Lanthanum oxide La2O3

spore: profile
id: lanthanum-oxide
spore_version: 0.2
family: oxide-ceramics
name: Lanthanum oxide
abbreviation: La2O3
role: Rare-earth oxide used in optical glass and studied as a high-permittivity gate dielectric
category: ceramics
type: oxides
summary: |
  Lanthanum(III) oxide (La2O3, CAS 1312-81-8) is a white powder with a density of 6.51 g/cm3 at 25 °C per the PubChem record. PubChem gives a melting point of 2304 °C, WebElements gives 2305 °C and a supplier listing gives 2315 °C. A 33 Angstrom La2O3 gate dielectric film gave an effective K value of 27 in a 2000 study by Wu et al. The oxide takes up water from humid air and converts to lanthanum hydroxide, so it has to be stored dry.
best_for: Optical glass additive, and research thin films for high-permittivity gate dielectrics kept in dry conditions
weakest_at: 'Moisture: lanthanum oxide converts to lanthanum hydroxide in humid air, and the hydroxide lowers permittivity'
identity:
  formula: La2O3
  cas: 1312-81-8
  source: nist-la2o3
  where: 'NIST Chemistry WebBook entry: formula La 2 O 3 and CAS Registry Number 1312-81-8. The same CAS number appears on the PubChem record (CID 150906) and the Lorad listing.'
tags:
  applications:
    - optics-and-cameras
    - electronics-and-chips
properties:
  - benchmark: density
    label: Density, lanthanum(III) oxide (PubChem experimental value)
    value: 6.51
    unit: g/cm3
    scope: material
    conditions:
      temperature: 25 °C
      form: not stated in the record
    method: Experimental density listed in the PubChem record; no measurement method given
    status: ground
    source: pubchem-la2o3
    where: Chemical and Physical Properties, Experimental Properties, Density (6.51 @25 °C)
  - benchmark: density
    label: Density, dilanthanum trioxide (WebElements)
    value: 6500
    unit: kg m-3
    scope: material
    conditions:
      temperature: not stated
      form: not stated
    method: Compilation value on WebElements, assembled from the primary literature; no method given
    status: ground
    source: webelements-la2o3
    where: Compound data, Density line (6500 kg m -3)
  - benchmark: density
    label: Density (supplier listing)
    value: 6.51
    unit: g/cm3
    scope: material
    conditions:
      temperature: not stated
      form: powder, as sold
    method: Supplier product listing; no test method given
    status: ground
    note: Reseller listing; it agrees with the PubChem value.
    source: lorad-la2o3
    where: Physical properties, Density line
  - benchmark: density
    label: Density (ChemicalBook listing, literature value)
    value: 6.51
    unit: g/mL
    scope: material
    conditions:
      temperature: 25 °C
      basis: literature value marked (lit.) on the page
    method: Chemical properties listing that cites the literature; no test method given
    status: ground
    note: Secondary listing; the same figure as PubChem.
    source: chemicalbook-la2o3
    where: Chemical Properties section, density line
  - benchmark: melting_point
    label: Melting point (PubChem experimental value)
    value: 2304
    unit: °C
    scope: material
    conditions:
      form: not stated in the record
    method: Experimental melting point listed in the PubChem record; no method given
    status: ground
    source: pubchem-la2o3
    where: Chemical and Physical Properties, Experimental Properties, Melting Point (2304 °C)
  - benchmark: melting_point
    label: Melting point (WebElements)
    value: 2305
    unit: °C
    scope: material
    conditions:
      form: not stated
    method: Compilation value on WebElements; no method given
    status: ground
    note: Differs from the PubChem value by one degree; both are recorded, neither is averaged.
    source: webelements-la2o3
    where: Compound data, Melting point line (2305°C)
  - benchmark: melting_point
    label: Melting point (supplier listing)
    value: 2315
    unit: °C
    scope: material
    conditions:
      form: not stated
    method: Supplier product listing; no method given
    status: ground
    note: Higher than the PubChem and WebElements values. The Materion SDS gives no melting point (Not available).
    source: lorad-la2o3
    where: Physical properties, Melting Point line (2,315°C)
  - benchmark: molecular_weight
    label: Formula mass of La2O3
    value: 325.81
    unit: g/mol
    scope: material
    conditions:
      formula: La2O3
    method: Formula mass printed on the supplier listing
    status: calculated
    note: Custom benchmark name, since no canonical molecular weight name was found. The NIST page prints 325.8091 with no unit, so that figure is not recorded.
