Yttrium oxide Y2O3

spore: profile
id: yttrium-oxide
spore_version: 0.2
family: oxide-ceramics
name: Yttrium oxide
abbreviation: Y2O3
role: transparent and plasma-resistant oxide ceramic
category: ceramics
type: oxides
summary: |
  Yttrium oxide (yttria, Y2O3) is a white, air-stable oxide ceramic. Supplier data put its density at 4.90 g/cm3 or more for a 99.7% grade (Kyocera DEGUSSIT Y23) and at 5.01 g/cm3 for a Konoshima sintered body, and they show a four-point flexural strength of 180 MPa and an elastic modulus of 160 to 188 GPa. Suppliers sell it for infrared-transparent viewing windows, laser host ceramics and plasma-resistant coatings. The space record is limited to NASA work: a 2024 flight test of a spray-on coating made of yttria particles in a potassium bromide matrix, and a yttria tile that spent 17 months outside the ISS and changed only from 7.1% to 7.7% solar absorbance.
best_for: Plasma-resistant and infrared-transparent ceramic parts (Konoshima lists viewing windows and plasma-resistant use; CoorsTek describes exceptional plasma resistance)
weakest_at: Brittle fracture (fracture toughness 2.5 MPa·m½ in Konoshima's data) and air sensitivity of the powder (the supplier SDS calls it hygroscopic)
identity:
  formula: Y2O3
  cas: 1314-36-9
  source: pubchem-yttria
  where: PubChem CID 159374, molecular formula O3Y2, molecular weight 225.810; CAS 1314-36-9 printed in Section 1 of the Ereztech SDS (product Y4369)
tags:
  environments:
    - low-earth-orbit
  stresses:
    - atomic-oxygen
    - uv
    - extreme-heat
  applications:
    - thermal-control
    - electronics-and-chips
    - optics-and-cameras
properties:
  - benchmark: density
    label: Density, 99.7% grade (DEGUSSIT Y23)
    value: 4.9
    bound: lower
    unit: g/cm3
    scope: material
    conditions:
      grade: Kyocera DEGUSSIT Y23, content above 99.7%
      standard: DIN EN ISO 18754
      porosity: open porosity 0 vol-%
      reference_temperature: 20 °C
    method: Typical value from a manufacturer datasheet (printed as 4.90 with a greater-than-or-equal sign)
    status: ground
    source: kyocera-y23
    where: Mechanical and physical characteristics table, Density row
  - benchmark: density
    label: Density, Konoshima Y2O3 ceramic
    value: 5.01
    unit: g/cm3
    scope: material
    conditions:
      grade: Konoshima Y2O3 ceramics, purity not stated on the page
      table: 'Physical properties: Y2O3 ceramics'
    method: Value printed in a manufacturer physical-properties table
    status: ground
    source: konoshima-y2o3
    where: Physical properties table, Density row
  - benchmark: density
    label: Density, PubChem experimental record
    value: 4.84
    unit: g/cm3
    scope: material
    conditions:
      temperature: 25 °C
      basis: experimental value in the PubChem record (grade and method not stated)
    method: Experimental value quoted in a chemical database
    status: ground
    note: Lower than the two manufacturer values above; the record does not name the sample or method.
    source: pubchem-yttria
    where: Chemical and Physical Properties, Experimental Properties, Density (reference 27)
  - benchmark: melting_point
    label: Melting point
    value: 2410
    unit: °C
    scope: material
    conditions:
      material: yttrium oxide, Ereztech product Y4369, purity 99.9% or more
    method: Value printed in a supplier safety data sheet
    status: ground
    note: The SDS prints 2410 °C (4370 °F); PubChem's experimental record prints the same 2410 °C.
    source: ereztech-sds
    where: Section 9, Melting Point
  - benchmark: flexural_strength
    label: Flexural strength, 99.7% grade (DEGUSSIT Y23)
    value: 180
    unit: MPa
    scope: material
    conditions:
      grade: Kyocera DEGUSSIT Y23, content above 99.7%
      test: DIN EN 843-1, four-point bending
      temperature: 20 °C
      grain_size: 20 to 30 µm (ISO 13383-1 A1)
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-y23
    where: Mechanical and physical characteristics table, Flexural strength row
  - benchmark: flexural_strength
    label: Flexural strength range, Y2O3 (CoorsTek)
    value: 100
    value_high: 430
    bound: range
    unit: MPa
    scope: material
    conditions:
      material: CoorsTek yttria, grade not named on the page
      test: MOR at 20 °C
    method: Range printed on a manufacturer materials page
    status: ground
    note: The range is wide and the page does not give the grade or manufacturing route for each end of it.
