Vanadium pentoxide V2O5

spore: profile
id: vanadium-pentoxide
spore_version: 0.2
family: oxide-ceramics
name: Vanadium pentoxide
abbreviation: V2O5
role: catalyst, flow-battery feedstock and infrared-sensor film material
category: ceramics
type: oxides
summary: |
  Vanadium pentoxide (V2O5) is a yellow-to-red oxide of vanadium with the vanadium in its +5 state. It melts at 690 °C on the ICSC safety card (681 °C in PubChem's database record) and decomposes at 1750 °C. Its industrial role is as the oxygen-transfer catalyst for sulfuric acid and maleic anhydride, and as a starting point for vanadium metal and ferrovanadium. In laboratory tests, sputtered V2O5 and vanadium multilayers gave high temperature coefficients of resistance for infrared microbolometers, and the powder is toxic: the ECHA notifications in PubChem carry the Danger signal word.
best_for: Lab-scale thermometer films for uncooled infrared sensors, and as a vanadium source for flow batteries and catalysts
weakest_at: Toxicity. Fatal if inhaled (H330) and toxic if swallowed (H301) in the aggregated EU classification, with an occupational limit of 0.05 mg/m3 as V
identity:
  formula: V2O5
  cas: 1314-62-1
  crystal_system: orthorhombic
  space_group: Pmmn
  source: icsc-0596
  where: 'Header, CAS #; Physical and Chemical Information, Formula. Crystal system and space group: Wikipedia infobox (wikipedia-v2o5)'
tags:
  environments: []
  stresses: []
  applications:
    - batteries
    - optics-and-cameras
properties:
  - benchmark: melting_point
    label: Melting point, ICSC card
    value: 690
    unit: °C
    scope: material
    conditions:
      form: powder or solid, as printed on the card
    method: Value printed on an International Chemical Safety Card
    status: ground
    source: icsc-0596
    where: Physical and Chemical Information, Melting point
  - benchmark: melting_point
    label: Melting point, HSDB record in PubChem
    value: 681
    unit: °C
    scope: material
    conditions:
      basis: PubChem experimental property, cited to the Hazardous Substances Data Bank
    method: Value in PubChem experimental properties
    status: ground
    note: A second database value. The ICSC card gives 690 °C, so the two sources differ by 9 °C.
    source: pubchem-v2o5
    where: Experimental Properties, Melting Point (reference 35)
  - benchmark: decomposition_temperature
    label: Decomposition temperature
    value: 1750
    unit: °C
    scope: material
    conditions:
      atmosphere: not stated in the record
    method: Value in PubChem experimental properties, cited to the Hazardous Substances Data Bank
    status: ground
    source: pubchem-v2o5
    where: Experimental Properties, Decomposition (reference 35)
  - benchmark: density
    label: Relative density, water = 1
    value: 3.4
    unit: '-'
    scope: material
    conditions:
      basis: relative density to water, as printed; the card gives no temperature
    method: Value printed on an International Chemical Safety Card
    status: ground
    note: The card prints a relative density, not a density in g/cm3. PubChem gives 3.35 at 25 °C without a unit, and that value was not used.
    source: icsc-0596
    where: Physical and Chemical Information, Relative density (water = 1)
  - benchmark: water_solubility
    label: Solubility in water
    value: 0.8
    unit: g/100ml
    scope: material
    conditions:
      temperature: not stated on the card
    method: Value printed on an International Chemical Safety Card
    status: ground
    note: PubChem's HSDB entry gives 0.07 g/100 g water at 25 °C, a much lower figure. The two sources disagree.
