{
  "spore": "profile",
  "id": "ytterbium",
  "spore_version": "0.2",
  "family": "rare-earth-metals",
  "name": "Ytterbium",
  "abbreviation": "Yb",
  "role": "dopant for fibre lasers, stainless-steel additive and reactive rare-earth metal",
  "category": "metals",
  "type": "heavy-metals",
  "summary": "Ytterbium is the element Yb (atomic number 70), a soft, silvery, malleable rare-earth metal. The Goodfellow 99.9 % pellet has a density of 6.977 g/cm3 at 20 °C and a melting point of 819 °C, and Wikipedia gives 6.967 g/cm3 and 824 °C for the element. It is a heavy rare earth (USGS), with an average crustal abundance of about 3 mg/kg (Wikipedia). The metal is made by reducing its oxide with lanthanum, aluminium, cerium or zirconium in high vacuum. One documented technical use is as a dopant in fibre lasers, and NASA Goddard has built a Yb-doped fibre ring laser at 1064 nm for the LISA gravitational-wave mission. The metal itself is a flammable solid. Fine powder ignites, and contact with water releases flammable gas, so it needs dry, inert handling.\n",
  "best_for": "Dopant for solid-state and fibre lasers, and reference data for a heavy rare-earth metal (NASA Goddard LISA laser; Wikipedia)",
  "weakest_at": "Fine powder that ignites in air, and metal that releases flammable gas on contact with water (Samat and Trace Sciences SDS, PubChem)",
  "identity": {
    "formula": "Yb (element, atomic number 70); unalloyed metal, sold as 99.9 % pellets by Goodfellow",
    "cas": "7440-64-4",
    "designations": [],
    "source": "pubchem-yb",
    "where": "PubChem CID 23992 record, Other Identifiers, CAS 7440-64-4; EC number 231-173-2 is printed in the Trace Sciences SDS, Section 3"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "optics-and-cameras",
      "structures"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density, ytterbium pellet (99.9 %)",
      "value": 6.977,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C",
        "purity": "99.9%",
        "form": "pellets"
      },
      "method": "Typical value printed in a supplier product datasheet",
      "status": "ground",
      "source": "goodfellow-yb",
      "where": "Physical Properties table, row Density (6.977 at 20 °C)",
      "source_detail": {
        "title": "Ytterbium pellets, 99.9 % (Goodfellow product datasheet)",
        "url": "https://www.goodfellow.com/uk/ytterbium-pellets-1000220085",
        "kind": "datasheet",
        "license": "supplier web page (cited, not reproduced)"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, ytterbium powder (Samat SDS)",
      "value": 6.97,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C",
        "form": "powder"
      },
      "method": "Value printed in a safety data sheet, Section 9",
      "status": "ground",
      "source": "samat-yb-sds",
      "where": "Section 9, Physical and Chemical Properties, row Density at 20 °C (68 °F) 6.97 g/cm3",
      "source_detail": {
        "title": "Safety data sheet: Ytterbium powder, Stanford Advanced Materials (revised 29/12/2022)",
        "id": "CAS 7440-64-4",
        "url": "https://samaterials.com/tds/1697121476-1098-ytterbium-metal-powder-sds.pdf",
        "year": 2022,
        "kind": "datasheet",
        "license": "supplier safety data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, ytterbium metal powder (Trace Sciences SDS)",
      "value": 6.54,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "temperature": "25 °C",
        "form": "powder"
      },
      "method": "Value printed in a safety data sheet, Section 9",
      "status": "ground",
      "note": "The Trace Sciences SDS gives 6.54 g/cm3 at 25 °C, which is about 6 % below the 6.97 g/cm3 at 20 °C from Goodfellow and Samat. The difference may come from the temperature or the sample, and both values are kept.",
      "source": "trace-yb-sds",
      "where": "Section 9, Physical and Chemical Properties, row Density 6.54 g/cm3 at 25 °C (77 °F)",
      "source_detail": {
        "title": "Safety data sheet: Ytterbium (metal powder), Trace Sciences International",
        "url": "https://tracesciences.com/wp-content/uploads/2025/04/Ytterbium-metal-powder-SDS.pdf",
        "year": 2025,
        "kind": "datasheet",
        "license": "supplier safety data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, ytterbium (Wikipedia)",
      "value": 6.967,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C",
        "unit_in_source": "6.967 g/cm3"
      },
      "method": "Value printed in the Wikipedia infobox",
      "status": "ground",
      "source": "wikipedia-yb",
      "where": "Infobox, row Density (at 20° C) 6.967 g/cm3",
      "source_detail": {
        "title": "Ytterbium (Wikipedia)",
        "url": "https://en.wikipedia.org/wiki/Ytterbium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "density",
      "label": "Density of solid, ytterbium (WebElements)",
      "value": 6570,
      "bound": "exact",
      "unit": "kg/m3",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the table"
      },
      "method": "Value printed on the WebElements physical-properties page",
      "status": "ground",
      "note": "WebElements prints 6570 kg m-3 (6.57 g/cm3) with no temperature. That is lower than the 6.97 g/cm3 values above, and it is entered as printed.",
      "source": "webelements-yb",
      "where": "Physical properties table, row Density of solid 6570 kg m-3",
      "source_detail": {
        "title": "WebElements: Ytterbium, physical properties (University of Sheffield)",
        "url": "https://winter.group.shef.ac.uk/webelements/ytterbium/physics.html",
