; Substitutes; list status from the USGS 2025 list page
  - subject: Boron (in MgB2 precursor and boron feedstock)
    producers: []
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (Boron, used to harden steel and glass and in nuclear energy)
        listed: true
    recycling: 'USGS: insignificant.'
    substitutes:
      - 'USGS: substitution is possible in detergents, enamels, insulation and soaps.'
    source: usgs-mcs2026-boron
    where: 'Production table: Turkey, refined borates, 1,500 in 2025 (units as printed); the world total is withheld (XX), so no share is calculated. Recycling; Substitutes; list status from the USGS 2025 list page'
documents:
  - title: 'Wikipedia: Magnesium diboride'
    type: database
    url: https://en.wikipedia.org/wiki/Magnesium_diboride
    year: 2026
  - title: 'Wikipedia: Yttrium barium copper oxide'
    type: database
    url: https://en.wikipedia.org/wiki/Yttrium_barium_copper_oxide
    year: 2026
  - title: 'Wikipedia: Bismuth strontium calcium copper oxide'
    type: database
    url: https://en.wikipedia.org/wiki/Bismuth_strontium_calcium_copper_oxide
    year: 2026
  - title: Synthesis, Characterization and Ageing of MgB2 (Serquis et al., arXiv cond-mat/0112259)
    type: paper
    url: https://arxiv.org/abs/cond-mat/0112259
    year: 2001
  - title: Abstract of arXiv cond-mat/0106002, MgB2 tapes with stainless-steel and Cu-Ni sheaths
    type: paper
    url: https://arxiv.org/abs/cond-mat/0106002
    year: 2001
  - title: DC Performance Testing of MgB2 Superconducting Straight Wire Samples with a Cryocooler (Vankeuls, NASA NTRS 20220010640)
    type: report
    url: https://ntrs.nasa.gov/api/citations/20220010640/downloads/Aviation%20Paper.pdf
    year: 2022
  - title: Electro-Mechanical Properties of REBCO Coated Conductors from various Industrial Manufacturers at 77 K, self-field and 4.2 K, 19 T (Barth, Mondonico, Senatore, arXiv:1502.06713)
    type: paper
    url: https://arxiv.org/pdf/1502.06713
    year: 2015
  - title: Commercialization of Bi-2223 Superconducting Wires and Their Applications (Sumitomo Electric Technical Review No. 197, including DI-BSCCO Table 1)
    type: report
    url: https://sei.co.jp/technology/tr/bn197/pdf/197-13.pdf
  - title: Stanford Advanced Materials safety data sheet, magnesium boride (MgB2), version 3.0
    type: sds
    url: https://www.samaterials.com/pdf/Nano-Magnesium-Diboride-Powder-sds.pdf
    year: 2017
  - title: Angstrom Sciences safety data sheet, yttrium barium copper oxide (last revised 07/06/15)
    type: sds
    url: https://angstromsciences.com/wp-content/uploads/files/SDS/Yttrium%20Barium%20Copper%20Oxide.pdf
    year: 2015
  - title: 'USGS Mineral Commodity Summaries 2026: Copper'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Rare Earths'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Bismuth'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bismuth.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Silver'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Boron'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf
    year: 2026
  - title: USGS 2025 final list of critical minerals
    type: report
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
gaps:
  - No manufacturer REBCO datasheet was read. The SuperPower specification page returned an expired certificate, and the Faraday Factory and Fujikura datasheets were not found, so the REBCO current figures come from a 2015 academic comparison of five tapes.
  - No manufacturer datasheet for MgB2 wire was found. The MgB2 current figures come from a 2001 abstract and a NASA test of one Hyper Tech strand, and no 20 K or 2 T current value was read.
  - No corrosion or humidity test was found for REBCO or Bi-2223 wire. The MgB2 ageing data come from bulk pellets, not wire.
  - No safety data sheet for Bi-2212 or Bi-2223 powder was opened. The only BSCCO hazard data are a supplier listing for a related composition, which was not read as a source.
  - No space-environment result (vacuum, radiation, atomic oxygen, thermal cycling) was found for any of the three wire families.
  - Only one use matches the application list (aircraft propulsion concept). MRI, accelerator and fusion magnets (ITER, SPARC) are not on the list, so they are recorded in story.uses only.
  - 'Property names not in spores/property-canon.yaml: critical_temperature, upper_critical_field, critical_current_density, critical_current, engineering_current_density, filling_factor, irreversible_strain_limit, irreversible_stress_limit, bending_diameter. They are snake_case names as the brief allows; canonical names would need adding before import.'
