spore: profile
id: indium-tin-oxide
spore_version: 0.2
family: transparent-conductive-oxides
name: Indium tin oxide (ITO) coating
abbreviation: ITO
role: transparent conductive coating for static control on thermal-control sheets and displays
category: coatings
type: conductive-coatings
summary: >
  Indium tin oxide (ITO) is a mixed oxide of indium and tin, deposited as a thin film that conducts electricity and stays optically transparent. A supplier data page lists a sheet resistance of 70 to 100 ohm/square for a 70 nm ITO film on unpolished soda-lime glass, with nominal transmittance greater than 88 %. On NASA's MISSE-9 mission, ITO-coated thermal-control sheets were not significantly damaged in low Earth orbit. Their atomic oxygen erosion yields ranged from 9.04e-28 to 3.19e-23 cm3/atom, and the sheet resistance of ITO on Kapton HN/Al doubled after ram exposure, to 10,820 ohm/square.
best_for: "Transparent films that must conduct enough to bleed off static charge while staying optically clear, such as thermal-control sheets in low Earth orbit"
weakest_at: "Heat and flight stability of sheet resistance: 16 % rise after three 12-hour cycles at 250 C, and widely scattered readings on silver-Teflon sheets"
identity:
  formula: "Mixed oxide of indium and tin, 74% In, 8% Sn and 18% O by weight (Wikipedia). The Angstrom Sciences SDS names the product In2O3 SnO2. The Sigma-Aldrich SDS for an ITO-coated PET film lists diindium trioxide (CAS 1312-43-2, 90 to 100 %) and tin(IV) oxide (CAS 18282-10-5, 10 to 30 %)."
  source: wikipedia-ito
  where: "Introduction (formulation by weight); Angstrom SDS Section 1 (product name); Sigma-Aldrich SDS Section 3 (composition table)"
tags:
  environments: [low-earth-orbit]
  stresses: [atomic-oxygen]
  applications: [thermal-control, solar-arrays, electronics-and-chips]
properties:
  - benchmark: sheet_resistance
    label: Sheet resistance, 70 nm ITO on unpolished soda-lime glass
    value: 70
    value_high: 100
    bound: range
    unit: ohm/square
    scope: material
    conditions: {substrate: "float soda-lime glass microscope slide, unpolished", film_thickness: "70 nm (table column ITO thickness, printed as 70 NM)", temperature: "not stated"}
    method: Range printed in a supplier data table
    status: ground
    source: 2spi-ito
    where: "Float glass (soda lime) microscope slides, Unpolished table, row 70-100 / 70"
  - benchmark: optical_transmittance
    label: Nominal transmittance, 70 nm ITO on unpolished soda-lime glass
    value: 88
    bound: lower
    unit: "%"
    scope: material
    conditions: {substrate: "float soda-lime glass microscope slide, unpolished", film_thickness: "70 nm", wavelength: "not stated"}
    method: Nominal figure printed as greater than 88% in a supplier data table
    status: ground
    note: Nominal figure for the coated slide; the page gives no wavelength.
    source: 2spi-ito
    where: "Float glass (soda lime) microscope slides, Unpolished table, row 70"
  - benchmark: sheet_resistance
    label: Sheet resistance, 350 nm ITO on unpolished soda-lime glass
    value: 15
    value_high: 30
    bound: range
    unit: ohm/square
    scope: material
    conditions: {substrate: "float soda-lime glass microscope slide, unpolished", film_thickness: "350 nm", temperature: "not stated"}
    method: Range printed in a supplier data table
    status: ground
    source: 2spi-ito
    where: "Float glass (soda lime) microscope slides, Unpolished table, row 15-30 / 350"
  - benchmark: optical_transmittance
    label: Nominal transmittance, 350 nm ITO on unpolished soda-lime glass
    value: 85
    bound: lower
    unit: "%"
    scope: material
    conditions: {substrate: "float soda-lime glass microscope slide, unpolished", film_thickness: "350 nm", wavelength: "not stated"}
    method: Nominal figure printed as greater than 85% in a supplier data table
    status: ground
    note: Nominal figure; the page gives no wavelength.
    source: 2spi-ito
    where: "Float glass (soda lime) microscope slides, Unpolished table, row 350"
  - benchmark: sheet_resistance
    label: Sheet resistance, 700 nm ITO on unpolished soda-lime glass
    value: 8
    value_high: 12
    bound: range
    unit: ohm/square
    scope: material
    conditions: {substrate: "float soda-lime glass microscope slide, unpolished", film_thickness: "700 nm", temperature: "not stated"}
    method: Range printed in a supplier data table
    status: ground
    source: 2spi-ito
    where: "Float glass (soda lime) microscope slides, Unpolished table, row 8-12 / 700"
  - benchmark: optical_transmittance
    label: Nominal transmittance, 700 nm ITO on unpolished soda-lime glass
    value: 83
    bound: lower
    unit: "%"
    scope: material
    conditions: {substrate: "float soda-lime glass microscope slide, unpolished", film_thickness: "700 nm", wavelength: "not stated"}
    method: Nominal figure printed as greater than 83% in a supplier data table
    status: ground
    note: Nominal figure; the page gives no wavelength.
