Barium fluoride (BaF2) BaF2

spore: profile
id: barium-fluoride
spore_version: 0.2
family: optical-crystals
name: Barium fluoride (BaF2)
abbreviation: BaF2
role: Infrared optical crystal and fast scintillator
category: glasses-optics
type: optical-crystals
summary: |
  Barium fluoride (BaF2) is a cubic fluorite-structure crystal. Crystran prints a transmission range of 0.15 to 12 μm and a density of 4.89 g/cc. Its melting point is printed as 1386 °C by Crystran and as 1368 °C by Korth and Wikipedia. It is also a fast scintillator: an arXiv review prints a sub-ns decay time with an emission peak at 220 nm. Crystran and Korth both warn that it is susceptible to thermal shock. PubChem records harmful and toxic hazard statements for the substance. No space flight or orbital test result for barium fluoride was found in the sources read.
best_for: Infrared windows, lenses and fast X-ray and gamma-ray scintillators, where the crystal is protected from rapid temperature changes
weakest_at: Susceptibility to thermal shock and cleavage on (111) (Crystran, Korth); the powder is classed as toxic by PubChem's notifications
identity:
  formula: BaF2
  cas: 7787-32-8
  crystal_system: cubic
  space_group: Fm3m (#225)
  source: crystran
  where: Product Data table, Class/Structure row (cubic Fm3m (#225), fluorite structure, cleaves on (111)); CAS from the Wikipedia identifiers and PubChem record
tags:
  environments: []
  stresses:
    - thermal-shock
    - ionizing-radiation
  applications:
    - optics-and-cameras
properties:
  - benchmark: density
    value: 4.89
    unit: g/cc
    scope: material
    conditions:
      temperature: not stated in the source
    method: Manufacturer product data table; no test method printed
    status: ground
    source: crystran
    where: Product Data table, Density row
  - benchmark: density
    value: 4.893
    unit: g/cm3
    scope: material
    conditions:
      basis: infobox value; temperature not stated
    method: Infobox value, which cites a CRC Handbook reference
    status: ground
    source: wiki
    where: Infobox, Density row
  - benchmark: melting_point
    value: 1386
    unit: °C
    scope: material
    conditions:
      basis: printed as Melting Point in the manufacturer product data table
    method: Manufacturer product data table; no test method printed
    status: ground
    note: Differs from the 1368 °C printed by Korth and by Wikipedia; both values are recorded and the source gives no reason for the difference.
    source: crystran
    where: Product Data table, Melting Point row
  - benchmark: melting_point
    value: 1368
    unit: °C
    scope: material
    conditions:
      basis: printed as Melting point on the product page
    method: Manufacturer product page property list
    status: ground
    source: korth
    where: Eigenschaften (properties) list, Melting point row
  - benchmark: melting_point
    value: 1368
    unit: °C
    scope: material
    conditions:
      basis: infobox value
    method: Infobox value, which cites a CRC Handbook reference
    status: ground
    source: wiki
    where: Infobox, MeltingPtC field
  - benchmark: boiling_point
    value: 2260
    unit: °C
    scope: material
    conditions:
      basis: infobox value as printed, pressure not stated in the infobox
    method: Infobox value, printed with its Kelvin and Fahrenheit equivalents
    status: ground
    source: wiki
    where: Infobox, Boiling point row
  - benchmark: refractive_index
    value: 1.45
    unit: '-'
    scope: material
    conditions:
      wavelength: 5 μm
    method: Manufacturer product data table, refractive index with reference (1)
    status: ground
    source: crystran
    where: Product Data table, Refractive Index row
  - benchmark: refractive_index
    value: 1.47326
    unit: '-'
    scope: material
    conditions:
      wavelength: 633 nm
    method: Manufacturer product page property list
    status: ground
    source: korth
    where: Eigenschaften (properties) list, Refractive Index row
  - benchmark: refractive_index
    value: 1.4744
    unit: '-'
    scope: material
    conditions:
      wavelength: 589 nm
    method: Infobox refractive index (n_D), which cites a handbook reference
    status: ground
    source: wiki
    where: Infobox, RefractIndex field (589 nm entry)
  - benchmark: transmission_range
    value: 0.15
    value_high: 12
    bound: range
    unit: μm
    scope: material
    conditions:
      basis: printed transmission range; sample thickness not stated
    method: Printed range in the manufacturer product data table
    status: ground
    source: crystran
    where: Product Data table, Transmission Range row
  - benchmark: thermal_conductivity
    value: 11.72
    unit: W m⁻¹ K⁻¹
    scope: material
    conditions:
      temperature: 286 K
    method: Manufacturer product data table
    status: ground
    source: crystran
    where: Product Data table, Thermal Conductivity row
  - benchmark: thermal_conductivity
    value: 10.9
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: 305 K
    method: Manufacturer product page property list
    status: ground
    note: Differs from the 11.72 W m⁻¹ K⁻¹ at 286 K printed by Crystran; both are recorded.