    source: coorstek-yttria
    where: Yttria materials table, Flexural Strength MOR (20 °C) row
  - benchmark: elastic_modulus
    label: Elastic modulus, dynamic (DEGUSSIT Y23)
    value: 160
    unit: GPa
    scope: material
    conditions:
      grade: Kyocera DEGUSSIT Y23
      test: EN 843-2, dynamic
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-y23
    where: Mechanical and physical characteristics table, Young's modulus row
  - benchmark: elastic_modulus
    label: Elastic modulus, Konoshima Y2O3 ceramic
    value: 188
    unit: GPa
    scope: material
    conditions:
      grade: Konoshima Y2O3 ceramics
      temperature: not stated
    method: Value printed in a manufacturer physical-properties table
    status: ground
    source: konoshima-y2o3
    where: Physical properties table, Elastic modulus row
  - benchmark: poissons_ratio
    value: 0.32
    unit: '-'
    scope: material
    conditions:
      grade: Konoshima Y2O3 ceramics
    method: Value printed in a manufacturer physical-properties table
    status: ground
    source: konoshima-y2o3
    where: Physical properties table, Poisson ratio row
  - benchmark: fracture_toughness
    label: Fracture toughness, Konoshima Y2O3 ceramic
    value: 2.5
    unit: MPa·m½
    scope: material
    conditions:
      grade: Konoshima Y2O3 ceramics
      test: not stated on the page
    method: Value printed in a manufacturer physical-properties table (printed as MPam1/2)
    status: ground
    source: konoshima-y2o3
    where: Physical properties table, Fracture toughness row
  - benchmark: fracture_toughness
    label: Fracture toughness range, Y2O3 (CoorsTek)
    value: 1
    value_high: 4
    bound: range
    unit: MPa·m½
    scope: material
    conditions:
      material: CoorsTek yttria, grade not named on the page
      symbol: K Ic
    method: Range printed on a manufacturer materials page
    status: ground
    note: The CoorsTek low end (1.0) is less than half the Konoshima value (2.5), so toughness depends on the process.
    source: coorstek-yttria
    where: Yttria materials table, Fracture Toughness K Ic row
  - benchmark: vickers_hardness
    label: Vickers hardness, DEGUSSIT Y23
    value: 6.7
    unit: GPa
    scope: material
    conditions:
      grade: Kyocera DEGUSSIT Y23
      test: DIN EN ISO 14705, procedure A, HV 1.0
    method: Typical value from a manufacturer datasheet
    status: ground
    source: kyocera-y23
    where: Mechanical and physical characteristics table, Vickers Hardness row
  - benchmark: thermal_conductivity
    label: Thermal conductivity, Konoshima Y2O3 ceramic
    value: 14.5
    unit: W/mK
    scope: material
    conditions:
      grade: Konoshima Y2O3 ceramics
      temperature: not stated
    method: Value printed in a manufacturer physical-properties table (printed as W/mK)
    status: ground
    source: konoshima-y2o3
    where: Physical properties table, Thermal conductivity row
  - benchmark: thermal_conductivity
    label: Thermal conductivity range, Y2O3 (CoorsTek)
    value: 10
    value_high: 14
    bound: range
    unit: W/m K
    scope: material
    conditions:
      material: CoorsTek yttria, grade not named on the page
      temperature: 20 °C
    method: Range printed on a manufacturer materials page
    status: ground
    source: coorstek-yttria
    where: Yttria materials table, Thermal Conductivity (20 °C) row
  - benchmark: specific_heat
    value: 466
    unit: J/kgK
    scope: material
    conditions:
      grade: Konoshima Y2O3 ceramics
      unit_in_source: 0.466×10³ J/kgK
    method: Value printed as 0.466×10³ J/kgK in a manufacturer physical-properties table and written here as 466 J/kgK
    status: ground
    source: konoshima-y2o3
    where: Physical properties table, Specific heat row
  - benchmark: cte
    label: Mean linear expansion, 20 to 500 °C (DEGUSSIT Y23)
    value: 7.2
    unit: ppm/K
    scope: material
    conditions:
      grade: Kyocera DEGUSSIT Y23
      temperature_range: 20 to 500 °C
      standard: DIN EN ISO 17562
    method: Mean coefficient from a manufacturer datasheet (printed as 10-6/K)
    status: ground
    source: kyocera-y23
    where: Mechanical and physical characteristics table, Mean coefficient of linear thermal expansion, 20 to 500 °C row
  - benchmark: cte
    label: Mean linear expansion, 20 to 1000 °C (DEGUSSIT Y23)
    value: 7.9
    unit: ppm/K
    scope: material
    conditions:
      grade: Kyocera DEGUSSIT Y23
      temperature_range: 20 to 1000 °C
      standard: DIN EN ISO 17562
    method: Mean coefficient from a manufacturer datasheet (printed as 10-6/K)
    status: ground
    source: kyocera-y23
    where: Mechanical and physical characteristics table, Mean coefficient of linear thermal expansion, 20 to 1000 °C row
  - benchmark: cte
    label: Coefficient of thermal expansion range, Y2O3 (CoorsTek)
    value: 7.9
    value_high: 8.2
    bound: range
    unit: ppm/K
    scope: material
    conditions:
      material: CoorsTek yttria, grade not named on the page
      unit_in_source: 1x10-6 per °C
    method: Range printed on a manufacturer materials page
    status: ground
    source: coorstek-yttria
    where: Yttria materials table, Coefficient of Thermal Expansion row
  - benchmark: max_service_temp
    label: Maximum service temperature in air (DEGUSSIT Y23)
    value: 2200
    unit: °C