    source: 2spi-ito
    where: "Float glass (soda lime) microscope slides, Unpolished table, row 700"
  - benchmark: sheet_resistance_change
    label: Sheet resistance rise after heating at 250 C, three 12-hour cycles
    value: 16
    unit: "%"
    scope: material
    conditions: {temperature: "250 C", cycles: "3 cycles of 12 hours", substrate: "not named on the page"}
    method: Percentage change printed in the High Temperature Applications test table of a supplier data page
    status: ground
    source: 2spi-ito
    where: "High Temperature Applications table, 250 C row"
  - benchmark: sheet_resistance_change
    label: Sheet resistance rise after heating at 210 C, three 12-hour cycles
    value: 4
    unit: "%"
    scope: material
    conditions: {temperature: "210 C", cycles: "3 cycles of 12 hours", substrate: "not named on the page"}
    method: Percentage change printed in the High Temperature Applications test table of a supplier data page
    status: ground
    source: 2spi-ito
    where: "High Temperature Applications table, 210 C row"
  - benchmark: sheet_resistance_change
    label: Sheet resistance rise after heating at 160 C, three 12-hour cycles
    value: 2.5
    unit: "%"
    scope: material
    conditions: {temperature: "160 C", cycles: "3 cycles of 12 hours", substrate: "not named on the page"}
    method: Percentage change printed in the High Temperature Applications test table of a supplier data page
    status: ground
    source: 2spi-ito
    where: "High Temperature Applications table, 160 C row"
  - benchmark: max_service_temp
    label: Maximum recommended temperature for ITO coatings
    value: 300
    unit: "°C"
    scope: material
    conditions: {basis: "maximum recommended temperature stated by the supplier, printed as 300 C"}
    method: Value printed on a supplier data page
    status: ground
    source: 2spi-ito
    where: "High Temperature Applications section, text below the table"
  - benchmark: refractive_index
    label: Refractive index of sputtered ITO coating at 600 nm
    value: 2
    unit: "-"
    scope: material
    conditions: {wavelength: "600 nm", coating: "sputtered ITO coating", extinction_coefficient: "0.0065 at 600 nm (printed in the same table)"}
    method: Value printed in a refractive index table on a supplier data page
    status: ground
    source: 2spi-ito
    where: "Refractive index values table, row 600"
  - benchmark: refractive_index
    label: Refractive index of sputtered ITO coating at 400 nm
    value: 2.15
    unit: "-"
    scope: material
    conditions: {wavelength: "400 nm", coating: "sputtered ITO coating", extinction_coefficient: "0.025 at 400 nm (printed in the same table)"}
    method: Value printed in a refractive index table on a supplier data page
    status: ground
    source: 2spi-ito
    where: "Refractive index values table, row 400"
  - benchmark: band_gap
    label: Band gap of ITO (approximate)
    value: 4
    unit: eV
    scope: material
    conditions: {basis: "around 4 eV, as printed in an encyclopedia article", material: "ITO thin film"}
    method: Approximate figure printed in an encyclopedia article, with no measurement method given
    status: ground
    note: The article gives only an approximate figure, around 4 eV.
    source: wikipedia-ito
    where: "Material and properties section"
  - benchmark: electrical_resistivity
    label: Electrical resistivity of ITO (approximate)
    value: 1.0e-4
    unit: "Ω·cm"
    scope: material
    conditions: {basis: "printed as approximately 10 to the power minus 4 ohm cm in an encyclopedia article", film: "not stated"}
    method: Approximate figure printed in an encyclopedia article, with no measurement method given
    status: ground
    note: Approximate figure only; the article gives no thickness or temperature.
    source: wikipedia-ito
    where: "Material and properties section"
  - benchmark: optical_transmittance
    label: Optical transmittance of a thin ITO film (lower bound)
    value: 80
    bound: lower
    unit: "%"
    scope: material
    conditions: {basis: "thin film; wavelength and thickness not stated"}
    method: Lower bound printed in an encyclopedia article
    status: ground
    source: wikipedia-ito
    where: "Material and properties section"
  - benchmark: optical_transmittance
    label: Transmittance of sputtered ITO-MgF2 films (variant with magnesium fluoride added)
    value: 75
    value_high: 86
    bound: range
    unit: "%"
    scope: material
    conditions: {material: "sputtered ITO with magnesium fluoride added (ITO-MgF2, not pure ITO)", wavelength: "not stated in the abstract"}
    method: Range printed in the abstract of a 1994 NASA conference paper
    status: ground
    note: A related coating with magnesium fluoride, not pure ITO; included because the same study tested ITO at several MgF2 contents.
    source: nasa-1994-itomgf2
    where: "Abstract"
  - benchmark: density
    label: Density of ITO film used in the erosion-yield calculation
    value: 6.8
    unit: g/cm3
    scope: material
    conditions: {basis: "ITO density column of Table 6, cited to reference 10 (Journal Vac. Sci. Tech A 19:5, 2001)", film: "ITO on Kapton HN/Al or FEP/Ag/Inconel sheet"}
    method: Value printed in a NASA table that the authors use in the erosion-yield calculation
    status: ground
    source: nasa-tm-2024
    where: "Table 6, column ITO Density (g/cm3)"
  - benchmark: sheet_resistance
    label: Sheet resistance of ITO on Kapton HN/Al after ram exposure (MISSE-9 flight)
    value: 10820
    unit: ohm/square
    scope: material
    conditions: {sample: "M9R-S5 flight, ITO coated Kapton HN/aluminum, ram orientation", exposure: "0.77 years direct space exposure (ram)", film_thickness: "approximately 10 nm", measurement: "four-point probe; the report says absolute accuracy is unknown"}
    method: Average printed for the flight sample in Table 4 and in the abstract
    status: flight
    note: The unexposed backup average for the same material is 5,230 ohm/square in Table 4; the report says the flight value doubled.