        "kind": "database",
        "license": "WebElements, cited not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, ytterbium pellet (99.9 %)",
      "value": 819,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "pressure": "not stated",
        "purity": "99.9%",
        "form": "pellets"
      },
      "method": "Value printed in a supplier product datasheet",
      "status": "ground",
      "source": "goodfellow-yb",
      "where": "Thermal Properties table, row Melting point (819)",
      "source_detail": {
        "title": "Ytterbium pellets, 99.9 % (Goodfellow product datasheet)",
        "url": "https://www.goodfellow.com/uk/ytterbium-pellets-1000220085",
        "kind": "datasheet",
        "license": "supplier web page (cited, not reproduced)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, ytterbium powder (Samat SDS)",
      "value": 819,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "powder"
      },
      "method": "Value printed in a safety data sheet, Section 9",
      "status": "ground",
      "source": "samat-yb-sds",
      "where": "Section 9, row Melting point/Melting range 819 °C (1506 °F)",
      "source_detail": {
        "title": "Safety data sheet: Ytterbium powder, Stanford Advanced Materials (revised 29/12/2022)",
        "id": "CAS 7440-64-4",
        "url": "https://samaterials.com/tds/1697121476-1098-ytterbium-metal-powder-sds.pdf",
        "year": 2022,
        "kind": "datasheet",
        "license": "supplier safety data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, ytterbium metal powder (Trace Sciences SDS)",
      "value": 824,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "powder"
      },
      "method": "Value printed in a safety data sheet, Section 9",
      "status": "ground",
      "source": "trace-yb-sds",
      "where": "Section 9, row Melting point/freezing point 824 °C (1,515 °F)",
      "source_detail": {
        "title": "Safety data sheet: Ytterbium (metal powder), Trace Sciences International",
        "url": "https://tracesciences.com/wp-content/uploads/2025/04/Ytterbium-metal-powder-SDS.pdf",
        "year": 2025,
        "kind": "datasheet",
        "license": "supplier safety data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, ytterbium (Wikipedia)",
      "value": 824,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "pressure": "not stated",
        "unit_in_source": "1097 K (824 °C, 1515 °F)"
      },
      "method": "Value printed in the Wikipedia infobox",
      "status": "ground",
      "source": "wikipedia-yb",
      "where": "Infobox, row Melting point, 1097 K (824 °C, 1515 °F)",
      "source_detail": {
        "title": "Ytterbium (Wikipedia)",
        "url": "https://en.wikipedia.org/wiki/Ytterbium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point, ytterbium pellet (99.9 %)",
      "value": 1194,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "pressure": "not stated",
        "purity": "99.9%"
      },
      "method": "Value printed in a supplier product datasheet",
      "status": "ground",
      "note": "Goodfellow gives 1194 °C and the SDS and Wikipedia sources give 1196 °C. The 2 °C difference is kept, and both values are entered.",
      "source": "goodfellow-yb",
      "where": "Physical Properties table, row Boiling point (1194)",
      "source_detail": {
        "title": "Ytterbium pellets, 99.9 % (Goodfellow product datasheet)",
        "url": "https://www.goodfellow.com/uk/ytterbium-pellets-1000220085",
        "kind": "datasheet",
        "license": "supplier web page (cited, not reproduced)"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point, ytterbium powder (Samat SDS)",
      "value": 1196,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "pressure": "not stated",
        "form": "powder"
      },
      "method": "Value printed in a safety data sheet, Section 9",
      "status": "ground",
      "source": "samat-yb-sds",
      "where": "Section 9, row Boiling point/Boiling range 1196 °C (2185 °F)",
      "source_detail": {
        "title": "Safety data sheet: Ytterbium powder, Stanford Advanced Materials (revised 29/12/2022)",
        "id": "CAS 7440-64-4",
        "url": "https://samaterials.com/tds/1697121476-1098-ytterbium-metal-powder-sds.pdf",
        "year": 2022,
        "kind": "datasheet",
        "license": "supplier safety data sheet, cited not reproduced"
      }
    },
    {
      "benchmark": "boiling_point",
      "label": "Boiling point, ytterbium (Wikipedia)",
      "value": 1196,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "pressure": "not stated",
        "unit_in_source": "1469 K (1196 °C, 2185 °F)"
      },
      "method": "Value printed in the Wikipedia infobox",
      "status": "ground",
      "source": "wikipedia-yb",
      "where": "Infobox, row Boiling point, 1469 K (1196 °C, 2185 °F)",
      "source_detail": {
        "title": "Ytterbium (Wikipedia)",
        "url": "https://en.wikipedia.org/wiki/Ytterbium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity, ytterbium pellet (99.9 %)",
      "value": 145,
      "bound": "exact",
      "unit": "J/(kg·K)",
      "scope": "material",
      "conditions": {
        "temperature": "25 °C",
        "purity": "99.9%"
      },
      "method": "Typical value printed in a supplier product datasheet",
      "status": "ground",
      "source": "goodfellow-yb",
      "where": "Thermal Properties table, row Specific heat (145 at 25 °C)",
      "source_detail": {
        "title": "Ytterbium pellets, 99.9 % (Goodfellow product datasheet)",
