Europium Eu

spore: profile
id: europium
spore_version: 0.2
family: rare-earth-metals
name: Europium
abbreviation: Eu
role: red phosphor activator, neutron absorber and scintillator activator
category: metals
type: heavy-metals
summary: |
  Europium is the element Eu (atomic number 63), a silvery-white rare-earth metal that tarnishes rapidly in air. Its density is 5.246 g/cm3 at 20 °C and its melting point is 826 °C (Wikipedia, Goodfellow). It is about 2 ppm of the Earth's crust and is mined only as part of the rare-earth group, with China producing about 69 % of world output in 2025 (USGS). Fresh metal tarnishes rapidly in air and reacts with water to release hydrogen, and finely divided metal may ignite spontaneously in air (Ames SDS). In the sources read, its main uses are as a red phosphor activator, as an activator in strontium iodide scintillators under development for planetary gamma-ray spectroscopy (named only in the arXiv paper), and as a neutron-absorbing control material in some reactors.
best_for: Red phosphor activator in display and lamp phosphors (Y2O3:Eu, YVO4:Eu) and as the activator of strontium iodide scintillators for planetary gamma-ray spectroscopy (Wikipedia, PSI, arXiv 1111.5505)
weakest_at: Tarnishes quickly in air, reacts with water to release flammable hydrogen, and finely divided metal can ignite spontaneously (Ames SDS, Wikipedia)
identity:
  formula: Eu (element, atomic number 63); unalloyed metal, sold by Goodfellow at up to 99.95 % (3N5) purity
  cas: 7440-53-1
  source: ames-eu-sds
  where: Section 3 Composition/Information on Ingredients, CAS# row (CAS 7440-53-1 also in the Wikipedia infobox)
tags:
  applications:
    - radiation-shielding
    - electronics-and-chips
properties:
  - benchmark: density
    label: Density, europium at 20 °C
    value: 5.264
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 °C
    method: Value printed in the Goodfellow general product table for europium
    status: ground
    source: goodfellow-eu
    where: General Properties table, row Density (20 °C) 5.264 g/cm³
  - benchmark: density
    label: Density, europium (Wikipedia)
    value: 5.246
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 °C
    method: Value printed in the Wikipedia infobox
    status: ground
    source: wikipedia-eu
    where: Infobox, row Density (20 °C) 5.246 g/cm3
  - benchmark: density
    label: Relative density, europium (Ames SDS)
    value: 5.25
    unit: g/cm3
    scope: material
    conditions:
      temperature: not stated
    method: Value printed in the Ames Laboratory safety data sheet, physical properties section
    status: ground
    source: ames-eu-sds
    where: Section 9 Physical and Chemical Properties, row Relative Density (Specific Gravity) 5.25 g/cc
  - benchmark: melting_point
    label: Melting point, europium (Goodfellow)
    value: 826
    unit: °C
    scope: material
    conditions:
      purity: up to 99.95 % (3N5)
      unit_in_source: 826 °C (1,099 K)
    method: Value printed in the Goodfellow general product table for europium
    status: ground
    note: Wikipedia prints the same 826 °C (1099 K) in its infobox. Suppliers and the Ames SDS use 822 °C, so both are kept.
    source: goodfellow-eu
    where: General Properties table, row Melting Point 826 °C (1,099 K)
  - benchmark: melting_point
    label: Melting point, europium (Ames SDS)
    value: 822
    unit: °C
    scope: material
    conditions:
      temperature: not stated
    method: Value printed in the Ames Laboratory safety data sheet, physical properties section
    status: ground
    note: The Ames sheet and several resellers use 822 °C, while Goodfellow and Wikipedia print 826 °C.
    source: ames-eu-sds
    where: Section 9 Physical and Chemical Properties, row Melting Point 822 oC
  - benchmark: boiling_point
    label: Boiling point, europium (Goodfellow)
    value: 1529
    unit: °C
    scope: material
    conditions:
      pressure: not stated
    method: Value printed in the Goodfellow general product table for europium
    status: ground
    source: goodfellow-eu
    where: General Properties table, row Boiling Point 1,529 °C
  - benchmark: boiling_point
    label: Boiling point, europium (Ames SDS)
    value: 1527
    unit: °C
    scope: material
    conditions:
      pressure: not stated
    method: Value printed in the Ames Laboratory safety data sheet, physical properties section
    status: ground
    note: The Ames sheet gives 1527 °C, which is 2 °C below the Goodfellow and Wikipedia figure of 1529 °C.