    source: nasa-tm-2024
    where: "Abstract; Table 4, row M9R-S5 Flight, column Average"
  - benchmark: atomic_oxygen_erosion_yield
    label: Atomic oxygen erosion yield, M9R-S5 ITO/Kapton HN/Al, ram
    value: 6.72e-27
    unit: cm3/atom
    scope: material
    conditions: {sample: "M9R-S5 F, ITO/Kapton HN/Al, 2 mil", flight_direction: "ram", atomic_oxygen_fluence: "3.44E+20 atoms/cm2", mass_loss: "0.000069 g", exposed_area: "4.414 cm2", density_used: "6.8 g/cm3"}
    method: Erosion yield calculated by the authors from dehydrated mass loss, exposed area, density and fluence (equation 1)
    status: flight
    source: nasa-tm-2024
    where: "Table 6, row M9R-S5 F"
  - benchmark: atomic_oxygen_erosion_yield
    label: Atomic oxygen erosion yield, M9R-S6 ITO/FEP/Ag/Inconel, ram
    value: 9.04e-28
    unit: cm3/atom
    scope: material
    conditions: {sample: "M9R-S6 F, ITO/FEP/Ag/Inconel, 5 mil", flight_direction: "ram", atomic_oxygen_fluence: "3.44E+20 atoms/cm2", mass_loss: "0.000009 g", exposed_area: "4.420 cm2", density_used: "6.8 g/cm3"}
    method: Erosion yield calculated by the authors from dehydrated mass loss, exposed area, density and fluence (equation 1)
    status: flight
    note: Mass loss is just above the balance error range, per the report.
    source: nasa-tm-2024
    where: "Table 6, row M9R-S6 F; Section 5.4"
  - benchmark: atomic_oxygen_erosion_yield
    label: Atomic oxygen erosion yield, M9W-S1 ITO/Kapton HN/Al, wake
    value: 3.19e-23
    unit: cm3/atom
    scope: material
    conditions: {sample: "M9W-S1 F, ITO/Kapton HN/Al, 2 mil", flight_direction: "wake", atomic_oxygen_fluence: "4.46E+16 atoms/cm2", mass_loss: "0.000043 g", exposed_area: "4.406 cm2", density_used: "6.8 g/cm3"}
    method: Erosion yield calculated by the authors from dehydrated mass loss, exposed area, density and fluence (equation 1)
    status: flight
    note: The largest of the six flight values; the report still calls all six very low.
    source: nasa-tm-2024
    where: "Table 6, row M9W-S1 F"
  - benchmark: atomic_oxygen_erosion_yield
    label: Atomic oxygen erosion yield, M9W-S2 ITO/FEP/Ag/Inconel, wake
    value: 2.00e-24
    unit: cm3/atom
    scope: material
    conditions: {sample: "M9W-S2 F, ITO/FEP/Ag/Inconel, 5 mil", flight_direction: "wake", atomic_oxygen_fluence: "4.46E+16 atoms/cm2", mass_loss: "0.000003 g", exposed_area: "4.387 cm2", density_used: "6.8 g/cm3"}
    method: Erosion yield calculated by the authors from dehydrated mass loss, exposed area, density and fluence (equation 1)
    status: flight
    note: Mass loss is within the balance error (plus or minus 0.005 mg), per the report.
    source: nasa-tm-2024
    where: "Table 6, row M9W-S2 F; Section 5.4"
  - benchmark: atomic_oxygen_erosion_yield
    label: Atomic oxygen erosion yield, M9W-S3 ITO/FEP/Ag/Inconel, wake
    value: 1.74e-24
    unit: cm3/atom
    scope: material
    conditions: {sample: "M9W-S3 F, ITO/FEP/Ag/Inconel, 5 mil", flight_direction: "wake", atomic_oxygen_fluence: "4.46E+16 atoms/cm2", mass_loss: "0.000002 g", exposed_area: "4.416 cm2", density_used: "6.8 g/cm3"}
    method: Erosion yield calculated by the authors from dehydrated mass loss, exposed area, density and fluence (equation 1)
    status: flight
    note: Mass loss is within the balance error (plus or minus 0.005 mg), per the report.