  - Quench and protection data for MgB2, REBCO and Bi-2223 wire were not read, so the failure risks cover strain and bending only.
  - Magnesium production and share were not read from the USGS magnesium chapter; its 2025 list status is taken from the USGS list page only.
  - Boron world production is withheld in the USGS table (XX), so no producer share is calculated, and the table's unit was not confirmed.
  - Density and melting point were read for MgB2 and YBCO only. The Bi-2223 density and any tape-stack density were not found.
  - Atomic weights were not read from a NIST page, so the recipe parts have no atomic_weight.
  - No designations for MgB2 wire, REBCO tape or Bi-2223 tape were printed by a fetched source except the DI-BSCCO trade name, so identity.designations holds that one entry only.
sources:
  wikipedia-mgb2:
    title: Magnesium diboride, Wikipedia (formula, critical temperature, critical fields, density, melting point, process temperatures)
    url: https://en.wikipedia.org/wiki/Magnesium_diboride
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
  wikipedia-ybco:
    title: Yttrium barium copper oxide, Wikipedia (critical temperature, density, melting point, hazard statements, coated conductor)
    url: https://en.wikipedia.org/wiki/Yttrium_barium_copper_oxide
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
  wikipedia-bscco:
    title: Bismuth strontium calcium copper oxide, Wikipedia (Bi-2212 and Bi-2223 critical temperatures, general formula, powder-in-tube tape)
    url: https://en.wikipedia.org/wiki/Bismuth_strontium_calcium_copper_oxide
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
  arxiv-mgb2-jc:
    title: Abstract of arXiv cond-mat/0106002, MgB2 tapes with stainless-steel and Cu-Ni sheaths (transport Jc at 4.2 K and zero-field extrapolation)
    id: arXiv:cond-mat/0106002
    url: https://arxiv.org/abs/cond-mat/0106002
    year: 2001
    kind: paper
    license: arXiv (cited, not reproduced)
  nasa-mgb2-cryocooler:
    title: DC Performance Testing of MgB2 Superconducting Straight Wire Samples with a Cryocooler (F. W. Vankeuls, Vantage Partners and NASA Glenn)
    id: NASA NTRS 20220010640
    url: https://ntrs.nasa.gov/api/citations/20220010640/downloads/Aviation%20Paper.pdf
    year: 2022
    kind: report
    license: public domain (NASA)
  serquis-mgb2-ageing:
    title: Synthesis, Characterization and Ageing of MgB2 (Serquis et al., Los Alamos)
    id: arXiv:cond-mat/0112259
    url: https://arxiv.org/abs/cond-mat/0112259
    year: 2001
    kind: paper
    license: arXiv (cited, not reproduced)
  arxiv-rebco-barth:
    title: Electro-Mechanical Properties of REBCO Coated Conductors from various Industrial Manufacturers at 77 K, self-field and 4.2 K, 19 T (Barth, Mondonico, Senatore)
    id: arXiv:1502.06713
    url: https://arxiv.org/pdf/1502.06713
    year: 2015
    kind: paper
    license: arXiv (cited, not reproduced)
  sumitomo-dibscco-review:
    title: Commercialization of Bi-2223 Superconducting Wires and Their Applications, Sumitomo Electric Technical Review No. 197 (DI-BSCCO Table 1)
    id: Sumitomo Electric Technical Review 197
    url: https://sei.co.jp/technology/tr/bn197/pdf/197-13.pdf
    kind: report
    license: technical review (cited, not reproduced)
  samaterials-mgb2-sds:
    title: Stanford Advanced Materials safety data sheet, magnesium boride (CAS 12007-25-9), version 3.0
    id: CAS 12007-25-9
    url: https://www.samaterials.com/pdf/Nano-Magnesium-Diboride-Powder-sds.pdf
    year: 2017
    kind: datasheet
    license: supplier safety data sheet (cited, not reproduced)
  angstrom-ybco-sds:
    title: Angstrom Sciences safety data sheet, yttrium barium copper oxide (CAS 107539-20-8)
    id: CAS 107539-20-8
    url: https://angstromsciences.com/wp-content/uploads/files/SDS/Yttrium%20Barium%20Copper%20Oxide.pdf
    year: 2015
    kind: datasheet
    license: supplier safety data sheet (cited, not reproduced)
  usgs-mcs2026-copper:
    title: Mineral Commodity Summaries 2026, Copper
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-copper.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-rare-earths:
    title: Mineral Commodity Summaries 2026, Rare Earths
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-bismuth:
    title: Mineral Commodity Summaries 2026, Bismuth
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bismuth.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-silver:
    title: Mineral Commodity Summaries 2026, Silver
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-silver.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-boron:
    title: Mineral Commodity Summaries 2026, Boron
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS, final list of 60 minerals or commodities)
    id: Final 2025 List of Critical Minerals, November 2025
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 28
  unreachable: 3
  caveats: 5
  note: 'Read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry. Not reachable: the SuperPower 2G HTS specification page (expired certificate), the NIMS REBCO round-cable dataset (HTTP 504) and the Bologna EUCAS 2021 REBCO postprint (returned HTML, not PDF). The MgB2 and REBCO current figures are academic or NASA test values, not manufacturer datasheets.'
