{
  "spore": "profile",
  "id": "lithium-fluoride",
  "spore_version": "0.2",
  "family": "optical-crystals",
  "name": "Lithium fluoride (single-crystal LiF)",
  "abbreviation": "LiF",
  "role": "VUV and X-ray optical crystal, with dosimetry and battery-interphase uses",
  "category": "glasses-optics",
  "type": "optical-crystals",
  "summary": "Lithium fluoride is the cubic NaCl-structure crystal LiF. Crystran grows it by the vacuum Stockbarger method in ingots about 100 mm in diameter and says it has the most extreme UV transmission of all its materials, reaching the hydrogen Lyman-alpha line at 121 nm. Its data sheet gives a refractive index of 1.392 at 0.6 µm, a transmission range of 0.12 to 6 µm, a density of 2.639 g/cc and a melting point of 848 °C, and it says the crystal cleaves easily. Lithium fluoride is also used in thermoluminescent dosimeters, and a 2020 PNAS study finds that its role in lithium-metal battery interphases is limited by its mechanical integrity. The sources read give no space or radiation-ageing test for lithium fluoride.\n",
  "best_for": "Optics that must transmit into the vacuum ultraviolet, down to 121 nm (Crystran)",
  "weakest_at": "Brittleness: the crystal cleaves easily on (100), and it reacts with strong mineral acids (Crystran; SDS)",
  "identity": {
    "formula": "LiF",
    "cas": "7789-24-4",
    "crystal_system": "cubic",
    "space_group": "Fm3m (#221), NaCl structure",
    "designations": [],
    "source": "crystran-lif-datasheet",
    "where": "Class/Structure row (Cubic FCC, Fm3m (#221), NaCl structure, (100) cleavage); CAS 7789-24-4 and EC 232-152-0 from crystran-lif-msds section 3.1; molecular weight 25.94 on the Crystran data sheet"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "optics-and-cameras",
      "batteries",
      "habitats-and-suits"
    ]
  },
  "properties": [
    {
      "benchmark": "refractive_index",
      "label": "Refractive index at 0.6 µm",
      "value": 1.392,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "wavelength": "0.6 µm"
      },
      "method": "Value printed on the Crystran materials data sheet (footnote 1, Laporte et al., J. Opt. Soc. Am. 73, 1062); the same sheet prints a reflection loss of 5.2 percent at 0.6 µm",
      "status": "ground",
      "source": "crystran-lif-datasheet",
      "where": "Data table, Refractive Index row (1.392 at 0.6µm)",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "refractive_index",
      "label": "Refractive index at 5 µm",
      "value": 1.3266,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "wavelength": "5 µm"
      },
      "method": "Value printed in the refractive index table of the Crystran data sheet",
      "status": "ground",
      "source": "crystran-lif-datasheet",
      "where": "Refractive Index table, row 5.000 µm",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "transmission_range",
      "label": "Transmission range",
      "value": 0.12,
      "value_high": 6,
      "bound": "range",
      "unit": "µm",
      "scope": "material",
      "conditions": {
        "thickness": "not stated on the page"
      },
      "method": "Range printed on the Crystran data sheet; the Crystran product page gives the same range",
      "status": "ground",
      "note": "The data sheet shows a VUV transmission curve for a 1 mm to 48 mm sample range; the range is taken from the data table, not the curve.",
      "source": "crystran-lif-datasheet",
      "where": "Data table, Transmission Range row",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density",
      "value": 2.639,
      "bound": "exact",
      "unit": "g/cc",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a manufacturer materials data sheet",
      "status": "ground",
      "source": "crystran-lif-datasheet",
      "where": "Data table, Density row",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point",
      "value": 848,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "single crystal"
      },
      "method": "Value printed on the Crystran data sheet (footnote 6, Douglas and Dever, J. Am. Chem. Soc. 1954)",
      "status": "ground",
      "note": "The Crystran safety data sheet prints 842 C for the same material; the data sheet value is used.",
      "source": "crystran-lif-datasheet",
      "where": "Data table, Melting Point row",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point",
      "value": 1676,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "pressure": "760 mmHg"
      },
      "method": "Value printed in section 9.1 of the Crystran safety data sheet",
      "status": "ground",
      "source": "crystran-lif-msds",
      "where": "Section 9.1, BOILING POINT (760mm Hg) row",
      "source_detail": {