        "url": "https://www.goodfellow.com/uk/ytterbium-pellets-1000220085",
        "kind": "datasheet",
        "license": "supplier web page (cited, not reproduced)"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity, ytterbium (Wikipedia)",
      "value": 154.522,
      "bound": "exact",
      "unit": "J/(kg·K)",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the infobox"
      },
      "method": "Value printed in the Wikipedia infobox",
      "status": "ground",
      "note": "The Wikipedia infobox gives this value with no temperature, and the supplier value is at 25 °C. The two differ by about 6 %.",
      "source": "wikipedia-yb",
      "where": "Infobox, row Specific heat capacity 154.522 J/(kg·K)",
      "source_detail": {
        "title": "Ytterbium (Wikipedia)",
        "url": "https://en.wikipedia.org/wiki/Ytterbium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, ytterbium pellet (99.9 %)",
      "value": 32.9,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "temperature": "0 to 100 °C",
        "purity": "99.9%"
      },
      "method": "Typical value printed in a supplier product datasheet",
      "status": "ground",
      "source": "goodfellow-yb",
      "where": "Thermal Properties table, row Thermal conductivity (32.9 at 0-100 °C)",
      "source_detail": {
        "title": "Ytterbium pellets, 99.9 % (Goodfellow product datasheet)",
        "url": "https://www.goodfellow.com/uk/ytterbium-pellets-1000220085",
        "kind": "datasheet",
        "license": "supplier web page (cited, not reproduced)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, ytterbium (WebElements)",
      "value": 34.9,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the table"
      },
      "method": "Value printed on the WebElements physical-properties page",
      "status": "ground",
      "source": "webelements-yb",
      "where": "Thermal properties table, row Thermal conductivity 34.9 W m-1 K-1",
      "source_detail": {
        "title": "WebElements: Ytterbium, physical properties (University of Sheffield)",
        "url": "https://winter.group.shef.ac.uk/webelements/ytterbium/physics.html",
        "kind": "database",
        "license": "WebElements, cited not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, ytterbium (Wikipedia)",
      "value": 38.5,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the infobox"
      },
      "method": "Value printed in the Wikipedia infobox",
      "status": "ground",
      "note": "The Wikipedia infobox gives 38.5 W/(m·K) with no temperature, and the Goodfellow pellet gives 32.9 W/(m·K) at 0 to 100 °C. The two differ by about 15 %.",
      "source": "wikipedia-yb",
      "where": "Infobox, row Thermal conductivity 38.5 W/(m⋅K)",
      "source_detail": {
        "title": "Ytterbium (Wikipedia)",
        "url": "https://en.wikipedia.org/wiki/Ytterbium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion, ytterbium pellet (99.9 %)",
      "value": 25,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "temperature": "0 to 100 °C",
        "purity": "99.9%",
        "unit_in_source": "25 x10-6 K-1"
      },
      "method": "Typical value printed in a supplier product datasheet",
      "status": "ground",
      "source": "goodfellow-yb",
      "where": "Thermal Properties table, row Coefficient of thermal expansion (25 at 0-100 °C)",
      "source_detail": {
        "title": "Ytterbium pellets, 99.9 % (Goodfellow product datasheet)",
        "url": "https://www.goodfellow.com/uk/ytterbium-pellets-1000220085",
        "kind": "datasheet",
        "license": "supplier web page (cited, not reproduced)"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of linear thermal expansion, ytterbium (WebElements)",
      "value": 26.3,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the table",
        "unit_in_source": "26.3 × 10-6 K-1"
      },
      "method": "Value printed on the WebElements physical-properties page",
      "status": "ground",
      "source": "webelements-yb",
      "where": "Thermal properties table, row Coefficient of linear thermal expansion 26.3 × 10-6 K-1",
      "source_detail": {
        "title": "WebElements: Ytterbium, physical properties (University of Sheffield)",
        "url": "https://winter.group.shef.ac.uk/webelements/ytterbium/physics.html",
        "kind": "database",
        "license": "WebElements, cited not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Tensile modulus, ytterbium pellet (99.9 %)",
      "value": 17.8,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the table",
        "purity": "99.9%",
        "form": "pellets"
      },
      "method": "Typical value printed in a supplier product datasheet, under the row Tensile modulus",
      "status": "ground",
      "note": "The Goodfellow page prints this row as Tensile modulus, and does not print Young's modulus. It is entered under the canonical elastic_modulus name.",
      "source": "goodfellow-yb",
      "where": "Mechanical Properties table, row Tensile modulus (17.8 GPa)",
      "source_detail": {
        "title": "Ytterbium pellets, 99.9 % (Goodfellow product datasheet)",
        "url": "https://www.goodfellow.com/uk/ytterbium-pellets-1000220085",
        "kind": "datasheet",
        "license": "supplier web page (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus, ytterbium beta form (Wikipedia)",
      "value": 23.9,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the infobox",
        "form": "beta form, as printed in the infobox"
      },
      "method": "Value printed in the Wikipedia infobox",
      "status": "ground",