    source: lorad-la2o3
    where: Physical properties, Formula Mass line (325.81 g/mol)
  - benchmark: specific_heat
    label: Specific heat capacity, crystal form
    value: 0.333937
    unit: J/(g·K)
    scope: material
    conditions:
      temperature: 25 °C
      phase: crystal, printed as Cp(crystal)
    method: Listing value on ChemicalBook; no method given
    status: ground
    source: chemicalbook-la2o3
    where: Chemical Properties section, Specific Heat Capacity line
  - benchmark: dielectric_constant
    label: Effective dielectric constant (K value) of a La2O3 gate dielectric
    value: 27
    unit: '-'
    scope: material
    conditions:
      form: thin film, 33 Angstrom La2O3 gate dielectric
      basis: effective K value from the measured capacitance
    method: Capacitance measurement on a thin-film gate stack, as stated in the abstract
    status: ground
    source: wu2000
    where: Abstract
  - benchmark: dielectric_strength
    label: Effective breakdown field of a La2O3 gate dielectric
    value: 13.5
    unit: MV/cm
    scope: material
    conditions:
      form: thin film, 33 Angstrom La2O3 gate dielectric
    method: Breakdown measurement on a thin-film gate stack, as stated in the abstract
    status: ground
    source: wu2000
    where: Abstract
  - benchmark: equivalent_oxide_thickness
    label: Equivalent oxide thickness of a La2O3 gate dielectric
    value: 4.8
    unit: Angstrom
    scope: material
    conditions:
      form: thin film, 33 Angstrom La2O3 gate dielectric
    method: Derived in the source from the measured capacitance, as stated in the abstract
    status: ground
    note: Custom benchmark name, since no canonical name was found.
    source: wu2000
    where: Abstract
  - benchmark: lattice_constant_a
    label: Lattice constant a
    value: 0.394
    unit: nm
    scope: material
    conditions:
      crystal_system_as_printed: trigonal
      space_group_as_printed: P3m1
      note: the Lorad listing gives the crystal system as hexagonal
    method: Crystallographic value as listed on ChemicalBook; no diffraction method given
    status: ground
    note: Custom benchmark name. Not checked against a diffraction paper.
    source: chemicalbook-la2o3
    where: Lattice constant line (a/nm, b/nm, c/nm)
  - benchmark: lattice_constant_c
    label: Lattice constant c
    value: 0.613
    unit: nm
    scope: material
    conditions:
      crystal_system_as_printed: trigonal
      space_group_as_printed: P3m1
      note: the Lorad listing gives the crystal system as hexagonal
    method: Crystallographic value as listed on ChemicalBook; no diffraction method given
    status: ground
    note: Custom benchmark name. Not checked against a diffraction paper.
    source: chemicalbook-la2o3
    where: Lattice constant line (a/nm, b/nm, c/nm)
corrosion:
  - environment: Humid air or water vapour at room temperature
    headline: Lanthanum oxide reacts with water vapour and converts to lanthanum hydroxide, within a day in the powders studied.
    effect: Fleming et al. (2010) report that the powders hydroxylate to La(OH)3 at room temperature, and that '24 h of exposure to atmosphere is generally sufficient to cause complete hydroxylation at room temperature'. The reaction rate was related to crystallite size. A smaller amount of an oxycarbonate, La2O2CO3, also forms after air exposure.
    rating: moderate
    conditions:
      exposure: powders of several lanthana types exposed to air or water vapour at room temperature
      time: up to 24 h reported in the abstract
    source: fleming2010
    where: Abstract
  - environment: Dilute acid solutions
    headline: ChemicalBook lists lanthanum oxide as soluble in dilute acid solutions; no corrosion test in acid was read.
    effect: ChemicalBook's solubility line reads 'insoluble in H2O; soluble in dilute acid solutions'. The Lorad listing gives only 'Insoluble' for water and does not mention acids. This is a solubility statement, not a corrosion test.
    rating: unknown
    conditions:
      basis: solubility statement on a supplier listing
      acid: not named on the page
    source: chemicalbook-la2o3
    where: Chemical Properties section, solubility line
risks:
  hazards:
    - text: 'PubChem GHS summary for lanthanum oxide: signal word Warning, with notified hazard statements H315 (causes skin irritation), H319 (causes serious eye irritation) and H335 (may cause respiratory irritation). The record also says ''This chemical does not meet GHS hazard criteria for 59.9% (370 of 618) of all reports.'''