        "title": "Crystran: Safety Data Sheet, Lithium Fluoride Optical Crystal (REACH format, revision 2026)",
        "id": "Revision 2026, issued 6 July 2026; CAS 7789-24-4; EC 232-152-0",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-msds.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity",
      "value": 11.3,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "temperature": "314 K"
      },
      "method": "Value printed on the Crystran data sheet (footnote 2, Combes et al. 1951)",
      "status": "ground",
      "source": "crystran-lif-datasheet",
      "where": "Data table, Thermal Conductivity row",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion",
      "value": 37,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "unit_in_source": "x 10-6 K-1",
        "temperature": "283 K"
      },
      "method": "Printed as 37 x 10-6 K-1 on the data sheet, which is the same as ppm/K; no conversion of the number",
      "status": "ground",
      "source": "crystran-lif-datasheet",
      "where": "Data table, Thermal Expansion row",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity",
      "value": 1562,
      "bound": "exact",
      "unit": "J/(kg·K)",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a manufacturer materials data sheet",
      "status": "ground",
      "source": "crystran-lif-datasheet",
      "where": "Data table, Specific Heat Capacity row",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus",
      "value": 64.97,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on the Crystran data sheet (footnote 2, Combes et al. 1951)",
      "status": "ground",
      "source": "crystran-lif-datasheet",
      "where": "Data table, Youngs Modulus (E) row",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "shear_modulus",
      "label": "Shear modulus",
      "value": 55.14,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed in the PDF data sheet",
      "status": "ground",
      "note": "The Crystran product web page prints 54.14 GPa for the same material; the PDF value is used.",
      "source": "crystran-lif-datasheet",
      "where": "Data table, Shear Modulus (G) row",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "bulk_modulus",
      "label": "Bulk modulus",
      "value": 62.03,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a manufacturer materials data sheet",
      "status": "ground",
      "source": "crystran-lif-datasheet",
      "where": "Data table, Bulk Modulus (K) row",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "poissons_ratio",
      "label": "Poisson ratio",
      "value": 0.326,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Printed on the data sheet as calculated by the supplier",
      "status": "ground",
      "source": "crystran-lif-datasheet",
      "where": "Data table, Poisson Ratio row",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "apparent_elastic_limit",
      "label": "Apparent elastic limit",
      "value": 11.2,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on the data sheet as 11.2 MPa (1620 psi); not a canonical property name",
      "status": "ground",
      "source": "crystran-lif-datasheet",
      "where": "Data table, Apparent Elastic Limit row",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "reststrahlen_peak",
      "label": "Reststrahlen peak",
      "value": 25,
      "bound": "exact",
      "unit": "µm",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on the data sheet; not a canonical property name",
      "status": "ground",
      "source": "crystran-lif-datasheet",
      "where": "Data table, Reststrahlen Peak row",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "refractive_index_temperature_coefficient",
      "label": "Refractive index change with temperature (dn/dT)",
      "value": -16,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "unit_in_source": "x 10-6 K-1",
        "wavelength": "1.15 µm"
      },
      "method": "Printed as -16 x 10-6 at 1.15 µm on the data sheet, which is the same as ppm/K; not a canonical property name",
      "status": "ground",
      "source": "crystran-lif-datasheet",
      "where": "Data table, dn/dT row",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "water_solubility",
      "label": "Solubility in water at 20 °C",
      "value": 0.27,
      "bound": "exact",
      "unit": "g/100 g water",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C"
      },
      "method": "Value printed on the data sheet; the safety sheet prints the same figure as 270 mg/100 ml at 20 C; not a canonical property name",
      "status": "ground",
      "source": "crystran-lif-datasheet",
      "where": "Data table, Solubility row",
      "source_detail": {
        "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
        "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