    source: icsc-0596
    where: Physical and Chemical Information, Solubility in water
  - benchmark: molecular_weight
    label: Molecular weight, V2O5
    value: 181.88
    unit: g/mol
    scope: material
    conditions:
      basis: computed from the formula V2O5
    method: Computed property in the PubChem record
    status: calculated
    source: pubchem-v2o5
    where: Computed Properties, Molecular Weight
  - benchmark: temperature_coefficient_of_resistance
    label: TCR, sputtered V2O5/V multilayer film, O2 anneal 30 min
    value: -3.0036
    unit: '%/K'
    scope: material
    conditions:
      film: V2O5 and V 5 nm layers, 105 nm total, sputtered and annealed (a mixed VOx film, not bulk V2O5)
      anneal: 300 °C (573 K) in O2 for 30 min
      temperature: about 298 K
    method: Resistance against temperature measured on resistive thermometers; TCR from the paper's equation
    status: ground
    source: mdpi-bolometer-2019
    where: Abstract, first results sentence; Results, Table 1
  - benchmark: temperature_coefficient_of_resistance
    label: TCR, sputtered V2O5/V multilayer film, O2 anneal 40 min
    value: -2.4964
    unit: '%/K'
    scope: material
    conditions:
      film: V2O5 and V 5 nm layers, 105 nm total, sputtered and annealed (a mixed VOx film, not bulk V2O5)
      anneal: 300 °C (573 K) in O2 for 40 min
      temperature: about 298 K
    method: Resistance against temperature measured on resistive thermometers; TCR from the paper's equation
    status: ground
    source: mdpi-bolometer-2019
    where: Abstract, first results sentence; Results, Table 1
  - benchmark: temperature_coefficient_of_resistance
    label: TCR, sputtered V2O5/V multilayer film, N2 anneal 30 min
    value: -3.18
    unit: '%/K'
    scope: material
    conditions:
      film: V2O5 and V 5 nm layers, 105 nm total, sputtered and annealed (a mixed VOx film, not bulk V2O5)
      anneal: 300 °C (573 K) in N2 for 30 min
      temperature: about 298 K
    method: Resistance against temperature measured on resistive thermometers; TCR from the paper's equation
    status: ground
    source: mdpi-bolometer-2019
    where: Abstract, second results sentence; Results, Table 1
  - benchmark: temperature_coefficient_of_resistance
    label: TCR, sputtered V2O5/V multilayer film, N2 anneal 40 min
    value: -1.1181
    unit: '%/K'
    scope: material
    conditions:
      film: V2O5 and V 5 nm layers, 105 nm total, sputtered and annealed (a mixed VOx film, not bulk V2O5)
      anneal: 300 °C (573 K) in N2 for 40 min
      temperature: about 298 K
    method: Resistance against temperature measured on resistive thermometers; TCR from the paper's equation
    status: ground
    source: mdpi-bolometer-2019
    where: Abstract, second results sentence; Results, Table 1
  - benchmark: electrical_resistivity
    label: Resistivity, sputtered V2O5/V multilayer film, O2 anneal 30 min
    value: 0.01477
    unit: Ω·cm
    scope: material
    conditions:
      film: V2O5 and V 5 nm layers, 105 nm total, sputtered and annealed (a mixed VOx film, not bulk V2O5)
      anneal: 300 °C (573 K) in O2 for 30 min
      temperature: about 298 K
    method: Resistivity printed by the paper at room temperature
    status: ground
    source: mdpi-bolometer-2019
    where: Abstract, first results sentence; Results, Table 1
  - benchmark: electrical_resistivity
    label: Resistivity, sputtered V2O5/V multilayer film, O2 anneal 40 min
    value: 0.00819
    unit: Ω·cm
    scope: material
    conditions:
      film: V2O5 and V 5 nm layers, 105 nm total, sputtered and annealed (a mixed VOx film, not bulk V2O5)
      anneal: 300 °C (573 K) in O2 for 40 min
      temperature: about 298 K
    method: Resistivity printed by the paper at room temperature
    status: ground
    source: mdpi-bolometer-2019
    where: Abstract, first results sentence; Results, Table 1
  - benchmark: electrical_resistivity
    label: Resistivity, sputtered V2O5/V multilayer film, N2 anneal 30 min
    value: 0.04718
    unit: Ω·cm
    scope: material
    conditions:
      film: V2O5 and V 5 nm layers, 105 nm total, sputtered and annealed (a mixed VOx film, not bulk V2O5)
      anneal: 300 °C (573 K) in N2 for 30 min
      temperature: about 298 K
    method: Resistivity printed by the paper at room temperature
    status: ground
    source: mdpi-bolometer-2019
    where: Abstract, second results sentence; Results, Table 1
  - benchmark: electrical_resistivity
    label: Resistivity, sputtered V2O5/V multilayer film, N2 anneal 40 min
    value: 0.002527
    unit: Ω·cm
    scope: material
    conditions:
      film: V2O5 and V 5 nm layers, 105 nm total, sputtered and annealed (a mixed VOx film, not bulk V2O5)
      anneal: 300 °C (573 K) in N2 for 40 min
      temperature: about 298 K
    method: Resistivity printed by the paper at room temperature
    status: ground
    source: mdpi-bolometer-2019
    where: Abstract, second results sentence; Results, Table 1
corrosion:
  - environment: Molten sodium sulfate and V2O5 salt at 700 to 800 °C (hot corrosion of a nickel alloy)
    headline: V2O5 with sodium sulfate forms a molten salt that attacks nickel alloys at high temperature.