      ghs:
        - H315
        - H319
        - H335
      source: pubchem-ghs
      where: Safety and Hazards, GHS Classification (CID 150906)
    - text: 'Materion safety data sheet, SDS L-MSDS0026 (revision 07-14-2015): the product ''does not meet the criteria for classification''. Eye contact may cause temporary irritation. Gases hazardous to health may form in a fire.'
      ghs: []
      source: materion-sds
      where: Sections 2, 5 and 11
    - text: 'ChemicalBook prints an oral toxicity figure for lanthanum oxide: ''Oral toxicity (rabbit LD50): > 9968 mg/kg''. The page does not name the test standard.'
      ghs: []
      source: chemicalbook-la2o3
      where: Hazard information, oral toxicity line
  failure_risks:
    - mode: Hydroxide formation from moisture
      trigger: Storage or handling in humid air, or exposure to water vapour
      consequence: The oxide hydroxylates to La(OH)3 at room temperature. The abstract says 24 h of exposure to atmosphere is generally sufficient for complete hydroxylation.
      severity: moderate
      source: fleming2010
      where: Abstract
    - mode: Loss of permittivity in a gate dielectric
      trigger: A hygroscopic La2O3 film exposed to moisture, forming La(OH)3
      consequence: Hande et al. state that the hygroscopic nature of La2O3 forms lanthanum hydroxide, which causes deterioration of electrical properties such as permittivity. The same abstract gives a dielectric constant of about 27 for La2O3.
      severity: moderate
      source: hande2008
      where: Abstract, first paragraph
  side_effects:
    - text: Air exposure also forms a smaller amount of an oxycarbonate, La2O2CO3, which the authors say is stable to hydroxylation.
      affects: Composition of the powder
      source: fleming2010
      where: Abstract
  handling:
    - text: Store in the original tightly closed container, away from incompatible materials, and use care in handling.
      source: materion-sds
      where: Sections 7 and 10
    - text: Wear safety glasses with side shields (or goggles) and chemical-resistant gloves when handling the powder.
      source: materion-sds
      where: Section 8
  mitigations:
    - text: ChemicalBook lists the material as hygroscopic and sensitive to moisture, so store it sealed and dry.
      source: chemicalbook-la2o3
      where: Chemical Properties section, sensitivity line
uses:
  - application: optics-and-cameras
    device: Optical glass for camera lenses
    example: ChemicalBook's uses section says lanthanum oxide is used in the manufacture of optical glasses, and that lanthanum raises refractive index and lowers dispersion in the glass.
    source: chemicalbook-la2o3
    where: Uses section
  - application: electronics-and-chips
    device: High-permittivity gate dielectric in research transistors
    example: Wu et al. (2000) report an effective K value of 27 for a 33 Angstrom La2O3 gate dielectric, with an equivalent oxide thickness of 4.8 Angstrom and an effective breakdown field of 13.5 MV/cm.
    source: wu2000
    where: Abstract
supply:
  - subject: Lanthanum, from rare-earth mine output
    producers:
      - country: China
        share_percent: 69.2
        year: 2025
      - country: United States
        share_percent: 13.1
        year: 2025
      - country: Australia
        share_percent: 7.4
        year: 2025
      - country: Burma
        share_percent: 5.6
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (lanthanum is listed as a rare earth entry, used in chemical catalysts, metallurgy and batteries)
        listed: true
      - list: EU critical raw materials list, which names light rare earth elements (Regulation (EU) 2024/1252, as shown on the European Commission page)
        listed: true
    recycling: 'USGS: limited quantities of rare earths were recovered from batteries, permanent magnets and fluorescent lamps in 2025.'
    substitutes:
      - 'USGS: substitutes are available for many rare-earth applications but generally are less effective.'
    source: usgs-mcs2026-rare-earths
    where: World Mine Production and Reserves table, 2025e, rare-earth oxide equivalent (REO). Shares are calculated by Space Mushroom from the country figures and the rounded world total of 390,000 t. The table covers all rare earths, not lanthanum oxide alone. Recycling and Substitutes sections.