        "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Strong mineral acids and strong oxidising materials",
      "headline": "Lithium fluoride reacts with strong mineral acids and strong oxidising materials, and gives off hydrogen fluoride gas in contact with a mineral acid.",
      "effect": "The Crystran safety sheet lists strong mineral acids and strong oxidising materials as incompatible, says it avoids acids, particularly hot concentrated sulphuric acid, and gives hydrogen fluoride as the decomposition product. No rate or concentration is printed, so the rating is qualitative.",
      "rating": "moderate",
      "conditions": {
        "basis": "qualitative reactivity statement; no rate or concentration printed",
        "agent": "strong mineral acids and strong oxidising materials"
      },
      "source": "crystran-lif-msds",
      "where": "Sections 7.2, 10.1, 10.4, 10.5 and 10.6"
    },
    {
      "environment": "Water at 20 °C",
      "headline": "Lithium fluoride is slightly soluble in water.",
      "effect": "The data sheet gives a solubility of 0.27 g per 100 g of water at 20 C, and the safety sheet says slightly soluble, 270 mg per 100 ml at 20 C. The safety sheet also lists the material as hazardous to drinking water. No dissolution or corrosion test is printed.",
      "rating": "low",
      "conditions": {
        "temperature": "20 °C",
        "note": "solubility figure, not a corrosion rate"
      },
      "source": "crystran-lif-datasheet",
      "where": "Data table, Solubility row; crystran-lif-msds sections 9.1 and 12.1"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "The Crystran safety sheet (revision 2026) classes lithium fluoride as a Class 6.1 poison, with signal word Warning and the statements H302 (harmful if swallowed), H315 (causes skin irritation), H319 (causes serious eye irritation) and H332 (harmful if inhaled).",
        "ghs": [
          "H302",
          "H315",
          "H319",
          "H332"
        ],
        "source": "crystran-lif-msds",
        "where": "Sections 2.1 and 2.2"
      },
      {
        "text": "The same sheet gives an oral LD50 above 143 mg/kg in rats and 119 mg/kg in mice, and says that if swallowed the material causes nausea, vomiting, stomach pains and diarrhoea.",
        "ghs": [],
        "source": "crystran-lif-msds",
        "where": "Sections 2.1 and 11.1"
      },
      {
        "text": "The sheet gives an occupational exposure limit of 2.5 mg/m3 as fluoride, as an 8 hour time-weighted average, and advises avoiding dust.",
        "ghs": [],
        "source": "crystran-lif-msds",
        "where": "Sections 6.1 and 8.1"
      },
      {
        "text": "For transport the sheet gives UN 3288, Toxic solid, inorganic, N.O.S. (Lithium Fluoride), class 6.1, packing group III, and marine pollutant.",
        "ghs": [],
        "source": "crystran-lif-msds",
        "where": "Section 14"
      }
    ],
    "failure_risks": [
      {
        "mode": "Cleavage on (100)",
        "trigger": "Impact, mechanical stress, or polishing at steep radii",
        "consequence": "The data sheet says lithium fluoride cleaves easily and must be worked with extreme care, and that polishing, particularly at steep radii, often causes surface rip-out. The apparent elastic limit is 11.2 MPa.",
        "severity": "moderate",
        "source": "crystran-lif-datasheet",
        "where": "Introduction text; Apparent Elastic Limit row; Class/Structure row"
      },
      {
        "mode": "Loss of mechanical integrity in a LiF-rich interphase on lithium metal",
        "trigger": "Plating of lithium metal against a LiF-enriched interphase",
        "consequence": "The PNAS study finds that the mechanical integrity of LiF is easily compromised during plating, so LiF alone cannot protect the lithium. It finds that in situ repair of the interface by the electrolyte is the more critical determinant of electrode performance.",
        "severity": "moderate",
        "source": "he-pnas-2020",
        "where": "Abstract"
      }
    ],
    "side_effects": [
      {
        "text": "In contact with a mineral acid the material gives off hydrogen fluoride gas, according to the safety sheet.",
        "affects": "Operators and nearby equipment",
        "source": "crystran-lif-msds",
        "where": "Section 10.6"
      }
    ],
    "handling": [
      {
        "text": "Wear PVA gloves, a laboratory coat and safety goggles where chipping or dust may occur. Provide general mechanical and local exhaust ventilation, and wash hands immediately after handling.",
        "source": "crystran-lif-msds",
        "where": "Section 8.2"
      },
      {
        "text": "Avoid generating dust. Take up and containerise broken pieces for disposal, and do not let product enter drains.",