    effect: In a crucible test with about 20% Na2SO4 and 80% V2O5, Inconel 625 corroded more the longer it was exposed. After 24 h, CrVO4 and Ni3V2O8 formed on the surface, and sulfur entered the alloy to form internal sulfides that sped up intergranular attack. The paper gives no corrosion-rate scale, so no rating is assigned here.
    rating: unknown
    conditions:
      temperature: 700, 750 and 800 °C
      exposure: 24 to 120 h, weight-loss method
      salt: about 20% Na2SO4 and 80% V2O5 (section 2.2)
    source: metals-inconel-2023
    where: Abstract; Section 2.2; Section 3.1
  - environment: Aqueous acids and alkalis
    headline: V2O5 dissolves in concentrated acids and alkalis, and forms vanadates in alkali.
    effect: PubChem's HSDB-based summary says V2O5 is soluble in concentrated acids and alkalies and insoluble in alcohol, and that it forms vanadates in alkalis. The ICSC card gives a water solubility of 0.8 g/100 ml.
    rating: unknown
    conditions:
      form: powder
      temperature: not stated
    source: pubchem-v2o5
    where: Experimental Properties, Solubility (reference 35); Other Experimental Properties (reference 35)
  - environment: Heating above about 700 °C (oxygen loss)
    headline: V2O5 loses oxygen on heating, and decomposes at 1750 °C to give irritating vanadium oxide fumes.
    effect: The PubChem record says V2O5 loses oxygen reversibly between 700 and 1125 °C. When heated to decomposition it gives acrid smoke and irritating fumes of vanadium oxides. No ageing or reduction rate was found in a source read here.
    rating: unknown
    conditions:
      temperature: 700 to 1125 °C for the reversible oxygen loss; decomposition at 1750 °C
    source: pubchem-v2o5
    where: Other Experimental Properties (reference 35); Decomposition (reference 35)
risks:
  hazards:
    - text: Signal word Danger. The EU harmonised classification listed in PubChem (Regulation (EC) No 1272/2008) gives H301 toxic if swallowed, H330 fatal if inhaled, H335 may cause respiratory irritation, H341 suspected of causing genetic defects, H350 may cause cancer, H361fd, H362, H372 causes damage to organs through prolonged or repeated exposure, and H411 toxic to aquatic life with long lasting effects.
      ghs:
        - H301
        - H330
        - H335
        - H341
        - H350
        - H361fd
        - H362
        - H372
        - H411
      source: pubchem-v2o5
      where: GHS Classification, Regulation (EC) No 1272/2008 entry (reference 48)
    - text: PubChem gives a probable oral lethal dose for humans of 5 to 50 mg/kg, which the record says is about the same magnitude as pentavalent arsenic. Chronic bronchitis has been described in boiler cleaners exposed to the dust.
      ghs: []
      source: pubchem-v2o5
      where: Hazards Identification, Health Hazards (reference 6); Hazards Summary (reference 33)
    - text: 'Occupational exposure limit on the ICSC card: TLV 0.05 mg/m3 as V, inhalable fraction, as TWA; A3, confirmed animal carcinogen with unknown relevance to humans.'
      ghs: []
      source: icsc-0596
      where: Occupational Exposure Limits
    - text: The aerosol irritates the eyes, skin and respiratory tract, and can be absorbed by inhalation and by ingestion. Upon heating, toxic fumes are formed, and the material is not combustible.
