{
  "spore": "profile",
  "id": "indium",
  "spore_version": "0.2",
  "family": "low-melting-metals-and-solders",
  "name": "Indium",
  "abbreviation": "In",
  "role": "soft low-melting metal for indium tin oxide coatings, solders, seals and bump bonds",
  "category": "metals",
  "type": "heavy-metals",
  "summary": "Indium is the element In (atomic number 49), a soft, ductile, silvery-white metal that melts at 156.6 degC. Most of it is used as indium tin oxide (ITO), a transparent conductive coating for flat-panel displays and touchscreens (USGS). Foil from one supplier has a density of 7.3 g/cm3 at 20 degC, a thermal conductivity of 81.8 W/(m K) at 0 to 100 degC and a tensile modulus of 10.6 GPa. The metal is softer than tin, with a Mohs hardness of 1.2 (WebElements), and it forms a thin indium oxide crust in room-temperature air, which the NASA Goddard report on bump bonding says must be removed before a good electrical joint is made.\n",
  "best_for": "Soft, low-melting metal for seals, solders and bonds: melting point 156.6 degC and ductile enough to form a wire O-ring (NASA)",
  "weakest_at": "Strength and cost: tensile strength of 2.6 to 4.5 MPa in the supplier foil, and a 2025 U.S. price of about 370 dollars per kg (USGS)",
  "identity": {
    "formula": "In (element, atomic number 49, group 13); high-purity foil sold at 99.8 % to 99.999 % In",
    "cas": "7440-74-6",
    "designations": [],
    "source": "pubchem-in",
    "where": "Identifiers section of the PubChem record (CID 5359967, CAS 7440-74-6); purity range from the Goodfellow indium foil page"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "electronics-and-chips",
      "thermal-control",
      "mechanisms"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density of indium (PubChem)",
      "value": 7.31,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "temperature": "20 degC"
      },
      "method": "Value printed in the density section of the PubChem record",
      "status": "ground",
      "source": "pubchem-in",
      "where": "Density section, entry 7.31 g/cu cm at 20 degC",
      "source_detail": {
        "title": "PubChem compound record: Indium (CID 5359967), including GHS, NIOSH and ERG excerpts",
        "id": "CID 5359967; CAS 7440-74-6; PubChem REST pug_view JSON",
        "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/5359967/JSON",
        "year": 2026,
        "kind": "database",
        "license": "PubChem (NCBI), public domain; sections attributed to ECHA, NIOSH and ERG"
      }
    },
    {
      "benchmark": "density",
      "label": "Density of indium foil (Goodfellow)",
      "value": 7.3,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "temperature": "20 degC",
        "form": "foil, 99.8 % to 99.999 % In (as sold)"
      },
      "method": "Value printed on the supplier foil page",
      "status": "ground",
      "source": "goodfellow-in",
      "where": "Physical Properties table, Density row (7.3 at 20 degC)",
      "source_detail": {
        "title": "Goodfellow indium foil, 99.8 % to 99.999 %, product properties",
        "id": "CAS 7440-74-6; Goodfellow product page, Properties table",
        "url": "https://www.goodfellow.com/eu/indium-foil-group",
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density of solid indium (WebElements)",
      "value": 7310,
      "bound": "exact",
      "unit": "kg/m3",
      "scope": "material",
      "conditions": {
        "form": "solid",
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a reference-database physical properties page",
      "status": "ground",
      "source": "webelements-in",
      "where": "Density properties, Density of solid row (7310 kg m-3)",
      "source_detail": {
        "title": "WebElements: Indium - 49 In, physical properties (Mark Winter, University of Sheffield)",
        "url": "https://www.webelements.com/indium/physics.html",
        "kind": "database",
        "license": "WebElements, cited not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point of indium (Goodfellow)",
      "value": 156.6,
      "bound": "exact",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "form": "foil, as sold"
      },
      "method": "Value printed on the supplier foil page",
      "status": "ground",
      "source": "goodfellow-in",
      "where": "Thermal Properties table, Melting point row (156.6)",
      "source_detail": {
        "title": "Goodfellow indium foil, 99.8 % to 99.999 %, product properties",
        "id": "CAS 7440-74-6; Goodfellow product page, Properties table",
        "url": "https://www.goodfellow.com/eu/indium-foil-group",
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point of indium (PubChem)",
      "value": 156.6,
      "bound": "exact",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "pressure": "not stated"
      },
      "method": "Value listed in the melting point section of the PubChem record",
      "status": "ground",
      "source": "pubchem-in",
      "where": "Melting Point section, entry 156.6 degC (the record also lists 156.61 degC)",
      "source_detail": {
        "title": "PubChem compound record: Indium (CID 5359967), including GHS, NIOSH and ERG excerpts",
        "id": "CID 5359967; CAS 7440-74-6; PubChem REST pug_view JSON",
        "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/5359967/JSON",
        "year": 2026,
        "kind": "database",
        "license": "PubChem (NCBI), public domain; sections attributed to ECHA, NIOSH and ERG"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point of indium",
      "value": 2080,
      "bound": "exact",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "pressure": "760 mmHg"
      },
      "method": "Value listed in the boiling point section of the PubChem record",
      "status": "ground",