        "source": "crystran-lif-msds",
        "where": "Sections 6.1, 6.2, 6.3 and 7.1"
      },
      {
        "text": "Keep away from heat, foodstuffs, acids and strong bases, and protect the crystal from physical damage.",
        "source": "crystran-lif-msds",
        "where": "Sections 7.1 and 7.2"
      }
    ],
    "mitigations": [
      {
        "text": "Keep the crystal away from strong mineral acids and strong oxidising materials, which react with it.",
        "source": "crystran-lif-msds",
        "where": "Sections 10.1 and 10.5"
      }
    ]
  },
  "uses": [
    {
      "application": "optics-and-cameras",
      "device": "Special UV optics and vacuum-ultraviolet windows",
      "example": "Crystran says lithium fluoride is the material with the most extreme UV transmission of all, and that it transmits well into the vacuum ultraviolet at the hydrogen Lyman-alpha line (121 nm) and beyond.",
      "source": "crystran-lif-datasheet",
      "where": "Materials data text, applications paragraph"
    },
    {
      "application": "optics-and-cameras",
      "device": "X-ray monochromator plates",
      "example": "Crystran says lithium fluoride is used for X-ray monochromator plates, where its lattice spacing makes it the most useful analysis crystal.",
      "source": "crystran-lif-datasheet",
      "where": "Materials data text, applications paragraph"
    },
    {
      "application": "habitats-and-suits",
      "device": "Thermoluminescent dosimeters (LiF:Mg,Ti)",
      "example": "A 2021 paper on LiF:Mg,Ti detectors states that a fraction of the thermoluminescence signal comes from the supralinear dose range, and that prediction of TL efficiency is particularly important in space dosimetry.",
      "source": "tl-pmc7840113",
      "where": "Abstract"
    },
    {
      "application": "batteries",
      "device": "Lithium-metal anode solid electrolyte interphase",
      "example": "A 2020 PNAS study examines LiF-enriched interphases on lithium anodes, made artificially or from fluorinated electrolytes, and finds that LiF's mechanical integrity is easily compromised during plating.",
      "source": "he-pnas-2020",
      "where": "Abstract"
    }
  ],
  "supply": [
    {
      "subject": "Lithium (feedstock, 2025 world mine production)",
      "producers": [
        {
          "country": "Australia",
          "share_percent": 31.7,
          "year": 2025
        },
        {
          "country": "China",
          "share_percent": 21.4,
          "year": 2025
        },
        {
          "country": "Chile",
          "share_percent": 19.3,
          "year": 2025
        },
        {
          "country": "Zimbabwe",
          "share_percent": 9.7,
          "year": 2025
        },
        {
          "country": "Argentina",
          "share_percent": 7.9,
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 List of Critical Minerals (lithium, used in rechargeable batteries)",
          "listed": true
        },
        {
          "list": "EU critical raw materials list (Regulation (EU) 2024/1252, fifth list)",
          "listed": true
        }
      ],
      "recycling": "USGS: construction of lithium battery recycling plants continued throughout 2025.",
      "substitutes": [
        "USGS: substitution for lithium compounds is possible in batteries, ceramics, greases and manufactured glass."
      ],
      "source": "usgs-mcs2026-lithium",
      "where": "World Mine Production and Reserves table, 2025 column (shares calculated by Space Mushroom as country value divided by the 290,000 t world total); Recycling; Substitutes"
    },
    {
      "subject": "Fluorspar (fluorine feedstock, 2025 world mine production)",
      "producers": [
        {
          "country": "China",
          "share_percent": 60,
          "year": 2025
        },
        {
          "country": "Mexico",
          "share_percent": 15,
          "year": 2025
        },
        {
          "country": "Mongolia",
          "share_percent": 15,
          "year": 2025
        },
        {
          "country": "South Africa",
          "share_percent": 4.1,
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 List of Critical Minerals (fluorspar)",
          "listed": true
        },
        {
          "list": "EU critical raw materials list (fluorspar)",
          "listed": true
        }
      ],
      "recycling": "USGS: synthetic fluorspar may be produced from waste neutralization in uranium enrichment, petroleum alkylation and stainless-steel pickling, but undesirable impurities constrain its use.",
      "substitutes": [
        "USGS: fluosilicic acid has been used as an alternative to fluorspar in producing aluminum fluoride and hydrogen fluoride."