      "source": "wikipedia-yb",
      "where": "Infobox, row Young's modulus, beta form 23.9 GPa",
      "source_detail": {
        "title": "Ytterbium (Wikipedia)",
        "url": "https://en.wikipedia.org/wiki/Ytterbium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus, ytterbium (WebElements)",
      "value": 24,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the table"
      },
      "method": "Value printed on the WebElements physical-properties page",
      "status": "ground",
      "source": "webelements-yb",
      "where": "Mechanical properties table, row Young's modulus 24 GPa",
      "source_detail": {
        "title": "WebElements: Ytterbium, physical properties (University of Sheffield)",
        "url": "https://winter.group.shef.ac.uk/webelements/ytterbium/physics.html",
        "kind": "database",
        "license": "WebElements, cited not reproduced"
      }
    },
    {
      "benchmark": "shear_modulus",
      "label": "Shear modulus, ytterbium beta form (Wikipedia)",
      "value": 9.9,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the infobox",
        "form": "beta form, as printed in the infobox"
      },
      "method": "Value printed in the Wikipedia infobox",
      "status": "ground",
      "source": "wikipedia-yb",
      "where": "Infobox, row Shear modulus, beta form 9.9 GPa",
      "source_detail": {
        "title": "Ytterbium (Wikipedia)",
        "url": "https://en.wikipedia.org/wiki/Ytterbium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "shear_modulus",
      "label": "Rigidity modulus, ytterbium (WebElements)",
      "value": 9.9,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the table"
      },
      "method": "Value printed on the WebElements physical-properties page",
      "status": "ground",
      "source": "webelements-yb",
      "where": "Mechanical properties table, row Rigidity modulus 9.9 GPa",
      "source_detail": {
        "title": "WebElements: Ytterbium, physical properties (University of Sheffield)",
        "url": "https://winter.group.shef.ac.uk/webelements/ytterbium/physics.html",
        "kind": "database",
        "license": "WebElements, cited not reproduced"
      }
    },
    {
      "benchmark": "bulk_modulus",
      "label": "Bulk modulus, ytterbium pellet (99.9 %)",
      "value": 13.5,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the table",
        "purity": "99.9%",
        "form": "pellets"
      },
      "method": "Typical value printed in a supplier product datasheet",
      "status": "ground",
      "note": "The Goodfellow bulk modulus of 13.5 GPa is less than half the 30.5 GPa and 31 GPa values from Wikipedia and WebElements. The conflict is kept, and this value is entered as printed.",
      "source": "goodfellow-yb",
      "where": "Mechanical Properties table, row Bulk modulus (13.5 GPa)",
      "source_detail": {
        "title": "Ytterbium pellets, 99.9 % (Goodfellow product datasheet)",
        "url": "https://www.goodfellow.com/uk/ytterbium-pellets-1000220085",
        "kind": "datasheet",
        "license": "supplier web page (cited, not reproduced)"
      }
    },
    {
      "benchmark": "bulk_modulus",
      "label": "Bulk modulus, ytterbium beta form (Wikipedia)",
      "value": 30.5,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the infobox",
        "form": "beta form, as printed in the infobox"
      },
      "method": "Value printed in the Wikipedia infobox",
      "status": "ground",
      "source": "wikipedia-yb",
      "where": "Infobox, row Bulk modulus, beta form 30.5 GPa",
      "source_detail": {
        "title": "Ytterbium (Wikipedia)",
        "url": "https://en.wikipedia.org/wiki/Ytterbium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "bulk_modulus",
      "label": "Bulk modulus, ytterbium (WebElements)",
      "value": 31,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the table"
      },
      "method": "Value printed on the WebElements physical-properties page",
      "status": "ground",
      "source": "webelements-yb",
      "where": "Mechanical properties table, row Bulk modulus 31 GPa",
      "source_detail": {
        "title": "WebElements: Ytterbium, physical properties (University of Sheffield)",
        "url": "https://winter.group.shef.ac.uk/webelements/ytterbium/physics.html",
        "kind": "database",
        "license": "WebElements, cited not reproduced"
      }
    },
    {
      "benchmark": "poissons_ratio",
      "label": "Poisson's ratio, ytterbium pellet (99.9 %)",
      "value": 0.28,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the table",
        "purity": "99.9%",
        "form": "pellets"
      },
      "method": "Typical value printed in a supplier product datasheet",
      "status": "ground",
      "source": "goodfellow-yb",
      "where": "Mechanical Properties table, row Poisson's ratio (0.28, no unit printed)",
      "source_detail": {
        "title": "Ytterbium pellets, 99.9 % (Goodfellow product datasheet)",
        "url": "https://www.goodfellow.com/uk/ytterbium-pellets-1000220085",
        "kind": "datasheet",
        "license": "supplier web page (cited, not reproduced)"
      }
    },
    {
      "benchmark": "poissons_ratio",
      "label": "Poisson's ratio, ytterbium beta form (Wikipedia)",
      "value": 0.207,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the infobox",
        "form": "beta form, as printed in the infobox"
      },
      "method": "Value printed in the Wikipedia infobox",
      "status": "ground",
      "source": "wikipedia-yb",
      "where": "Infobox, row Poisson ratio, beta form 0.207",