    source: korth
    where: Eigenschaften (properties) list, Thermal Conductivity row
  - benchmark: specific_heat
    value: 410
    unit: J/(kg·K)
    scope: material
    conditions:
      temperature: not stated in the source
    method: Manufacturer product page property list
    status: ground
    source: korth
    where: Eigenschaften (properties) list, Spec. Heat Capacity row
  - benchmark: elastic_modulus
    value: 53.07
    unit: GPa
    scope: material
    conditions:
      basis: Young's modulus as printed; temperature not stated
    method: Manufacturer product data table, citing a reference (3)
    status: ground
    source: crystran
    where: Product Data table, Young's Modulus (E) row
  - benchmark: shear_modulus
    value: 25.4
    unit: GPa
    scope: material
    conditions:
      basis: shear modulus as printed; temperature not stated
    method: Manufacturer product page property list
    status: ground
    source: korth
    where: Eigenschaften (properties) list, Shear Modulus row
  - benchmark: bulk_modulus
    value: 56.4
    unit: GPa
    scope: material
    conditions:
      basis: bulk modulus as printed; temperature not stated
    method: Manufacturer product data table
    status: ground
    source: crystran
    where: Product Data table, Bulk Modulus (K) row
  - benchmark: bulk_modulus
    value: 57.8
    unit: GPa
    scope: material
    conditions:
      basis: bulk modulus as printed; temperature not stated
    method: Manufacturer product page property list
    status: ground
    note: Differs from the 56.4 GPa printed by Crystran; both are recorded.
    source: korth
    where: Eigenschaften (properties) list, Bulk Modulus row
  - benchmark: poissons_ratio
    value: 0.343
    unit: '-'
    scope: material
    conditions:
      basis: Poisson ratio as printed; temperature not stated
    method: Manufacturer product data table
    status: ground
    source: crystran
    where: Product Data table, Poisson Ratio row
  - benchmark: poissons_ratio
    value: 0.31
    unit: '-'
    scope: material
    conditions:
      basis: Poisson ratio as printed; temperature not stated
    method: Manufacturer product page property list
    status: ground
    note: Differs from the 0.343 printed by Crystran; both are recorded.
    source: korth
    where: Eigenschaften (properties) list, Poisson Ratio row
  - benchmark: dielectric_constant
    value: 7.33
    unit: '-'
    scope: material
    conditions:
      frequency: 1 MHz
    method: Manufacturer product data table
    status: ground
    note: Korth prints 7.33 at 2 MHz; the Crystran frequency is recorded here.
    source: crystran
    where: Product Data table, Dielectric Constant row
  - benchmark: knoop_hardness
    value: 82
    unit: '-'
    scope: material
    conditions:
      load: 500 g indenter
      scale: Knoop, as printed
    method: Manufacturer product data table, Knoop hardness with reference (4)
    status: ground
    note: Korth prints the same 82 as Mohs hardness with a 500 g load; the Knoop label from Crystran is used here.
    source: crystran
    where: Product Data table, Hardness row
  - benchmark: solubility_in_water
    value: 0.17
    unit: g/100 g water
    scope: material
    conditions:
      temperature: 23 °C
    method: Manufacturer product data table
    status: ground
    source: crystran
    where: Product Data table, Solubility row
  - benchmark: solubility_in_water
    value: 0.16
    unit: g/100g
    scope: material
    conditions:
      temperature: 25 °C
    method: Manufacturer product page property list
    status: ground
    source: korth
    where: Eigenschaften (properties) list, Solubility in Water row
  - benchmark: solubility_in_water
    value: 1.61
    unit: g/L
    scope: material
    conditions:
      temperature: 25 °C
    method: Infobox solubility value
    status: ground
    note: The same infobox gives 1.58 g/L at 10 °C; the 25 °C value is recorded.
