spore: profile id: barium spore_version: 0.2 family: alkali-and-alkaline-earth-metals name: Barium metal abbreviation: Ba role: getter category: metals type: heavy-metals summary: | Barium is a soft, silvery alkaline earth metal. It reacts with water, giving off hydrogen, and it oxidizes readily in moist air. Its spaceflight role comes from barium oxide, which is pressed into the tungsten emitters of dispenser cathodes that supply the electrons used by ion and Hall thrusters and by plasma contactors. Barium alloys with aluminium or magnesium also serve as getters that remove residual gases in electronic vacuum tubes. best_for: Getter alloys and barium-impregnated electron emitters inside a sealed vacuum, where the metal is never exposed to water or air weakest_at: 'Any contact with water or moist air: it reacts at once and releases hydrogen, and powdered barium reacts violently with air' identity: formula: Ba cas: 7440-39-3 crystal_system: cubic source: atsdr-2007 where: 'Table 4-2, Barium column: CAS registry and Physical description (silvery-yellow metal; cubic)' tags: environments: - low-earth-orbit stresses: - vacuum-and-outgassing applications: - electronics-and-chips - propulsion-and-tanks - structures properties: - benchmark: density value: 3.51 unit: g/cm3 scope: material conditions: temperature: 20 C method: Value printed in the supplier safety data sheet status: ground source: aci-ba-sds where: 'Section 9, Physical and chemical properties: Density at 20 C' - benchmark: density value: 3.62 unit: g/cm3 scope: material conditions: temperature: not stated by source method: Value printed in the ATSDR profile status: ground note: The supplier sheet gives 3.51 g/cm3 at 20 C. The profile keeps both values and does not average them. source: atsdr-2007 where: 'Table 4-2, Barium column: Density' - benchmark: melting_point value: 727 unit: °C scope: material conditions: pressure: not stated by source method: Value printed in the ATSDR profile status: ground source: atsdr-2007 where: 'Table 4-2, Barium column: Melting point' - benchmark: melting_point value: 725 unit: °C scope: material conditions: pressure: not stated by source method: Value printed in the supplier safety data sheet status: ground note: The supplier sheet gives 725 C, 2 C below the ATSDR value. Both are kept. source: aci-ba-sds where: Section 9, Melting point/Melting range - benchmark: boiling_point value: 1897 unit: °C scope: material conditions: pressure: not stated by source method: Value printed in the ATSDR profile status: ground note: The ATSDR table prints the row label as Boling point. The University of Waterloo page gives the same 1897 C, citing the CRC Handbook 91st edition. The supplier sheet disagrees (1640 C). source: atsdr-2007 where: 'Table 4-2, Barium column: boiling point row' - benchmark: boiling_point value: 1640 unit: °C scope: material conditions: pressure: not stated by source method: Value printed in the supplier safety data sheet status: ground note: Conflicts with the 1897 C in ATSDR and the Waterloo page. The profile does not choose between them. source: aci-ba-sds where: Section 9, Boiling point/Boiling range - benchmark: electrical_resistivity value: 34.3 unit: microohm cm scope: material conditions: temperature: 300 K unit_in_source: 34.3 x 10-8 ohm m method: 'Printed as 34.3 x 10-8 ohm m and converted: 1 microohm cm equals 10-8 ohm m, so the number is unchanged' status: ground note: The page is an aggregator that does not attribute each value to a handbook. source: knowledgedoor-barium where: Electrical Resistivity (solid) entry at 300 K - benchmark: thermal_conductivity value: 18.4 unit: W/(m·K) scope: material conditions: temperature: 295 K method: Value printed on the page, which marks each thermal conductivity entry as estimated status: calculated source: knowledgedoor-barium where: Thermal Conductivity (solid) entry at 295 K - benchmark: specific_heat value: 0.204 unit: J/(g K) scope: material conditions: temperature: 298.15 K pressure: 1 bar method: Isobaric specific heat capacity printed on the page status: ground source: knowledgedoor-barium where: 'Specific heat: Isobaric Specific Heat Capacity row' - benchmark: cte value: 20.6 unit: ppm/K scope: material conditions: temperature: not stated by source method: Printed as 20.6 x 10-6 K-1, which is the same as ppm/K status: ground source: webelements-physics where: 'Heat and conduction: Coefficient of linear thermal expansion' - benchmark: elastic_modulus value: 13 unit: GPa scope: material conditions: temperature: not stated by source method: Young's modulus printed on the page status: ground source: webelements-physics where: 