      "source_detail": {
        "title": "Ytterbium (Wikipedia)",
        "url": "https://en.wikipedia.org/wiki/Ytterbium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "vickers_hardness",
      "label": "Vickers hardness, ytterbium (WebElements)",
      "value": 206,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the table"
      },
      "method": "Value printed on the WebElements physical-properties page, given as MN m-2 (equal to MPa)",
      "status": "ground",
      "note": "No canonical name exists for hardness in the property file, so vickers_hardness is a new name and is listed in gaps.",
      "source": "webelements-yb",
      "where": "Hardnesses, row Vickers hardness 206 MN m-2",
      "source_detail": {
        "title": "WebElements: Ytterbium, physical properties (University of Sheffield)",
        "url": "https://winter.group.shef.ac.uk/webelements/ytterbium/physics.html",
        "kind": "database",
        "license": "WebElements, cited not reproduced"
      }
    },
    {
      "benchmark": "vickers_hardness",
      "label": "Vickers hardness range, ytterbium (Wikipedia)",
      "value": 205,
      "value_high": 250,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temperature": "not stated in the infobox",
        "note_on_range": "the infobox gives a range, not a single test value"
      },
      "method": "Range printed in the Wikipedia infobox",
      "status": "ground",
      "note": "No canonical name exists for hardness, so vickers_hardness is a new name and is listed in gaps. Wikipedia gives a range without test conditions.",
      "source": "wikipedia-yb",
      "where": "Infobox, row Vickers hardness 205–250 MPa",
      "source_detail": {
        "title": "Ytterbium (Wikipedia)",
        "url": "https://en.wikipedia.org/wiki/Ytterbium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "label": "Electrical resistivity, ytterbium pellet (99.9 %)",
      "value": 28,
      "bound": "exact",
      "unit": "µOhm·cm",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C",
        "purity": "99.9%",
        "form": "pellets"
      },
      "method": "Typical value printed in a supplier product datasheet",
      "status": "ground",
      "source": "goodfellow-yb",
      "where": "Electrical Properties table, row Electrical resistivity (28 at 20 °C)",
      "source_detail": {
        "title": "Ytterbium pellets, 99.9 % (Goodfellow product datasheet)",
        "url": "https://www.goodfellow.com/uk/ytterbium-pellets-1000220085",
        "kind": "datasheet",
        "license": "supplier web page (cited, not reproduced)"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "label": "Electrical resistivity, ytterbium beta polycrystalline (Wikipedia)",
      "value": 0.25,
      "bound": "exact",
      "unit": "µΩ·m",
      "scope": "material",
      "conditions": {
        "temperature": "room temperature, as printed",
        "form": "beta, polycrystalline"
      },
      "method": "Value printed in the Wikipedia infobox",
      "status": "ground",
      "note": "0.250 µΩ·m equals 25.0 µΩ·cm, about 11 % below the Goodfellow pellet value of 28 µOhm·cm at 20 °C. Both are entered with their conditions.",
      "source": "wikipedia-yb",
      "where": "Infobox, row Electrical resistivity, beta poly 0.250 µΩ⋅m (at r.t.)",
      "source_detail": {
        "title": "Ytterbium (Wikipedia)",
        "url": "https://en.wikipedia.org/wiki/Ytterbium",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, ytterbium pellet (99.9 %)",
      "value": 68.9,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temper": "not printed",
        "purity": "99.9%",
        "form": "pellets",
        "temperature": "not stated in the table"
      },
      "method": "Typical value printed in a supplier product datasheet",
      "status": "ground",
      "note": "The datasheet gives one tensile value for a pellet and does not print the temper. It should not be read as a value for a wrought or annealed form.",
      "source": "goodfellow-yb",
      "where": "Mechanical Properties table, row Tensile strength (68.9 MPa)",
      "source_detail": {
        "title": "Ytterbium pellets, 99.9 % (Goodfellow product datasheet)",
        "url": "https://www.goodfellow.com/uk/ytterbium-pellets-1000220085",
        "kind": "datasheet",
        "license": "supplier web page (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength, ytterbium pellet (99.9 %)",
      "value": 65.5,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "temper": "not printed",
        "purity": "99.9%",
        "form": "pellets",
        "temperature": "not stated in the table"
      },
      "method": "Typical value printed in a supplier product datasheet",
      "status": "ground",
      "source": "goodfellow-yb",
      "where": "Mechanical Properties table, row Yield strength (65.5 MPa)",
      "source_detail": {
        "title": "Ytterbium pellets, 99.9 % (Goodfellow product datasheet)",
        "url": "https://www.goodfellow.com/uk/ytterbium-pellets-1000220085",
        "kind": "datasheet",
        "license": "supplier web page (cited, not reproduced)"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Air at room temperature",
      "headline": "Ytterbium tarnishes slowly in air, but finely divided metal oxidizes readily.",
      "effect": "Wikipedia says the metal tarnishes slowly in air and takes on a golden or brown hue, and that finely dispersed ytterbium oxidizes readily in air and under oxygen. No corrosion rate is given in the sources read.",
      "rating": "moderate",
      "conditions": {