    source: wiki
    where: Infobox, Solubility row
  - benchmark: scintillation_decay_time
    value: 0.5
    unit: ns
    scope: material
    conditions:
      readout: photomultiplier tube (PMT), BaF2 sample shown in the review's Fig. 4
      basis: decay time as printed
    method: Pulse shape measured with a PMT, as reported in an open-access review
    status: ground
    source: arxiv-zhu2022
    where: BaF2:Y progress section, Fig. 4 text
  - benchmark: pulse_fwhm
    value: 0.9
    unit: ns
    scope: material
    conditions:
      readout: photomultiplier tube (PMT), BaF2 sample shown in the review's Fig. 4
      basis: FWHM width as printed
    method: Pulse shape measured with a PMT, as reported in an open-access review
    status: ground
    source: arxiv-zhu2022
    where: BaF2:Y progress section, Fig. 4 text
  - benchmark: scintillation_slow_component
    value: 600
    unit: ns
    scope: material
    conditions:
      peak: 300 nm
      component: slow component, as printed
    method: Printed in an open-access review (BaF2:Y section)
    status: ground
    source: arxiv-zhu2022
    where: BaF2:Y progress section, first paragraph
  - benchmark: emission_peak_wavelength
    value: 220
    unit: nm
    scope: material
    conditions:
      component: fast cross-luminescence, as printed
    method: Printed in an open-access review (BaF2:Y section)
    status: ground
    source: arxiv-zhu2022
    where: BaF2:Y progress section, first paragraph
corrosion:
  - environment: Water (immersion or humid air)
    headline: Barium fluoride dissolves slightly in water, at about 0.16 g per 100 g at 25 °C (Korth).
    effect: Korth prints a solubility of 0.16 g/100g at 25 °C and Crystran prints 0.17 g / 100 g water at 23 °C; Wikipedia prints 1.61 g/L at 25 °C. The sources read give no humidity or surface-attack test for the crystal, so no service rating beyond solubility is recorded.
    rating: low
    conditions:
      basis: room-temperature solubility in water as printed; no humidity test in the sources
    source: korth
    where: Eigenschaften (properties) list, Solubility in Water row
  - environment: Ionizing radiation (X-ray and gamma)
    headline: Korth calls the crystal radiation resistant; an accelerator review reports saturated damage at high dose.
    effect: Korth lists 'Radiation resistant to ionizing radiation' as a remark. An open-access review states that 'Undoped BaF2 crystals show saturated damage from 10 krad to 100 Mrad after an initial loss, so are more radiation hard than CsI at a large integrated dose.' Those tests are accelerator-experiment doses, and no proton, heavy-ion or flight data were found.
    rating: low
    conditions:
      basis: doses as printed in the review; the review compares undoped BaF2 with CsI
    source: arxiv-zhu2022
    where: Radiation hardness section, sentence on undoped BaF2
risks:
  hazards:
    - text: 'PubChem aggregates 253 company reports: H302 (92.1%): Harmful if swallowed; H332 (99.2%): Harmful if inhaled. One of the 253 reports (0.4%) does not meet GHS hazard criteria.'
      ghs:
        - H302
        - H332
      source: pubchem
      where: Safety and Hazards, GHS Classification (first notification set, CID 62670)
    - text: 'A second PubChem notification set gives H301: Toxic if swallowed; H319: Causes serious eye irritation; H335: May cause respiratory irritation; H361: Suspected of damaging fertility or the unborn child; H372: Causes damage to organs through prolonged or repeated exposure, Category 1, with bone among the organs listed.'
      ghs:
        - H301
        - H319
        - H335
        - H361
        - H372
      source: pubchem
      where: Safety and Hazards, GHS Classification (later notification sets)
    - text: 'Acute toxicity: LD50 250 mg/kg (oral, rat), as printed in PubChem''s toxicity data; Wikipedia prints the same figure as 250 mg/kg, oral (rat).'
      ghs: []
      source: pubchem
      where: Toxicity, Toxicity Data and Values, Toxicity Data row
    - text: PubChem lists a permissible exposure limit of 0.5 mg/m3 as Ba (2.5 mg/m3 as F), and an immediately dangerous to life or health value of 50.0 mg/m3 as Ba.
      ghs: []
      source: pubchem
      where: Safety and Hazards, Exposure Control and Personal Protection
    - text: 'PubChem''s hazards summary quotes a supplier MSDS (Alfa Aesar) as saying: ''Harmful by ingestion and inhalation''.'
      ghs: []
      source: pubchem
      where: Safety and Hazards, Hazards Summary
  failure_risks:
    - mode: Cracking from thermal shock
      trigger: Rapid temperature change
      consequence: Crystran says the crystal 'cleaves easily and is highly susceptible to thermal shock'; Korth lists 'Susceptible to thermal shock' as a remark. Crystran gives the cleavage plane as (111).