'Elastic properties: Young''s modulus' - benchmark: pauling_electronegativity label: Pauling electronegativity value: 0.89 unit: '-' scope: material conditions: scale: Pauling method: Value printed on the page, which cites the CRC Handbook 91st edition status: ground note: Not in the canonical property file, so this snake_case name is used. Listed in gaps. source: uwaterloo-barium where: 'Atomic properties: Electronegativity' - benchmark: first_ionization_energy label: First ionization energy value: 5.211664 unit: eV scope: material conditions: order: first ionization method: Value printed on the page status: ground note: Not in the canonical property file, so this snake_case name is used. Listed in gaps. source: knowledgedoor-barium where: 'Ionization Energies: I (1)' - benchmark: enthalpy_of_fusion label: Enthalpy of fusion value: 7.66 unit: kJ/mol scope: material conditions: pressure: 1 atm method: Value printed on the page status: ground source: knowledgedoor-barium where: Enthalpy of Fusion entry corrosion: - environment: Liquid water headline: Barium reacts violently with water and releases flammable hydrogen gas. effect: The supplier sheet says barium reacts violently with water and that contact liberates extremely flammable gases. ATSDR says the metal decomposes in water and evolves hydrogen gas. rating: severe conditions: form: bulk metal source: aci-ba-sds where: 'Section 2 (R14 Reacts violently with water) and Section 10 (Water: reacts violently)' - environment: Moist air headline: Barium oxidizes readily in moist air and takes on a silver-yellow colour. effect: Metallic barium is silvery-white but takes on a silver-yellow colour when exposed to air. It oxidizes readily in moist air, and in powdered form it reacts violently with air. rating: severe conditions: atmosphere: moist air source: atsdr-2007 where: Section 4.2, Physical and chemical properties - environment: Air, once ignited headline: Once ignited, barium burns in air to give barium oxide and barium nitride. effect: Once ignited, barium metal burns in air to give a mixture of white barium oxide and barium nitride, Ba3N2. rating: severe conditions: temperature: not stated; the page describes ignition only source: webelements-chemistry where: Reaction of barium with air - environment: Dry argon headline: The supplier recommends handling under dry argon. effect: 'The supplier sheet gives a handling instruction only: handle under dry argon. It states no corrosion rate in dry argon.' rating: low conditions: atmosphere: dry argon source: aci-ba-sds where: Section 7, Handling and storage - environment: Fire-fighting media headline: Water, carbon dioxide and halogenated extinguishers are unsuitable for barium fires. effect: The supplier sheet lists water, carbon dioxide and halogenated extinguishers as unsuitable. Extinguishing powder is the suitable agent, and contact with water releases hydrogen. rating: severe conditions: state: burning or hot barium source: aci-ba-sds where: Section 5, Fire-fighting measures risks: hazards: - text: Reacts violently with water. Contact with water liberates extremely flammable gases, and the sheet notes that the released hydrogen is explosive. ghs: [] source: aci-ba-sds where: Section 2 (R14), Section 5 (Special hazard) - text: Classified with the old EU irritant symbol Xi. The sheet prints no GHS hazard statement (H-code). ghs: [] source: aci-ba-sds where: Section 2, Hazard description - text: UN1400, Barium, hazard class 4.3. ghs: [] source: aci-ba-sds where: Section 14, Transport information - text: In powdered form, barium reacts violently with air. ghs: [] source: atsdr-2007 where: Section 4.2, Physical and chemical properties failure_risks: - mode: Barium depletion ends cathode life trigger: Evolution and transport of barium away from the emitter surface of a barium-impregnated thermionic cathode consequence: NASA Glenn states that this process determines the entitlement lifetime of the cathode. severity: high source: nasa-kovaleski where: Abstract - mode: Hydrogen release on contact with water trigger: Water or moisture reaching bulk barium consequence: Liberates extremely flammable gas, which the sheet calls explosive hydrogen. severity: high source: aci-ba-sds where: Section 5 (Special hazard) - mode: Ignition of powdered barium trigger: Powdered barium exposed to air consequence: Reacts violently with air, so the powder is a fire hazard. severity: high source: atsdr-2007 where: Section 4.2, Physical and chemical properties side_effects: - text: Reaction with water releases hydrogen gas, which can ignite. affects: Storage area and fire response source: aci-ba-sds