    source: ames-eu-sds
    where: Section 9 Physical and Chemical Properties, row Boiling Point 1527 oC
  - benchmark: thermal_conductivity
    label: Thermal conductivity, europium (Goodfellow)
    value: 13.9
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: not stated
    method: Value printed in the Goodfellow general product table for europium
    status: ground
    source: goodfellow-eu
    where: Thermal Properties table, row Thermal Conductivity 13.9 W/m·K
  - benchmark: thermal_conductivity
    label: Thermal conductivity, europium (WebElements)
    value: 14
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page
    status: ground
    source: webelements-eu
    where: Thermal properties, row Thermal conductivity 14 W m-1 K-1
  - benchmark: elastic_modulus
    label: Young's modulus, europium (Goodfellow)
    value: 18.2
    unit: GPa
    scope: material
    conditions:
      temperature: not stated
    method: Value printed in the Goodfellow general product table for europium
    status: ground
    source: goodfellow-eu
    where: Mechanical Properties table, row Young's Modulus 18.2 GPa
  - benchmark: elastic_modulus
    label: Young's modulus, europium (WebElements)
    value: 18
    unit: GPa
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page
    status: ground
    source: webelements-eu
    where: Elastic properties, row Young's modulus 18 GPa
  - benchmark: shear_modulus
    label: Rigidity modulus, europium
    value: 7.9
    unit: GPa
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page
    status: ground
    source: webelements-eu
    where: Elastic properties, row Rigidity modulus 7.9 GPa
  - benchmark: bulk_modulus
    label: Bulk modulus, europium
    value: 8.3
    unit: GPa
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page
    status: ground
    source: webelements-eu
    where: Elastic properties, row Bulk modulus 8.3 GPa
  - benchmark: poissons_ratio
    label: Poisson's ratio, europium (Goodfellow)
    value: 0.15
    unit: '-'
    scope: material
    conditions:
      temperature: not stated
    method: Value printed in the Goodfellow general product table for europium
    status: ground
    source: goodfellow-eu
    where: Mechanical Properties table, row Poisson's Ratio 0.15
  - benchmark: poissons_ratio
    label: Poisson's ratio, europium (Wikipedia)
    value: 0.152
    unit: '-'
    scope: material
    conditions:
      temperature: not stated
    method: Value printed in the Wikipedia infobox
    status: ground
    source: wikipedia-eu
    where: Infobox, row Poisson ratio 0.152
  - benchmark: vickers_hardness
    label: Vickers hardness, europium
    value: 167
    unit: MPa
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on the WebElements physical-properties page, given as MN m-2 (equal to MPa)
    status: ground
    note: No canonical name exists for hardness, so vickers_hardness is a new name and is listed in gaps.
    source: webelements-eu
    where: Hardnesses, row Vickers hardness 167 MN m-2
  - benchmark: vickers_hardness
    label: Vickers hardness range, europium
    value: 165
    value_high: 200
    unit: MPa
    scope: material
    conditions:
      temperature: not stated
    method: Range printed in the Wikipedia infobox
    status: ground
    note: No canonical name exists for hardness, so vickers_hardness is a new name and is listed in gaps. Wikipedia gives a range, not a single test value.