      "source": "pubchem-in",
      "where": "Boiling Point section, entry 2080 degC @760 [mm Hg]",
      "source_detail": {
        "title": "PubChem compound record: Indium (CID 5359967), including GHS, NIOSH and ERG excerpts",
        "id": "CID 5359967; CAS 7440-74-6; PubChem REST pug_view JSON",
        "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/5359967/JSON",
        "year": 2026,
        "kind": "database",
        "license": "PubChem (NCBI), public domain; sections attributed to ECHA, NIOSH and ERG"
      }
    },
    {
      "benchmark": "latent_heat_of_fusion",
      "label": "Latent heat of fusion of indium",
      "value": 28.5,
      "bound": "exact",
      "unit": "J/g",
      "scope": "material",
      "conditions": {
        "form": "foil, as sold"
      },
      "method": "Value printed on the supplier foil page",
      "status": "ground",
      "source": "goodfellow-in",
      "where": "Thermal Properties table, Latent heat of fusion row (28.5)",
      "source_detail": {
        "title": "Goodfellow indium foil, 99.8 % to 99.999 %, product properties",
        "id": "CAS 7440-74-6; Goodfellow product page, Properties table",
        "url": "https://www.goodfellow.com/eu/indium-foil-group",
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity of indium foil (Goodfellow)",
      "value": 81.8,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "temperature": "0 to 100 degC",
        "form": "foil, as sold"
      },
      "method": "Value printed on the supplier foil page",
      "status": "ground",
      "source": "goodfellow-in",
      "where": "Thermal Properties table, Thermal conductivity row (81.8 at 0-100 degC)",
      "source_detail": {
        "title": "Goodfellow indium foil, 99.8 % to 99.999 %, product properties",
        "id": "CAS 7440-74-6; Goodfellow product page, Properties table",
        "url": "https://www.goodfellow.com/eu/indium-foil-group",
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity of indium (WebElements)",
      "value": 82,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a reference-database physical properties page",
      "status": "ground",
      "source": "webelements-in",
      "where": "Heat and conduction, Thermal conductivity row (82 W m-1 K-1)",
      "source_detail": {
        "title": "WebElements: Indium - 49 In, physical properties (Mark Winter, University of Sheffield)",
        "url": "https://www.webelements.com/indium/physics.html",
        "kind": "database",
        "license": "WebElements, cited not reproduced"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat of indium foil (Goodfellow)",
      "value": 234,
      "bound": "exact",
      "unit": "J/(kg·K)",
      "scope": "material",
      "conditions": {
        "temperature": "25 degC",
        "form": "foil, as sold"
      },
      "method": "Value printed on the supplier foil page",
      "status": "ground",
      "source": "goodfellow-in",
      "where": "Thermal Properties table, Specific heat row (234 at 25 degC)",
      "source_detail": {
        "title": "Goodfellow indium foil, 99.8 % to 99.999 %, product properties",
        "id": "CAS 7440-74-6; Goodfellow product page, Properties table",
        "url": "https://www.goodfellow.com/eu/indium-foil-group",
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion of indium foil (Goodfellow)",
      "value": 24.8,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "temperature": "0 to 100 degC",
        "unit_in_source": "x10-6 K-1",
        "form": "foil, as sold"
      },
      "method": "Value printed on the supplier foil page",
      "status": "ground",
      "source": "goodfellow-in",
      "where": "Thermal Properties table, Coefficient of thermal expansion row (24.8 at 0-100 degC)",
      "source_detail": {
        "title": "Goodfellow indium foil, 99.8 % to 99.999 %, product properties",
        "id": "CAS 7440-74-6; Goodfellow product page, Properties table",
        "url": "https://www.goodfellow.com/eu/indium-foil-group",
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of linear thermal expansion (WebElements)",
      "value": 32.1,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "unit_in_source": "x10-6 K-1",
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a reference-database physical properties page",
      "status": "ground",
      "note": "Differs from the supplier value of 24.8 ppm/K by about 30 %. The two pages give no common temperature, so both are recorded and neither is preferred.",
      "source": "webelements-in",
      "where": "Heat and conduction, Coefficient of linear thermal expansion row (32.1 x 10-6 K-1)",
      "source_detail": {
        "title": "WebElements: Indium - 49 In, physical properties (Mark Winter, University of Sheffield)",
        "url": "https://www.webelements.com/indium/physics.html",
        "kind": "database",
        "license": "WebElements, cited not reproduced"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "label": "Electrical resistivity of indium foil (Goodfellow)",
      "value": 8.8,
      "bound": "exact",
      "unit": "µΩ·cm",
      "scope": "material",
      "conditions": {
        "temperature": "20 degC",
        "form": "foil, as sold"
      },
      "method": "Value printed on the supplier foil page",
      "status": "ground",
      "source": "goodfellow-in",
      "where": "Electrical Properties table, Electrical resistivity row (8.8 at 20 degC)",
      "source_detail": {
        "title": "Goodfellow indium foil, 99.8 % to 99.999 %, product properties",
        "id": "CAS 7440-74-6; Goodfellow product page, Properties table",
        "url": "https://www.goodfellow.com/eu/indium-foil-group",
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "superconducting_transition_temperature",
      "label": "Superconducting critical temperature of indium",