    source: nasa-tm-2024
    where: "Table 6, row M9W-S3 F; Section 5.4"
  - benchmark: atomic_oxygen_erosion_yield
    label: Atomic oxygen erosion yield, M9Z-S5 ITO/FEP/Ag/Inconel, zenith
    value: 6.83e-27
    unit: cm3/atom
    scope: material
    conditions: {sample: "M9Z-S5 F, ITO/FEP/Ag/Inconel, 5 mil", flight_direction: "zenith", atomic_oxygen_fluence: "3.19E+18 atoms/cm2", mass_loss: "0.000001 g", exposed_area: "4.501 cm2", density_used: "6.8 g/cm3"}
    method: Erosion yield calculated by the authors from dehydrated mass loss, exposed area, density and fluence (equation 1)
    status: flight
    source: nasa-tm-2024
    where: "Table 6, row M9Z-S5 F"
  - benchmark: solar_absorptance
    label: AM0 solar absorptance, unflown control ITO/Kapton HN/Al
    value: 0.423
    unit: "-"
    scope: material
    conditions: {material: "ITO/Kapton HN/Al control (backup) sample M9R-S5 B", spectrum: "AM0 integrated, 250 to 2500 nm", method: "Cary 5000 with integrating sphere"}
    method: Integrated value printed in Table 5 (control row)
    status: ground
    source: nasa-tm-2024
    where: "Table 5, row M9R-S5 B"
  - benchmark: solar_absorptance
    label: AM0 solar absorptance, unflown control ITO/FEP/Ag/Inconel
    value: 0.098
    unit: "-"
    scope: material
    conditions: {material: "ITO/FEP/Ag/Inconel control (backup) sample M9W-S2 B", spectrum: "AM0 integrated, 250 to 2500 nm", method: "Cary 5000 with integrating sphere"}
    method: Integrated value printed in Table 5 (control row)
    status: ground
    source: nasa-tm-2024
    where: "Table 5, row M9W-S2 B"
  - benchmark: total_reflectance
    label: AM0 total reflectance, unflown control ITO/Kapton HN/Al
    value: 0.577
    unit: "-"
    scope: material
    conditions: {material: "ITO/Kapton HN/Al control (backup) sample M9R-S5 B", spectrum: "AM0 integrated, 250 to 2500 nm"}
    method: Integrated value printed in Table 5 (control row)
    status: ground
    source: nasa-tm-2024
    where: "Table 5, row M9R-S5 B"
  - benchmark: total_reflectance
    label: AM0 total reflectance, unflown control ITO/FEP/Ag/Inconel
    value: 0.902
    unit: "-"
    scope: material
    conditions: {material: "ITO/FEP/Ag/Inconel control (backup) sample M9W-S2 B", spectrum: "AM0 integrated, 250 to 2500 nm"}
    method: Integrated value printed in Table 5 (control row)
    status: ground
    source: nasa-tm-2024
    where: "Table 5, row M9W-S2 B"
  - benchmark: solar_absorptance_change
    label: Largest solar absorptance increase on a MISSE-9 flight sample (zenith)
    value: 0.002
    unit: "-"
    scope: material
    conditions: {sample: "M9Z-S5 F, ITO/FEP/Ag/Inconel, zenith", exposure: "0.54 years direct space exposure", measurement_error: "within error of the Cary data, per the report"}
    method: Change printed in Table 5 and in Section 5.3
    status: flight
    source: nasa-tm-2024
    where: "Table 5, row M9Z-S5 F; Section 5.3"
corrosion:
  - environment: Atomic oxygen in low Earth orbit (ram, wake and zenith flight orientations)
    headline: "In the MISSE-9 flight, ITO sheets were not significantly damaged by atomic oxygen, and their erosion yields were very low."
    effect: "NASA flew six ITO-coated sheets for 0.77 years (ram) and 0.54 years (wake and zenith). The report says the samples were not significantly damaged, the erosion yields were very low, and solar absorptance changed very little. The sheet resistance of the ITO on Kapton HN/Al doubled after ram exposure, which NASA traces to atomic oxygen."
    rating: low
    conditions: {exposure: "MISSE-9 PCE-1 flight, ISS, 2018 to 2020", atomic_oxygen_fluence: "3.44E+20 atoms/cm2 (ram); 4.46E+16 (wake); 3.19E+18 (zenith)", coating_thickness: "approximately 10 nm"}
    source: nasa-tm-2024
    where: "Abstract; Sections 4.0, 5.2, 5.4 and 6.0; Table 3"
  - environment: Atomic oxygen plasma in the laboratory (ITO-MgF2 films)
    headline: "Lab plasma tests found ITO-MgF2 films with low magnesium fluoride content not durable to atomic oxygen, while high-content films were durable."
    effect: "A 1994 NASA study of sputtered ITO with magnesium fluoride, along with ZnO and AZO, found that the high MgF2 content ITO-MgF2 films were durable to atomic oxygen plasma, while the low MgF2 content films were not. This is a ground plasma test, not a flight result, and it covers ITO with MgF2 added."
    rating: moderate
    conditions: {test: "atomic oxygen plasma, laboratory", material: "sputtered ITO with varying MgF2 content"}
    source: nasa-1994-itomgf2
    where: "Abstract"
  - environment: Heating in air or vacuum (laboratory cycles, 3 x 12 hours)
    headline: "Sheet resistance rises with temperature: 2.5 % at 160 C, 4 % at 210 C and 16 % at 250 C after three 12-hour cycles."
    effect: "The supplier test table gives the sheet resistance change after three 12-hour cycles at each temperature. The page also gives a maximum recommended temperature of 300 C. The atmosphere and substrate used in the heating test are not named on the page."
    rating: moderate
    conditions: {cycles: "3 cycles of 12 hours each", substrate: "not named on the page", atmosphere: "not stated"}
    source: 2spi-ito
    where: "High Temperature Applications table and text below it"
  - environment: Ultraviolet light after LEO flight
    headline: "After flight, the ITO on Kapton HN/Al did not change under UV light, but the ITO on silver-Teflon fluoresced slightly more with atomic oxygen exposure."
    effect: "NASA compared flight and control samples under 365 nm UV light. The Kapton HN/Al samples looked the same as their controls. The ITO/FEP/Ag/Inconel samples showed a small amount of fluorescence, which increased with atomic oxygen exposure. Under normal light the differences were minimal."
    rating: low
    conditions: {light: "365 nm UV source and normal visible light", samples: "MISSE-9 flight and control pairs"}
    source: nasa-tm-2024
    where: "Section 5.1 (Figures 6 to 8)"
risks:
  hazards:
    - text: "Sigma-Aldrich safety data sheet for indium tin oxide coated PET (product 639303, version 4.1): classified under OSHA HCS as skin irritation (Category 2, H315), eye irritation (Category 2A, H319) and respiratory system STOT single exposure (Category 3, H335). Signal word Warning."
