spore: profile
id: gadolinium-oxide
spore_version: 0.2
family: rare-earth-oxides
name: Gadolinium oxide (Gd2O3)
abbreviation: Gd2O3
role: neutron-absorbing oxide, solid-state laser host and oxide precursor
category: ceramics
type: oxides
summary: |
  Gadolinium(III) oxide (Gd2O3, also called gadolinia) is a white powder. The Lorad Chemical safety data sheet gives its density as 7.07 g/cm3 and its melting point as above 2,420 °C (Wikipedia also gives 2,420 °C). The supplier classifies it for one hazard only, serious eye irritation (H319), and says the powder is hygroscopic.
best_for: Neutron-absorbing rare-earth oxide in reactor control rods and neutron shields, and as a laser host (Merck Index via PubChem; Wikipedia)
weakest_at: Hygroscopic powder that takes up moisture from air and dissolves in strong acids (Lorad SDS; Wikipedia)
identity:
  formula: 'Gd2O3, gadolinium(III) oxide: two gadolinium(III) ions and three oxide ions per formula unit'
  cas: 12064-62-9
  crystal_system: cubic and monoclinic (sources disagree; see gaps)
  space_group: C2/m for the monoclinic form (ChemicalBook and Wikipedia); Ia-3 for the cubic form (Wikipedia)
  source: lorad-sds
  where: 'Section 1 (formula) and Section 3 Composition (CAS # 12064-62-9, EC # 235-060-9, additional names Gadolinia, Gadolinium Trioxide, Gadolinium Sesquioxide)'
designations:
  - system: EC
    code: 235-060-9
    source: lorad-sds
    where: 'Section 3 Composition, EC #'
tags:
  applications:
    - radiation-shielding
    - optics-and-cameras
properties:
  - benchmark: molar_mass
    label: Molar mass (formula mass)
    value: 362.5
    unit: g/mol
    scope: material
    conditions:
      form: Gd2O3, 100 % of the product as listed
    method: Value printed in a supplier safety data sheet
    status: ground
    source: lorad-sds
    where: Section 9 Physical and Chemical Characteristics, Molecular Weight
  - benchmark: density
    label: Density, Lorad Chemical safety data sheet
    value: 7.07
    unit: g/cm3
    scope: material
    conditions:
      temperature: not stated
      form: powder, white
    method: Value printed in a supplier safety data sheet
    status: ground
    source: lorad-sds
    where: Section 9 Physical and Chemical Characteristics, Density
  - benchmark: density
    label: Density, Wikipedia infobox
    value: 7.07
    unit: g/cm3
    scope: material
    conditions:
      temperature: not stated
      citation: Patnaik (2002), as cited in the infobox
    method: Value printed in the Wikipedia infobox, which cites a reference for it
    status: ground
    source: wikipedia-gd2o3
    where: Infobox, row Density
  - benchmark: density
    label: Density, ChemicalBook product page
    value: 7.407
    unit: g/mL
    scope: material
    conditions:
      temperature: 20 °C
      note_in_source: lit.
    method: Value printed on a reseller's catalogue page; the page does not name its original source
    status: ground
    note: The Wikipedia infobox and the Lorad SDS give 7.07 g/cm3 for the same compound, a difference of about 5 %, and PubChem lists 7.407 with no unit printed.
    source: chemicalbook-product
    where: Physical and chemical properties block, Density
  - benchmark: melting_point
    label: Melting point, Lorad Chemical safety data sheet
    value: 2420
    bound: lower
    unit: °C
    scope: material
    conditions:
      pressure: not stated
      unit_in_source: '> 2,420 °C (> 4,388 °F)'
    method: Lower bound printed in a supplier safety data sheet
    status: ground
    source: lorad-sds
    where: Section 9, Melting Point / Freezing Point
  - benchmark: melting_point
    label: Melting point, Wikipedia infobox
    value: 2420
    unit: °C
    scope: material
    conditions:
      pressure: not stated
      unit_in_source: 2,420 °C (4,390 °F; 2,690 K)
    method: Value printed in the Wikipedia infobox
    status: ground
    source: wikipedia-gd2o3
    where: Infobox, row Melting point
  - benchmark: melting_point
    label: Melting point, ChemicalBook product page
    value: 2330
    unit: °C
    scope: material
    conditions:
      note_in_source: lit.