      "value": 3.41,
      "bound": "exact",
      "unit": "K",
      "scope": "material",
      "conditions": {
        "form": "foil, as sold"
      },
      "method": "Value printed on the supplier foil page",
      "status": "ground",
      "source": "goodfellow-in",
      "where": "Electrical Properties table, Superconductivity critical temperature row (3.41)",
      "source_detail": {
        "title": "Goodfellow indium foil, 99.8 % to 99.999 %, product properties",
        "id": "CAS 7440-74-6; Goodfellow product page, Properties table",
        "url": "https://www.goodfellow.com/eu/indium-foil-group",
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus of indium (WebElements)",
      "value": 11,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a reference-database physical properties page",
      "status": "ground",
      "source": "webelements-in",
      "where": "Elastic properties, Young's modulus row (11 GPa)",
      "source_detail": {
        "title": "WebElements: Indium - 49 In, physical properties (Mark Winter, University of Sheffield)",
        "url": "https://www.webelements.com/indium/physics.html",
        "kind": "database",
        "license": "WebElements, cited not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Tensile modulus of indium foil (Goodfellow)",
      "value": 10.6,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "material_condition": "polycrystalline"
      },
      "method": "Value printed on the supplier foil page",
      "status": "ground",
      "source": "goodfellow-in",
      "where": "Mechanical Properties table, Tensile modulus row (10.6 GPa)",
      "source_detail": {
        "title": "Goodfellow indium foil, 99.8 % to 99.999 %, product properties",
        "id": "CAS 7440-74-6; Goodfellow product page, Properties table",
        "url": "https://www.goodfellow.com/eu/indium-foil-group",
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "bulk_modulus",
      "label": "Bulk modulus of indium foil (Goodfellow)",
      "value": 35.3,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "material_condition": "polycrystalline"
      },
      "method": "Value printed on the supplier foil page",
      "status": "ground",
      "source": "goodfellow-in",
      "where": "Mechanical Properties table, Bulk modulus row (35.3 GPa)",
      "source_detail": {
        "title": "Goodfellow indium foil, 99.8 % to 99.999 %, product properties",
        "id": "CAS 7440-74-6; Goodfellow product page, Properties table",
        "url": "https://www.goodfellow.com/eu/indium-foil-group",
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "poissons_ratio",
      "label": "Poisson's ratio of indium foil (Goodfellow)",
      "value": 0.45,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "material_condition": "polycrystalline"
      },
      "method": "Value printed on the supplier foil page",
      "status": "ground",
      "source": "goodfellow-in",
      "where": "Mechanical Properties table, Poisson's ratio row (0.45)",
      "source_detail": {
        "title": "Goodfellow indium foil, 99.8 % to 99.999 %, product properties",
        "id": "CAS 7440-74-6; Goodfellow product page, Properties table",
        "url": "https://www.goodfellow.com/eu/indium-foil-group",
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength of indium foil (Goodfellow)",
      "value": 2.6,
      "value_high": 4.5,
      "bound": "range",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "material_condition": "soft, as listed in the supplier table"
      },
      "method": "Range printed on the supplier foil page",
      "status": "ground",
      "source": "goodfellow-in",
      "where": "Mechanical Properties table, Tensile strength row (2.6-4.5 MPa)",
      "source_detail": {
        "title": "Goodfellow indium foil, 99.8 % to 99.999 %, product properties",
        "id": "CAS 7440-74-6; Goodfellow product page, Properties table",
        "url": "https://www.goodfellow.com/eu/indium-foil-group",
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "mohs_hardness",
      "label": "Mineral hardness, Mohs scale (WebElements)",
      "value": 1.2,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "temperature": "not stated on the page"
      },
      "method": "Value printed on a reference-database physical properties page",
      "status": "ground",
      "source": "webelements-in",
      "where": "Hardnesses, Mineral hardness row (1.2)",
      "source_detail": {
        "title": "WebElements: Indium - 49 In, physical properties (Mark Winter, University of Sheffield)",
        "url": "https://www.webelements.com/indium/physics.html",
        "kind": "database",
        "license": "WebElements, cited not reproduced"
      }
    },
    {
      "benchmark": "brinell_hardness",
      "label": "Brinell hardness of indium (WebElements)",
      "value": 8.83,
      "bound": "exact",
      "unit": "MN/m2",
      "scope": "material",
      "conditions": {
        "test_conditions": "not stated on the page"
      },
      "method": "Value printed on a reference-database physical properties page",
      "status": "ground",
      "source": "webelements-in",
      "where": "Hardnesses, Brinell hardness row (8.83 MN m-2)",
      "source_detail": {
        "title": "WebElements: Indium - 49 In, physical properties (Mark Winter, University of Sheffield)",
        "url": "https://www.webelements.com/indium/physics.html",
        "kind": "database",
        "license": "WebElements, cited not reproduced"
      }
    },
    {
      "benchmark": "vickers_hardness",
      "label": "Vickers hardness of indium foil (Goodfellow)",
      "value": 10,
      "bound": "exact",
      "unit": "kgf/mm2",
      "scope": "material",
      "conditions": {
        "material_condition": "polycrystalline"