      ghs: [H315, H319, H335]
      source: sigma-ito-pet-sds
      where: "Section 2.1 (GHS classification) and Section 2.2 (label elements)"
    - text: "Angstrom Sciences safety data sheet for indium tin oxide (powder, granules, pellets, sputtering targets): signal word Warning, hazard statement H335 (may cause respiratory irritation), precautionary statement P261 (avoid breathing dust/fume)."
      ghs: [H335]
      source: angstrom-ito-sds
      where: "Section 2 (Hazard identification)"
    - text: "PubChem record for indium(III) oxide (a component of ITO, not ITO itself): 71.2% (195 of 274) of company reports say it does not meet GHS hazard criteria. Among reports that gave codes, H315 16.8%, H319 15.7%, H335 16.8%, H372 12% and H412 10.6%; the signal word is Danger."
      ghs: [H315, H319, H335, H372, H412]
      source: pubchem-in2o3
      where: "Safety and Hazards, GHS Classification (CID 150905)"
  failure_risks:
    - mode: Sheet resistance rises after ram exposure in low Earth orbit
      trigger: "Ram-facing ITO on Kapton HN/Al, 0.77 years direct exposure on MISSE-9"
      consequence: "Sheet resistance doubled to 10,820 ohm/square. NASA judged this low enough to dissipate electrostatic charge, and attributes the change to atomic oxygen."
      severity: low
      source: nasa-tm-2024
      where: "Abstract; Section 5.2"
    - mode: Sheet resistance rises with heat
      trigger: "Heating at 250 C for three 12-hour cycles"
      consequence: "Sheet resistance rose 16 %. At 210 C the rise was 4 %, and at 160 C it was 2.5 %."
      severity: moderate
      source: 2spi-ito
      where: "High Temperature Applications table"
    - mode: Scattered sheet-resistance readings on silver-Teflon sheets
      trigger: "ITO on FEP/Ag/Inconel, flight and backup samples, measured by four-point probe"
      consequence: "Readings varied widely within a sample, and some flight readings were above 370,000 ohm/square. NASA called the measurements inconsistent and recommended re-measuring all samples with calibrated equipment."
      severity: moderate
      source: nasa-tm-2024
      where: "Abstract; Section 5.2; Section 6.0"
    - mode: Low magnesium fluoride content in ITO-MgF2 films
      trigger: "Atomic oxygen plasma (laboratory)"
      consequence: "Low MgF2 content ITO-MgF2 films were not durable to atomic oxygen plasma, while high MgF2 content films were. This is for the MgF2 variant, not pure ITO."
      severity: moderate
      source: nasa-1994-itomgf2
      where: "Abstract"
  side_effects:
    - text: "Indium tin oxide dust and fume can irritate the respiratory tract, so the powder, pellets and sputtering targets must be handled to avoid dust formation."
      affects: "Operators handling powders, pellets or sputtering targets"
      source: angstrom-ito-sds
      where: "Section 2 (H335 and P261) and Section 6 (accidental release)"
  handling:
    - text: "Angstrom Sciences: avoid breathing dust and fume, wash thoroughly after handling, and store in a cool, dry place in a tightly sealed container. Clean spills by vacuuming with a HEPA filter and do not raise dust."
      source: angstrom-ito-sds
      where: "Sections 6 and 7"
    - text: "Exposure limit: 0.1 mg/m3 as indium (OSHA and ACGIH) per the Angstrom Sciences SDS. The Sigma-Aldrich SDS lists a TWA of 0.1 mg/m3 for diindium trioxide (ACGIH)."
      source: angstrom-ito-sds
      where: "Section 8 (Permissible Exposure Limits, Threshold Limit Value); Sigma-Aldrich SDS Section 8.1"
  mitigations:
    - text: "Keep films at or below 300 C, the supplier's maximum recommended temperature, since sheet resistance rises with heat (2.5 % at 160 C, 4 % at 210 C, 16 % at 250 C)."
      source: 2spi-ito
      where: "High Temperature Applications section"
uses:
  - application: thermal-control
    device: "Spacecraft thermal-control sheets (ITO on Kapton HN/Al and on silver-Teflon)"
    example: "NASA flew six ITO-coated sheets on the MISSE-9 mission, for 0.77 years in ram and 0.54 years in wake and zenith. The report says all were not noticeably damaged and are suitable for thermal-control sheet materials."
    source: nasa-tm-2024
    where: "Abstract; Section 6.0 (Conclusions)"
  - application: solar-arrays
    device: "Conductive protective coatings for space solar cells (research)"
    example: "A 1994 NASA study states that a conductive protective coating is essential for the operation and efficiency of photovoltaic systems in space, and tested ITO films with magnesium fluoride against atomic oxygen."
    source: nasa-1994-itomgf2
    where: "Introduction"
  - application: electronics-and-chips
    device: "Transparent electrodes in flat-panel displays"
    example: "The USGS says ITO thin-film coatings were mainly used for electrical conductivity in flat-panel displays, most commonly liquid crystal displays (LCDs), and that ITO accounts for most global indium consumption."
    source: usgs-mcs2026-indium
    where: "Domestic Production and Use paragraph"
supply:
  - subject: Indium (in ITO and other uses)
    producers:
      - {country: China, share_percent: 70, year: 2025}
      - {country: Republic of Korea, share_percent: 16.4, year: 2025}
      - {country: Japan, share_percent: 5.9, year: 2025}
      - {country: Canada, share_percent: 3.6, year: 2025}
    critical_lists:
      - {list: "USGS 2025 List of Critical Minerals (indium listed, used in flat-panel displays and touchscreens)", listed: true}
    recycling: "USGS: indium is most commonly recovered from ITO scrap in Japan and the Republic of Korea. Quantities recovered from scrap were not available, and there were no readily available recycling or end-use data."