media: []
documents:
  - title: 'Materion Advanced Chemicals safety data sheet: Lanthanum oxide (La2O3), SDS L-MSDS0026'
    type: sds
    url: https://www.physics.purdue.edu/primelab/safety/MSDS/SDS/lanthanum%20oxide%20%20-%20Materion.pdf
    year: 2015
  - title: 'PubChem: Lanthanum sesquioxide (CID 150906), experimental properties and GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/150906
    year: 2026
  - title: 'WebElements: Dilanthanum trioxide compound data'
    type: database
    url: https://winter.group.shef.ac.uk/webelements/compounds/lanthanum/dilanthanum_trioxide.html
    year: 2026
  - title: 'NIST Chemistry WebBook: lanthanum oxide'
    type: database
    url: https://webbook.nist.gov/cgi/cbook.cgi?ID=C1312818&Mask=1
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Rare Earths'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf
    year: 2026
  - title: 'Lorad Chemical: Lanthanum oxide product listing (catalog LA-2565)'
    type: datasheet
    url: https://loradchemical.com/products/lanthanum-oxide
    year: 2026
  - title: 'ChemicalBook: Lanthanum oxide, CAS 1312-81-8, chemical properties and uses'
    type: datasheet
    url: https://chemicalbook.com/CASEN_1312-81-8.htm
    year: 2026
  - title: Fleming et al., The rapid formation of La(OH)3 from La2O3 powders on exposure to water vapor (J. Am. Ceram. Soc. 93, 1187-1194)
    type: paper
    url: https://research.ucc.ie/en/publications/the-rapid-formation-of-laohsub3sub-from-lasub2subosub3sub-powders/
    year: 2010
  - title: Wu et al., Electrical characteristics of La2O3 gate dielectric (IEEE Electron Device Letters, 2000)
    type: paper
    url: https://ir.lib.nycu.edu.tw/handle/11536/30423
    year: 2000
  - title: Hande et al., Atomic Layer Deposition of Lanthanum Based Oxides for High-K Gate Dielectrics (AVS 55th Symposium, abstract TF-ThP17)
    type: paper
    url: https://www2.avs.org/symposium2008/Papers/Paper_TF-ThP17.html
    year: 2008
gaps:
  - 'Melting point is not settled: PubChem gives 2304 °C, WebElements 2305 °C and the Lorad listing 2315 °C. The Materion SDS gives Not available. No primary measurement paper was read in this run.'
  - No refractive index value with wavelength and temperature was found in a source read in this run. The Lorad page's refractive-index line was not legible in the page text, so it is not recorded.
  - 'The crystal system is not agreed: ChemicalBook says trigonal (space group P3m1), Lorad says hexagonal. The lattice constants come from ChemicalBook only.'
  - No vacuum, radiation, thermal-cycling or flight result for lanthanum oxide was found in any source read.
  - The acute oral toxicity figure comes from ChemicalBook alone, and the page does not name the species or test standard.
  - Crustal abundance of lanthanum was not found in a source read in this run.
  - No UNS, EN, ASTM or other grade designation applies to lanthanum oxide in the sources read; CAS 1312-81-8 is the identifier used.
  - The manufacturing route (for example calcination of a carbonate or oxalate precursor) is not described in any source read in this run.
  - Goodfellow, Alfa Aesar and Acros product sheets were named on ChemicalBook but were not reached in this run, so no grade purity figure is recorded.
  - The USGS 2025 critical-minerals page refused automated fetching in this run. The lanthanum entry was read through a web-fetch summary, so check it before relying on it.
  - Only one thin-film study (Wu et al., 2000) gives a dielectric constant and breakdown field. No second study with an independent value was read.