      ghs: []
      source: icsc-0596
      where: Exposure and Health Effects; Fire Hazard
  failure_risks:
    - mode: Vanadate attack on a nickel alloy at high temperature
      trigger: Sodium sulfate and V2O5 deposits from high-sulfur, high-vanadium fuel at 700 to 800 °C, in the crucible test
      consequence: Corrosion of Inconel 625 rose with time and temperature. Sulfur entered the alloy and formed internal sulfides that sped up intergranular attack.
      severity: high
      source: metals-inconel-2023
      where: Abstract; Introduction; Section 3.1
    - mode: Film resistivity and TCR shift with the anneal
      trigger: Changing the anneal atmosphere (O2 or N2) or time (30 or 40 min) of a sputtered V2O5/V multilayer
      consequence: The TCR moved from -3.0036 to -2.4964 %/K in O2 and from -3.18 to -1.1181 %/K in N2. Resistivity in N2 fell from 0.04718 to 0.002527 Ω·cm.
      severity: moderate
      source: mdpi-bolometer-2019
      where: Abstract; Results, Table 1
  side_effects:
    - text: When heated to decomposition, V2O5 gives acrid smoke and irritating fumes of vanadium oxides, and the record notes that it may increase the intensity of a fire when in contact with combustible materials.
      affects: People and equipment near a fire or a hot process
      source: pubchem-v2o5
      where: Experimental Properties, Decomposition (reference 35); Fire Hazards (reference 6)
  handling:
    - text: Prevent dispersion of dust. Use ventilation, local exhaust or breathing protection, gloves, and safety goggles, and do not eat, drink or smoke at work.
      source: icsc-0596
      where: Prevention
    - text: Store separated from food and feedstuffs, and do not transport with food.
      source: icsc-0596
      where: Storage; Packaging
    - text: For spills, moisten the powder first to prevent dusting, sweep it into covered containers, and do not let the chemical enter the environment.
      source: icsc-0596
      where: Spillage disposal
  mitigations:
    - text: Keep airborne vanadium below the ICSC TLV of 0.05 mg/m3 (as V, inhalable fraction, TWA).
      source: icsc-0596
      where: Occupational Exposure Limits
    - text: Use a particulate filter respirator adapted to the airborne concentration when clearing a spill, as the ICSC card advises.
      source: icsc-0596
      where: Spillage disposal
uses:
  - application: batteries
    device: Vanadium redox flow battery for grid-scale energy storage
    example: The USGS says vanadium redox flow batteries continued to be used in large-scale energy storage in 2025, because of their operational safety, long cycle life and suitability for medium- to long-duration use. It calls high-purity vanadium feedstock a key challenge.
    source: usgs-mcs2026-vanadium
    where: Events, Trends, and Issues (vanadium chapter)
  - application: optics-and-cameras
    device: Uncooled infrared microbolometer thermometer film, lab-made from sputtered V2O5 and vanadium layers
    example: Annealed at 300 °C, the films reached TCRs between -1.1181 and -3.18 %/K, depending on the anneal atmosphere and time. The authors say the films have TCR and resistivity properties suitable for microbolometer applications.
    source: mdpi-bolometer-2019
    where: Abstract; Conclusions
supply:
  - subject: Vanadium (feedstock for V2O5 and vanadium alloys)
    producers:
      - country: China
        share_percent: 71.2
        year: 2024
      - country: Russia
        share_percent: 17.8
        year: 2024
      - country: South Africa
        share_percent: 6.8
        year: 2024
      - country: Brazil
        share_percent: 4.4
        year: 2024
    critical_lists:
      - list: 'USGS 2025 List of Critical Minerals (entry: Vanadium, used to strengthen iron and steel)'
        listed: true
      - list: EU critical raw materials list, fifth list of 34 (2023), as shown on the European Commission page
        listed: true
    recycling: 'USGS: recycling of vanadium is mainly reprocessing of vanadium catalysts into new catalysts.'
    substitutes:
      - 'USGS: platinum and nickel can replace vanadium compounds as catalysts in some chemical processes.'