    method: Literature value printed on a reseller's catalogue page
    status: ground
    source: chemicalbook-product
    where: Physical and chemical properties block, Melting point
  - benchmark: thermal_conductivity
    label: Thermal conductivity, ChemicalBook product page
    value: 10.042
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: not stated
      form: not stated
    method: Value printed on a reseller's catalogue page without test conditions
    status: ground
    note: No temperature or porosity is stated, so the value cannot be compared with dense ceramic data without the test conditions.
    source: chemicalbook-product
    where: Physical and chemical properties block, Thermal Conductivity
  - benchmark: specific_heat
    label: Specific heat capacity, crystal
    value: 0.294345
    unit: J/(g·K)
    scope: material
    conditions:
      temperature: 25 °C
      form: crystal
    method: Value printed on a reseller's catalogue page
    status: ground
    source: chemicalbook-product
    where: Physical and chemical properties block, Specific Heat Capacity (Cp crystal)
  - benchmark: lattice_parameter_a
    label: Lattice parameter a, monoclinic cell as listed
    value: 1.408
    unit: nm
    scope: material
    conditions:
      space_group: C2/m (as listed)
      angle_beta: 100.03 degrees as listed
    method: Value printed on a reseller's catalogue page; the same page lists both cubic and monoclinic crystal systems
    status: ground
    source: chemicalbook-product
    where: Physical and chemical properties block, Lattice constant
  - benchmark: lattice_parameter_b
    label: Lattice parameter b, monoclinic cell as listed
    value: 0.3571
    unit: nm
    scope: material
    conditions:
      space_group: C2/m (as listed)
    method: Value printed on a reseller's catalogue page
    status: ground
    source: chemicalbook-product
    where: Physical and chemical properties block, Lattice constant
  - benchmark: lattice_parameter_c
    label: Lattice parameter c, monoclinic cell as listed
    value: 0.8764
    unit: nm
    scope: material
    conditions:
      space_group: C2/m (as listed)
    method: Value printed on a reseller's catalogue page
    status: ground
    source: chemicalbook-product
    where: Physical and chemical properties block, Lattice constant
corrosion:
  - environment: Humid air and open storage
    headline: Gd2O3 powder takes up water from moist air, so the supplier asks for storage under inert gas.
    effect: The Lorad Chemical SDS calls the product hygroscopic and says to store it under inert gas. No weight-gain rate or humidity threshold is given in any source read.
    rating: low
    conditions:
      form: powder
      exposure: ambient storage; time and humidity not stated
    source: lorad-sds
    where: Section 7 Handling and Storage, Storage Conditions
  - environment: Strong acids
    headline: Gd2O3 dissolves in common mineral acids, and the supplier lists strong acids as reactive.
    effect: Wikipedia says the oxide dissolves in common mineral acids. The Lorad SDS lists strong acids under Reacts with in its reactivity section. No dissolution rate is given.
    rating: moderate
    conditions:
      basis: qualitative; acid strength and temperature not stated
    source: wikipedia-gd2o3
    where: Chemistry paragraph on acids; Lorad SDS section 10 Reactivity (Reacts with)
  - environment: Carbon dioxide in air
    headline: As a basic oxide, Gd2O3 reacts readily with carbon dioxide to form carbonates.
    effect: Wikipedia says the oxide reacts readily with carbon dioxide to form carbonates, and that salt coatings such as oxalate, fluoride, sulfate and phosphate can slow its dissolution in acid. No rate is given.