      ],
      "source": "usgs-mcs2026-fluorspar",
      "where": "World Mine Production and Reserves table, 2025 column (China 6,000, Mexico 1,500, Mongolia 1,500, South Africa 410 of a world total of 10,000 thousand tons; shares calculated by Space Mushroom); Recycling; Substitutes"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (PDF, data table and refractive index table)",
      "type": "datasheet",
      "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
      "year": 2026
    },
    {
      "title": "Crystran: Safety Data Sheet, Lithium Fluoride Optical Crystal (revision 2026, issued 6 July 2026)",
      "type": "sds",
      "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-msds.pdf",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Lithium",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lithium.pdf",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Fluorspar",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf",
      "year": 2026
    },
    {
      "title": "Microdosimetric understanding of dose response and relative efficiency of thermoluminescence detectors (Radiat Prot Dosimetry 2021, open access)",
      "type": "paper",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7840113/",
      "year": 2021
    },
    {
      "title": "He et al.: The intrinsic behavior of lithium fluoride in solid electrolyte interphases on lithium (PNAS 2020)",
      "type": "paper",
      "url": "https://doi.org/10.1073/pnas.1911017116",
      "year": 2020
    }
  ],
  "gaps": [
    "No space, radiation-ageing, UV-ageing, outgassing (TML/CVCM) or atomic-oxygen result for lithium fluoride was found in a source we could open.",
    "The molten-salt reactor role of LiF is not sourced in this file. The ORNL/OSTI record, the RSC and DOAJ article pages and the IPEN repository could not be opened in this run, so no LiF-BeF2 mixture figures are entered.",
    "PubChem could not be read (bot check). Hazard data rest on one supplier safety data sheet (Crystran), and other suppliers' classifications are not checked.",
    "Melting point differs: 848 C on the data sheet and 842 C on the safety sheet. The data sheet value is used.",
    "Dielectric constant is printed as 0.1 on the data sheet. That looks wrong for a fluoride, so it is not entered.",
    "Knoop hardness is printed as 102 with a 600 g indenter, without a scale unit, so it is not entered.",
    "Absorption coefficient 5.9 x 10-3 cm-1 at 4.3 µm and 300 K is printed on the data sheet but not entered; it can be added once the value is checked against the cited page.",
    "Five benchmark names are kept as snake_case and may not be canonical: apparent_elastic_limit, reststrahlen_peak, refractive_index_temperature_coefficient, water_solubility and transmission_range.",
    "Wikipedia gives a lower water solubility and describes the crystals as hygroscopic. Neither is entered: Wikipedia is not used for values, and no supplier sheet read here confirms either point.",
    "The transmission curves are not read as numbers; the range is from the data table only.",
    "Lithium and fluorspar supply shares are Space Mushroom calculations from the USGS 2025 production tables, not printed shares.",
    "No media (photograph or drawing with a licence) was checked for this profile."
  ],
  "story": {
    "why": "Lithium fluoride is a cubic crystal that Crystran supplies for the deepest ultraviolet optics. Its data sheet gives a refractive index of 1.392 at 0.6 µm, a transmission range of 0.12 to 6 µm, a density of 2.639 g/cc and a melting point of 848 °C. Its use is driven by ultraviolet transmission, X-ray monochromators and thermoluminescent dosimetry, rather than by mechanical strength: the crystal cleaves easily and its apparent elastic limit is 11.2 MPa.",
    "uses": [
      {
        "where": "Vacuum-ultraviolet optics",
        "line": "Crystran says lithium fluoride has the most extreme UV transmission of all its materials, and transmits into the vacuum ultraviolet at the 121 nm hydrogen Lyman-alpha line and beyond."
      },
      {
        "where": "X-ray monochromators",
        "line": "Crystran says its lattice spacing makes lithium fluoride the most useful analysis crystal for X-ray monochromator plates."
      },
      {
        "where": "Thermoluminescent dosimetry",
        "line": "A 2021 open-access paper on LiF:Mg,Ti detectors says that prediction of their thermoluminescence efficiency is particularly important in space dosimetry."
      },
      {
        "where": "Lithium-metal battery interphase",
        "line": "A 2020 PNAS study looks at LiF-enriched interphases on lithium anodes, which are formed either artificially or from fluorinated electrolytes, and finds that LiF's mechanical integrity is easily compromised."