        "temperature": "room temperature",
        "form": "massive metal and finely dispersed powder"
      },
      "source": "wikipedia-yb",
      "where": "Chemical properties section, paragraph on air"
    },
    {
      "environment": "Air and moisture in storage (powder)",
      "headline": "The Samat powder is air sensitive and moisture sensitive, and must be kept under dry inert gas.",
      "effect": "The Samat SDS gives air sensitivity, the need for dry inert gas, and protection from humidity and water as storage conditions. It does not give a corrosion rate.",
      "rating": "moderate",
      "conditions": {
        "atmosphere": "air and humidity",
        "form": "powder"
      },
      "source": "samat-yb-sds",
      "where": "Section 7, Storage; Further information about storage conditions"
    },
    {
      "environment": "Cold and hot water",
      "headline": "Ytterbium reacts slowly with cold water and quite quickly with hot water to form ytterbium(III) hydroxide.",
      "effect": "Wikipedia says the metal reacts slowly with cold water and quite quickly with hot water to form ytterbium(III) hydroxide. The Samat SDS says contact with water releases flammable gases which may ignite spontaneously.",
      "rating": "moderate",
      "conditions": {
        "temperature": "cold and hot water",
        "form": "metal"
      },
      "source": "wikipedia-yb",
      "where": "Chemical properties section, paragraph on water"
    },
    {
      "environment": "Strong and dilute acids",
      "headline": "Ytterbium dissolves quickly in acids and releases hydrogen.",
      "effect": "Wikipedia says ytterbium dissolves slowly in water but quickly in acids, liberating hydrogen. The Trace Sciences SDS lists strong acids as a material with which violent reactions are possible.",
      "rating": "severe",
      "conditions": {
        "acid": "strong, not named",
        "temperature": "not stated"
      },
      "source": "wikipedia-yb",
      "where": "Chemical properties section, paragraph on acids"
    },
    {
      "environment": "Halogens and strong oxidizing agents",
      "headline": "Violent reactions are possible with halogens, and the metal is incompatible with strong oxidizers.",
      "effect": "The Trace Sciences SDS says violent reactions are possible with strong acids and halogens, and lists strong oxidizing agents and halogens as materials to avoid. The Samat SDS lists oxidizing agents and halogens as incompatible materials.",
      "rating": "severe",
      "conditions": {
        "atmosphere": "halogens and oxidizers",
        "temperature": "not stated"
      },
      "source": "trace-yb-sds",
      "where": "Section 10.2 Possibility of hazardous reactions; Section 10.4 Materials to avoid"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "PubChem GHS summary (ECHA C&L notifications, 50 company reports): H228 flammable solid in 84 % of reports, H250 catches fire spontaneously if exposed to air in 10 %. H302, H312 and H332 (harmful) are in 84 % of reports each, H315 and H319 in 82 %, and H335 in 82 %. Signal word Danger. 3 of 50 reports say the substance does not meet GHS criteria.",
        "ghs": [
          "H228",
          "H250",
          "H252",
          "H302",
          "H312",
          "H315",
          "H319",
          "H332",
          "H335"
        ],
        "source": "pubchem-yb",
        "where": "Safety and Hazards, Hazards Identification, GHS Classification"
      },
      {
        "text": "Trace Sciences SDS for ytterbium metal powder: flammable solid, Category 1 (H228), harmful if swallowed, in contact with skin or if inhaled (H302, H312, H332), skin irritation (H315), eye irritation (H319), and respiratory irritation (H335). Signal word Danger.",
        "ghs": [
          "H228",
          "H302",
          "H312",
          "H315",
          "H319",
          "H332",
          "H335"
        ],
        "source": "trace-yb-sds",
        "where": "Section 2, Hazards identification"
      },
      {
        "text": "Stanford Advanced Materials SDS for ytterbium powder (revised 29/12/2022): flammable solid (H228) and water-reactive, Category 1 (H260, in contact with water releases flammable gases which may ignite spontaneously). Signal word Danger, WHMIS class B6, reactive flammable material.",
        "ghs": [
          "H228",
          "H260"
        ],
        "source": "samat-yb-sds",
        "where": "Section 2, Classification and GHS label elements"
      },
      {
        "text": "PubChem toxicity summary: its acute toxic rating is low, and the record links occupational disease to rare-earth metals in general. The Trace Sciences SDS says the acute and chronic toxicity is not fully known.",
        "ghs": [],
        "source": "pubchem-yb",
        "where": "Safety and Hazards, Hazards Summary; Trace Sciences SDS, Section 11"
      }
    ],
    "failure_risks": [
      {
        "mode": "Fire in powder and fines",
        "trigger": "Ytterbium powder or fines exposed to air, to ignition sources, or to electrostatic charge",
        "consequence": "The metal is a flammable solid, Category 1 (H228, Trace and Samat SDS). PubChem records H250, catches fire spontaneously if exposed to air, in 10 % of its notifications, so fine metal in air can ignite on its own. Dust must be kept away from ignition sources.",
        "severity": "critical",
        "source": "trace-yb-sds",
        "where": "Section 2 (H228); Section 7, Handling and Storage (avoid dust, keep away from ignition); Samat Section 7 (protect against electrostatic charges); PubChem GHS Classification"