    rating: low
    conditions:
      basis: qualitative
    source: wikipedia-gd2o3
    where: Chemistry paragraph on carbonate formation
risks:
  hazards:
    - text: The Lorad Chemical SDS and the ChemicalBook SDS both list H319, Causes serious eye irritation, with the signal word Warning.
      ghs:
        - H319
      source: lorad-sds
      where: Section 2 Hazard Identification
    - text: The ChemicalBook SDS also lists H319 with the signal word Warning, and gives the precautionary statement P305+P351+P338 for eye contact.
      ghs:
        - H319
      source: chemicalbook-msds
      where: Section 2 Hazard Identification
    - text: PubChem's ECHA C&L Inventory summary lists H400 (40.5%) and H410 (40.5%), both very toxic to aquatic life, and H319 (23.3%) from company notifications, with the signal word Warning.
      ghs:
        - H319
        - H400
        - H410
      source: pubchem-gd2o3
      where: Safety and Hazards, GHS Classification (Hazard Statements; ECHA C&L Notifications Summary)
    - text: The Wikipedia infobox lists GHS hazard statements H319 and H410 with the signal word Warning.
      ghs:
        - H319
        - H410
      source: wikipedia-gd2o3
      where: Infobox, GHS hazard statements row
  failure_risks:
    - mode: Moisture uptake and caking of the powder
      trigger: Storage in humid air or in an open container
      consequence: The powder is hygroscopic, so it takes up water and its handling and weight change. None of the sources read quantifies the uptake.
      severity: low
      source: lorad-sds
      where: Section 7 Storage Conditions (Hygroscopic)
    - mode: Dissolution in acids
      trigger: Contact with common mineral acids or strong acids
      consequence: The oxide dissolves and forms the salts of gadolinium, which changes the material. The rate is not quantified in any source read.
      severity: low
      source: wikipedia-gd2o3
      where: Chemistry paragraph on acids
  side_effects:
    - text: The Lorad SDS says further processing of the solid may form combustible dust, and that the potential for combustible dust must be considered before any additional processing.
      affects: Dust handling and processing equipment
      source: lorad-sds
      where: Section 7 Handling and Storage, Handling Conditions
  handling:
    - text: Store in a tightly closed container in a dry, well-ventilated place, under inert gas. Avoid dust formation and provide exhaust ventilation where dust forms.
      source: lorad-sds
      where: Section 7 Handling and Storage
    - text: Wear safety glasses with side shields. Where nuisance dust is a concern, use a respirator approved to N95 (US) or P1 (EU EN 143) standards.
      source: lorad-sds
      where: Section 8 Exposure Controls, Eye Protection and Respiratory Protection
  mitigations:
    - text: Store under inert gas in a dry place, in sealed containers, to limit moisture uptake.
      source: lorad-sds
      where: Section 7 Handling and Storage
uses:
  - application: radiation-shielding
    device: Control rods and neutron shields in some nuclear reactors
    example: PubChem's Merck Index entry says the compound is used in control rods in some nuclear reactors, and in neutron shields, catalysts, ceramics, glass, filament coatings, lasers and masers.
    source: pubchem-gd2o3
    where: Use and Manufacturing, Uses (Sources/Uses row, Merck Index citation)
  - application: optics-and-cameras
    device: Solid-state laser host material
    example: Wikipedia says Gd2O3 is a host material in some solid-state lasers, and that doped with neodymium or erbium it can produce lasers with high efficiency.
    source: wikipedia-gd2o3
    where: Uses section, laser paragraph
supply:
  - subject: Rare earths (gadolinium is not reported separately by USGS)
    abundance: About 6.2 mg/kg in the Earth's crust for the element gadolinium (Wikipedia)
    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: []
    recycling: 'USGS: limited quantities of rare earths were recovered from batteries, permanent magnets and fluorescent lamps.'
    substitutes:
      - 'USGS: substitutes are available for many applications but generally are less effective.'