    source: wikipedia-eu
    where: Infobox, row Vickers hardness 165–200 MPa
  - benchmark: cte
    label: Coefficient of linear thermal expansion, europium
    value: 35
    unit: ppm/K
    scope: material
    conditions:
      temperature: not stated
      unit_in_source: 35 × 10-6 K-1
    method: Value printed on the WebElements physical-properties page
    status: ground
    source: webelements-eu
    where: Thermal expansion, row Coefficient of linear thermal expansion 35 × 10-6 K-1
  - benchmark: electrical_resistivity
    label: Electrical resistivity, europium (Goodfellow)
    value: 920
    unit: nΩ·m
    scope: material
    conditions:
      temperature: 20 °C
    method: Value printed in the Goodfellow general product table for europium
    status: ground
    source: goodfellow-eu
    where: Electrical Properties table, row Electrical Resistivity 920 nΩ·m at 20 °C
  - benchmark: electrical_resistivity
    label: Electrical resistivity, europium (Wikipedia)
    value: 0.9
    unit: µΩ·m
    scope: material
    conditions:
      temperature: room temperature (not given as 20 °C)
      form: polycrystalline
    method: Value printed in the Wikipedia infobox
    status: ground
    note: Wikipedia gives 0.900 µΩ·m (900 nΩ·m) at room temperature, which is about 2 % below the Goodfellow figure of 920 nΩ·m at 20 °C. Both are kept with their conditions.
    source: wikipedia-eu
    where: Infobox, row Electrical resistivity, poly 0.900 µΩ·m (at r.t.)
  - benchmark: neel_temperature
    label: Néel temperature, europium metal
    value: 91
    unit: K
    scope: material
    conditions:
      transition: antiferromagnetic ordering
      unit_in_source: about 91 K
    method: Value printed in the Wikipedia article text, which gives it for the element as a Néel temperature
    status: ground
    note: The element has no Curie point in the infobox. The Wikipedia Curie figure of about 69 K applies to EuO, the compound, and is not entered. neel_temperature is a new name and is listed in gaps.
    source: wikipedia-eu
    where: Infobox, Curie point row (no value for the element); article text, magnetic properties paragraph, below a Néel temperature of about 91 K
corrosion:
  - environment: Air at room temperature
    headline: Fresh europium tarnishes rapidly in air and burns readily in oxygen to Eu2O3.
    effect: Wikipedia says fresh europium is silvery-white but rapidly tarnishes on exposure to air, and that it burns readily in oxygen to form Eu2O3. The Ames SDS says the metal is extremely reactive to oxygen and water or moisture, and that finely divided metal may ignite spontaneously in air.
    rating: severe
    conditions:
      atmosphere: air
      temperature: room temperature
    source: wikipedia-eu
    where: Chemical properties section, first paragraph and the oxygen reaction
  - environment: Cold water
    headline: Europium reacts slowly with cold water and releases hydrogen.
    effect: Wikipedia says the metal reacts slowly with cold water and more rapidly with hot water, releasing hydrogen. The Ames SDS says it reacts with water and releases flammable hydrogen gas.
    rating: moderate
    conditions:
      temperature: cold water
      form: metal
    source: wikipedia-eu
    where: Chemical properties section, paragraph on water
  - environment: Hot water
    headline: Europium reacts more rapidly with hot water than with cold water.
    effect: Wikipedia gives this as the faster case. The Ames SDS (section 10) lists water as incompatible and says the reaction releases flammable hydrogen gas.
    rating: severe
    conditions:
      temperature: hot water
      form: metal
    source: wikipedia-eu
    where: Chemical properties section, paragraph on water; Ames SDS section 10 Incompatible Materials
  - environment: Dilute non-oxidising acids
    headline: Europium dissolves readily in dilute non-oxidising acids to form Eu(III).
    effect: Wikipedia says the metal dissolves readily in dilute non-oxidising acids, forming Eu(III) in solution. The Ames SDS lists strong acids and acid chlorides as incompatible.
    rating: severe
    conditions:
      acid: dilute non-oxidising, not named
      temperature: not stated
    source: wikipedia-eu
    where: Chemical properties section, paragraph on acids; Ames SDS section 10 Incompatible Materials
  - environment: Halogens and strong oxidizers
    headline: Europium is listed as incompatible with halogens and strong oxidizing agents.
    effect: The Ames SDS lists strong oxidizing agents and halogens as incompatible materials, and the ESPI SDS lists the same. Neither sheet gives a reaction rate.