    substitutes: ["USGS lists antimony tin oxide, carbon nanotube coatings, PEDOT, copper or silver nanowires, graphene and a zinc oxide nanopowder as substitutes for ITO in some uses."]
    source: usgs-mcs2026-indium
    where: "Refinery production table, 2025e (world total 1,100 t; shares for Republic of Korea, Japan and Canada calculated by Space Mushroom from 180, 65 and 40 t); China 70 % is printed in Events, Trends, and Issues; Recycling; Substitutes"
  - subject: Tin (in the tin oxide and solder components)
    producers:
      - {country: China, share_percent: 24.5, year: 2025}
      - {country: Indonesia, share_percent: 21.0, year: 2025}
      - {country: Peru, share_percent: 11.4, year: 2025}
      - {country: Brazil, share_percent: 9.7, year: 2025}
    critical_lists:
      - {list: "USGS 2025 List of Critical Minerals (tin listed, used for food and beverage cans, circuit board components and corrosion-resistant metal coatings)", listed: true}
    recycling: "USGS: about 17,000 tons of tin from old and new scrap was estimated to have been recycled in 2025."
    substitutes: ["USGS: aluminum, glass, paper, plastic or tin-free steel substitute for tin in cans and containers."]
    source: usgs-mcs2026-tin
    where: "World Mine Production table, 2025e (world total 290,000 t; shares calculated by Space Mushroom from China 71,000, Indonesia 61,000, Peru 33,000 and Brazil 28,000 t); Recycling; Substitutes"
documents:
  - {title: "2-SPI: Indium tin oxide technical data (coated glass, quartz and PET)", type: datasheet, url: "https://www.2spi.com/ito-tech-data"}
  - {title: "NASA/TM-20240002413: Space Exposure of Indium Tin Oxide Coatings (MISSE-9 PCE-1)", type: report, url: "https://ntrs.nasa.gov/citations/20240002413", year: 2024}
  - {title: "NASA TM-106466 (AIAA-94-0375): Transparent Conducting Thin Films for Spacecraft Applications", type: paper, url: "https://ntrs.nasa.gov/citations/19940018897", year: 1994}
  - {title: "Wikipedia: Indium tin oxide", type: database, url: "https://en.wikipedia.org/wiki/Indium_tin_oxide", year: 2026}
  - {title: "USGS Mineral Commodity Summaries 2026: Indium", type: report, url: "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-indium.pdf", year: 2026}
  - {title: "USGS Mineral Commodity Summaries 2026: Tin", type: report, url: "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf", year: 2026}
  - {title: "Angstrom Sciences safety data sheet: Indium Tin Oxide", type: sds, url: "https://angstromsciences.com/wp-content/uploads/files/SDS/Indium%20Tin%20Oxide.pdf"}
  - {title: "Sigma-Aldrich safety data sheet: Indium tin oxide coated PET, product 639303 (hosted copy, version 4.1)", type: sds, url: "https://www.nanofab.utah.edu/wp-content/uploads/2018/08/Indium-tin-oxide-coated-PET-Sigma-Aldrich-05mApr14_v4.1.pdf", year: 2014}
  - {title: "PubChem: Indium oxide (CID 150905), GHS classification", type: database, url: "https://pubchem.ncbi.nlm.nih.gov/compound/150905", year: 2026}
gaps:
  - "No CAS number for indium tin oxide itself. The CAS 50926-11-9 appeared only in search-result links, and the pages that would print it (American Elements, NITE) returned 403 and 404, so it is not recorded."
  - "No abundance figure for indium or tin in the crust or in regolith: the USGS chapters give production and use, not crustal abundance, and no other opened source gave one."
  - "No melting point, electrical resistance of a bulk target, or carrier concentration for ITO films was found in an opened source."
  - "No ground or flight test of humidity, salt or radiation (electron, proton or UV dose) on ITO sheets was opened. The only UV result is a qualitative fluorescence comparison in NASA/TM-20240002413."
  - "No thermal-vacuum outgassing (total mass loss, collected volatile condensable material) for ITO sheets was found."
  - "The 1994 NASA study's sheet-resistance range for ITO-MgF2 (10^2 to 10^11 ohm/square) could not be read reliably from the scanned text, so only its transmittance range is recorded."
  - "The sheet-resistance and transmittance rows were read from a rendered summary of the supplier page; the figures should be checked against the printed page."
  - "The USGS 2026 indium chapter gives the refinery price as 390 dollars per kilogram in one place and 370 in its table; neither price is entered."
  - "The EU critical raw materials list status of indium and tin was not checked; only the USGS 2025 list is recorded."
  - "The Angstrom Sciences SDS revision date is printed as 076/21/15, which is not a clear date; the document is recorded as printed."
  - "The NITE (Japan) GHS record for ITO returned 404, and a Louisville SDS for ITO pellets was not a readable PDF; neither hazard entry is recorded."