    scope: material
    conditions:
      grade: Kyocera DEGUSSIT Y23
      atmosphere: in air
    method: Rating from a manufacturer datasheet
    status: ground
    source: kyocera-y23
    where: Mechanical and physical characteristics table, Maximum service temperature row
  - benchmark: max_service_temp
    label: Maximum use temperature, Y2O3 (CoorsTek)
    value: 2000
    unit: °C
    scope: material
    conditions:
      material: CoorsTek yttria, grade not named on the page
      load: not stated on the page
    method: Rating printed on a manufacturer materials page
    status: ground
    source: coorstek-yttria
    where: Yttria materials table, Maximum Use Temperature row
  - benchmark: dielectric_strength
    value: 16.5
    unit: kV/mm
    scope: material
    conditions:
      material: CoorsTek yttria
      test: ac, 6.35 mm specimen thickness
    method: Value printed on a manufacturer materials page
    status: ground
    source: coorstek-yttria
    where: Yttria materials table, Dielectric Strength (6.35 mm) row
  - benchmark: refractive_index
    value: 1.92
    unit: '-'
    scope: material
    conditions:
      grade: Konoshima Y2O3 ceramics
      wavelength: 532 nm
    method: Value printed in a manufacturer physical-properties table (printed as 1.92 at 532 nm)
    status: ground
    source: konoshima-y2o3
    where: Physical properties table, Refractive index row
  - benchmark: solar_absorptance
    label: Solar absorptance, spray-on solar white (flight test, modelled)
    value: 0.02
    value_high: 0.04
    bound: range
    unit: '-'
    scope: material
    conditions:
      coating: 'spray-on solar white: yttrium oxide scattering particles in a potassium bromide crystal matrix, on aluminium discs'
      flight: Vulcan Centaur CERT-2, launched 4 October 2024, about 5 hours in low Earth orbit
      basis: numerical thermal model fitted to flight temperatures
    method: Range inferred by modelling of flight temperature data (the memo's abstract and conclusion)
    status: calculated
    note: Not a direct solar absorptance measurement; the memo's model range is consistent with laboratory measurements, per its abstract.
    source: nasa-tm-2026
    where: Abstract; Section 4 and Table 2 (model parameters); Section 5 (Conclusion)
  - benchmark: thermal_emittance
    label: Thermal emittance, spray-on solar white (flight test, modelled)
    value: 0.93
    value_high: 0.99
    bound: range
    unit: '-'
    scope: material
    conditions:
      coating: spray-on solar white on aluminium discs
      flight: Vulcan Centaur CERT-2 mission, 2024
    method: Range inferred by modelling of flight temperature data
    status: calculated
    source: nasa-tm-2026
    where: Abstract; Section 5 (Conclusion)
  - benchmark: solar_absorbance
    label: Solar absorbance after 17 months outside the ISS (MISSE-11 Y2O3 tile)
    value: 7.7
    unit: '%'
    scope: material
    conditions:
      specimen: rigid Y2O3 tile, wake position on the MISSE-11 carrier
      exposure: about 17 months outside the ISS, net solar exposure roughly 1000 hours (estimate in the report)
      before: 7.1 % before flight (control tile comparison)
      returned: 13 January 2021
    method: Measured reflectance spectrum after flight, compared with a control tile
    status: flight
    note: The report says the sample was recessed in its holder, which shifts the reflectance measurement downward, so the change matters more than the absolute value.
    source: nasa-gibson-2022
    where: Section 3.5.4.2 (MISSE-11 Y2O3) and Figure 3-31
  - benchmark: solar_absorbance
    label: Solar absorbance, rigid Y2O3 tile (ground test)
    value: 1.2
    unit: '%'
    scope: material
    conditions:
      measurement: GRC deep space simulator
      form: rigid Y2O3 tile
    method: Value reported in the report's abstract as the achieved result
    status: ground
    note: Measured against a 1% threshold goal set by the project.
    source: nasa-gibson-2022
    where: Abstract
  - benchmark: solar_absorbance
    label: Solar absorbance, spray-on solar white (ground test)
    value: 4
    unit: '%'
    scope: material
    conditions:
      measurement: KSC reflectance spectrometer referenced to Spectralon
      form: spray-on coating on aluminium
    method: Value reported in the report's abstract as the achieved result
    status: ground
    note: Measured against a 6% threshold goal set by the project.
    source: nasa-gibson-2022
    where: Abstract
  - benchmark: solar_absorbance
    label: Solar absorbance of spray-on coating after atomic oxygen exposure (ground test)
    value: 12
    value_high: 13
    bound: range
    unit: '%'
    scope: material
    conditions:
      form: spray-on coating on aluminium
      start: about 8 % before exposure
      fluence: total atomic oxygen fluence axis of Figure 3-36 (not read as a number)
    method: Range read from the report's text describing a laboratory atomic oxygen chamber test
    status: ground
    source: nasa-gibson-2022
    where: Section 3.5.5.1 (Atomic Oxygen), text and Figure 3-36
corrosion:
  - environment: High-density CF4/O2 plasma (inductively coupled etch chamber, plasma density 10^12 to 10^13 cm-3)
    headline: A Y2O3 coating in fluorocarbon plasma forms an oxyfluoride surface film and sheds more contamination particles than YF3.