    rating: severe
    conditions:
      atmosphere: halogens or strong oxidizers
      temperature: not stated
    source: ames-eu-sds
    where: Section 10 Stability and Reactivity, row Incompatible Materials
risks:
  hazards:
    - text: 'Ames Laboratory SDS (revised 2018): GHS Danger, water reactive solid and flammable. H228 Flammable solid, and H261 In contact with water releases flammable gas. Classed as Flammable solid, category 1 and Substances which, in contact with water, emit flammable gases, category 1 (EC CLP).'
      ghs:
        - H228
        - H261
      source: ames-eu-sds
      where: Section 2 Hazards Identification, GHS Classification and Hazard Statements; Section 15 Regulatory Information, CLP row
    - text: 'ESPI Metals SDS (revised July 2015): GHS Flammable solids, category 1, signal word Danger, H228 Flammable solid. Water may release flammable hydrogen gas under fire conditions.'
      ghs:
        - H228
      source: espi-eu-sds
      where: Section 2 Hazards Identification, GHS Classification and Hazard Statements; Section 5 Specific Hazards
    - text: Ames SDS section 10 says that finely divided metal may ignite spontaneously in air and that the metal reacts with water, releasing flammable hydrogen gas. The SDS gives NFPA flammability 3 and HMIS flammability 3.
      ghs: []
      source: ames-eu-sds
      where: Section 10 Possibility of Hazardous Reactions; Section 16 Other Information, HMIS and NFPA ratings
  failure_risks:
    - mode: Spontaneous ignition of fines in air
      trigger: Finely divided europium exposed to air, or to heat, sparks or flame
      consequence: The Ames SDS says finely divided metal may ignite spontaneously in air, and both SDS sheets say the metal is flammable when exposed to heat, spark or flame. Fines need the same controls as a pyrophoric metal.
      severity: critical
      source: ames-eu-sds
      where: Section 10 Possibility of Hazardous Reactions; Section 5 Specific Hazards, flammable when exposed to heat, spark or flame
    - mode: Hydrogen release on contact with water
      trigger: Metal in contact with water or moisture
      consequence: The reaction gives off flammable hydrogen and europium hydroxide. The SDS says to protect the material from water and moisture, and to store it under inert gas.
      severity: critical
      source: ames-eu-sds
      where: Section 5 Specific Hazards; Section 7 Handling and Storage; Section 10 Possibility of Hazardous Reactions
    - mode: Surface loss by tarnishing in air
      trigger: Fresh metal exposed to air at room temperature
      consequence: Wikipedia says fresh europium tarnishes rapidly, so the surface is oxidised quickly unless the metal is kept in a dry inert atmosphere.
      severity: high
      source: wikipedia-eu
      where: Chemical properties section, first paragraph
    - mode: Reaction with halogens or strong oxidizers
      trigger: Contact with halogens or strong oxidizing agents
      consequence: Both SDS sheets list these as incompatible, and the Ames sheet lists halogens in its incompatible materials row.
      severity: high
      source: ames-eu-sds
      where: Section 10 Stability and Reactivity, row Incompatible Materials
  side_effects:
    - text: The Ames SDS gives no exposure limit for europium (OSHA/PEL and ACGIH/TLV both not established) and lists only irritation as a symptom. It gives no toxicology data.
      affects: Anyone handling the metal, including dust and fume
      source: ames-eu-sds
      where: Section 8 Exposure Limits; Section 11 Toxicological Information
  handling:
    - text: Handle under inert gas such as argon in an enclosed, controlled process, with local exhaust. Protect from water and moisture (P231+P232, P422).
      source: ames-eu-sds
      where: Section 7 Handling and Storage; Section 8 Engineering Controls; Section 2 precautionary statements
    - text: Store in tightly closed containers under argon or mineral oil, away from sparks, heat and flame, and do not store with acids or oxidizers.
      source: espi-eu-sds
      where: Section 7 Conditions for Safe Storage, Including Any Incompatibilities
    - text: Use a Class D dry powder extinguishing agent. Do not use water. Water releases flammable hydrogen on the burning metal.
      source: ames-eu-sds
      where: Section 5 Firefighting Measures, Extinguishing Media and Unsuitable Extinguishing Media
    - text: Do not use water for spill clean-up. Use only non-sparking tools and natural bristle brushes, and place spilled metal in a closed container for disposal.