where: Section 5 and Section 10 - text: Burning barium gives barium oxide and barium nitride as fire residues. affects: Fire area source: webelements-chemistry where: Reaction of barium with air handling: - text: Handle and store under dry argon. source: aci-ba-sds - text: Keep water away. Use extinguishing powder for fires and do not use water. source: aci-ba-sds - text: Ship as UN1400, hazard class 4.3. source: aci-ba-sds mitigations: - text: Barium oxide pressed with tungsten in a matrix is the best-performing reservoir cathode material in the NASA Glenn work. The reservoir design aims at more than 100,000 hours of life. source: nasa-reservoir where: Abstract uses: - application: electronics-and-chips device: Getter alloy in an electronic vacuum tube example: Barium alloys with aluminium or magnesium are used as getters in electronic tubes to remove residual gases. source: atsdr-2007 where: Section 4.1, Chemical identity - application: propulsion-and-tanks device: Barium-impregnated hollow cathode in ion and Hall thrusters example: Hollow cathodes provide electrons for propellant ionization and neutralization in ion and Hall thrusters, and emit electron current in International Space Station plasma contactors. source: nasa-kovaleski where: Introduction, first paragraph - application: propulsion-and-tanks device: Miniature reservoir dispenser cathode example: NASA Glenn and FDE report a miniature reservoir cathode with an objective of more than 100,000 hours of life at high loading. source: nasa-reservoir where: Abstract - application: structures device: Deoxidizer for steel and other metals example: Barium is used as a deoxidizer for steel and other metals. source: atsdr-2007 where: Section 4.1, Chemical identity supply: - subject: Barium, mined as barite (barium sulfate) abundance: 'World barite mine production was 8,700 thousand metric tons in 2025 (rounded total; the United States is withheld). Reserves in thousand metric tons: China 120,000; India 51,000; Iran 100,000; Kazakhstan 85,000; Russia 12,000; Turkey 34,000. Identified barite resources in the United States are 150 million tons. Net import reliance is more than 75 percent. More than 90 percent of barite sold in the United States is a weighting agent in oil and gas drilling fluids. Barium metal is not a separate line in the USGS data.' producers: - country: India share_percent: 34.5 year: 2025 - country: China share_percent: 25.3 year: 2025 - country: Morocco share_percent: 11.5 year: 2025 - country: Kazakhstan share_percent: 8 year: 2025 - country: Iran share_percent: 3.4 year: 2025 - country: Mexico share_percent: 3.4 year: 2025 - country: Laos share_percent: 3 year: 2025 - country: Turkey share_percent: 3 year: 2025 - country: Russia share_percent: 2.6 year: 2025 - country: Pakistan share_percent: 1.1 year: 2025 critical_lists: - list: 'USGS 2025 final list of critical minerals: barite is listed; barium is not named separately' listed: true recycling: No recycling figure for barium was found in the sources read for this profile. substitutes: - 'For barite in drilling fluids (USGS): calcium carbonate, hematite, ilmenite and manganese tetroxide.' source: usgs-barite-2026 where: Salient statistics and World Mine Production and Reserves table (2025 values); Substitutes section. Shares are computed by the editors as 2025 mine production divided by the rounded world total of 8,700 thousand tons. Critical list status from usgs-critical-2025. story: recipe: line: Barium metal is the pure element, Ba, with one atom per formula unit. It is not an alloy in this profile. The supplier sheet says to handle it under dry argon. parts: - name: Barium symbol: Ba atoms: 1 atomic_weight: 137.327 role: The only element in the metal. The atomic weight is the value given by ATSDR for the element (molecular weight row, Table 4-2). why: Barium is a soft, silvery alkaline earth metal. Because it is so reactive, ATSDR says it does not exist as the metal in the environment. Its useful forms in the sources read are its getter alloys and its oxide. Barium alloys with aluminium or magnesium remove residual gases in electronic vacuum tubes. Barium oxide is pressed into the tungsten emitters of dispenser cathodes, which give electrons for ion and Hall thrusters. The metal must never meet water. uses: - where: Electron emitters for electric propulsion line: NASA reports that hollow cathodes with barium calcium aluminate impregnated tungsten emitters provide electrons for ion and Hall thrusters, and emit electron current in International Space Station plasma contactors. The lifetime of the cathode is set by the transport of barium away from its