      - 'USGS: no acceptable substitute for vanadium is available for use in aerospace titanium alloys.'
    source: usgs-mcs2026-vanadium
    where: 'World Mine Production and Reserves table, 2024 column, vanadium content in thousand metric tons. Shares calculated by Space Mushroom against the printed 2024 world total of 118,000. The China and Russia figures are marked e (estimated) in the USGS table. The 2025e column does not add up to its printed world total, so it was not used. Recycling; Substitutes. Critical lists: usgs-crit2025 and ec-crm.'
  - subject: Vanadium pentoxide, U.S. import sources (not world production)
    producers:
      - country: Brazil
        share_percent: 47
      - country: South Africa
        share_percent: 43
      - country: Russia
        share_percent: 6
      - country: Other
        share_percent: 4
    critical_lists: []
    recycling: 'USGS: vanadium pentoxide is recovered from processed waste materials such as petroleum residues, spent catalysts and utility ash in the United States.'
    substitutes: []
    source: usgs-mcs2026-vanadium
    where: Import Sources (2021-24), vanadium pentoxide, as printed in the USGS vanadium chapter. The year field is left out because the USGS gives a 2021 to 2024 range.
documents:
  - title: 'International Chemical Safety Card 0596: Vanadium pentoxide'
    type: database
    url: https://chemicalsafety.ilo.org/dyn/icsc/showcard.display?p_card_id=0596
  - title: 'PubChem: Vanadium oxide (V2O5), CID 14814, computed and experimental properties and GHS classification'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/14814
    year: 2026
  - title: 'Mineral Commodity Summaries 2026: Vanadium (USGS)'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-vanadium.pdf
    year: 2026
  - title: Temperature-Dependent Resistive Properties of Vanadium Pentoxide/Vanadium Multi-Layer Thin Films for Microbolometer and Antenna-Coupled Microbolometer Applications (Sensors 2019, 19, 1320)
    type: paper
    url: https://www.mdpi.com/1424-8220/19/6/1320
    year: 2019
  - title: Hot Corrosion Behavior of Inconel 625 in Na2SO4 and V2O5 Molten Salt System (Metals 2023, 13, 1069)
    type: paper
    url: https://www.mdpi.com/2075-4701/13/6/1069
    year: 2023
  - title: A Comparative Study about Production of Vanadium Carbide (Archives of Metallurgy and Materials 2024, 69, 257-262)
    type: paper
    url: https://czasopisma.pan.pl//Content/130944/PDF/AMM-2024-1-42-Bugdayci.pdf
    year: 2024
  - title: Theoretical study of the crystal structure, stability, and properties of phases in the V-N system (Physical Review B 104, 134111, 2021)
    type: paper
    url: https://uspex-team.org/static/file/Zhang2021.pdf
    year: 2021
gaps:
  - No safety data sheet for V2O5 from a supplier was read in this run. The Sigma-Aldrich and Parchem SDS pages were found in search but not opened, so the hazard codes rest on PubChem's aggregated notifications, the ICSC card and the EU entry in PubChem.
  - The hazard codes differ between sources. Wikipedia's infobox lists H302, H332, H335, H341, H361, H372 and H411, while PubChem's aggregate lists H301 and H330. Only the PubChem and ICSC data were used.
  - Melting point (681 and 690 °C) and water solubility (0.8 g/100 ml on the ICSC card against 0.07 g/100 g in PubChem) disagree between sources. Both values are kept and labelled.
  - The 3.35 and 3.36 density values in PubChem have no printed unit, so they were not used. The ICSC card gives relative density 3.4 (water = 1) instead.
  - No bulk V2O5 hardness, elastic modulus, thermal expansion or thermal conductivity was found in a source read in this run.
  - The TCR and resistivity values are for sputtered mixed VOx multilayer films with vanadium metal, not for bulk V2O5. No measured TCR for bulk V2O5 was found.
  - 'The USGS chapter does not tie the flow-battery demand to V2O5 specifically: it discusses vanadium feedstock. No peer-reviewed source read in this run describes making a flow-battery electrolyte from V2O5.'
  - Catalysis (sulfuric acid and maleic anhydride), a major use named by the USGS and PubChem, is not in the allowed application list, so it is given only in the story section.
  - No space, vacuum, radiation or flight result for V2O5 or its films was found in a source read in this run.