    effect: After high-density CF4/O2 etching, transmission electron microscopy showed a yttrium oxyfluoride film 5.2 nm thick on the Y2O3 coating, against 6.8 nm on YF3. The authors conclude that YF3 is more erosion-resistant and produces fewer contamination particles than Y2O3, and attribute this to Y-O bonds being weaker than Y-F bonds.
    rating: moderate
    conditions:
      coating: atmospheric-plasma-sprayed Y2O3 and YF3 coatings
      equipment: industrial ICP etcher (LAM 2300 Metal) under a routine etch recipe
      note: laboratory and production-tool test, not a space environment
    source: pmc-erosion-2017
    where: Abstract; Results (TEM, Figure 6); Conclusions
  - environment: Air and moisture (storage and handling of the powder)
    headline: The powder is hygroscopic and air sensitive, so the supplier asks for storage under inert gas.
    effect: Ereztech states that the product is hygroscopic and air sensitive, recommends handling under a dry inert gas with nitrogen containing less than 5 ppm each of moisture and oxygen, and lists exposure to air, water or moisture as a condition to avoid. The SDS gives no weight-gain figure for moisture uptake.
    rating: moderate
    conditions:
      form: yttrium oxide powder, product Y4369
      exposure: not quantified in the SDS
    source: ereztech-sds
    where: Section 7 (Safe Storage Conditions); Section 10 (Conditions to Avoid)
  - environment: Solar ultraviolet, laboratory lamp and flight exposure
    headline: Lab ultraviolet exposure darkened Y2O3 far more than the flown sample did, and heating partly healed the damage.
    effect: The report says that laboratory exposure was predicted to raise solar absorption by 25% after 800 hours of full sun, but the MISSE-11 tile changed by less than 1% (7.1% to 7.7%) after about 1000 hours of net solar exposure in the wake position. Discoloured tiles healed partly when heated in air or argon, which the authors offer as one reason for the gap between lab and flight.
    rating: moderate
    conditions:
      lab: Y2O3 tile exposed to UV in a vacuum chamber (wavelength and dose details in Appendix E)
      flight: MISSE-11 external ISS tray, about 17 months
      note: the report also considers solar simulation (lamp spectrum) as a possible reason for the difference
    source: nasa-gibson-2022
    where: Section 3.5.5.4 (Y2O3 Ultraviolet Degradation) and Section 3.5.4.2 (MISSE-11 Y2O3); Appendix E
  - environment: Atomic oxygen (laboratory chamber)
    headline: Atomic oxygen degraded the Y2O3 tile slightly and the spray-on coating more, in the ground test.
    effect: The report says the tiles start at 1 to 2% solar absorbance and degrade to above 4%, and the spray-on coating starts at about 8% and degrades to about 12 to 13%. It also says atomic oxygen caused some degradation, and that the MISSE-11 tile saw very little atomic oxygen because of its position on the rack.
    rating: low
    conditions:
      lab: atomic oxygen chamber at NASA Glenn Research Center, Appendix D
      coating: rigid Y2O3 tile and spray-on coating on aluminium
    source: nasa-gibson-2022
    where: Section 3.5.5.1 (Atomic Oxygen), Figure 3-36; Appendix D
risks:
  hazards:
    - text: PubChem reports that yttrium oxide does not meet GHS hazard criteria for 50% (274 of 548) of company reports. The classifications that remain are H315 (causes skin irritation, 43.6% of reports), H319 (causes serious eye irritation, 36.7%) and H335 (may cause respiratory irritation, 43.6%), with the signal word Warning.
      ghs:
        - H315
        - H319
        - H335
      source: pubchem-yttria
      where: Safety and Hazards, GHS Classification (CID 159374)
    - text: The Ereztech SDS for product Y4369 (issued 17 March 2026) classifies the powder as skin irritation category 2, serious eye irritation category 2 and specific target organ toxicity (single exposure, respiratory tract irritation) category 3, with the signal word WARNING.
      ghs:
        - H315
        - H319
        - H335
      source: ereztech-sds
      where: Section 2 (Hazards Identification), Classification and Hazard Statements
    - text: PubChem's aggregated record also lists Aquatic Chronic 4 at 100%, with the hazard statement H413 (may cause long lasting harmful effects to aquatic life).
      ghs:
        - H413
      source: pubchem-yttria
      where: Safety and Hazards, GHS Classification (CID 159374), second notification block
  failure_risks:
    - mode: Moisture uptake and air sensitivity of the powder
      trigger: Storage or handling of the powder in ordinary air
      consequence: The supplier calls the product hygroscopic and air sensitive and recommends storage under inert gas in a tightly sealed container. The SDS lists exposure to air, water and moisture as a condition to avoid, so an open container can change the material before use.
      severity: moderate
      source: ereztech-sds
      where: Section 7 (Safe Storage Conditions); Section 10 (Conditions to Avoid)
    - mode: Brittle cracking under tension or bending
      trigger: Tensile load or bending on a part with a flaw or sharp corner
      consequence: Konoshima gives a fracture toughness of 2.5 MPa·m½ and CoorsTek a range of 1.0 to 4.0 MPa·m½, against a flexural strength of 180 MPa for the Kyocera 99.7% grade. Ceramic parts crack suddenly rather than bend.