emitter surface. - where: Vacuum tubes and getters line: Barium alloys with aluminium or magnesium are used as getters in electronic tubes to remove residual gases. Barium is also used as a deoxidizer for steel and other metals. can_do: - label: Density value: 3.51 g/cm3 line: The supplier sheet gives 3.51 g/cm3 at 20 C and ATSDR gives 3.62 g/cm3. The two sources differ, and the profile keeps both. - label: Melting point value: 727 °C line: ATSDR gives 727 C and the supplier sheet 725 C. The heat of fusion is 7.66 kJ/mol, as printed on the aggregator page. - label: Electrical resistivity value: 34.3 microohm cm at 300 K line: Resistivity as printed on the aggregator page, converted from 34.3 x 10-8 ohm m. - label: Specific heat value: 0.204 J/(g K) line: Isobaric specific heat capacity at 298.15 K and 1 bar, as printed on the aggregator page. compare: Barium is not a battery material, so the collection does not compare it with lithium cells. In the sources read for this profile, barium is used for its getter alloys and for barium oxide in emitters inside sealed vacuum systems. Its two sources give densities of 3.51 and 3.62 g/cm3, and its melting point is 727 C (ATSDR) or 725 C (supplier sheet). compare_rows: - label: Density benchmark: density scope: material - label: Melting point benchmark: melting_point scope: material - label: Electrical resistivity benchmark: electrical_resistivity scope: material handling: - Handle and store under dry argon. Keep it away from water and moist air. - Use extinguishing powder for fires. Water, carbon dioxide and halogenated extinguishers are unsuitable. - Ship as UN1400, hazard class 4.3. good_for: - Electron emitters in dispenser cathodes, which NASA has used for ion and Hall thrusters. - Getter alloys that remove residual gases in electronic vacuum tubes. watch_out: - It reacts violently with water and releases flammable hydrogen. - Powdered barium reacts violently with air. - The handbook values for the boiling point do not agree (1897 C and 1640 C), so check a primary table before using it. verdict: Barium is a useful getter metal, but it is hazardous to handle. The space uses in the sources read are of barium oxide in emitters inside vacuum hardware, not of bare barium metal. risk_groups: - title: For people level: 3 verdict: Reacts violently with water; releases hydrogen lead: The supplier sheet describes barium as reacting violently with water and gives the old EU irritant classification. It prints no GHS hazard codes. points: - label: Water reaction line: Contact with water releases extremely flammable gas, which the sheet calls explosive hydrogen (R14 and Section 5). - label: Powder line: In powdered form barium reacts violently with air (ATSDR). - label: Transport line: Shipped as UN1400, hazard class 4.3. - title: Fire level: 3 verdict: Use dry powder; never use water lead: Burning barium forms oxides and nitrides, and water, carbon dioxide and halogenated extinguishers are unsuitable. points: - label: Extinguishing line: Extinguishing powder is the suitable agent (Section 5 of the supplier sheet). - label: Residues line: Once ignited, barium burns in air to give barium oxide and barium nitride (WebElements). - title: Handling and storage points: - label: Storage line: Handle and store under dry argon, away from water and moist air (Section 7 of the supplier sheet). - label: Shipping line: Ship as UN1400, hazard class 4.3 (Section 14 of the supplier sheet). license: CC-BY-4.0 updated: '2026-10-26' review: status: draft method: assistant checked_values: 14 unreachable: 2 caveats: 3 note: 'Read by an AI assistant on 2026-10-26: 14 property rows from 10 sources. Two melting points, two boiling points and two densities are kept as printed. PubChem and the UNR safety data sheet could not be opened.' documents: - title: Barium safety data sheet (ACI Alloys) type: sds url: https://www.acialloys.com/wp-content/uploads/msds/ba.html - title: ATSDR Toxicological Profile for Barium type: report url: https://www.atsdr.cdc.gov/ToxProfiles/tp24-c4.pdf year: 2007 - title: 'WebElements: Barium, physical properties' type: database url: https://www.webelements.com/barium/physics.html - title: 'WebElements: Barium, chemistry' type: database url: https://www.webelements.com/barium/chemistry.html - title: University of Waterloo chemistry page on barium (CRC Handbook 91st edition) type: database url: https://uwaterloo.ca/chemistry/node/700 - title: 'Elements handbook: barium (aggregator page)' type: database url: https://www.knowledgedoor.com/2/elements_handbook/barium.html - title: 'USGS Mineral Commodity Summaries 2026: Barite' type: report