      },
      "method": "Value printed on the supplier foil page",
      "status": "ground",
      "source": "goodfellow-in",
      "where": "Mechanical Properties table, Hardness Vickers row (10 kgf mm-2)",
      "source_detail": {
        "title": "Goodfellow indium foil, 99.8 % to 99.999 %, product properties",
        "id": "CAS 7440-74-6; Goodfellow product page, Properties table",
        "url": "https://www.goodfellow.com/eu/indium-foil-group",
        "kind": "datasheet",
        "license": "supplier product page, cited not reproduced"
      }
    },
    {
      "benchmark": "vapor_pressure",
      "label": "Vapour pressure of indium at its melting point",
      "value": 1.14e-19,
      "bound": "exact",
      "unit": "Pa",
      "scope": "material",
      "conditions": {
        "temperature": "at the melting point"
      },
      "method": "Value listed in the vapour pressure section of the PubChem record",
      "status": "ground",
      "source": "pubchem-in",
      "where": "Vapor Pressure section, entry 1.14X10-19 Pa at melting point",
      "source_detail": {
        "title": "PubChem compound record: Indium (CID 5359967), including GHS, NIOSH and ERG excerpts",
        "id": "CID 5359967; CAS 7440-74-6; PubChem REST pug_view JSON",
        "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/5359967/JSON",
        "year": 2026,
        "kind": "database",
        "license": "PubChem (NCBI), public domain; sections attributed to ECHA, NIOSH and ERG"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Room-temperature air",
      "headline": "In room-temperature air, indium quickly forms a thin indium oxide (In2O3) crust that must be removed before a good electrical joint.",
      "effect": "NASA Goddard's bump-bonding report says indium readily oxidizes in air at room temperature to form a thin In2O3 crust. The oxide resists rupture during bonding, which can cause poor adhesion and block electrical conduction. Ellipsometry on untreated indium gave a steady Delta of about 128, which the report links to the native oxide; a plasma treatment removed it, and the oxide regrows once the reduced surface leaves vacuum. The report gives no oxide thickness or growth rate.",
      "rating": "moderate",
      "conditions": {
        "basis": "NASA Goddard observation during flip-chip hybridization; cleanroom air",
        "thickness": "not given in the source"
      },
      "source": "ntrs-mosaic",
      "where": "Section 2.2 (Plasma Cleaning) and the ellipsometry discussion that follows"
    },
    {
      "environment": "Air at room temperature (supplier statement)",
      "headline": "The supplier says the oxide layer protects indium without much loss of thermal or electrical performance.",
      "effect": "Goodfellow states that indium forms a stable, self-passivating oxide layer and that this supports long-term reliability in sealed or exposed systems. The supplier page gives no test data, no thickness and no time scale, so this is recorded as a claim, not a measured result.",
      "rating": "low",
      "conditions": {
        "basis": "supplier product text, no test data"
      },
      "source": "goodfellow-in",
      "where": "Product text, Indium foil description (self-passivating behaviour paragraph)"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "PubChem reports that the first GHS notification block for indium carries signal word Danger, with H302 (15.1 %), H312 (12.7 %), H315 (15.4 %) and H319 (13.2 %). It also says 18.6 % (69 of 371) of company reports do not meet GHS criteria. The record does not say which indium substance each notification covers.",
        "ghs": [
          "H302",
          "H312",
          "H315",
          "H319"
        ],
        "source": "pubchem-in",
        "where": "GHS Classification section, first block (ECHA C&L aggregated notifications, 371 reports)"
      },
      {
        "text": "A second PubChem GHS block for indium lists H303 (may be harmful if swallowed) and H372 (causes damage to organs through prolonged or repeated exposure), with signal word Danger.",
        "ghs": [
          "H303",
          "H372"
        ],
        "source": "pubchem-in",
        "where": "GHS Classification section, second block"
      },
      {
        "text": "The NIOSH excerpt in PubChem lists the exposure routes as inhalation, ingestion, and skin or eye contact. Symptoms include irritation of the eyes, skin and respiratory system, and possible liver, kidney, heart and blood effects. Target organs are listed as the eyes, skin, respiratory system, liver, kidneys, heart and blood.",
        "ghs": [],
        "source": "pubchem-in",
        "where": "Health Hazards section, NIOSH Pocket Guide excerpt (2024)"
      },
      {
        "text": "PubChem's human toxicity excerpts say that indium may damage the developing fetus and may damage the lungs. Higher exposures can cause pulmonary oedema, which can be delayed by several hours.",
        "ghs": [],
        "source": "pubchem-in",
        "where": "Human Toxicity Excerpts, long-term and short-term exposure entries"
      }
    ],
    "failure_risks": [
      {
        "mode": "Dust explosion of indium powder",
        "trigger": "Indium in powder or granular form mixed with air",
        "consequence": "PubChem's physical-dangers entry says a dust explosion is possible, and that finely dispersed particles form explosive mixtures in air.",
        "severity": "moderate",
        "source": "pubchem-in",
        "where": "Physical Dangers and Fire Potential sections"
      },
      {
        "mode": "Leakage of an indium seal on rapid cooling",
        "trigger": "Rapid cooling of a demountable indium seal, especially after repeated cycles",