      source: ames-eu-sds
      where: Section 6 Accidental Release Measures
uses:
  - application: radiation-shielding
    device: Neutron-absorbing control elements in pressurised-water reactors
    example: Wikipedia says europium compounds have been used as neutron-absorbing control materials, with Eu2O3 and stainless steel control elements in the SM-1 and SM-1A pressurised-water reactors. The naturally occurring isotopes have large neutron-capture cross sections, particularly 151Eu. Wikipedia gives no numerical cross-section value.
    source: wikipedia-eu
    where: Uses section, Neutron absorber paragraph; Isotopes and neutron cross sections section
  - application: electronics-and-chips
    device: Red phosphor in display and lamp phosphors
    example: Wikipedia says europium-doped yttrium orthovanadate (YVO4:Eu) was introduced during the 1960s as a red component for cathode-ray tube displays, and that Y2O3:Eu and Y2O2S:Eu were later widely used as red CRT phosphors. USGS says rare earths are recovered from fluorescent lamps, which is a recycling route for this use.
    source: wikipedia-eu
    where: Uses section, Phosphors paragraph
  - application: electronics-and-chips
    device: Strontium iodide gamma-ray scintillator for planetary spectrometers (in development)
    example: The PSI project page describes a gamma-ray spectrometer based on SrI2, which it calls a very bright new scintillator. It targets CubeSats, orbiters, atmospheric probes, landers and rovers, and claims two to four times better energy resolution than scintillators with flight heritage. The project entered at TRL 3, with a NASA award and dates from 2016 to 2021. The page does not name the europium activator. The arXiv paper gives SrI2(Eu) as strontium iodide activated by europium, with 5.8 % FWHM at 662 keV on a ground-test crystal.
    source: psi-srI2
    where: Project description and Numbers section; arXiv 1111.5505, Sections 2.1 and 3 (5.8 % FWHM at 662 keV)
supply:
  - subject: Rare earths (europium is not reported separately by USGS)
    abundance: about 2 ppm in the Earth's crust (Wikipedia Occurrence section)
    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: India
        share_percent: 0.7
        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 rare-earth applications but generally are less effective.'
    source: usgs-ree-2026
    where: 'World Mine Production and Reserves table, 2025 (world total 390,000 t, rounded; shares calculated from China 270,000, United States 51,000, Australia 29,000 and India 2,900). Reserves: China 44,000,000 t. Recycling and Substitutes sections. Abundance: Wikipedia Occurrence section.'
  - subject: Rare-earth compounds and metals imported into the United States
    producers:
      - country: China
        share_percent: 71
        year: 2024
      - country: Malaysia
        share_percent: 13
        year: 2024
      - country: Japan
        share_percent: 5
        year: 2024
      - country: Estonia
        share_percent: 5
        year: 2024
    critical_lists: []
    recycling: ''
    substitutes: []
    source: usgs-ree-2026
    where: 'Import Sources (2021–24) paragraph: China 71 %, Malaysia 13 %, Japan 5 %, Estonia 5 %. The year column shows the end of the 2021 to 2024 range.'
  - subject: Europium oxide price (99.99 % minimum) and export controls
    producers: []
    critical_lists: []
    recycling: ''
    substitutes: []
    source: usgs-ree-2026
    where: 'Salient Statistics, price row Europium oxide, 99.99% minimum: 27 dollars per kg in 2025e (27 in 2024, 31 in 2021). Events, Trends and Issues: in October 2025 China expanded its rare-earth export controls to include europium; in November it suspended the October controls for one year; the April 2025 controls stayed in effect.'