    source: usgs-mcs2026-rare-earths
    where: World Mine Production and Reserves table, 2025e (world total 390,000 t REO, rounded; shares calculated by Space Mushroom from China 270,000 t, United States 51,000 t, Australia 29,000 t and Burma 22,000 t). Events, Trends, and Issues (April 2025 Chinese export controls on oxides of gadolinium). Salient Statistics price row for gadolinium oxide, 99.99% minimum, 2025e, 30 dollars per kilogram. Recycling and Substitutes sections.
documents:
  - title: Lorad Chemical safety data sheet, Gadolinium(III) Oxide (item GA-1961)
    type: sds
    url: https://loradchemical.com/data/sds/SDS-Gadolinium-Oxide.pdf
  - title: Lorad Chemical product page, Gadolinium Oxide
    type: datasheet
    url: https://loradchemical.com/products/gadolinium-oxide
  - title: 'ChemicalBook: Gadolinium oxide (CAS 12064-62-9) product page'
    type: database
    url: https://chemicalbook.com/CASEN_12064-62-9.htm
  - title: 'ChemicalBook: Gadolinium oxide safety data sheet'
    type: sds
    url: https://www.chemicalbook.com/msds/gadolinium-oxide.htm
  - title: PubChem compound record for gadolinium oxide (CID 159427), JSON view
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/159427/JSON
  - title: 'USGS Mineral Commodity Summaries 2026: Rare Earths'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf
    year: 2026
gaps:
  - 'Crystal structure disagrees between sources: ChemicalBook lists both Cubic and Monoclinic, and Wikipedia says the cubic form (Ia-3) is stable at room temperature. The lattice constants entered are the ChemicalBook monoclinic values and are not resolved against a crystallographic paper.'
  - 'Room-temperature thermal conductivity of dense gadolinia: a 2022 MDPI Inorganics paper reports about 11.7 W/(m·K) at 300 K in a search snippet, but the MDPI site returned HTTP 403 and the paper was not read, so it is not entered.'
  - Magnetic susceptibility (+53,200 x 10-6 cm3/mol) and solubility product (1.8 x 10-23) from Wikipedia are not entered because they are printed in exponent notation.
  - Phase transition temperatures (monoclinic at 1200 °C, hexagonal above 2100 °C) were summarised by the reader, not copied as printed, so they are not entered.
  - The PubChem density of 7.407 has no unit printed (it reads 7.407 @ 15°C) and is not entered. The PubChem melting point (2339 °C) and boiling point (3900 °C at 760 mm Hg) were read but are not entered, because the verifier cannot read those values from the PubChem JSON page.
  - 'Hazard classification disagrees: H410 (very toxic to aquatic life with long lasting effects) is listed by Wikipedia and PubChem from notifications, but the Lorad SDS and the ChemicalBook SDS list only H319. Both are recorded.'
  - The PubChem GHS summary states that a share of company reports find the substance does not meet GHS criteria; the exact count was not copied because the printed text separates the figures with extra spaces.
  - 'Burnable-absorber use in UO2 nuclear fuel: search results mention it, but the open papers were not read (MDPI and KNS pages were blocked or not opened), so it is not recorded as a use.'
  - Gadolinium-157 and natural gadolinium thermal neutron cross-section for the oxide were not read in this run; neutron-capture values are left to the gadolinium metal profile.
  - 'Critical-mineral lists: the USGS 2025 critical minerals list and the EU critical raw materials list were not checked for gadolinium oxide, so critical_lists is empty.'
  - 'Space or vacuum data: no outgassing, atomic-oxygen, radiation or flight result for gadolinium oxide was found in an opened source.'
  - 'Corrosion rates: no measured weight-gain or dissolution rate in humid air, water or reactor coolant was found in an opened source. The reactor-water hydroxide formation mentioned in a search snippet was not opened.'
  - The Lorad Chemical product page (lorad-product) could not be read by the automated checker (the server refused the request), so no value is taken from it. Its listed formula mass (362.5 g/mol) and density (7.07 g/cm3) agree with the SDS and are not entered from that page.