      }
    ],
    "can_do": [
      {
        "label": "Range",
        "line": "Crystran's data table gives a transmission range of 0.12 to 6 µm, and says the material reaches the 121 nm Lyman-alpha line.",
        "scope": "material",
        "value": "0.12 to 6 µm"
      },
      {
        "label": "Refraction",
        "line": "Refractive index 1.392 at 0.6 µm and 1.3266 at 5 µm, per the Crystran data table and its refractive index table.",
        "scope": "material",
        "value": "1.392"
      },
      {
        "label": "Heat",
        "line": "Melting point 848 °C on the data sheet (842 °C on the safety sheet). Thermal conductivity 11.3 W/(m·K) at 314 K.",
        "scope": "material",
        "value": "848 °C"
      },
      {
        "label": "Stiffness",
        "line": "Young's modulus 64.97 GPa, shear modulus 55.14 GPa and bulk modulus 62.03 GPa, from the Crystran data table.",
        "scope": "material",
        "value": "64.97 GPa"
      }
    ],
    "compare": "This profile does not compare numbers with the other fluorides in this collection, because their sheets were not read in this run. Crystran describes lithium fluoride as having the most extreme UV transmission of all its materials, and its own sheet shows that it is soft and easily cleaved: its apparent elastic limit is 11.2 MPa and it cleaves on (100). The sources read give no side-by-side ground or space test.",
    "compare_rows": [
      {
        "label": "Heat conduction",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      },
      {
        "label": "Thermal expansion",
        "benchmark": "cte",
        "scope": "material"
      },
      {
        "label": "Stiffness",
        "benchmark": "elastic_modulus",
        "scope": "material"
      }
    ],
    "handling": [
      "Wear PVA gloves and goggles where chipping or dust may occur, and avoid making dust when cutting, grinding or cleaning.",
      "Keep the crystal away from strong mineral acids and strong oxidising materials, which give off hydrogen fluoride gas on reaction.",
      "Do not let product enter drains, and take up broken pieces into containers for disposal."
    ],
    "good_for": [
      "Vacuum-ultraviolet optics that must transmit to 121 nm (Crystran).",
      "X-ray monochromator plates, where its lattice spacing suits analysis (Crystran).",
      "Thermoluminescent dosimetry with LiF:Mg,Ti detectors, where space dosimetry relies on predicting their response (2021 paper)."
    ],
    "watch_out": [
      "Cleavage. The crystal cleaves easily on (100), and polishing at steep radii can cause rip-out (Crystran).",
      "Acids. Strong mineral acids and strong oxidising materials react with it and give off hydrogen fluoride (safety sheet).",
      "Solubility. It dissolves to 0.27 g per 100 g of water at 20 C, and the safety sheet lists it as hazardous to drinking water.",
      "No space test. No flight, radiation-ageing or outgassing result for lithium fluoride was found in the sources read."
    ],
    "verdict": "Lithium fluoride is Crystran's choice for the deepest ultraviolet optics, with a 0.12 to 6 µm transmission range and a reach to 121 nm. Its brittleness and acid sensitivity are the trade-off. The thermoluminescent and battery uses rest on papers rather than flight data, and this profile does not establish its behaviour in orbit.",
    "recipe": {
      "line": "Lithium fluoride is LiF, one lithium ion and one fluoride ion per formula unit, with a sodium-chloride-type structure. It is prepared from lithium hydroxide or lithium carbonate with hydrogen fluoride (Wikipedia). Crystran grows the optical crystal by the vacuum Stockbarger technique in ingots about 100 mm in diameter. Hydrogen fluoride, the fluorine source, is made from fluorspar, which USGS names as the feedstock for virtually all fluorine-bearing chemicals.",
      "parts": [
        {
          "name": "Lithium",
          "symbol": "Li",
          "role": "The mobile ion. Lithium ions are the species that carry charge in a lithium-metal interphase and in the lithium salts that the material supplies."
        },
        {
          "name": "Fluorine",
          "symbol": "F",
          "role": "The anion. Fluoride ions give the crystal its wide transmission in the ultraviolet and make it reactive with strong acids."
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The Crystran safety sheet (revision 2026) classes lithium fluoride as a Class 6.1 poison with H302, H315, H319 and H332, and gives an oral LD50 above 143 mg/kg in rats.",
        "points": [
          {
            "label": "Dust",
            "line": "The sheet gives an occupational limit of 2.5 mg/m3 as fluoride, as an 8 hour average, and says to avoid making dust."
          },
          {
            "label": "Swallowed",
            "line": "If swallowed, the material causes nausea, vomiting, stomach pains and diarrhoea, according to the sheet."
          },
          {
            "label": "Scope",
            "line": "Only the Crystran safety sheet was read. PubChem could not be opened, and other suppliers' classifications are not checked here."
          }
        ],
        "level": 1,
        "verdict": "Harmful if swallowed or inhaled; irritating"
      },
      {
        "title": "If it fails",
        "lead": "The failure results come from supplier data sheets and one interphase study. No flight failure record was read.",
        "points": [
          {
            "label": "Cleavage",
            "line": "The data sheet says the crystal cleaves easily on (100), and that polishing, particularly at steep radii, often causes surface rip-out."