  - Crustal abundance of vanadium was not read in a source opened for this profile.
  - The water solubility is recorded as printed, in g/100ml. The name water_solubility is not in the canonical property list, so it is a short snake_case name.
  - The USGS 2025e column for vanadium does not add up to its printed world total, so the shares use the 2024 column, which does.
  - The Wikipedia infobox gives the crystal system and space group. Its lattice constants and density were not used, because the Wikipedia pages are for composition and history only.
  - 'Vanadium nitride: the density and melting point were not confirmed in a source read here. A search snippet gave 2,050 and 2,320 °C for the melting point, and those figures were not used. The only value kept is a calculated hardness.'
  - 'Vanadium carbide: the values come from one 2024 paper. A thermal expansion value in the same sentence is left out.'
  - The hot-corrosion paper gives no corrosion-rate scale, so the corrosion rating is unknown. Only the abstract and the first sections were read.
  - The related sections (vanadium carbide and nitride) are kept in the top-level related key. The site schema does not declare that key, so the site will not display it until the schema is extended.
  - No media (figures or photographs) were added. The lithium iron phosphate profile has three media entries; this profile has none.
  - verify-values could not read the PubChem page (it returns a verification screen) or the MDPI bolometer page (HTTP 403). Those values were read in this run from the PubChem REST data and from the MDPI page in a browser, so they were checked by hand, not by the script.
sources:
  icsc-0596:
    title: 'International Chemical Safety Card 0596: Vanadium pentoxide'
    id: CAS 1314-62-1; ICSC 0596
    url: https://chemicalsafety.ilo.org/dyn/icsc/showcard.display?p_card_id=0596
    kind: database
    license: ILO International Chemical Safety Cards (cited, not reproduced)
  pubchem-v2o5:
    title: PubChem compound record, Vanadium oxide (V2O5), CID 14814
    id: CID 14814; CAS 1314-62-1; molecular formula O5V2
    url: https://pubchem.ncbi.nlm.nih.gov/compound/14814
    year: 2026
    kind: database
    license: public domain (NCBI)
  usgs-mcs2026-vanadium:
    title: Mineral Commodity Summaries 2026, Vanadium
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-vanadium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS, final list of 60 minerals, November 2025)
    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, fifth list of 34 critical raw materials)
    id: Regulation (EU) 2024/1252 (the page does not print the number)
    url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
    year: 2023
    kind: web
    license: European Commission web page
  mdpi-bolometer-2019:
    title: Temperature-Dependent Resistive Properties of Vanadium Pentoxide/Vanadium Multi-Layer Thin Films for Microbolometer and Antenna-Coupled Microbolometer Applications (Abdel-Rahman, Zia, Alduraibi; Sensors)
    id: doi:10.3390/s19061320
    url: https://www.mdpi.com/1424-8220/19/6/1320
    year: 2019
    kind: paper
    license: CC BY 4.0
  metals-inconel-2023:
    title: Hot Corrosion Behavior of Inconel 625 in Na2SO4 and V2O5 Molten Salt System (Li et al.; Metals)
    id: doi:10.3390/met13061069
    url: https://www.mdpi.com/2075-4701/13/6/1069
    year: 2023
    kind: paper
    license: CC BY 4.0
  wikipedia-v2o5:
    title: 'Vanadium(V) oxide, Wikipedia (infobox only: crystal system and space group)'
    url: https://en.wikipedia.org/wiki/Vanadium(V)_oxide
    kind: web
    license: CC BY-SA 4.0
  amm-vc-2024:
    title: A Comparative Study about Production of Vanadium Carbide (Bugdayci et al.; Archives of Metallurgy and Materials 69, 1, 257-262)
    id: doi:10.24425/amm.2024.147816
    url: https://czasopisma.pan.pl//Content/130944/PDF/AMM-2024-1-42-Bugdayci.pdf
    year: 2024
    kind: paper
    license: open access (cited, not reproduced)
  uspex-vn-2021:
    title: Theoretical study of the crystal structure, stability, and properties of phases in the V-N system (Zhang et al.; Physical Review B 104, 134111)
    id: doi:10.1103/PhysRevB.104.134111
    url: https://uspex-team.org/static/file/Zhang2021.pdf
    year: 2021
    kind: paper
    license: cited, not reproduced
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 14
  unreachable: 0
  caveats: 4
  note: 'Read by an AI assistant on 2026-10-26 from the pages and PDFs fetched in that run: the ICSC card, the PubChem record (REST data), the Sensors 2019 and Metals 2023 pages, the USGS vanadium chapter and critical list page, the EC page, the Archives 2024 PDF and the PRB 2021 PDF. Search snippets were not used as values. Caveats: the TCR and resistivity values are for lab films, not bulk V2O5; the hazard codes differ between sources; the melting point and water solubility disagree between sources; the vanadium carbide and nitride sections rest on one paper each.'