      severity: moderate
      source: konoshima-y2o3
      where: Physical properties table, Fracture toughness row; Kyocera DEGUSSIT Y23 flexural strength row; CoorsTek Fracture Toughness row
    - mode: Particle shedding in fluorocarbon plasma
      trigger: High-density CF4/O2 plasma etching of a Y2O3-coated chamber wall
      consequence: The Y2O3 coating produced more contamination particles than YF3 in the same test. The flaking particles contained yttrium, oxide and fluoride, which can end up on a wafer and cause integrated-circuit defects.
      severity: moderate
      source: pmc-erosion-2017
      where: Abstract; Results (EDX of circular particles); Discussion
    - mode: Darkening under ultraviolet exposure
      trigger: Solar ultraviolet exposure without the protection of the flight tray
      consequence: In the laboratory the tile darkened much more than the flown sample, and the report says the effect is serious enough for a section of its own. A thermal-control surface whose absorbance rises changes its equilibrium temperature.
      severity: moderate
      source: nasa-gibson-2022
      where: Section 3.5.5.4 (Y2O3 Ultraviolet Degradation)
  side_effects: []
  handling:
    - text: Handle the powder under a dry inert gas. The SDS recommends nitrogen with less than 5 ppm each of moisture and oxygen, keeps the container tightly sealed, and asks that the product be stored protected from direct sunlight in a cool, dry, well-ventilated area.
      source: ereztech-sds
      where: Section 7 (Handling and Storage), Precautions and Safe Storage Conditions
    - text: Avoid forming and breathing dust. The SDS asks for adequate ventilation or an explosion-proof fume hood, and lists the ACGIH threshold limit value of 1 mg/m3 as yttrium, time-weighted average.
      source: ereztech-sds
      where: Section 7 (Precautions); Section 8 (Occupational Exposure Limits)
    - text: Keep away from strong oxidizing agents and strong acids. In a fire the product gives yttrium oxides as decomposition products.
      source: ereztech-sds
      where: Section 10 (Incompatible Materials, Hazardous Decomposition Products)
  mitigations:
    - text: Ask the supplier for specified values for critical parts. CoorsTek states that property values vary somewhat with the method of manufacture, the size and shape of the part.
      source: coorstek-yttria
      where: Yttria materials page, property table notes
    - text: Kyocera states that its values are typical properties and may vary with the product configuration and manufacturing process.
      source: kyocera-y23
      where: Preliminary remark under the property table (DIN 60672-2)
uses:
  - application: optics-and-cameras
    device: Infrared viewing windows (ceramic, supplier application)
    example: Konoshima lists a viewing window among its Y2O3 applications and states that its ceramics have excellent light transmission from the visible region to the infrared region.
    source: konoshima-y2o3
    where: Applications list and features (Y2O3 ceramics page)
  - application: optics-and-cameras
    device: Solid-state laser host ceramic (dopant ions added, supplier application)
    example: Konoshima says a laser oscillation medium is available by adding various dopant ions to its Y2O3 ceramic.
    source: konoshima-y2o3
    where: Applications list and features (Y2O3 ceramics page)
  - application: electronics-and-chips
    device: Protective chamber-wall coating in high-density fluorocarbon plasma etch tools (laboratory and production-tool test)
    example: A 2017 study coated an inductively coupled etch chamber wall with atmospheric-plasma-sprayed Y2O3 and YF3 and compared particle contamination on 300 mm wafers under CF4/O2 plasma.
    source: pmc-erosion-2017
    where: Abstract; Introduction; Experimental section
  - application: electronics-and-chips
    device: Plasma-resistant barrier coating and solid parts (commercial supplier offer)
    example: CoorsTek describes yttria as having exceptional plasma resistance and sells its Exyria yttria as solid parts and coatings, including a PlasmaResist coating that creates a corrosively inert barrier of pure yttria on compatible components.
    source: coorstek-yttria
    where: Yttria Overview
  - application: thermal-control
    device: Spray-on solar white cryogenic thermal control coating (spacecraft flight test)
    example: NASA's April 2026 memo reports that discs coated with spray-on solar white were flown in low Earth orbit for about five hours on the Vulcan Centaur CERT-2 mission, launched 4 October 2024. The spray-on coating absorbed the least sunlight of the three coatings tested.
    source: nasa-tm-2026
    where: Abstract; Section 1 (Introduction); Section 2 (Payload); Figure 4 and Section 3 (flight data)
  - application: thermal-control
    device: Rigid Y2O3 tile on an external ISS experiment (MISSE-11)
    example: A Y2O3 tile flown outside the ISS for about 17 months on the MISSE-11 mission changed from 7.1% to 7.7% solar absorbance, a small degradation that the report calls impressive.
    source: nasa-gibson-2022
    where: Section 3.5.4.2 (MISSE-11 Y2O3)
supply:
  - subject: Yttrium (reported as Y2O3 equivalent)
    producers: []
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (yttrium is on the final list)
        listed: true
    recycling: 'USGS: Recycling: Insignificant.'
    substitutes:
      - 'USGS: as a stabilizer in zirconia ceramics, Y2O3 may be substituted with calcium oxide or magnesium oxide, but the substitutes generally impart lower toughness. In most uses, especially in electronics, lasers and phosphors, yttrium is generally not subject to direct substitution.'