        "consequence": "NASA Ames notes that leakage frequently occurs under rapid cooling of indium seals. Its own test seals, flat indium/silver alloy rings in a stainless steel guard, were cooled rapidly by immersion and showed no detectable leak at any temperature, including 1.6 K after 13 mount and demount cycles.",
        "severity": "moderate",
        "source": "ntrs-seal-1989",
        "where": "Introduction and results, NASA TM 102190 (1989)"
      },
      {
        "mode": "Oxide film blocks an electrical joint",
        "trigger": "Indium exposed to room-temperature air before bonding, or a surface reduced but then returned to air",
        "consequence": "The In2O3 crust resists rupture when bonding, and the report says it can block electrical conduction and inhibit a superconducting joint. The oxide regrows once a reduced surface is exposed to air again.",
        "severity": "moderate",
        "source": "ntrs-mosaic",
        "where": "Section 2.2 (Plasma Cleaning)"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "PubChem fire-prevention guidance for indium powder: no open flames, no sparks and no smoking. Use a closed system, dust-explosion-proof electrical equipment and lighting, and prevent dust from settling.",
        "source": "pubchem-in",
        "where": "Fire Prevention section"
      },
      {
        "text": "PubChem's fire-fighting excerpt, taken from ERG Guide 170 for metal powders, says not to use water, foam or CO2 on metal fires because water can generate hydrogen. It recommends dry sand, graphite powder or a dry sodium-chloride-based powder. The excerpt is a generic guide for metal powders, not an indium-specific test.",
        "source": "pubchem-in",
        "where": "Fire Fighting section, ERG Guide 170 excerpt"
      }
    ],
    "mitigations": [
      {
        "text": "The NASA Goddard team cleaned indium surfaces in a plasma of nitrogen-rich, reducing gas just before bonding, which removed the native oxide and gave a good electrical joint.",
        "source": "ntrs-mosaic",
        "where": "Section 2.2 (Plasma Cleaning)"
      }
    ]
  },
  "uses": [
    {
      "application": "electronics-and-chips",
      "device": "Indium tin oxide (ITO) transparent conductive coatings in flat-panel displays",
      "example": "USGS says ITO production continued to account for most global indium consumption, mainly for liquid crystal displays. Estimated U.S. consumption of refined indium was 220 tons in 2025.",
      "source": "usgs-mcs2026-indium",
      "where": "Domestic Production and Use paragraph and Salient Statistics table"
    },
    {
      "application": "electronics-and-chips",
      "device": "Indium phosphide substrates, lasers and photodetectors for fibre-optic networks",
      "example": "USGS says indium phosphide (InP) substrates are used in 5G fibre-optic networks, and that InP lasers and receivers send data over fibre lines. It also says InP is used in high-speed photodetectors and laser diodes.",
      "source": "usgs-mcs2026-indium",
      "where": "Events, Trends, and Issues paragraph"
    },
    {
      "application": "electronics-and-chips",
      "device": "Indium bump bonds that join detector arrays to silicon readout chips (far-infrared detector model)",
      "example": "NASA Goddard built a 32 by 40 pixel detector model in which 10 µm of indium was deposited by lift-off on the readout chip's under-bump metal. When hybridized, the indium cold-welds to the detector's molybdenum nitride. The report is a ground demonstration with no flight heritage.",
      "source": "ntrs-mosaic",
      "where": "Section 2.1 (Fabrication)"
    },
    {
      "application": "mechanisms",
      "device": "Flat indium/silver alloy seal in a stainless steel guard for demountable cryogenic joints (ground test, not flown)",
      "example": "NASA Ames leak-tested two all-metal demountable seals of this design at 300 K, 77 K, 4.2 K and 1.6 K, with no detectable leak above the helium background. The report notes that indium has been used in demountable cryogenic seals because it is easy to form into an O-ring from wire.",
      "source": "ntrs-seal-1989",
      "where": "Introduction, NASA TM 102190 (1989)"
    },
    {
      "application": "thermal-control",
      "device": "Indium foil as a thermal interface between surfaces in electronics",
      "example": "The supplier describes indium foil as a thermal interface material that fills microscopic gaps. The page gives no thermal-resistance value, so this is a product claim, not a measured result.",
      "source": "goodfellow-in",
      "where": "Product text, Indium foil description (thermal interface paragraph)"
    }
  ],
  "supply": [
    {
      "subject": "Indium (refinery production)",
      "abundance": "0.25 ppm in the Earth's crust (USGS Professional Paper 1802-A, Table A1)",
      "producers": [
        {
          "country": "China",
          "share_percent": 70,
          "year": 2025
        },
        {
          "country": "Republic of Korea",
          "share_percent": 16.4,
          "year": 2025
        },
        {
          "country": "Japan",
          "share_percent": 5.9,
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 List of Critical Minerals",
          "listed": true
        },
        {
          "list": "EU critical raw materials list (Commission page, 2023 assessment)",
          "listed": false
        }
      ],
      "recycling": "USGS: indium is most commonly recovered from ITO scrap in Japan and the Republic of Korea. Recycling quantities were not available.",
      "substitutes": [
        "USGS: antimony tin oxide, carbon nanotube coatings, PEDOT, copper or silver nanowires, graphene and zinc oxide nanopowder have been developed or explored to replace ITO. Hafnium can replace indium in nuclear reactor control rod alloys."