story:
  recipe:
    line: V2O5 is an oxide of vanadium with two vanadium and five oxygen per formula unit. Vanadium can take several oxidation states, which is the basis of its redox and catalytic chemistry.
    parts:
      - name: Vanadium
        symbol: V
        role: The metal centre. Vanadium changes between oxidation states as the oxide is reduced or reoxidised, which is what makes it useful in batteries and catalysts.
      - name: Oxygen
        symbol: O
        role: Bonded to the vanadium in the orthorhombic lattice. The oxide gives up oxygen reversibly between 700 and 1125 °C.
  risk_groups:
    - title: For people
      level: 3
      verdict: Toxic dust and fume, H330 fatal if inhaled
      lead: The EU harmonised classification in PubChem carries the Danger signal word. The ICSC card sets an exposure limit of 0.05 mg/m3 as V.
      points:
        - label: Inhaled
          line: Fatal if inhaled (H330), and may cause respiratory irritation (H335). The ICSC card calls the aerosol irritating to the eyes, skin and respiratory tract.
        - label: Swallowed
          line: Toxic if swallowed (H301). PubChem gives a probable oral lethal dose for humans of 5 to 50 mg/kg.
        - label: Long term
          line: Suspected of causing genetic defects (H341), may cause cancer (H350), and causes organ damage through repeated exposure (H372).
        - label: In a fire
          line: Heating gives acrid smoke and irritating fumes of vanadium oxides. The ICSC card says toxic fumes form on heating.
    - title: Handling and storage
      points:
        - label: Dust
          line: Prevent the dust from spreading. Use ventilation or breathing protection, and gloves and goggles.
        - label: Storage
          line: Store away from food and feedstuffs.
        - label: Spills
          line: Moisten the powder first to stop it dusting, then sweep it into covered containers.
    - title: If heated or in a melt
      lead: These effects come from laboratory and industrial data, not from incidents.
      points:
        - label: Molten salt
          line: With sodium sulfate at 700 to 800 °C, the melt attacks Inconel 625. Corrosion rose with time, and sulfur formed internal sulfides in the alloy.
        - label: Film anneal
          line: In lab films, changing the N2 anneal from 30 to 40 min moved the TCR from -3.18 to -1.1181 %/K.
  why: Vanadium pentoxide is used in industry as a catalyst for sulfuric acid and maleic anhydride, and as a route to vanadium metal and ferrovanadium. In this collection it matters for flow batteries and for infrared sensor films, both of which depend on vanadium chemistry. The data come from safety cards, databases and laboratory papers. No flight record for V2O5 itself was found.
  uses:
    - where: Catalysts for sulfuric acid and maleic anhydride
      line: The USGS says the major non-metallurgical use of vanadium is in catalysts that make maleic anhydride and sulfuric acid.
    - where: Flow batteries
      line: The USGS says vanadium redox flow batteries kept being used for large-scale energy storage in 2025, and it calls high-purity vanadium feedstock a key challenge.
    - where: Infrared sensor films (laboratory)
      line: Sputtered V2O5 and vanadium films, annealed at 300 °C, reached TCRs between -1.1181 and -3.18 %/K. The authors say they suit microbolometer applications.
    - where: Glazes and glass
      line: PubChem lists V2O5 as a ceramic colouring material and as an agent that inhibits UV transmission in glass.
  can_do:
    - label: Thermal sensing (lab film)
      value: TCR -3.18 %/K
      line: A sputtered V2O5 and vanadium multilayer annealed in N2 for 30 min reached -3.18 %/K at a resistivity of 0.04718 Ω·cm.