    source: usgs-mcs2026-yttrium
    where: 'Yttrium chapter: Domestic Production and Use; Salient Statistics (net import reliance 100% in 2025e); World Mine Production and Reserves (2025 world mine production 10,000 to 15,000 t Y2O3 equivalent in rare-earth concentrates; China produced most, and Burma a significant share; no country shares are printed); Recycling; Substitutes. The critical-list entry is confirmed on the USGS 2025 list page (usgs-crit2025). The EU critical raw materials list is not included: its web page names only the heavy rare earths as a group.'
documents:
  - title: Kyocera Fineceramics Europe DEGUSSIT Y23 datasheet (yttrium oxide, February 2025)
    type: datasheet
    url: https://kyocera-fineceramics.de/fileadmin/user_upload/Download/werkstoffdatenblaetter/Yttriumoxid/KFEG_Data_sheets_EN_2025_Y23.pdf
    year: 2025
  - title: 'Konoshima: Y2O3 ceramics (physical properties, applications)'
    type: datasheet
    url: https://konoshima.co.jp/eng/ceramics/y2o3.html
    year: 2026
  - title: 'CoorsTek: Yttria (Exyria) materials page with property table'
    type: datasheet
    url: https://coorstek.com/en/materials/yttria/
    year: 2026
  - title: 'PubChem: Yttrium oxide (CID 159374), GHS classification and experimental properties'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/159374
    year: 2026
  - title: 'Ereztech safety data sheet: Yttrium oxide, product Y4369 (revision 1.00, issued 17 March 2026)'
    type: sds
    url: https://ereztech.com/wp-content/uploads/chemical_sds/SDS-Y4369.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Yttrium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-yttrium.pdf
    year: 2026
  - title: 'NASA KSC: In-Space Demonstration of Spray-on Solar White Paint (NASA/TM-20260002733)'
    type: report
    url: https://ntrs.nasa.gov/citations/20260002733
    year: 2026
  - title: 'NASA KSC: Cryogenic Thermal Coatings Final Report (NTRS 20220016987)'
    type: report
    url: https://ntrs.nasa.gov/citations/20220016987
    year: 2022
  - title: Comparison of Erosion Behavior and Particle Contamination in Mass-Production CF4/O2 Plasma Chambers Using Y2O3 and YF3 Protective Coatings (open access)
    type: paper
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC5535249/
    year: 2017
gaps:
  - No vacuum outgassing (TML/CVCM) result for bulk yttria was found in a source we could open. The flown results are for a spray-on coating and a MISSE-11 tile, not for a bulk part.
  - The spray-on solar white is yttria particles in a potassium bromide matrix. Its flight and ground absorptance values describe that coating, not pure Y2O3 alone, and are kept separate from the bulk properties.
  - Crystal system and space group were not read in a primary source. Wikipedia names the cubic bixbyite structure and space group Ia3 (No. 206), but the page is not used for structure here.
  - Atomic weights for yttrium and oxygen were not read in a source opened for this profile, so the recipe parts carry no atomic_weight.
  - Abundance of yttrium in the Earth's crust was not found in a source we could open. The USGS yttrium chapter gives no country shares for world mine production, so producers are left empty.
  - The EU critical raw materials web page names only the heavy rare earths as a group, so no EU list entry is given for yttrium.
  - 'Konoshima''s hardness of 10 GPa is not used: the page does not name the test method, so it cannot be compared with the Vickers value from Kyocera.'
  - Thermal shock temperature difference and fracture energy were not found in any source opened for yttria.
  - Vickers hardness, solar absorptance, thermal emittance and solar absorbance are not in the property canon. They use short snake_case benchmark names, and the values are as printed.
  - A 2024 MDPI coating paper on fluorine-chemistry degradation of Y2O3 and the 2025 Korean densified-yttria abstract were seen in search results only and were not read in full, so their findings are not used.
  - Hydration of Y2O3 to yttrium hydroxide on exposure to water was not confirmed in a pure-yttria source; only a patent and mixed-oxide studies were seen.
  - Hazard data rest on the PubChem summary and one supplier SDS; the SDS toxicology section was not read for this profile, and the SDS reports no relative density.
  - Dielectric loss (4 x 10-4 at 1 MHz, 25 °C) and volume resistivity (10^14 to 10^16 ohm-cm at 25 °C) are printed on the CoorsTek materials page, but with superscript exponents that the value check could not match. They are left out until they are checked by hand against that page.