          },
          {
            "label": "Interphase",
            "line": "The 2020 PNAS study finds that LiF in a lithium-metal interphase is easily broken during plating, so the electrolyte's repair of the interface matters more."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Protective equipment",
            "line": "PVA gloves, a laboratory coat and safety goggles where chipping or dust may occur, with mechanical and local exhaust ventilation."
          },
          {
            "label": "Incompatible materials",
            "line": "Strong mineral acids and strong oxidising materials. Hydrogen fluoride gas forms in contact with a mineral acid."
          }
        ],
        "gap": "The sheets give no storage temperature or humidity limit."
      }
    ]
  },
  "updated": "2026-10-26",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 17,
    "unreachable": 5,
    "caveats": 4,
    "note": "Written by an AI assistant on 2026-10-26 from the Crystran data sheet and safety sheet (both read as PDF text), USGS Mineral Commodity Summaries 2026 for lithium and fluorspar, a 2021 open-access paper on TL detectors and a 2020 PNAS paper, read in the same run. Caveats: PubChem, OSTI, RSC, DOAJ and IPEN could not be opened; the molten-salt reactor use is not sourced; the Crystran dielectric constant is not entered."
  },
  "sources": {
    "crystran-lif-datasheet": {
      "title": "Crystran: Lithium Fluoride (LiF) materials data sheet (data table, refractive index table, VUV transmission curve)",
      "id": "lithium-fluoride-lif-data-sheet.pdf (undated; pages 66 and 67)",
      "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-data-sheet.pdf",
      "year": 2026,
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "crystran-lif-msds": {
      "title": "Crystran: Safety Data Sheet, Lithium Fluoride Optical Crystal (REACH format, revision 2026)",
      "id": "Revision 2026, issued 6 July 2026; CAS 7789-24-4; EC 232-152-0",
      "url": "https://www.crystran.com/wp-content/uploads/2025/09/lithium-fluoride-lif-msds.pdf",
      "year": 2026,
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "usgs-mcs2026-lithium": {
      "title": "Mineral Commodity Summaries 2026, Lithium (USGS)",
      "id": "USGS MCS 2026, February 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lithium.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "usgs-mcs2026-fluorspar": {
      "title": "Mineral Commodity Summaries 2026, Fluorspar (USGS, Vanessa Londono)",
      "id": "USGS MCS 2026, February 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-fluorspar.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "usgs-crit2025": {
      "title": "About the 2025 List of Critical Minerals (USGS, final list of 60 minerals)",
      "id": "Final 2025 List of Critical Minerals, November 2025",
      "url": "https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals",
      "year": 2025,
      "kind": "web",
      "license": "public domain (USGS)"
    },
    "ec-crm": {
      "title": "Critical raw materials (European Commission, list of 34 critical raw materials under Regulation (EU) 2024/1252)",
      "id": "Regulation (EU) 2024/1252",
      "url": "https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en",
      "year": 2024,
      "kind": "web",
      "license": "European Commission web page"
    },
    "tl-pmc7840113": {
      "title": "Microdosimetric understanding of dose response and relative efficiency of thermoluminescence detectors",
      "id": "doi:10.1093/rpd/ncaa211 (Radiat Prot Dosimetry 192(2), 165-177, 2021; PMC7840113)",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7840113/",
      "year": 2021,
      "kind": "paper",
      "license": "open access (Oxford University Press, PMC copy)"
    },
    "he-pnas-2020": {
      "title": "The intrinsic behavior of lithium fluoride in solid electrolyte interphases on lithium",
      "id": "doi:10.1073/PNAS.1911017116 (PNAS 2020; He, Guo, Hobold, Gao, Gallant)",
      "url": "https://doi.org/10.1073/pnas.1911017116",
      "year": 2020,
      "kind": "paper",
      "license": "MIT DSpace open access record; publisher terms apply"
    },
    "wikipedia-lif": {
      "title": "Lithium fluoride (Wikipedia article)",
      "id": "en.wikipedia.org, accessed 2026-10-26; used for preparation route only",
      "url": "https://en.wikipedia.org/wiki/Lithium_fluoride",
      "year": 2026,
      "kind": "web",
      "license": "CC BY-SA 4.0"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/lithium-fluoride/"
}