  - "Film optical properties (refractive index and extinction) come from a supplier table for sputtered coatings; no wavelength-resolved transmittance spectrum was opened."
sources:
  2spi-ito:
    title: "Indium tin oxide technical data (2-SPI, coated glass, quartz and PET)"
    url: https://www.2spi.com/ito-tech-data
    kind: datasheet
    license: "Supplier web page (cited, not reproduced)"
  nasa-tm-2024:
    title: "NASA/TM-20240002413: Space Exposure of Indium Tin Oxide Coatings (MISSE-9 PCE-1), NASA Glenn Research Center"
    id: "NTRS 20240002413"
    url: https://ntrs.nasa.gov/citations/20240002413
    year: 2024
    kind: report
    license: public domain (NASA)
  nasa-1994-itomgf2:
    title: "Transparent Conducting Thin Films for Spacecraft Applications (Perez-Davis et al., NASA Lewis, AIAA-94-0375, NASA TM-106466)"
    id: "NTRS 19940018897"
    url: https://ntrs.nasa.gov/citations/19940018897
    year: 1994
    kind: report
    license: public domain (NASA)
  wikipedia-ito:
    title: "Indium tin oxide (Wikipedia)"
    url: https://en.wikipedia.org/wiki/Indium_tin_oxide
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
  usgs-mcs2026-indium:
    title: Mineral Commodity Summaries 2026, Indium
    id: "USGS MCS 2026, February 2026"
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-indium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-tin:
    title: Mineral Commodity Summaries 2026, Tin
    id: "USGS MCS 2026, February 2026"
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tin.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS, final list)
    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)
  angstrom-ito-sds:
    title: "Safety Data Sheet: Indium Tin Oxide (Angstrom Sciences, Inc., Duquesne PA; revision date printed 076/21/15)"
    url: https://angstromsciences.com/wp-content/uploads/files/SDS/Indium%20Tin%20Oxide.pdf
    kind: datasheet
    license: "Manufacturer safety data sheet (cited, not reproduced)"
  sigma-ito-pet-sds:
    title: "Safety Data Sheet: Indium tin oxide coated PET (Sigma-Aldrich product 639303, version 4.1, revision 04/05/2014)"
    url: https://www.nanofab.utah.edu/wp-content/uploads/2018/08/Indium-tin-oxide-coated-PET-Sigma-Aldrich-05mApr14_v4.1.pdf
    year: 2014
    kind: datasheet
    license: "Supplier safety data sheet (cited, not reproduced)"
  pubchem-in2o3:
    title: "PubChem compound record: Indium oxide (CID 150905), GHS classification from ECHA C&L Inventory notifications"
    id: "CID 150905; molecular formula In2O3"
    url: https://pubchem.ncbi.nlm.nih.gov/compound/150905
    year: 2026
    kind: database
    license: "PubChem (NCBI), public domain; ECHA data attributed"
license: CC-BY-4.0
updated: "2026-11-01"
review:
  status: draft
  method: assistant
  checked_values: 29
  unreachable: 3
  caveats: 6
  note: "Values were read by an AI assistant on 2026-11-01 from the pages and PDFs named in each entry. The 2-SPI values come from a rendered summary of the supplier page. The NASA TM values are read from the PDF text (pdftotext). Unreachable: NITE GHS record (404), American Elements page (403), Louisville SDS (not a readable PDF). Caveats: the supplier table gives nominal figures without wavelength; the 1994 NASA study tested ITO with MgF2 added, not pure ITO; erosion yields are authors' calculations from mass loss; the flight sheet-resistance readings are of unknown absolute accuracy; the indium and tin figures are calculated shares from the USGS tables."
story:
  risk_groups:
    - title: For people
      lead: "The supplier safety data sheets give hazard codes for ITO films and powders, and for the indium oxide component. The codes differ by product form."
      level: 1
      verdict: "Irritant codes; no ITO-specific toxicity"
      points:
        - label: ITO film on PET (supplier SDS)
          line: "Sigma-Aldrich's safety data sheet for indium tin oxide coated PET classifies the product as a skin irritant (H315), an eye irritant (H319) and a possible respiratory irritant (H335), with signal word Warning."
        - label: ITO powder or pellets (supplier SDS)
          line: "Angstrom Sciences' sheet for ITO powder, granules, pellets and sputtering targets lists only H335, may cause respiratory irritation, with signal word Warning. Its exposure limit is 0.1 mg/m3 as indium."
        - label: Indium(III) oxide, a component
          line: "PubChem reports that 71.2% of company notifications for indium(III) oxide do not meet GHS criteria. Among the rest, codes include H372 (organ damage after prolonged exposure), with signal word Danger. These are data for the oxide, not for ITO films."
    - title: If it fails
      lead: "These failure routes come from the flight test, a heating test and a laboratory plasma test. The space results come from one NASA report on MISSE-9 samples."
      points:
        - label: Sheet resistance rises in ram orientation
          line: "On the MISSE-9 flight, ITO on Kapton HN/Al doubled its sheet resistance after ram exposure, to 10,820 ohm/square. NASA judged that low enough to dissipate static charge."
        - label: Heat
          line: "The supplier data show sheet resistance rising 16 % after three 12-hour cycles at 250 C, and 4 % at 210 C. The maximum recommended temperature is 300 C."
        - label: Silver-Teflon scatter
          line: "Sheet resistance readings on ITO/FEP/Ag/Inconel sheets scattered widely, with some flight readings above 370,000 ohm/square. NASA recommended re-measuring all samples with calibrated equipment."
        - label: Low MgF2 content
          line: "A 1994 NASA test in an oxygen plasma found low-MgF2 ITO-MgF2 films not durable, while high-MgF2 films were durable. This is a laboratory plasma result for the MgF2 variant, not a flight result."
    - title: Handling and storage
      points:
        - label: Dust
          line: "Angstrom Sciences says to avoid breathing dust and fume and to vacuum spills with a HEPA filter, without raising dust. Store locked up in a tightly closed container."