sources:
  kyocera-y23:
    title: 'Kyocera Fineceramics Europe: DEGUSSIT Y23 (yttrium oxide) material datasheet'
    id: Kyocera DEGUSSIT Y23, February 2025
    url: https://kyocera-fineceramics.de/fileadmin/user_upload/Download/werkstoffdatenblaetter/Yttriumoxid/KFEG_Data_sheets_EN_2025_Y23.pdf
    year: 2025
    kind: datasheet
    license: supplier document, linked not reproduced
  konoshima-y2o3:
    title: 'Konoshima: Y2O3 ceramics (physical properties and applications)'
    id: Konoshima Y2O3 ceramics page
    url: https://konoshima.co.jp/eng/ceramics/y2o3.html
    year: 2026
    kind: web
    license: supplier page, linked not reproduced
  coorstek-yttria:
    title: 'CoorsTek Technical Ceramics: Yttria (Exyria) materials page'
    id: CoorsTek yttria materials page
    url: https://coorstek.com/en/materials/yttria/
    year: 2026
    kind: web
    license: supplier page, linked not reproduced
  pubchem-yttria:
    title: PubChem compound record, Yttrium oxide (CID 159374)
    id: CID 159374; molecular formula O3Y2
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/159374/JSON
    year: 2026
    kind: database
    license: public domain (NCBI)
  ereztech-sds:
    title: 'Ereztech safety data sheet: Yttrium oxide, product Y4369 (revision 1.00)'
    id: Ereztech Y4369, date of issue 3/17/2026, CAS 1314-36-9
    url: https://ereztech.com/wp-content/uploads/chemical_sds/SDS-Y4369.pdf
    year: 2026
    kind: datasheet
    license: supplier document, linked not reproduced
  usgs-mcs2026-yttrium:
    title: Mineral Commodity Summaries 2026, Yttrium
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-yttrium.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)
  nasa-tm-2026:
    title: In-Space Demonstration of Spray-on Solar White Paint (NASA/TM-20260002733)
    id: NASA/TM-20260002733, NTRS 20260002733, April 2026
    url: https://ntrs.nasa.gov/api/citations/20260002733/downloads/20260002733%20TM%20Final.pdf
    year: 2026
    kind: report
    license: public domain (NASA)
  nasa-gibson-2022:
    title: Cryogenic Thermal Coatings Final Report (Kennedy Space Center)
    id: NTRS 20220016987, October 2022
    url: https://ntrs.nasa.gov/api/citations/20220016987/downloads/CFT-RPT-0015%20Cryogenic%20Thermal%20Coating%20Final%20Report_Basic_Native_Final_WO%20Signature%20Page.pdf
    year: 2022
    kind: report
    license: public domain (NASA)
  pmc-erosion-2017:
    title: Comparison of Erosion Behavior and Particle Contamination in Mass-Production CF4/O2 Plasma Chambers Using Y2O3 and YF3 Protective Coatings
    id: doi:10.3390/nano7070183 (Nanomaterials 7(7), 183, PMC5535249)
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC5535249/
    year: 2017
    kind: paper
    license: CC BY 4.0
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 28
  unreachable: 1
  caveats: 4
  note: 'Read by an AI assistant on 2026-10-26 from the source pages and PDFs fetched in that run. The Wikipedia page was used only for the crystal-system text in the gaps. One 2024 MDPI coating paper was seen in search results only and is not used. Caveats: the CoorsTek and Konoshima values have no grade named; the PubChem density and the NASA absorptance values come from different sample types; the NASA MISSE-11 change is a reflectance comparison, not a direct absorptance measurement.'
story:
  recipe:
    line: Y₂O₃ is a metal oxide. Each formula unit combines two yttrium atoms with three oxygen atoms. Yttria is a white solid that is insoluble in water.
    parts:
      - name: Yttrium
        symbol: 'Y'
        role: The metal. Yttrium is one of the rare-earth elements and sits in the oxide as Y³⁺ (the trivalent ion).
      - name: Oxygen
        symbol: O
        role: Three oxygen atoms per formula unit balance the charge of the two yttrium ions.
  risk_groups:
    - title: For people
      level: 1
      verdict: Irritant powder
      lead: The supplier and most PubChem reports classify yttria powder as an irritant to skin, eyes and the respiratory tract. Data for finished ceramic parts are thin.
      points:
        - label: The powder
          line: The supplier's safety data sheet classifies yttrium oxide as skin irritant category 2, serious eye irritant category 2 and respiratory irritant category 3, with the signal word Warning. PubChem reports the same three hazards in 43.6%, 36.7% and 43.6% of its notifications.
        - label: Exposure limit
          line: The SDS lists an ACGIH threshold limit value of 1 mg/m³ as yttrium, time-weighted average, and an IDLH of 500 mg/m³ as yttrium under NIOSH.
        - label: Aquatic life
          line: PubChem's aggregated record includes a long-term aquatic hazard, H413, at 100%.
    - title: If it fails
      lead: These results come from manufacturer tests, plasma tests and NASA ground and flight tests, not from incidents in service.
      points:
        - label: Cracking
          line: Yttria fails by cracking. Konoshima gives a fracture toughness of 2.5 MPa·m½, and CoorsTek gives 1.0 to 4.0 MPa·m½.
        - label: Ultraviolet
          line: In the laboratory, ultraviolet darkened a yttria tile far more than the flown tile, which changed from 7.1% to 7.7% solar absorbance after about 17 months on the ISS.
        - label: Plasma
          line: In a high-density fluorocarbon plasma, a Y2O3 coating shed more contamination particles than YF3 and formed a 5.2 nm oxyfluoride film.
    - title: Handling and storage
      points:
        - label: Keep it dry
          line: The supplier calls the powder hygroscopic and air sensitive. Store it under dry nitrogen with less than 5 ppm each of moisture and oxygen, in a tightly sealed container.