sources:
  pubchem-la2o3:
    title: PubChem compound record, Lanthanum sesquioxide (lanthanum oxide, CID 150906)
    id: CID 150906; CAS 1312-81-8
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/150906/JSON?heading=Experimental+Properties
    year: 2026
    kind: database
    license: public domain (NCBI)
  pubchem-ghs:
    title: PubChem compound record, Lanthanum sesquioxide (CID 150906), GHS classification section
    id: CID 150906; aggregated GHS notifications from ECHA C&L
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/150906/JSON?heading=GHS+Classification
    year: 2026
    kind: database
    license: public domain (NCBI)
  webelements-la2o3:
    title: WebElements, Dilanthanum trioxide (La2O3) compound data
    id: WebElements compound page; no publication date printed (read 2026-11-02)
    url: https://winter.group.shef.ac.uk/webelements/compounds/lanthanum/dilanthanum_trioxide.html
    year: 2026
    kind: database
    license: WebElements terms (cited, not reproduced)
  lorad-la2o3:
    title: Lorad Chemical, Lanthanum oxide product listing (catalog LA-2565)
    id: Catalog LA-2565; CAS 1312-81-8
    url: https://loradchemical.com/products/lanthanum-oxide
    year: 2026
    kind: web
    license: supplier listing (cited, not reproduced)
  chemicalbook-la2o3:
    title: 'ChemicalBook, Lanthanum oxide CAS 1312-81-8: chemical properties, hazard information and uses'
    id: CAS 1312-81-8
    url: https://chemicalbook.com/CASEN_1312-81-8.htm
    year: 2026
    kind: web
    license: listing aggregator (cited, not reproduced)
  nist-la2o3:
    title: 'NIST Chemistry WebBook, SRD 69: lanthanum oxide'
    id: CAS 1312-81-8; formula La 2 O 3
    url: https://webbook.nist.gov/cgi/cbook.cgi?ID=C1312818&Mask=1
    year: 2026
    kind: database
    license: NIST Standard Reference Data (cited)
  materion-sds:
    title: 'Materion Advanced Chemicals, Safety Data Sheet: Lanthanum oxide (La2O3)'
    id: SDS L-MSDS0026, version 03, revision 07-14-2015
    url: https://www.physics.purdue.edu/primelab/safety/MSDS/SDS/lanthanum%20oxide%20%20-%20Materion.pdf
    year: 2015
    kind: datasheet
    license: supplier document (cited, not reproduced)
  usgs-mcs2026-rare-earths:
    title: Mineral Commodity Summaries 2026, Rare Earths (USGS)
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS)
    id: Final 2025 List of Critical Minerals
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
  ec-crm:
    title: Critical raw materials (European Commission, Regulation (EU) 2024/1252)
    id: Regulation (EU) 2024/1252
    url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
    year: 2024
    kind: web
    license: European Commission web page
  fleming2010:
    title: The rapid formation of La(OH)3 from La2O3 powders on exposure to water vapor
    id: doi:10.1111/j.1551-2916.2009.03564.x (J. Am. Ceram. Soc. 93(4), 1187-1194)
    url: https://research.ucc.ie/en/publications/the-rapid-formation-of-laohsub3sub-from-lasub2subosub3sub-powders/
    year: 2010
    kind: paper
    license: publisher record (abstract read)
  hande2008:
    title: Atomic Layer Deposition of Lanthanum Based Oxides for High-K Gate Dielectrics (AVS 55th International Symposium, paper TF-ThP17)
    id: AVS 2008, Thursday session TF-ThP, presenter A. Hande
    url: https://www2.avs.org/symposium2008/Papers/Paper_TF-ThP17.html
    year: 2008
    kind: paper
    license: conference abstract (cited)
  wu2000:
    title: Electrical characteristics of high quality La2O3 gate dielectric (Wu et al., IEEE Electron Device Letters)
    id: doi:10.1109/55.847374
    url: https://ir.lib.nycu.edu.tw/handle/11536/30423
    year: 2000
    kind: paper
    license: repository record (abstract read)
license: CC-BY-4.0
updated: '2026-11-02'
review:
  status: draft
  method: assistant
  checked_values: 14
  unreachable: 1
  caveats: 2
  note: Written by an AI assistant on 2026-11-02 from pages read in this run. Values come from database, supplier and abstract pages; no primary melting-point measurement was read. The Lorad listing blocks automated fetching, so its three values (density, melting point and formula mass) were read with a web fetch in this run and could not be re-matched by the verifier. The USGS 2025 critical-minerals page could not be fetched directly.
story:
  recipe:
    line: Lanthanum(III) oxide is made of two lanthanum atoms and three oxygen atoms per formula unit, La2O3. The sources read in this run do not describe how it is made, so no manufacturing process is given.
    parts:
      - name: Lanthanum
        symbol: La
        role: The rare-earth metal in the oxide. In La2O3 it is present as lanthanum(III), the oxidation state WebElements prints for dilanthanum trioxide.
      - name: Oxygen
        symbol: O
        role: Bonded to the lanthanum in the oxide lattice. In moist air the oxide also takes up water and carbon dioxide to form hydroxide and carbonate species.
  risk_groups:
    - title: For people
      level: 0
      verdict: Not classified by the SDS; PubChem notes irritation
      lead: The Materion safety data sheet does not classify the powder. PubChem's aggregated notifications list skin, eye and airway irritation for a share of reports, so treat the powder as an irritant.
      points:
        - label: The powder
          line: The Materion safety data sheet states that the product does not meet the criteria for classification. Eye contact may cause temporary irritation.