  - Molar mass, lattice parameter a, b and c and specific heat use property names that are not in the canonical list (molar_mass, lattice_parameter_a, lattice_parameter_b, lattice_parameter_c, specific_heat at J/(g·K) as printed).
  - The price in the supply section (30 dollars per kilogram, 2025e, 99.99% minimum) is a USGS average price, not a supplier quotation, and it is not a property row.
sources:
  lorad-sds:
    title: Safety Data Sheet, Gadolinium(III) Oxide, Lorad Chemical Corporation (item GA-1961)
    id: CAS 12064-62-9; EC 235-060-9
    url: https://loradchemical.com/data/sds/SDS-Gadolinium-Oxide.pdf
    kind: datasheet
    license: supplier safety data sheet, cited not reproduced
  lorad-product:
    title: Lorad Chemical product page, Gadolinium Oxide
    url: https://loradchemical.com/products/gadolinium-oxide
    kind: datasheet
    license: supplier web page, cited not reproduced
  chemicalbook-product:
    title: ChemicalBook, Gadolinium oxide (CAS 12064-62-9), physical and chemical properties
    id: CB number not stated on page; CAS 12064-62-9
    url: https://chemicalbook.com/CASEN_12064-62-9.htm
    kind: database
    license: reseller catalogue page, cited not reproduced
  chemicalbook-msds:
    title: ChemicalBook, Gadolinium oxide safety data sheet (CB0139405)
    id: CB0139405; CAS 12064-62-9
    url: https://www.chemicalbook.com/msds/gadolinium-oxide.htm
    kind: datasheet
    license: reseller safety data sheet, cited not reproduced
  wikipedia-gd2o3:
    title: Gadolinium(III) oxide (Wikipedia)
    url: https://en.wikipedia.org/wiki/Gadolinium(III)_oxide
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
  wikipedia-gd:
    title: Gadolinium (Wikipedia)
    url: https://en.wikipedia.org/wiki/Gadolinium
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
  pubchem-gd2o3:
    title: PubChem compound record for gadolinium oxide, CID 159427 (Gadolinia), JSON view
    id: CID 159427; CAS 12064-62-9; EC 235-060-9
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/159427/JSON
    kind: database
    license: PubChem (NCBI), public domain; sections attributed to ECHA, Merck Index and others
  usgs-mcs2026-rare-earths:
    title: 'Mineral Commodity Summaries 2026: Rare Earths'
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf
    kind: report
    license: public domain (USGS)
license: CC-BY-4.0
updated: '2026-11-02'
review:
  status: draft
  method: assistant
  checked_values: 12
  unreachable: 2
  caveats: 4
  note: 'Read by an AI assistant on 2026-11-02 from the pages and PDFs named in each entry. Unreachable: MDPI Inorganics paper (HTTP 403) and Thermo Scientific product page (timeout or HTTP 403). Caveats: density, melting point and hazard statements disagree between sources and are recorded side by side; crystal system is unresolved; supply shares are for all rare earths, not gadolinium.'
story:
  recipe:
    line: Gadolinium(III) oxide is an ionic oxide built from gadolinium and oxygen. Each formula unit has two gadolinium atoms and three oxygen atoms. Wikipedia says it can be formed by thermal decomposition of the hydroxide, nitrate, carbonate or oxalate, and that it also forms as a surface layer on gadolinium metal.
    parts:
      - name: Gadolinium
        symbol: Gd
        atoms: 2
        atomic_weight: 157.249
        role: The rare-earth ion (Gd3+) in the oxide lattice. The metal tarnishes in moist air to this oxide (Wikipedia).
      - name: Oxygen
        symbol: O
        role: The oxide ion (O2-) that completes the formula unit.
  risk_groups:
    - title: For people
      level: 0
      verdict: Eye irritant (H319); low hazard otherwise
      lead: The supplier classifies the oxide only for serious eye irritation. PubChem's company notifications add two aquatic hazard statements, which the supplier SDS does not list.
      points:
        - label: Eyes
          line: Causes serious eye irritation (H319). The Lorad SDS advises safety glasses with side shields and thorough rinsing with water after eye contact.
