{
  "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.\n",
  "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)",
    "designations": [],
    "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,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "density",
      "value": 4.893,
      "bound": "exact",
      "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",
      "source_detail": {
        "title": "Barium fluoride, Wikipedia",
        "url": "https://en.wikipedia.org/wiki/Barium_fluoride",
        "kind": "web",
        "license": "CC BY-SA 4.0"
      }
    },
    {
      "benchmark": "melting_point",
      "value": 1386,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "melting_point",
      "value": 1368,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "melting_point",
      "value": 1368,
      "bound": "exact",
      "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",
      "source_detail": {
        "title": "Barium fluoride, Wikipedia",
        "url": "https://en.wikipedia.org/wiki/Barium_fluoride",
        "kind": "web",
        "license": "CC BY-SA 4.0"
      }
    },
    {
      "benchmark": "boiling_point",
      "value": 2260,
      "bound": "exact",
      "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",
      "source_detail": {
        "title": "Barium fluoride, Wikipedia",
        "url": "https://en.wikipedia.org/wiki/Barium_fluoride",
        "kind": "web",
        "license": "CC BY-SA 4.0"
      }
    },
    {
      "benchmark": "refractive_index",
      "value": 1.45,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "refractive_index",
      "value": 1.47326,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "wavelength": "633 nm"
      },
      "method": "Manufacturer product page property list",
      "status": "ground",
      "source": "korth",
      "where": "Eigenschaften (properties) list, Refractive Index row",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "refractive_index",
      "value": 1.4744,
      "bound": "exact",
      "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)",
      "source_detail": {
        "title": "Barium fluoride, Wikipedia",
        "url": "https://en.wikipedia.org/wiki/Barium_fluoride",
        "kind": "web",
        "license": "CC BY-SA 4.0"
      }
    },
    {
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "value": 11.72,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "value": 10.9,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "specific_heat",
      "value": 410,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "value": 53.07,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "shear_modulus",
      "value": 25.4,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "bulk_modulus",
      "value": 56.4,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "bulk_modulus",
      "value": 57.8,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "poissons_ratio",
      "value": 0.343,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "poissons_ratio",
      "value": 0.31,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "dielectric_constant",
      "value": 7.33,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "knoop_hardness",
      "value": 82,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "solubility_in_water",
      "value": 0.17,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "solubility_in_water",
      "value": 0.16,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "solubility_in_water",
      "value": 1.61,
      "bound": "exact",
      "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",
      "source_detail": {
        "title": "Barium fluoride, Wikipedia",
        "url": "https://en.wikipedia.org/wiki/Barium_fluoride",
        "kind": "web",
        "license": "CC BY-SA 4.0"
      }
    },
    {
      "benchmark": "scintillation_decay_time",
      "value": 0.5,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "pulse_fwhm",
      "value": 0.9,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "scintillation_slow_component",
      "value": 600,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    },
    {
      "benchmark": "emission_peak_wavelength",
      "value": 220,
      "bound": "exact",
      "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",
      "source_detail": {
        "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"
      }
    }
  ],
  "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."
  ],
  "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.",
    "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",
        "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.",
        "benchmark": "transmission_range",
        "scope": "material"
      },
      {
        "label": "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.",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "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.",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Scintillation",
        "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.",
        "benchmark": "scintillation_decay_time",
        "scope": "material"
      }
    ],
    "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",
        "scope": "material"
      },
      {
        "label": "Melting point",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      }
    ],
    "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.",
    "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.",
        "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)."
          }
        ],
        "level": 3,
        "verdict": "Harmful if swallowed or inhaled"
      },
      {
        "title": "If the crystal is shocked",
        "lead": "The main risk is to the optic, not to a person. Both manufacturers warn about 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."
          }
        ],
        "level": 2,
        "verdict": "Cracks under thermal shock"
      },
      {
        "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'."
          }
        ]
      }
    ]
  },
  "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"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/barium-fluoride/"
}