      ],
      "source": "usgs-mcs2026-indium",
      "where": "World Refinery Production and Capacity table, 2025e column (world total 1,100 t). China 70 % is as printed in Events, Trends, and Issues; Korea and Japan shares are calculated by Space Mushroom (180 and 65 over 1,100); Recycling; Substitutes"
    },
    {
      "subject": "Refined indium imports to the United States",
      "producers": [
        {
          "country": "Republic of Korea",
          "share_percent": 25,
          "year": 2024
        },
        {
          "country": "Japan",
          "share_percent": 22,
          "year": 2024
        },
        {
          "country": "China",
          "share_percent": 12,
          "year": 2024
        },
        {
          "country": "Canada",
          "share_percent": 11,
          "year": 2024
        }
      ],
      "critical_lists": [],
      "substitutes": [],
      "source": "usgs-mcs2026-indium",
      "where": "Import Sources (2021-24) paragraph; the year is the end of the 2021 to 2024 period as printed. The United States has no indium refinery output in 2025 (Salient Statistics)."
    },
    {
      "subject": "Trade restriction on indium exports from China",
      "producers": [],
      "critical_lists": [],
      "substitutes": [],
      "source": "usgs-mcs2026-indium",
      "where": "Events, Trends, and Issues paragraph"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "USGS Mineral Commodity Summaries 2026: Indium",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-indium.pdf",
      "year": 2026
    },
    {
      "title": "PubChem compound record for indium (CID 5359967): density, melting and boiling points, GHS and NIOSH excerpts",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Indium",
      "year": 2026
    },
    {
      "title": "WebElements: indium physical properties",
      "type": "database",
      "url": "https://www.webelements.com/indium/physics.html"
    },
    {
      "title": "Goodfellow indium foil, 99.8 % to 99.999 %, properties table",
      "type": "datasheet",
      "url": "https://www.goodfellow.com/eu/indium-foil-group"
    },
    {
      "title": "NIST Atomic Weights and Isotopic Compositions for All Elements, indium",
      "type": "database",
      "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=In&all=all&ascii=html"
    },
    {
      "title": "USGS Professional Paper 1802-A, Table A1, crustal abundances",
      "type": "report",
      "url": "https://pubs.usgs.gov/pp/1802/a/pp1802a.pdf",
      "year": 2017
    },
    {
      "title": "NASA Ames TM 102190: Performance of All-Metal Demountable Cryogenic Seals at Superfluid Helium Temperatures",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/19890013479/downloads/19890013479.pdf",
      "year": 1989
    },
    {
      "title": "NASA Goddard: Enabling large focal plane arrays through mosaic hybridization",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/20130013418/downloads/20130013418.pdf"
    },
    {
      "title": "Congressional Research Service IF13145: USGS Critical Minerals List (final 2025 list)",
      "type": "report",
      "url": "https://www.everycrsreport.com/files/2026-01-07_IF13145_e385924a2f20b8b1460afc40322d4137f1956556.pdf",
      "year": 2026
    }
  ],
  "gaps": [
    "No flight, vacuum, outgassing, atomic oxygen, UV or radiation data for indium in space were found in any fetched source. The seal and bump-bonding sources are ground tests.",
    "Tensile strength, yield strength and elongation are from one supplier page only. Its material condition is printed as soft, but the page does not say which temper or purity each row refers to.",
    "The coefficient of thermal expansion differs between sources: 24.8 ppm/K (supplier, 0 to 100 degC) and 32.1 ppm/K (WebElements, temperature not stated). Both are recorded and neither is preferred.",
    "WebElements prints electrical resistivity as 8 x 10 to the power -8 ohm m, with a special minus sign that the value check could not match, so that row is left out. The supplier value of 8.8 µΩ·cm at 20 degC is recorded instead.",
    "Two entries in the PubChem record were left out as not credible: 1.6 MPa tensile strength and 291 ohm m electrical resistivity, which sit in a mixed list of other experimental values.",
    "Latent heat of fusion and superconducting critical temperature are not in spores/property-canon.yaml and are used under the names given in the benchmark field.",
    "Corrosion rates in water, salt spray, acids and seawater were not found in a fetched source. PubChem gives only solubility (insoluble in water, soluble in acids).",
    "No supplier safety data sheet for indium was read in this run. Hazard data rest on the PubChem summary and the NIOSH excerpt it quotes.",
    "No UNS, ASTM, EN or other grade designation for indium was found in a fetched source.",
    "The USGS gives the 2025 refined price three ways: about 350,000 dollars per ton in the summary, 370 dollars per kg in the table and 390 dollars per kg in the text. None of the three is used as a property value.",
    "The EU critical raw materials list on the Commission page does not include indium. That page reflects the 2023 assessment and may not match the 2024 regulation cited in the lithium profile.",
    "The Wikipedia article was used only for history and the zinc-ore origin. Its values are not used.",
    "No photograph or diagram of indium was fetched in this run, so the media list is empty."
  ],
  "story": {
    "why": "Indium is a soft, ductile metal that melts at 156.6 degC. It is made into thin foils, wires and coatings, and its main use is indium tin oxide, a transparent conductor for displays. It is also used in solders and in cryogenic seals, because it can be formed into an O-ring from wire and stays soft at low temperature. Its drawbacks are its low strength, its oxide film in air and its concentrated supply: China produces about 70 % of refinery output (USGS).",
    "uses": [
      {
        "where": "Flat-panel displays and touchscreens",
        "line": "Indium tin oxide coatings took most global indium consumption. U.S. consumption of refined indium was 220 tons in 2025 (USGS)."