      severity: high
      source: crystran
      where: Product text on thermal shock; Product Data table, Crystal Type and Remarks rows
    - mode: Pile-up from the slow scintillation component
      trigger: High event rate in a scintillation detector
      consequence: The 600 ns slow component 'causes pileup in a high-rate environment', according to the open-access review of BaF2 scintillators.
      severity: moderate
      source: arxiv-zhu2022
      where: BaF2:Y progress section, first paragraph
  side_effects: []
  handling:
    - text: Crystran says the crystal cleaves easily and is highly susceptible to thermal shock. The source gives no numeric rate of temperature change, so avoid rapid temperature changes.
      source: crystran
      where: Product text, handling paragraph
    - text: The Crystran page gives no hazard statements. It links a safety data sheet for the powder, which was not opened in this run.
      source: crystran
      where: Product text, safety remarks
  mitigations: []
uses:
  - application: optics-and-cameras
    device: 'Infrared optics: windows and lenses for the passive IR band'
    example: Crystran says barium fluoride 'is often suitable for applications in the passive IR band (8 to 14 μm)' and that for equivalent thickness its transmission 'extends approximately 1 micron further into the IR than Calcium Fluoride'.
    source: crystran
    where: Product description, passive IR paragraph
  - application: optics-and-cameras
    device: Fast scintillation detectors for X-rays, gamma rays and 511 keV photons in positron emission tomography
    example: Wikipedia says barium fluoride is 'very fast (one of the fastest) scintillators' and that one of its applications is 'the detection of 511 keV gamma photons in positron emission tomography'. Korth lists its application as 'Scintillator, IR optics'.
    source: wiki
    where: Lead section and Applications text
supply:
  - subject: Barite (barium mineral)
    producers:
      - country: India
        year: 2025
      - country: China
        year: 2025
      - country: Morocco
        year: 2025
      - country: Kazakhstan
        year: 2025
    critical_lists:
      - list: EU critical raw materials list (Regulation (EU) 2024/1252, European Commission page; 'Baryte' is printed in the list)
        listed: true
    recycling: 'USGS barite summary: ''Recycling: None.'''
    substitutes:
      - 'USGS barite summary: ''there are no large-scale alternatives to barite in oil- and gas-drilling fluids''; this is a drilling use, not an optical one.'
    source: usgs-barite
    where: 'World Mine Production and Reserves table, 2025 column (thousand metric tons): India 3,000; China 2,200; Morocco 1,000; Kazakhstan 700; world total (rounded) 8,700. Producers are listed in the order of the printed tonnage.'
  - subject: Fluorspar (fluorine feedstock, CaF2)
    abundance: 'Feedstock: the USGS fluorspar summary says aqueous HF ''is the primary feedstock for the manufacture of virtually all fluorine-bearing chemicals''. Barium fluoride is one of those chemicals, but the sources read do not name the route.'
    producers:
      - country: China
        year: 2025
      - country: Mexico
        year: 2025
      - country: Mongolia
        year: 2025
      - country: South Africa
        year: 2025
    critical_lists:
      - list: EU critical raw materials list (Regulation (EU) 2024/1252, European Commission page; 'Fluorspar' is printed in the list)
        listed: true
    recycling: 'USGS fluorspar summary: synthetic fluorspar may be produced from neutralization of waste, but ''undesirable impurities constrain its use''.'
    substitutes:
      - 'USGS fluorspar summary: fluosilicic acid ''has been used as an alternative to fluorspar in the production of AlF3 and HF''.'
    source: usgs-fluorspar
    where: 'World Mine Production and Reserves table, 2025 column (thousand metric tons): China 6,000; Mexico 1,500; Mongolia 1,500; South Africa 410; world total (rounded) 10,000. Producers are listed in the order of the printed tonnage.'
media: []
documents:
  - title: 'Crystran: Barium Fluoride (BaF2) product data'
    type: datasheet
    url: https://www.crystran.com/optical-materials/barium-fluoride-baf2
  - title: 'Korth Kristalle: Barium Fluoride material page'
    type: datasheet
    url: https://www.korth.de/en/materials/detail/Barium%20Fluoride
  - title: 'PubChem: Barium fluoride (CID 62670), GHS classification and toxicity data'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/62670
  - title: Ultrafast Inorganic Crystals with Mass Production Capability for Future High-Rate Experiments (open access, arXiv:2203.06788)
    type: paper
    url: https://arxiv.org/pdf/2203.06788
  - title: 'USGS Mineral Commodity Summaries 2026: Barite'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-barite.pdf
  - title: 'USGS Mineral Commodity Summaries 2026: Fluorspar'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf
gaps:
  - No space flight, vacuum, thermal-vacuum or orbital result for barium fluoride was found in the sources read. The radiation data are accelerator-experiment doses from the open-access review.