      },
      {
        "mode": "Flammable gas on contact with water",
        "trigger": "Metal in contact with water, moisture or hot water",
        "consequence": "Water releases flammable gas that may ignite spontaneously (H260, Samat SDS). Wikipedia says the metal reacts quite quickly with hot water to form the hydroxide. Water must not be used on the burning metal.",
        "severity": "critical",
        "source": "samat-yb-sds",
        "where": "Section 2 (H260 water-reactive); Section 10, Reactivity; Section 5, Extinguishing media"
      },
      {
        "mode": "Surface oxidation in air",
        "trigger": "Exposure of massive metal or powder to air or moisture over time",
        "consequence": "The metal tarnishes slowly, and finely divided metal oxidizes readily. Storage under dry inert gas is needed to keep the surface and the powder unchanged.",
        "severity": "moderate",
        "source": "wikipedia-yb",
        "where": "Chemical properties section, paragraph on air"
      },
      {
        "mode": "Violent reaction with acids and halogens",
        "trigger": "Contact with strong acids, halogens or strong oxidizing agents",
        "consequence": "The Trace Sciences SDS says violent reactions are possible with strong acids and halogens. Wikipedia says the metal dissolves quickly in acids and releases hydrogen. Contact with the incompatible materials must be avoided.",
        "severity": "high",
        "source": "trace-yb-sds",
        "where": "Section 10.2 Possibility of hazardous reactions; Section 10.4 Materials to avoid"
      }
    ],
    "side_effects": [
      {
        "text": "PubChem's toxicity summary lists fibrogenic effects, meaning tissue injury and fibrosis (scarring), for rare-earth metals in its adverse-effects section, and says the acute toxic rating is low.",
        "affects": "Workers who breathe ytterbium dust or fume",
        "source": "pubchem-yb",
        "where": "Toxicity, Toxicological Information, Adverse Effects; Safety and Hazards, Hazards Summary"
      }
    ],
    "handling": [
      {
        "text": "Handle and store under inert gas. The Trace Sciences SDS says the metal is air and moisture sensitive.",
        "source": "trace-yb-sds",
        "where": "Section 7.2 Conditions for safe storage"
      },
      {
        "text": "Store under dry inert gas in a tightly sealed container, away from water and moisture, acids, oxidizing agents, halogens and acid chlorides (Samat SDS).",
        "source": "samat-yb-sds",
        "where": "Section 7, Storage, and Further information about storage conditions"
      },
      {
        "text": "Avoid forming dust and aerosols, and provide exhaust ventilation where dust is formed. Keep away from sources of ignition (Trace Sciences SDS).",
        "source": "trace-yb-sds",
        "where": "Section 7, Handling and Storage"
      },
      {
        "text": "For fire, the Trace SDS gives P370 + P378, dry sand, dry chemical or alcohol-resistant foam. The Samat SDS gives special powder for metal fires and says do not use water. The Trace SDS also lists water spray, which conflicts with the Samat SDS and is recorded in gaps.",
        "source": "samat-yb-sds",
        "where": "Section 5, Extinguishing media; Trace Sciences SDS, precautionary statement P370 + P378 and Section 5.2"
      },
      {
        "text": "Where risk assessment shows air-purifying respirators are appropriate, use a full-face particle respirator (Trace Sciences SDS).",
        "source": "trace-yb-sds",
        "where": "Section 8, Exposure controls and personal protection"
      }
    ],
    "mitigations": []
  },
  "uses": [
    {
      "application": "optics-and-cameras",
      "device": "Ytterbium-doped fibre ring laser, linearly polarized, single longitudinal mode, at 1064 nm, for LISA",
      "example": "NASA Goddard developed a Yb-doped fibre ring laser with single longitudinal-mode output at 1064 nm for LISA and other space applications. The gain fibre is a doped glass, not the metal, and the paper is a laboratory development. It does not report a flight.",
      "source": "lisa-yb-laser-arxiv",
      "where": "Abstract; introduction paragraph on the Yb-doped fibre ring laser"
    },
    {
      "application": "structures",
      "device": "Alloying addition in stainless steel",
      "example": "Wikipedia says ytterbium is added to stainless steel to improve grain refinement, strength and other mechanical properties. This is an industrial use and not a space use.",
      "source": "wikipedia-yb",
      "where": "Uses section, stainless steel paragraph"
    }
  ],
  "supply": [
    {
      "subject": "Rare earths (ytterbium is not reported separately by USGS)",
      "abundance": "About 3 mg/kg in the Earth's crust (Wikipedia, which also gives an average of 3 parts per million)",
      "producers": [
        {
          "country": "China",
          "share_percent": 69.2,
          "year": 2025
        },
        {
          "country": "United States",
          "share_percent": 13.1,
          "year": 2025
        },
        {
          "country": "Australia",
          "share_percent": 7.4,
          "year": 2025
        },
        {
          "country": "Burma",
          "share_percent": 5.6,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "USGS: limited quantities of rare earths were recovered from batteries, permanent magnets and fluorescent lamps.",
      "substitutes": [
        "USGS: substitutes are available for many rare-earth applications but generally are less effective."