      },
      {
        "where": "Fibre-optic and 5G networks",
        "line": "Indium phosphide substrates and devices are used in lasers and high-speed photodetectors for fibre-optic communications (USGS)."
      },
      {
        "where": "Far-infrared detector arrays",
        "line": "NASA Goddard bonds indium bumps to join detector arrays to readout chips. The work is a ground demonstration, not a flight unit."
      },
      {
        "where": "Cryogenic seals",
        "line": "NASA Ames leak-tested indium/silver alloy seals from 300 K down to 1.6 K (superfluid helium). It is a ground test, not a flight result."
      }
    ],
    "can_do": [
      {
        "label": "Melt low",
        "line": "Indium melts at 156.6 degC, printed by both the supplier and PubChem.",
        "benchmark": "melting_point",
        "scope": "material",
        "value": "156.6 degC melting point"
      },
      {
        "label": "Stay soft",
        "line": "The supplier foil has a tensile strength of 2.6 to 4.5 MPa and a Mohs hardness of 1.2 (WebElements).",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material",
        "value": "2.6 to 4.5 MPa tensile strength"
      },
      {
        "label": "Carry heat",
        "line": "The supplier foil has a thermal conductivity of 81.8 W/(m·K) at 0 to 100 degC. WebElements gives 82 W/(m·K).",
        "benchmark": "thermal_conductivity",
        "scope": "material",
        "value": "81.8 W/(m·K)"
      },
      {
        "label": "Weight",
        "line": "Density is 7.3 g/cm3 at 20 degC (supplier) and 7.31 g/cm3 at 20 degC (PubChem).",
        "benchmark": "density",
        "scope": "material",
        "value": "7.3 g/cm3"
      }
    ],
    "compare": "Indium is a soft, low-melting metal. Its melting point of 156.6 degC is low, and its tensile strength is far below that of structural alloys. The sources disagree on thermal expansion (24.8 and 32.1 ppm/K), so read the rows as ranges. The profile does not rank indium against other metals.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      },
      {
        "label": "Thermal expansion",
        "benchmark": "cte",
        "scope": "material"
      }
    ],
    "handling": [
      "Use dust control for powder and keep ignition sources away, because PubChem records an explosive dust hazard.",
      "Clean the surface just before bonding or sealing, because the oxide returns in air.",
      "Follow the PubChem hazard codes (H302, H312, H315, H319, H303, H372) when handling the metal.",
      "Keep the seal cool and cool it slowly, because NASA Ames found leaks on rapid cooling."
    ],
    "good_for": [
      "Low melting point and soft metal: 156.6 degC melting point, and a wire form that makes a cryogenic O-ring (NASA).",
      "Transparent conductive coatings: most indium goes into ITO for displays (USGS)."
    ],
    "watch_out": [
      "Low strength: tensile strength is 2.6 to 4.5 MPa in the supplier foil, and the Mohs hardness is 1.2.",
      "Oxide film: the In2O3 crust in air blocks electrical contact unless it is removed before bonding (NASA Goddard).",
      "Supply: China produces about 70 % of refinery output and cut its exports in 2025 (USGS).",
      "Thermal expansion: sources give 24.8 and 32.1 ppm/K.",
      "No flight, vacuum, outgassing, atomic oxygen or radiation data were found in this run."
    ],
    "verdict": "Indium is a soft, low-melting metal that is used mostly in transparent conductive coatings, with smaller roles in solders, cryogenic seals and bump bonds. Its weak points are its low strength, its oxide film in air, and its supply, which is concentrated in China. The profile has no flight or space-exposure data, so it can say what indium does on the ground but not how it behaves in orbit.",
    "recipe": {
      "line": "Indium is a single element (In, atomic number 49, group 13). Most of it is recovered as a by-product of zinc. Wikipedia and the USGS say it comes mainly from zinc-sulfide ore, sphalerite, and is refined from zinc residues. The USGS summary gives production statistics but not the refining route, so the process is stated only at that level.",
      "parts": [
        {
          "name": "Indium",
          "symbol": "In",
          "role": "The whole material. NIST gives the standard atomic weight as 114.818(1).",
          "atoms": 1,
          "atomic_weight": 114.818
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "PubChem's notifications mostly report irritation codes, and the NIOSH excerpt lists organ effects from exposure to indium compounds, so dust and fume should be avoided.",
        "points": [
          {
            "label": "The metal in PubChem",
            "line": "The first GHS block gives H302, H312, H315 and H319 with signal word Danger. A second block gives H303 and H372 (organ damage from repeated exposure). PubChem says 69 of 371 company reports do not meet GHS criteria. The record does not say which indium substance each report covers."
          },
          {
            "label": "Organs and development",
            "line": "NIOSH lists the eyes, skin, respiratory system, liver, kidneys, heart and blood as target organs. PubChem's excerpts say indium may damage the developing fetus."