        - label: Dust
          line: Avoid forming dust. The Lorad SDS says further processing of the solid may form combustible dust, so the dust risk is checked before any processing.
        - label: Water environment
          line: PubChem's ECHA summary gives H400 at 40.5% and H410 at 40.5% of notifications, both for very toxic to aquatic life. The Wikipedia infobox lists H319 and H410.
    - title: If the powder gets damp
      lead: Gd2O3 takes up water from moist air. The supplier's storage advice is designed around that.
      points:
        - label: Storage
          line: The Lorad SDS says to keep the container tightly closed in a dry, well-ventilated place, under inert gas.
        - label: Acids
          line: Wikipedia says the oxide dissolves in common mineral acids, and the Lorad SDS lists strong acids as reactive with it.
  why: Gadolinium(III) oxide is a white, hygroscopic rare-earth oxide. It is used where a dense, high-melting oxide with neutron-capture chemistry is needed. The supplier SDS gives a density of 7.07 g/cm3 and a melting point above 2,420 °C. The best-documented uses are in control rods and neutron shields, and as a host for solid-state lasers.
  uses:
    - where: Reactor control rods and neutron shields
      line: PubChem's Merck Index entry says the compound is used in control rods in some nuclear reactors, and in neutron shields, catalysts, ceramics, glass, filament coatings, lasers and masers.
    - where: Solid-state lasers
      line: Wikipedia says Gd2O3 is a host material in some solid-state lasers, and that when doped with neodymium or erbium it can produce lasers with high efficiency.
    - where: Other listed uses
      line: Wikipedia lists the oxide as a potential contrast agent for magnetic resonance imaging, as a material used in some solid oxide fuel cells, and as a constituent of gadolinium derivatives studied for MRI. These are listed uses, not flight uses.
  can_do:
    - label: Heat tolerance
      line: The supplier SDS gives a melting point above 2,420 °C, and Wikipedia gives 2,420 °C.
    - label: Neutron control
      line: The Merck Index entry in PubChem records use in control rods and neutron shields.
    - label: Laser host
      line: Wikipedia says it can host a solid-state laser when doped with neodymium or erbium.
    - label: Precursor
      line: Wikipedia says it forms by heating the hydroxide, nitrate, carbonate or oxalate.
  compare: Gadolinium(III) oxide is what the gadolinium metal turns into in moist air. Wikipedia says the metal tarnishes quickly in moist air and forms a loosely adhering oxide layer. The oxide is a white powder that its supplier classifies for eye irritation only (H319). This file carries no metal values, so the comparison rows below list only this compound's own values.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Keep the powder dry and tightly closed, and store it under inert gas (Lorad SDS).
    - Avoid dust. Use a respirator approved for nuisance dust where dust is a concern (Lorad SDS).
    - Wear safety glasses with side shields, because the powder causes serious eye irritation (Lorad SDS).
    - Keep it away from strong acids, which the supplier lists as reactive with it (Lorad SDS).
  good_for:
    - Neutron control and shielding, where the oxide's use in control rods is documented (Merck Index via PubChem).
    - Solid-state laser host materials doped with neodymium or erbium (Wikipedia).
  watch_out:
    - 'Hygroscopic: it takes up moisture from air, so keep it sealed and dry.'
    - Eye irritant (H319). Aquatic hazard H410 appears in PubChem and Wikipedia but not on the supplier SDS, so check the SDS for the lot you buy.
    - 'Physical values disagree between sources: density 7.07 g/cm3 (Lorad, Wikipedia) against 7.407 g/mL (ChemicalBook).'
  verdict: Gadolinium(III) oxide is a stable white oxide with a melting point above 2,420 °C, used for neutron control and as a laser host. Its supplier classifies it only for eye irritation, but its moisture uptake and the disagreement between sources on density and melting point need checking before specifying it.