story:
  recipe:
    line: 'MgB2 wire is powder-in-tube: magnesium and boron powder is packed into a metal tube, drawn to size and heat-treated, with the sintering and hot isostatic pressing steps given in Wikipedia. The Hyper Tech strand tested by NASA is 0.83 mm across, with a niobium barrier, a Monel sheath and a copper core, and it was made by a continuous tube-forming and filling method. REBCO tape is built up in layers on a flexible metal substrate: buffer oxides, then the REBCO superconductor, then a silver cap and a copper stabilizer. Bi-2223 tape is powder-in-tube: precursor powders are packed into a silver tube and compressed to tape.'
    parts:
      - name: Magnesium
        symbol: Mg
        share_note: one part per formula unit of MgB2, with two boron per magnesium
        role: Forms the magnesium diboride lattice with boron. The NASA strand powder is MgB2 with 2 percent molar carbon.
      - name: Boron
        symbol: B
        share_note: two parts per magnesium in MgB2
        role: Forms the boron sublattice that carries the superconducting current in MgB2.
      - name: Yttrium, barium, copper and oxygen (REBCO)
        symbol: YBa2Cu3O7-x
        share_note: one yttrium (or other rare-earth) per three copper and two barium per formula unit, from the Wikipedia YBCO article
        role: The superconducting layer in REBCO tape. Oxide layers on the substrate stop metal from diffusing into it.
      - name: Silver and copper (stabilizers and matrix)
        symbol: Ag and Cu
        share_note: an Ag-Au alloy is one Bi-2223 sheath option (Sumitomo Table 1); copper is the stabilizer in REBCO tapes
        role: Silver is the matrix of Bi-2223 tape and the cap of REBCO tape. Copper carries current if the superconductor goes normal.
  risk_groups:
    - title: For people
      lead: The MgB2 powder is classed as non-hazardous in one supplier sheet. The YBCO powder carries harmful-if-swallowed and harmful-if-inhaled hazard statements.
      level: 1
      verdict: 'Powders: harmful if inhaled or swallowed'
      points:
        - label: MgB2 powder
          line: A 2017 supplier safety data sheet classes magnesium boride as not hazardous. Other notified data are not read in this profile, so check the supplier's sheet for the lot you buy.
        - label: YBCO powder
          line: The Angstrom sheet gives H302 and H332, harmful if swallowed or inhaled. The Wikipedia infobox adds H315, H319 and H335 for irritation.
        - label: Wire and tape
          line: The finished tapes and wires are metal-clad composites, so the powder hazards apply mainly when the material is cut, ground or heated.
    - title: If it fails
      lead: The main failure is loss of critical current, from strain in REBCO and from bending or tension in Bi-2223.
      points:
        - label: Strain
          line: The Barth study gives irreversible strain limits of 0.47 to 0.72 percent at 77 K in self-field, and says critical current falls before the limit is reached.
        - label: Bending and tension
          line: The Sumitomo table gives typical bending limits of 40 to 80 mm and tensile limits of 130 to 400 MPa for 95 percent Ic retention at 77.3 K.
  why: Three superconducting wire families are grouped here because each is a composite of a superconductor in a metal matrix, and each fills a gap that NbTi and Nb3Sn leave. MgB2 has a critical temperature of 39 K and can be made into wire by powder-in-tube, so it can run at about 20 K where liquid hydrogen or a cryocooler is available. REBCO and Bi-2223 have critical temperatures of about 93 K and 108 K, so tapes made from them can run at 77 K in liquid nitrogen, though they are oxide ceramics, and the YBCO article calls oxides of this kind brittle.
  uses:
    - where: Aircraft propulsion concept
      line: NASA describes fully superconducting motors and generators for turboelectric aircraft, and tested a Hyper Tech MgB2 strand in a cryocooler rig. The test is a preliminary sample measurement, not a flight or a motor build.