        - label: Heat limit
          line: "Keep films at or below 300 C. Above that the supplier gives no data, and even at 160 C sheet resistance rises 2.5 % in the supplier test."
  why: >-
    Indium tin oxide (ITO) is a mixed oxide of indium and tin, used as a thin film that is both electrically conductive and optically transparent.
    NASA coated flexible thermal-control sheets with ITO because a spacecraft in low Earth orbit builds up electrostatic charge that can cause arcing (NASA/TM-20240002413, Introduction).
    The supplier data page lists a sheet resistance of 70 to 100 ohm/square for a 70 nm ITO film on unpolished soda-lime glass, with nominal transmittance greater than 88 %.
  uses:
    - where: Spacecraft thermal-control sheets
      line: >-
        NASA flew six ITO-coated Kapton HN and silver-Teflon sheets on the MISSE-9 mission, for 0.77 years in ram and 0.54 years in wake and zenith.
        The authors found the samples not significantly damaged and suitable for thermal-control sheet use.
    - where: Solar-cell coverglass coatings
      line: >-
        A 1994 NASA study says a conductive protective coating is essential for solar cells in space, and tested ITO films with magnesium fluoride against atomic oxygen.
        Those were ITO-MgF2 films, not pure ITO.
    - where: Flat-panel displays
      line: >-
        The USGS says ITO thin-film coatings are mainly used as electrical conductors in flat-panel displays, most commonly liquid crystal displays (LCDs), and that ITO accounts for most global indium consumption.
  can_do:
    - label: Conduct and stay clear
      value: "70 to 100 ohm/square at 70 nm"
      benchmark: sheet_resistance
      line: >-
        On unpolished soda-lime glass, a 70 nm ITO film is listed at 70 to 100 ohm/square, with greater than 88 % nominal transmittance (supplier data page).
    - label: Survive low Earth orbit
      value: "9.04e-28 to 3.19e-23 cm3/atom"
      benchmark: atomic_oxygen_erosion_yield
      line: >-
        Atomic oxygen erosion yields for the six MISSE-9 flight samples ranged from 9.04e-28 to 3.19e-23 cm3/atom, and NASA called all of them very low.
    - label: Heat cycles
      value: "16 % sheet resistance rise at 250 C"
      benchmark: sheet_resistance_change
      line: >-
        After three 12-hour cycles at 250 C, the supplier data show a 16 % rise in sheet resistance. At 210 C the rise is 4 %, and the maximum recommended temperature is 300 C.
    - label: Reflect and absorb sunlight
      value: "0.423 solar absorptance (control)"
      benchmark: solar_absorptance
      line: >-
        The unflown control ITO on Kapton HN/Al has an AM0 solar absorptance of 0.423 and a total reflectance of 0.577. The largest absorptance increase on any flight sample was 0.002 (zenith).
  compare: >-
    The USGS names antimony tin oxide, carbon nanotube coatings, PEDOT, copper or silver nanowires, graphene and zinc oxide nanopowder as substitutes for ITO in some uses.
    The sources opened here give no property values for those alternatives, so this profile does not rank them against ITO; read the rows as ITO values only.
  compare_rows:
    - {label: Sheet resistance, benchmark: sheet_resistance}
    - {label: Refractive index, benchmark: refractive_index}
    - {label: Density, benchmark: density}
  handling:
    - Avoid dust. Vacuum spills with a HEPA filter and keep the container tightly closed, per the Angstrom Sciences SDS.
    - Keep films at or below 300 C, the supplier's maximum recommended temperature.
    - Respect the exposure limit of 0.1 mg/m3 as indium (OSHA and ACGIH).
  good_for:
    - "Transparent conductive films on flexible or glass substrates: 70 to 100 ohm/square at 70 nm, with greater than 88 % nominal transmittance."
    - "Thermal-control sheets in low Earth orbit: the MISSE-9 flight samples were not significantly damaged, with erosion yields from 9.04e-28 to 3.19e-23 cm3/atom."
    - "Displays: the USGS identifies flat-panel LCDs as the main use of ITO coatings."
  watch_out:
    - "Heat drift: sheet resistance rose 16 % after three 12-hour cycles at 250 C."
    - "Flight scatter: readings on silver-Teflon sheets ranged widely, with some above 370,000 ohm/square, and NASA called for recalibrated measurements."
    - "Indium supply: China produces 70 % of world indium, and China added indium to its export restrictions in February 2025 (USGS)."
    - "Component hazards: the indium oxide component is reported with H372 in some notifications, and the film products carry H335."
  verdict: "ITO is a transparent conductor that flew on spacecraft thermal sheets with very low erosion yields and no significant damage in the NASA MISSE-9 test. Its sheet resistance rises with heat (16 % at 250 C) and was scattered on silver-Teflon samples. Its supply depends on indium, which is on the USGS 2025 critical list. This profile has no ground or flight data on humidity, radiation dose or outgassing, and no measured melting point."
  recipe:
    line: "Indium tin oxide is a mixed oxide of indium and tin (Wikipedia). Supplier and NASA sources describe thin films deposited by sputtering, and the MISSE-9 flight coatings were about 10 nm thick (NASA/TM-20240002413, Materials section)."
    parts:
      - name: Indium
        symbol: In
        share_percent: 74
        role: "Main metal, 74 % by weight (Wikipedia)"
      - name: Tin
        symbol: Sn
        share_percent: 8
        role: "Tin component, 8 % by weight (Wikipedia)"
      - name: Oxygen
        symbol: O
        share_percent: 18
        role: "Oxygen, 18 % by weight (Wikipedia)"