          }
        ],
        "level": 1,
        "verdict": "Hazard codes in PubChem, little toxicology data"
      },
      {
        "title": "If it fails",
        "lead": "The failure routes in these sources are a dust explosion of powder, a leaking seal on rapid cooling, and an oxide film that blocks a joint.",
        "points": [
          {
            "label": "Powder",
            "line": "PubChem says indium powder can form an explosive dust cloud in air, so keep dust down and use dust-explosion-proof equipment."
          },
          {
            "label": "Seals",
            "line": "NASA Ames notes that indium seals often leak on rapid cooling. Its own indium/silver test seals showed no detectable leak at any temperature down to 1.6 K, after 13 mount and demount cycles."
          },
          {
            "label": "Oxide",
            "line": "NASA Goddard found that the native In2O3 crust blocks electrical contact unless it is removed, for example by plasma cleaning just before bonding."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Fire",
            "line": "For powder, PubChem calls for no open flames, no sparks, a closed system and dust-explosion-proof equipment. Its fire guidance warns against water on metal powder fires (ERG Guide 170)."
          },
          {
            "label": "Surfaces",
            "line": "Cold-weld bonding needs a clean surface. Clean the metal just before it is joined, because the oxide returns when the reduced surface is exposed to air again."
          }
        ]
      }
    ]
  },
  "updated": "2026-10-26",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 23,
    "unreachable": 1,
    "caveats": 4,
    "note": "Values were read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry (USGS text extracted from the PDF; NASA reports from the NTRS PDFs; PubChem values from its JSON record). Unreachable: the Indium Corporation sealing page (blocked) and the USGS critical-minerals page (403); the list status comes from the CRS report. Caveats: the CTE values disagree between sources; the PubChem density and melting values carry no test conditions; the GHS notifications do not say which indium substance they cover; the Korea and Japan refinery shares are calculated."
  },
  "sources": {
    "usgs-mcs2026-indium": {
      "title": "Mineral Commodity Summaries 2026: Indium (U.S. Geological Survey)",
      "id": "USGS MCS 2026, February 2026, prepared by Rob Crangle",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-indium.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "pubchem-in": {
      "title": "PubChem compound record: Indium (CID 5359967), including GHS, NIOSH and ERG excerpts",
      "id": "CID 5359967; CAS 7440-74-6; PubChem REST pug_view JSON",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/5359967/JSON",
      "year": 2026,
      "kind": "database",
      "license": "PubChem (NCBI), public domain; sections attributed to ECHA, NIOSH and ERG"
    },
    "webelements-in": {
      "title": "WebElements: Indium - 49 In, physical properties (Mark Winter, University of Sheffield)",
      "url": "https://www.webelements.com/indium/physics.html",
      "kind": "database",
      "license": "WebElements, cited not reproduced"
    },
    "goodfellow-in": {
      "title": "Goodfellow indium foil, 99.8 % to 99.999 %, product properties",
      "id": "CAS 7440-74-6; Goodfellow product page, Properties table",
      "url": "https://www.goodfellow.com/eu/indium-foil-group",
      "kind": "datasheet",
      "license": "supplier product page, cited not reproduced"
    },
    "nist-in-weights": {
      "title": "NIST Atomic Weights and Isotopic Compositions for All Elements, indium (In)",
      "id": "standard atomic weight 114.818(1)",
      "url": "https://physics.nist.gov/cgi-bin/Compositions/stand_alone.pl?ele=In&all=all&ascii=html",
      "kind": "database",
      "license": "US government data"
    },
    "pp1802a-crust": {
      "title": "Critical Mineral Resources of the United States: An Introduction (USGS Professional Paper 1802-A), Table A1",
      "id": "USGS PP 1802-A",
      "url": "https://pubs.usgs.gov/pp/1802/a/pp1802a.pdf",
      "year": 2017,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "ntrs-seal-1989": {
      "title": "Performance of All-Metal Demountable Cryogenic Seals at Superfluid Helium Temperatures (NASA Technical Memorandum 102190, Ames Research Center)",
      "id": "NTRS 19890013479",
      "url": "https://ntrs.nasa.gov/api/citations/19890013479/downloads/19890013479.pdf",
      "year": 1989,
      "kind": "report",
      "license": "public domain (NASA)"
    },
    "ntrs-mosaic": {
      "title": "Enabling large focal plane arrays through mosaic hybridization (NASA Goddard Space Flight Center)",
      "id": "NTRS 20130013418",
      "url": "https://ntrs.nasa.gov/api/citations/20130013418/downloads/20130013418.pdf",
      "kind": "report",
      "license": "public domain (NASA)"
    },
    "crs-if13145": {
      "title": "Congressional Research Service IF13145: USGS Critical Minerals List, final 2025 list of 60 minerals",
      "id": "IF13145, updated 2026-01-07",
      "url": "https://www.everycrsreport.com/files/2026-01-07_IF13145_e385924a2f20b8b1460afc40322d4137f1956556.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (CRS)"
    },
    "ec-crm": {
      "title": "Critical raw materials (European Commission, critical raw materials list and 2023 assessment)",
      "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"
    },
    "wiki-in": {
      "title": "Indium, Wikipedia (history, naming and zinc-ore origin only)",
      "url": "https://en.wikipedia.org/wiki/Indium",
      "kind": "web",
      "license": "CC BY-SA 4.0, linked not reproduced"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/indium/"
}