url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-barite.pdf year: 2026 - title: 'USGS: Final 2025 list of critical minerals (science snippet)' type: report url: https://www.usgs.gov/news/science-snippet/interior-department-releases-final-2025-list-critical-minerals year: 2025 - title: 'NASA NTRS 20020013325: Life model of hollow cathodes using a barium calcium aluminate impregnated emitter' type: report url: https://ntrs.nasa.gov/api/citations/20020013325/downloads/20020013325.pdf - title: 'NASA NTRS 20020072844: Miniature reservoir cathode, an update (Vancil and Wintucky)' type: report url: https://ntrs.nasa.gov/api/citations/20020072844/downloads/20020072844.pdf gaps: - 'Electrode potential against the standard hydrogen electrode: no source with the number was read in this run.' - 'Specific heat, vapour pressure at room temperature and heat of vaporization: the aggregator page lists them without a handbook attribution, so they are left out apart from specific heat.' - 'Lattice type and space group: the aggregator page gives allotropes and a nearest-neighbour distance (435 pm) but no lattice type. Only cubic is given, from ATSDR.' - 'GHS hazard codes (H-codes) for barium metal: the supplier sheet uses the old EU classification only. No GHS table for barium metal was read in this run.' - 'Health effects and toxicity of the metal and of soluble barium compounds: the ATSDR PDF could not be extracted beyond its physical and chemical section in this run.' - 'Boiling point: sources disagree (1897 C in ATSDR and the Waterloo page citing CRC 91st ed.; 1640 C in the supplier sheet). Not resolved here.' - 'Density: 3.51 g/cm3 (supplier) and 3.62 g/cm3 (ATSDR) disagree. Both are kept and no value is chosen.' - Enthalpy of fusion, first ionization energy and Pauling electronegativity are not names in the canonical property file. The snake_case names are used as stated above, and enthalpy_of_fusion is already used in the lithium profile. - 'Alloying of barium into lead, bearing or aluminium-barium alloys for structural use: no source with compositions was read. Only ATSDR getter alloys with aluminium and magnesium are cited.' - 'Recycled share of barium supply: not read.' - 'Designations (UNS, EN, ASTM and similar codes) for barium metal: none printed by the sources read, so none are listed.' - No image with a checked licence was read in this run, so no media entries are included. sources: aci-ba-sds: title: 'Barium safety data sheet, ACI Alloys (Material Name: Barium)' url: https://www.acialloys.com/wp-content/uploads/msds/ba.html kind: datasheet license: supplier document atsdr-2007: title: Toxicological Profile for Barium and Barium Compounds, ATSDR (Table 4-2, physical and chemical properties) url: https://www.atsdr.cdc.gov/ToxProfiles/tp24-c4.pdf year: 2007 kind: report license: public domain (US government) webelements-physics: title: 'WebElements: Barium, physical properties' url: https://www.webelements.com/barium/physics.html kind: database license: web database webelements-chemistry: title: 'WebElements: Barium, chemistry (reaction with air and water)' url: https://www.webelements.com/barium/chemistry.html kind: database license: web database uwaterloo-barium: title: University of Waterloo chemistry page on barium (values cite CRC Handbook of Chemistry and Physics, 91st edition) url: https://uwaterloo.ca/chemistry/node/700 kind: database license: web page knowledgedoor-barium: title: 'Elements handbook: barium (aggregator, cites CRC 88th edition in its references without per-value attribution)' url: https://www.knowledgedoor.com/2/elements_handbook/barium.html kind: database license: web page usgs-barite-2026: title: 'Mineral Commodity Summaries 2026: Barite (USGS)' url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-barite.pdf year: 2026 kind: report license: public domain (US government) usgs-critical-2025: title: 'USGS: Interior Department releases final 2025 list of critical minerals' url: https://www.usgs.gov/news/science-snippet/interior-department-releases-final-2025-list-critical-minerals year: 2025 kind: web license: public domain (US government) nasa-kovaleski: title: Life model of hollow cathodes using a barium calcium aluminate impregnated emitter (NASA Glenn, NTRS 20020013325) url: https://ntrs.nasa.gov/api/citations/20020013325/downloads/20020013325.pdf kind: report license: public domain (US government) nasa-reservoir: title: Miniature Reservoir Cathode, an update (Vancil and Wintucky, FDE Inc. and NASA Glenn, NTRS 20020072844) url: https://ntrs.nasa.gov/api/citations/20020072844/downloads/20020072844.pdf kind: report license: public domain (US government)