  - Thermal expansion is not recorded. Crystran prints 18.1 × 10⁻⁶ K⁻¹ at 273 K and Korth prints 18.4 · 10 -6 /K over 273-573K; both are written with exponents, so they are left out. The refractive-index temperature coefficient (dn/dT) and the absorption coefficient are left out for the same reason.
  - No band gap value was found in the Crystran, Korth or Wikipedia pages read.
  - 'Hardness: Korth labels the value 82 as Mohs hardness; only the Knoop reading from Crystran is recorded.'
  - Crystal-growth route beyond 'vacuum Stockbarger technique' (Crystran) and the chemical route from barium and fluorine feedstocks are not described in the sources read.
  - Crustal abundance of barium and fluorine was not found in a source opened in this run.
  - The USGS 2025 critical minerals list page returned HTTP 403 when checked, so the USGS list status of barite and fluorspar is not recorded; the critical-list entries use the EU list only.
  - Supplier safety data sheet for the powder was not opened; the hazard entries rest on the PubChem GHS and toxicity records.
  - 'Non-canonical property names used because no canonical name exists in spores/property-canon.yaml: transmission_range, knoop_hardness, scintillation_decay_time, pulse_fwhm, scintillation_slow_component, emission_peak_wavelength.'
  - Production share by country is not calculated; the USGS summaries give 2025 tonnage, which is recorded as printed in the supply where field.
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 28
  unreachable: 1
  caveats: 4
  note: Written by an AI assistant on 2026-11-01 from pages read in this run. Values were copied as printed. Conflicting values from different sources are recorded side by side. The USGS critical-list page was blocked (403).
sources:
  crystran:
    title: Barium Fluoride (BaF2) product data, Crystran
    url: https://www.crystran.com/optical-materials/barium-fluoride-baf2
    kind: datasheet
    license: supplier web page, cited not reproduced
  korth:
    title: Barium Fluoride material page, Korth
    url: https://www.korth.de/en/materials/detail/Barium%20Fluoride
    kind: datasheet
    license: supplier web page, cited not reproduced
  wiki:
    title: Barium fluoride, Wikipedia
    url: https://en.wikipedia.org/wiki/Barium_fluoride
    kind: web
    license: CC BY-SA 4.0
  pubchem:
    title: PubChem compound record, Barium fluoride (CID 62670), JSON view
    url: https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/62670/JSON
    kind: database
    license: public domain (NCBI)
  arxiv-zhu2022:
    title: Ultrafast Inorganic Crystals with Mass Production Capability for Future High-Rate Experiments (arXiv:2203.06788)
    url: https://arxiv.org/pdf/2203.06788
    kind: paper
    license: arXiv preprint, as listed
  usgs-barite:
    title: 'Mineral Commodity Summaries 2026: Barite, U.S. Geological Survey'
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-barite.pdf
    kind: report
    license: public domain (USGS)
  usgs-fluorspar:
    title: 'Mineral Commodity Summaries 2026: Fluorspar, U.S. Geological Survey'
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf
    kind: report
    license: public domain (USGS)
  ec-crm:
    title: Critical raw materials, European Commission (Regulation (EU) 2024/1252)
    url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
    kind: web
    license: European Commission web page
story:
  why: 'Barium fluoride (BaF2) is a cubic crystal used where infrared light must pass through a window or lens, and where a fast scintillation signal is needed to detect X-rays and gamma rays. Crystran prints a transmission range of 0.15 to 12 μm, so for equivalent thickness its transmission extends further into the infrared than calcium fluoride. The crystal emits its light in a sub-ns decay with a peak at 220 nm. Its main weakness is thermal shock: Crystran and Korth both warn that the crystal cleaves easily and is susceptible to thermal shock.'
  recipe:
    line: 'BaF2 is barium fluoride: one barium ion for every two fluoride ions, arranged in a cubic fluorite-type lattice (Crystran, Fm3m (#225)). Crystran says the crystals are grown by the vacuum Stockbarger technique.'
    parts:
      - name: Barium
        symbol: Ba
        role: The heavy cation. Crystran prints the density of the crystal as 4.89 g/cc.