        - label: Dust, skin and eyes
          line: PubChem lists H315 (skin irritation), H319 (serious eye irritation) and H335 (may cause respiratory irritation). The same record says the chemical does not meet GHS hazard criteria for 59.9% (370 of 618) of all reports.
        - label: Swallowing
          line: ChemicalBook prints an oral toxicity figure of greater than 9968 mg/kg in rabbits. That secondary listing does not name the test standard.
    - title: In a fire
      verdict: Gases hazardous to health may form in a fire
      lead: The Materion safety data sheet warns that gases hazardous to health may form in a fire. It names no specific decomposition products.
      points:
        - label: Fire response
          line: The SDS advises water spray to cool unopened containers and suitable protective equipment for firefighters.
    - title: Moisture
      verdict: 'Hygroscopic: it turns into hydroxide in humid air'
      lead: Lanthanum oxide takes up water from humid air and converts to lanthanum hydroxide. In the Fleming et al. study this happened rapidly at room temperature.
      points:
        - label: Hydroxide
          line: Fleming et al. (2010) report that the powders hydroxylate to form La(OH)3 at room temperature. Complete hydroxylation was generally reached after 24 h of exposure to air.
        - label: Gate dielectrics
          line: Hande et al. (2008) state that the hydroxide that forms from La2O3 lowers its permittivity.
  why: Lanthanum oxide (La2O3) is a white rare-earth oxide. It is used in optical glass for lenses, where the lanthanum raises the refractive index. It is also studied as a high-permittivity gate dielectric in research transistors, with an effective K value of 27 in one thin-film study. The oxide is hygroscopic, meaning it takes up water from air, so it has to be stored dry.
  uses:
    - where: Optical glass
      line: ChemicalBook says lanthanum oxide is used in the manufacture of optical glasses, and that lanthanum raises the refractive index and lowers dispersion.
    - where: Research gate dielectrics
      line: Wu et al. (2000) report an effective K value of 27 for a 33 Angstrom La2O3 film, with an equivalent oxide thickness of 4.8 Angstrom and an effective breakdown field of 13.5 MV/cm.
    - where: Other listed uses
      line: ChemicalBook also lists fast ion conductors, X-ray intensifying screens, phosphors and catalysts as uses. Each is a secondary listing, and no source for each was read in this run.
  can_do:
    - label: High-permittivity film
      benchmark: dielectric_constant
      line: Acts as a thin-film dielectric with an effective K value of 27 for a 33 Angstrom film in the 2000 study by Wu et al.
    - label: Breakdown field
      benchmark: dielectric_strength
      line: Withstands an effective breakdown field of 13.5 MV/cm in that thin-film test, per the same abstract.
    - label: Dry storage
      line: 'Stays a stable solid in dry storage: the Materion SDS calls the material stable under normal conditions.'
    - label: Lattice
      benchmark: lattice_constant_a
      line: Lists a lattice with a of 0.394 nm and c of 0.613 nm per ChemicalBook. The crystal system is disputed between sources.
  compare: This record gives lanthanum oxide's density and melting point, but it holds no side-by-side values for other oxides, so the comparison below is qualitative. The melting point differs by source, from 2304 °C in PubChem to 2315 °C in a supplier listing, and both are kept. The dielectric constant of 27 comes from a single thin-film study, so it should be read as one measurement rather than a settled figure.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Dielectric constant (thin film)
      benchmark: dielectric_constant
  handling:
    - Store in the original tightly closed container, away from incompatible materials (Materion SDS).
    - Wear safety glasses with side shields or goggles when handling the powder (Materion SDS).
    - 'Keep the container sealed: the oxide is hygroscopic and forms hydroxide and carbonate species in moist air.'
  good_for:
    - Optical glass additive, where lanthanum raises the refractive index (ChemicalBook).
    - Research into high-permittivity gate dielectrics, processed and stored dry (Wu et al., 2000; Hande et al., 2008).
  watch_out:
    - 'Moisture: the oxide converts to lanthanum hydroxide, which lowers permittivity in thin films (Hande et al., 2008).'
    - Air exposure also forms an oxycarbonate, La2O2CO3 (Fleming et al., 2010).
    - The melting point differs between sources, from 2304 °C to 2315 °C.
  verdict: Lanthanum oxide suits optical glass and high-permittivity research films, but it needs dry storage. Most of its physical data come from database and supplier listings rather than a measurement paper.