documents:
  - title: 'USGS Mineral Commodity Summaries 2026: Rare Earths'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf
    year: 2026
  - title: 'Wikipedia: Europium'
    type: database
    url: https://en.wikipedia.org/wiki/Europium
    year: 2026
  - title: Europium metal, high purity (Goodfellow product page, general properties)
    type: datasheet
    url: https://www.goodfellow.com/usa/material/rare-earth-metals/europium
  - title: 'WebElements: Europium, physical properties (University of Sheffield)'
    type: datasheet
    url: https://winter.group.shef.ac.uk/webelements/europium/physics.html
  - title: 'Ames Laboratory safety data sheet: Europium, pieces, ingot, sheet, foil, rod (revised 2018)'
    type: sds
    url: https://www.ameslab.gov/sites/default/files/inline-files/63_Europium_SDS_0.pdf
    year: 2018
  - title: 'ESPI Metals safety data sheet: Europium metal (revised July 2015), copy hosted by Purdue PRIMELab'
    type: sds
    url: https://www.physics.purdue.edu/primelab/safety/MSDS/SDS/europium%20%20metal%20%20-%20ESPI.pdf
    year: 2015
  - title: Radioactive contamination of SrI2(Eu) crystal scintillator (arXiv 1111.5505)
    type: paper
    url: https://arxiv.org/pdf/1111.5505
    year: 2011
  - title: 'PSI project page: Ultra-bright scintillator for planetary gamma-ray spectroscopy'
    type: report
    url: https://www.psi.edu/project/ultra-bright-scintillator-for-planetary-gamma-ray-spectroscopy/
gaps:
  - 'Europium-specific production: USGS reports rare earths as one group, so the producer shares above are for all rare earths. No production route for the metal was read from a page in this run, so the recipe carries only the element.'
  - 'Critical-mineral listing: the USGS critical minerals list and the EU critical raw materials list were not opened for europium, so critical_lists is empty.'
  - 'Thermal neutron cross section of europium: Wikipedia gives isotope names but no numerical value for 151Eu or 153Eu in the text read, and no other source with a number was opened. No value is entered.'
  - 'Space flight of europium metal: the only space-related use found is a strontium iodide scintillator at TRL 3 for planetary spectrometers, which the PSI page describes as a concept. No flight, vacuum, radiation or thermal-cycling test of the metal was found in an opened source, so environments are not tagged.'
  - The activator concentration and the Eu-doped strontium iodide flight qualification (the SIRI papers) were not opened. The SPIE SIRI page returned no text.
  - Hardness and Néel temperature are entered under new names (vickers_hardness, neel_temperature) because the property file has no canonical name for them. Molar heat capacity (27.66 J/(mol·K), Wikipedia) and heat of fusion were not entered because they have no canonical name and are not specific heat.
  - Brinell hardness of annealed metal is printed by Goodfellow as ~17–20 HB with no test standard. It is not entered.
  - 'Hazard classes differ between sources: the Ames SDS (revised 2018) gives H228 and H261, the ESPI SDS (revised 2015) gives H228 only, and the Trace Sciences and American Elements sheets (not opened in this run) give pyrophoric or H250 classes. Only the two opened SDS sheets are cited.'
  - 'No toxicology data: the Ames SDS gives no exposure limit and no toxicology data, and the PubChem record could not be read because the site showed a browser check. No dose or toxicity figure is entered.'
  - Corrosion data are qualitative (Wikipedia and SDS text). No measured weight-gain or corrosion-rate figure for europium in air or water was found.
  - The Goodfellow page used is the general europium product page, not the EU000340 datasheet, which returned HTTP 404. Its values are cited as the general page.