        source: crystran
        where: Product Data table, Density row
      - name: Fluorine
        symbol: F
        role: The anion. Two fluoride ions balance each barium ion in the lattice.
        source: crystran
        where: Product Data table, Class/Structure row
  risk_groups:
    - title: For people
      lead: PubChem's notifications class barium fluoride as harmful or toxic. Its oral LD50 in rats is 250 mg/kg.
      level: 3
      verdict: Harmful if swallowed or inhaled
      points:
        - label: The powder
          line: PubChem records H302 (harmful if swallowed) in 92.1% of its reports and H332 (harmful if inhaled) in 99.2%. A second notification set classes it as toxic if swallowed (H301).
        - label: Long-term exposure
          line: One notification set classes repeated exposure as Category 1 with bone among the organs, and gives the hazard statement H372.
        - label: Occupational limit
          line: PubChem lists a permissible exposure limit of 0.5 mg/m3 as Ba (2.5 mg/m3 as F).
    - title: If the crystal is shocked
      lead: The main risk is to the optic, not to a person. Both manufacturers warn about thermal shock.
      level: 2
      verdict: Cracks under thermal shock
      points:
        - label: Cleavage
          line: Crystran says the crystal cleaves easily; its cleavage plane is (111).
        - label: Thermal shock
          line: Korth and Crystran both say the crystal is susceptible to thermal shock. Crystran gives no numeric limit on the rate of temperature change.
    - title: Handling and storage
      lead: The safety data sheet for the powder was not opened in this run.
      points:
        - label: Safety data
          line: The Crystran page gives no hazard statements. PubChem quotes a supplier MSDS as saying 'Harmful by ingestion and inhalation'.
  uses:
    - where: Infrared optics
      line: Crystran says barium fluoride is often suitable for the passive infrared band of 8 to 14 μm, and that its transmission extends approximately 1 micron further into the infrared than calcium fluoride for equivalent thickness.
    - where: Fast scintillation detectors
      line: Wikipedia calls barium fluoride one of the fastest scintillators and names its use for detecting 511 keV gamma photons in positron emission tomography. An open-access review prints a sub-ns decay time and a 220 nm emission peak.
  can_do:
    - label: Infrared transmission
      benchmark: transmission_range
      line: Crystran prints a transmission range of 0.15 to 12 μm. The range is for the printed sample and the thickness is not stated.
    - label: Density
      benchmark: density
      line: Crystran prints 4.89 g/cc and Wikipedia prints 4.893 g/cm3 for the crystal. The two values agree to within the rounding of the printed figures.
    - label: Melting point
      benchmark: melting_point
      line: Crystran prints 1386 °C and Korth and Wikipedia both print 1368 °C. The sources do not explain the difference, so both values are recorded.
    - label: Scintillation
      benchmark: scintillation_decay_time
      line: An open-access review describes a sub-ns decay time for the fast component; for one sample read on a PMT it reports a decay time of 0.5 ns. Its 600 ns slow component causes pileup at high event rates.
  compare: 'Barium fluoride transmits further into the infrared than calcium fluoride: Crystran says it extends approximately 1 micron further for equivalent thickness. Its density is 4.89 g/cc per Crystran. The crystal cleaves easily and is susceptible to thermal shock, which Crystran and Korth both warn about. The comparison rows give density, melting point and thermal conductivity as printed by the sources read; no calcium fluoride values were read in this run, so none are compared here.'
  compare_rows:
    - label: Density
      benchmark: density
    - label: Melting point
      benchmark: melting_point
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Avoid rapid temperature changes. Crystran says the crystal is highly susceptible to thermal shock, and gives no numeric rate.
    - Keep the powder out of the air you breathe. PubChem lists H332, harmful if inhaled.
    - Read the supplier's safety data sheet before handling the powder; it was not opened in this run.
  good_for:
    - 'Infrared windows and lenses: Crystran prints a transmission range of 0.15 to 12 μm.'
    - 'Fast X-ray and gamma-ray detectors: the review prints a sub-ns decay and a 220 nm emission peak.'
  watch_out:
    - Thermal shock. Crystran and Korth both warn that the crystal cleaves easily and is susceptible to thermal shock.
    - Slow component. A 600 ns slow component causes pileup at high event rates, according to the review.
    - Toxicity. PubChem records harmful and toxic hazard statements for the powder.
  verdict: Barium fluoride is a useful infrared window and fast scintillator. Its cost in use is care with temperature changes and with the toxic powder.