        - label: Avoid dust
          line: Avoid forming and breathing dust, and use adequate ventilation or a fume hood.
        - label: Keep it apart
          line: Keep the powder away from strong oxidizing agents and strong acids. In a fire it gives yttrium oxides.
  why: 'Yttrium oxide (yttria, Y₂O₃) is a white, air-stable oxide ceramic that is insoluble in water. Its ceramic form is dense, stiff and transparent to infrared light, and suppliers sell it for plasma resistance. The supplier data and the NASA tests show that it is a useful optical and thermal-control material, and they show its limits: a low toughness, sensitivity of the powder to moisture, and darkening under ultraviolet light in the laboratory.'
  uses:
    - where: Infrared viewing windows
      line: Konoshima lists viewing windows among its Y2O3 applications and states that its ceramics have excellent light transmission from the visible region to the infrared region.
    - where: Laser host ceramic
      line: Konoshima says a laser oscillation medium is available by adding various dopant ions to its Y2O3 ceramic.
    - where: Chamber coatings in plasma etch tools
      line: A 2017 study coated an inductively coupled etch chamber wall with atmospheric-plasma-sprayed Y2O3 and YF3 and compared particle contamination on 300 mm wafers under CF4/O2 plasma. It is a laboratory and production-tool test.
    - where: Spray-on thermal control coating in space
      line: NASA's April 2026 memo reports discs coated with spray-on solar white, a coating of yttria particles in potassium bromide, flown in low Earth orbit for about five hours on the Vulcan Centaur CERT-2 mission launched on 4 October 2024. The coating absorbed the least sunlight of the three coatings tested.
    - where: Tile on an external ISS experiment
      line: A rigid Y2O3 tile flown outside the ISS for about 17 months on the MISSE-11 mission changed from 7.1% to 7.7% solar absorbance.
  can_do:
    - label: Infrared transparency
      value: Visible to infrared
      line: Konoshima states that its Y2O3 ceramics transmit light from the visible region to the infrared region. Its printed refractive index is 1.92 at 532 nm.
    - label: Heat
      value: 2200 °C in air
      line: Kyocera lists a maximum service temperature in air of 2200 °C for its DEGUSSIT Y23 grade. CoorsTek lists 2000 °C for its yttria.
    - label: Stiffness and hardness
      value: 160 to 188 GPa
      line: The elastic modulus is 160 GPa (dynamic, Kyocera) and 188 GPa (Konoshima). The Vickers hardness of the Kyocera grade is 6.7 GPa.
    - label: Plasma resistance
      value: Plasma-resistant barrier
      line: CoorsTek describes yttria as having exceptional plasma resistance and sells PlasmaResist coatings of pure yttria. In a 2017 plasma study the Y2O3 coating formed a 5.2 nm oxyfluoride film.
    - label: Low solar absorbance
      value: 1.2% to 4% in ground tests
      line: In NASA ground tests the rigid tile reached 1.2% solar absorbance and the spray-on coating 4%. The spray-on coating's absorptance, modelled from its 2024 flight data, is 0.02 to 0.04.
  compare: The two supplier sources differ on strength and toughness. Kyocera's 99.7% grade has a flexural strength of 180 MPa, and CoorsTek's yttria spans 100 to 430 MPa, with fracture toughness of 1.0 to 4.0 MPa·m½ against 2.5 MPa·m½ from Konoshima. The CoorsTek page gives a lower maximum use temperature than Kyocera's, at 2000 against 2200 °C. The table compares yttria's use temperature, thermal conductivity and density across the sources.
  compare_rows:
    - label: Highest use temperature
      benchmark: max_service_temp
    - label: Heat conduction
      benchmark: thermal_conductivity
    - label: Density
      benchmark: density
  handling:
    - Handle and store the powder under dry inert gas. The supplier asks for nitrogen with less than 5 ppm each of moisture and oxygen.
    - Avoid dust. Use ventilation or a fume hood, and keep to the ACGIH limit of 1 mg/m³ as yttrium.
    - Keep it apart from strong oxidizing agents and strong acids.
  good_for:
    - Infrared-transparent optics. Konoshima states that its Y2O3 ceramics transmit from the visible to the infrared region.
    - Plasma-resistant chamber parts. CoorsTek offers yttria solid parts and coatings for corrosive environments, and a 2017 plasma study shows the Y2O3 coating forming a thin protective film.
    - Low-absorptance thermal coatings. A spray-on yttria coating reached 0.02 to 0.04 solar absorptance in a 2024 flight test (modelled).
  watch_out:
    - Brittle fracture. Fracture toughness is 2.5 MPa·m½ in one datasheet and 1.0 to 4.0 MPa·m½ in another.
    - Air and moisture sensitivity of the powder. Store it dry and sealed.
    - Darkening under ultraviolet light. The lab tile darkened much more than the flown tile, so flight results should not be expected from ground tests alone.
    - Particle shedding in fluorocarbon plasma. The Y2O3 coating shed more particles than YF3 in one test.
  verdict: Yttria is a strong candidate for plasma-resistant and infrared-transparent ceramic parts, and a useful low-absorptance coating in space. Its brittleness and its sensitivity to moisture and ultraviolet light are the main limits, and the space record is a coating and a single flown tile rather than a bulk part.