sources:
  wikipedia-eu:
    title: Europium (Wikipedia)
    url: https://en.wikipedia.org/wiki/Europium
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (cited, not reproduced)
  webelements-eu:
    title: 'WebElements: Europium, physical properties (University of Sheffield)'
    url: https://winter.group.shef.ac.uk/webelements/europium/physics.html
    kind: database
    license: WebElements, cited not reproduced
  goodfellow-eu:
    title: Europium metal, high purity (Goodfellow product page, general properties)
    url: https://www.goodfellow.com/usa/material/rare-earth-metals/europium
    kind: datasheet
    license: supplier web page (cited, not reproduced)
  ames-eu-sds:
    title: 'Safety Data Sheet: Europium, pieces, ingot, sheet, foil, rod (Ames Laboratory, US DOE, revised 2018)'
    url: https://www.ameslab.gov/sites/default/files/inline-files/63_Europium_SDS_0.pdf
    year: 2018
    kind: datasheet
    license: DOE laboratory safety data sheet, cited not reproduced
  espi-eu-sds:
    title: 'Safety Data Sheet: Europium metal (ESPI Metals, revised July 2015, copy hosted by Purdue PRIMELab)'
    url: https://www.physics.purdue.edu/primelab/safety/MSDS/SDS/europium%20%20metal%20%20-%20ESPI.pdf
    year: 2015
    kind: datasheet
    license: supplier safety data sheet, cited not reproduced
  usgs-ree-2026:
    title: 'Mineral Commodity Summaries 2026: Rare Earths (USGS)'
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  psi-srI2:
    title: Ultra-bright scintillator for planetary gamma-ray spectroscopy (Planetary Science Institute project page)
    url: https://www.psi.edu/project/ultra-bright-scintillator-for-planetary-gamma-ray-spectroscopy/
    kind: web
    license: project web page, cited not reproduced
  arxiv-srI2eu:
    title: Radioactive contamination of SrI2(Eu) crystal scintillator (Bellia et al., arXiv 1111.5505)
    url: https://arxiv.org/pdf/1111.5505
    year: 2011
    kind: paper
    license: arXiv preprint, cited not reproduced
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 21
  unreachable: 2
  caveats: 5
  note: 'Read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry. Unreachable: PubChem (browser check), Goodfellow EU000340 datasheet (HTTP 404), SPIE SIRI page (no text). Caveats: most physical values come from Wikipedia, Goodfellow and WebElements, and some Wikipedia values are summaries; melting point and boiling point differ by 4 °C and 2 °C between sources; the resistivity figures differ by about 2 % and have different temperature conditions; supply shares are for all rare earths, not europium; the SrI2(Eu) platform is a concept with a claim that is not measured.'
story:
  risk_groups:
    - title: For people
      lead: 'The sources read give little human toxicity data for europium metal. The hazard is physical: fines can ignite, and the metal releases hydrogen with water.'
      level: 1
      verdict: Form-dependent
      points:
        - label: Fines and dust
          line: The Ames SDS says finely divided metal may ignite spontaneously in air, and the ESPI sheet warns that it is flammable when exposed to heat, spark or flame.
        - label: Water
          line: Contact with water releases flammable hydrogen (Ames SDS), and Wikipedia says the reaction is faster with hot water.
        - label: Exposure limits
          line: The Ames SDS gives no OSHA or ACGIH exposure limit for europium and no toxicology data.
    - title: If it fails
      lead: 'The sources give four failure routes: a fire in fines, hydrogen release on contact with water, tarnishing in air, and reaction with halogens or strong oxidizers.'
      points:
        - label: Fire
          line: Use a Class D dry powder extinguisher. Do not use water on the burning metal (Ames SDS, ESPI SDS).
        - label: Tarnish
          line: Fresh metal tarnishes rapidly in air, so it needs to be stored dry and under inert gas (Wikipedia, Ames SDS).
        - label: Halogens
          line: Halogens and strong oxidizers are listed as incompatible (Ames SDS).
    - title: Handling and storage
      points:
        - label: Keep it dry
          line: Handle under argon in an enclosed, controlled process, and store under argon or mineral oil, away from sparks and moisture (Ames SDS, ESPI SDS).
        - label: Fire agents
          line: Use Class D dry powder for fires and never water. Use only non-sparking tools for spill clean-up (Ames SDS).
  why: Europium is a rare-earth metal that tarnishes rapidly in air (Wikipedia). Its main uses in the sources read are a red phosphor activator, a neutron-absorbing control material in some reactors, and the activator of strontium iodide scintillators under development for planetary gamma-ray spectrometers. Its space record is the planetary concept only, not a flown metal part.
  uses:
    - where: Display and lamp phosphors
      line: Wikipedia says europium-doped yttrium orthovanadate was a red CRT phosphor from the 1960s, and that Y2O3:Eu and Y2O2S:Eu were later used widely as red phosphors.