    - where: MRI, accelerator and fusion magnets
      line: The REBCO and MgB2 tapes are listed in the sources for high-field magnets and cables. The Wikipedia article on MgB2 reports a 0.5 tesla open MRI magnet built with MgB2 wire, and the YBCO article says superconducting tape is used for the SPARC tokamak. These uses are not on the application list, so they are recorded here only.
  can_do:
    - label: Current at 77 K
      value: 170 to 200 A
      benchmark: critical_current
      line: A Sumitomo table gives 170 to 200 A for DI-BSCCO Bi-2223 tape at 77.3 K in self-field. The table gives four values in one row.
    - label: Current density at 77 K
      value: 225 to 445 A/mm2
      benchmark: engineering_current_density
      line: Three commercial REBCO tapes from SuperPower, Fujikura and SuNAM, measured by Barth et al. at 77 K in self-field, carry 225, 350 and 445 A/mm2 engineering current density. Two other tapes, from SuperOx and Bruker HTS, were lower.
    - label: Current at 4.2 K in high field
      value: 2.0 to 3.9 kA/mm2 at 19 T
      benchmark: engineering_current_density
      line: At 4.2 K and 19 T with the field parallel to the tape, the same study gives 2.0 kA/mm2 for SuNAM (measured) and 3.9 kA/mm2 for SuperPower (extrapolated).
    - label: Strength at 77 K
      value: Irreversible strain 0.47 to 0.72 percent
      benchmark: irreversible_strain_limit
      line: The five commercial REBCO tapes in the Barth table reach an irreversible strain limit of 0.47 to 0.72 percent at 77 K in self-field, and an irreversible stress limit of 660 to 820 MPa.
    - label: MgB2 Tc and critical field
      value: 39 K, 14 T parallel to ab planes
      benchmark: critical_temperature
      line: Wikipedia gives a critical temperature of 39 K for MgB2, and an upper critical field of about 14 T parallel to the ab planes and about 3 T perpendicular. The NASA strand gave 102.64 A at 30.99 K.
  compare: The three families sit at different points on the temperature scale. MgB2 is the lowest, at 39 K, and has a density of 2.57 g/cm3. Bi-2223 at 108 K and YBCO at 93 K can carry current at liquid nitrogen temperature, but YBCO has a melting point above 1000 degC, and the YBCO article calls oxide materials of this kind brittle. The table below compares the critical temperature, density and melting point, as printed in the sources.
  compare_rows:
    - label: Critical temperature
      benchmark: critical_temperature
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
  handling:
    - 'Treat YBCO powder as a barium compound: avoid breathing dust and keep the exposure under 0.5 mg/m3 as Ba.'
    - Prefer well-sintered, dense MgB2. Poorly sintered, porous material lost superconducting fraction in ambient air over months.
    - Check the critical current and the strain limit of the actual tape before design, since they differ by maker.
  good_for:
    - 'Liquid-nitrogen-temperature tape: Bi-2223 and REBCO carry current at 77 K in self-field, with Bi-2223 at 170 to 200 A per tape.'
    - 'Lighter, lower-temperature magnets: MgB2 at 39 K can be cooled by a cryocooler, as the NASA test shows, instead of the liquid helium that NbTi needs; the sources show lower current at its warm operating points.'
  watch_out:
    - Brittleness and strain. The REBCO irreversible strain limit is 0.47 to 0.72 percent, and Bi-2223 tape keeps 95 percent of its Ic only above a bend diameter of about 40 to 80 mm (typical values).
    - Ageing and humidity. Poorly sintered MgB2 lost superconducting fraction in air, and no humidity test was found for REBCO or Bi-2223 wire.
    - Values differ by maker and test. The sources do not agree on field, temperature or criterion, so the figures are kept apart.
  verdict: Superconducting composites are the practical route to magnets at 77 K (REBCO and Bi-2223) and to MgB2 at about 20 K, but each carries its own strain, humidity and cost limits. The profile keeps the current figures with their own conditions, and no space-environment or manufacturer-datasheet test was found for any of the three.