    - label: Catalysis
      value: Sulfuric acid and maleic anhydride
      line: The USGS names both as the main non-metallurgical catalyst uses of vanadium.
    - label: Melting point
      value: 690 °C
      line: The ICSC card gives a melting point of 690 °C. PubChem's HSDB record gives 681 °C.
  compare: V2O5 melts at 690 °C and decomposes at 1750 °C. Its film TCRs in this record range from -1.1181 to -3.18 %/K, depending on the anneal, so the anneal is the main control on the film result. The carbide and nitride in the related section are hard materials, and their hardness values are given there.
  compare_rows:
    - label: Melting point
      benchmark: melting_point
    - label: Decomposition
      benchmark: decomposition_temperature
    - label: Density (relative)
      benchmark: density
  handling:
    - Prevent dust. Use ventilation or breathing protection, gloves and goggles.
    - Store away from food and feedstuffs, and keep the powder out of the environment.
    - Clean spills by moistening first, then sweeping into covered containers.
  good_for:
    - Vanadium redox flow batteries. The USGS reports continued use for long-duration grid storage in 2025.
    - Laboratory infrared sensor films. Annealed V2O5 and vanadium films reached TCRs of -1.1181 to -3.18 %/K.
  watch_out:
    - Toxicity. The EU harmonised classification lists H301, H330 and H350, and PubChem gives a probable oral lethal dose of 5 to 50 mg/kg.
    - Dust. The ICSC card calls for dust control, with an exposure limit of 0.05 mg/m3 as V.
    - Molten salt. With sodium sulfate at 700 to 800 °C, V2O5 attacks nickel alloys such as Inconel 625.
    - Conflicting data. Melting point 681 or 690 °C, and water solubility 0.8 g/100 ml on the ICSC card against 0.07 g/100 g in PubChem.
  verdict: V2O5 is a well-studied oxide with a clear industrial role in catalysis and a place in flow batteries. It is toxic as powder and fume, and the infrared results come from laboratory films rather than bulk material, so treat those values as laboratory data.
related:
  - name: Vanadium carbide
    formula: VC
    summary: Vanadium carbide is a hard, high-melting transition-metal carbide. The 2024 Archives of Metallurgy and Materials paper prints its melting point, density and hardness in one sentence, with a molar mass of 62.953 g/mol.
    properties:
      - benchmark: melting_point
        value: 2810
        unit: °C
        scope: material
        conditions:
          form: vanadium carbide, as printed
        method: Value printed in the Introduction of a 2024 review-style paper, citing earlier work
        status: ground
        source: amm-vc-2024
        where: Introduction, paragraph citing reference [7]
      - benchmark: density
        value: 5.77
        unit: g/cm3
        scope: material
        conditions:
          form: vanadium carbide, as printed
        method: Value printed in the Introduction of the same paper, citing earlier work
        status: ground
        source: amm-vc-2024
        where: Introduction, paragraph citing reference [7]
      - benchmark: hardness_vickers
        value: 28000
        unit: kg/mm2
        scope: material
        conditions:
          form: vanadium carbide, as printed; the printed sentence does not name the hardness scale
        method: Value printed in the Introduction of the same paper, citing earlier work
        status: ground
        note: The scale is not named in the printed sentence. The paper gives the unit as kg/mm2.
        source: amm-vc-2024
        where: Introduction, paragraph citing reference [7]
  - name: Vanadium nitride
    formula: VN
    summary: Vanadium nitride is a hard nitride. A 2021 Physical Review B study calculates a Vickers hardness of about 37 GPa for its WC-type phase. Density and melting point were not confirmed in a source read in this run.
    properties:
      - benchmark: hardness_vickers
        value: 37
        unit: GPa
        scope: material
        conditions:
          phase: WC-type VN, calculated
          temperature: 0 GPa pressure, as stated in the abstract
        method: Calculated from first principles and a hardness model in the paper (Chen-Niu model with a modification by Tian)
        status: calculated
        note: A calculated value, not a measured one. The paper calls it close to the superhardness threshold of 40 GPa.
        source: uspex-vn-2021
        where: Abstract; Table II