    - where: Neutron-absorbing control elements
      line: Wikipedia says europium compounds were used as control materials in the SM-1 and SM-1A pressurised-water reactors.
    - where: Planetary gamma-ray spectroscopy (concept)
      line: The PSI project describes a strontium iodide spectrometer for CubeSats, orbiters, landers and rovers, at TRL 3 and aimed at TRL 4 or higher. The arXiv paper gives SrI2(Eu) as an activated scintillator with 5.8 % FWHM at 662 keV in its ground test.
  can_do:
    - label: Emit red light
      value: not quantified
      line: Europium-doped phosphors are used for the red component of CRT displays (Wikipedia). No brightness or efficiency figure was read.
    - label: Stay solid at room temperature
      value: 826 °C
      benchmark: melting_point
      line: Melting point is 826 °C (Goodfellow and Wikipedia), and the Ames SDS gives 822 °C.
    - label: Weight
      value: 5.264 g/cm3
      benchmark: density
      line: Density is 5.264 g/cm3 at 20 °C (Goodfellow), and 5.246 g/cm3 at 20 °C in the Wikipedia infobox.
    - label: Heat conduction
      value: 13.9 W/(m·K)
      benchmark: thermal_conductivity
      line: Thermal conductivity is 13.9 W/(m·K) (Goodfellow, no temperature given), and 14 W/(m·K) on the WebElements page.
    - label: Stiffness
      value: 18.2 GPa
      benchmark: elastic_modulus
      line: Young's modulus is 18.2 GPa (Goodfellow and Wikipedia), and 18 GPa on WebElements.
  compare: Europium is a soft, low-density metal, at 5.264 g/cm3 for the general product page, with a melting point of 826 °C and a thermal conductivity of 13.9 W/(m·K). Its Young's modulus of 18.2 GPa is low for a structural metal. The properties that matter for its uses are its phosphor and neutron-capture behaviour, not its strength. It tarnishes in air and reacts with water, so it needs dry, inert handling. No comparison profile is carried in this file, so the rows below list europium values only.
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Young's modulus
      benchmark: elastic_modulus
  recipe:
    line: Europium is a single-element metal (Eu). The Ames SDS names the form as pieces, ingot, sheet, foil or rod, and the Goodfellow page sells it as ingot, rod or powder at up to 99.95 % (3N5) purity. The production route is not read in this run.
    parts:
      - name: Europium
        symbol: Eu
        atoms: 1
        atomic_weight: 151.964
        role: The whole material. Goodfellow sells the metal at up to 99.95 % purity, and the Wikipedia standard atomic weight is 151.964.
  handling:
    - Handle under inert gas such as argon in an enclosed, controlled process (Ames SDS).
    - Store under argon or mineral oil, away from sparks, heat and moisture (ESPI SDS).
    - Use Class D dry powder for fires and never water (Ames SDS).
    - Use only non-sparking tools for spill clean-up (Ames SDS).
  good_for:
    - 'Red phosphor activator: Eu-doped oxide and vanadate phosphors gave the red component of CRT displays (Wikipedia).'
    - 'Neutron-absorbing control material: europium oxide and stainless steel control elements were used in the SM-1 and SM-1A reactors (Wikipedia).'
    - 'Scintillator activator for planetary gamma-ray spectroscopy: SrI2(Eu) reached 5.8 % FWHM at 662 keV in a ground test (arXiv 1111.5505).'
  watch_out:
    - Fines can ignite spontaneously in air, and the metal releases flammable hydrogen with water (Ames SDS).
    - Fresh metal tarnishes rapidly in air (Wikipedia).
    - 'Supply is concentrated: China produced about 69 % of world rare-earth mine output in 2025, and China added europium to its export controls in October 2025, then suspended those controls for one year in November (USGS).'
    - The planetary scintillator is a concept at TRL 3, and the PSI page does not name the europium activator.
  verdict: Europium is the red phosphor activator and a neutron-absorbing control material, and it is being developed as an activator in planetary gamma-ray scintillators. Its density is 5.264 g/cm3 and its melting point is 826 °C. The metal tarnishes in air and releases hydrogen with water, so it needs dry, inert handling and Class D fire agents.