      ],
      "source": "usgs-ree-2026",
      "where": "World Mine Production table, 2025 (world total 390,000 t, rounded; shares calculated by Space Mushroom from China 270,000, United States 51,000, Australia 29,000 and Burma 22,000). Recycling and Substitutes sections. Abundance: Wikipedia Occurrence section."
    },
    {
      "subject": "Heavy rare-earth compounds and metals, including ytterbium",
      "producers": [
        {
          "country": "China",
          "share_percent": 86,
          "year": 2024
        },
        {
          "country": "Germany",
          "share_percent": 4,
          "year": 2024
        },
        {
          "country": "Chile",
          "share_percent": 4,
          "year": 2024
        },
        {
          "country": "Republic of Korea",
          "share_percent": 3,
          "year": 2024
        }
      ],
      "critical_lists": [],
      "recycling": "USGS: small quantities of heavy rare earths were recovered from permanent magnets.",
      "substitutes": [
        "USGS: substitutes are available for some applications but are generally less effective. Light rare earths can substitute for heavy rare earths in several applications."
      ],
      "source": "usgs-heavy-ree-2026",
      "where": "Import Sources (2021–24), ytterbium compounds and metals: China 86%, Germany 4%, Chile 4%, Republic of Korea 3%, other 3%; the year column shows the end of the 2021 to 2024 range. Net import reliance for heavy rare-earth compounds and metals is 100 % in 2025e, from the Salient Statistics table."
    },
    {
      "subject": "Ytterbium oxide price and export controls",
      "producers": [],
      "critical_lists": [],
      "recycling": "",
      "substitutes": [],
      "source": "usgs-heavy-ree-2026",
      "where": "Salient Statistics, price row Ytterbium oxide, 99.99% minimum, 15 dollars per kg in 2025e (14 in 2024). Events, Trends and Issues: in October 2025 China expanded its rare-earth export controls to include ytterbium, and in November it suspended the October controls for one year (USGS light and heavy chapters)."
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "USGS Mineral Commodity Summaries 2026: Rare Earths",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Rare Earths (Heavy)",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths-heavy.pdf",
      "year": 2026
    },
    {
      "title": "Wikipedia: Ytterbium",
      "type": "database",
      "url": "https://en.wikipedia.org/wiki/Ytterbium",
      "year": 2026
    },
    {
      "title": "PubChem compound record for ytterbium (CID 23992), including ECHA C&L Inventory classification",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Ytterbium",
      "year": 2026
    },
    {
      "title": "Ytterbium pellets, 99.9 % (Goodfellow product datasheet)",
      "type": "datasheet",
      "url": "https://www.goodfellow.com/uk/ytterbium-pellets-1000220085"
    },
    {
      "title": "WebElements: Ytterbium, physical properties (University of Sheffield)",
      "type": "datasheet",
      "url": "https://winter.group.shef.ac.uk/webelements/ytterbium/physics.html"
    },
    {
      "title": "Safety data sheet: Ytterbium (metal powder), Trace Sciences International",
      "type": "sds",
      "url": "https://tracesciences.com/wp-content/uploads/2025/04/Ytterbium-metal-powder-SDS.pdf",
      "year": 2025
    },
    {
      "title": "Safety data sheet: Ytterbium powder, Stanford Advanced Materials (revised 29/12/2022)",
      "type": "sds",
      "url": "https://samaterials.com/tds/1697121476-1098-ytterbium-metal-powder-sds.pdf",
      "year": 2022
    },
    {
      "title": "Fiber laser development for LISA (arXiv 1003.3687, NASA Goddard)",
      "type": "paper",
      "url": "https://arxiv.org/pdf/1003.3687",
      "year": 2010
    },
    {
      "title": "In Situ Growth of a Yb2O3 Layer for Sublimation Suppression for Yb14MnSb11 Thermoelectric Material for Space Power Applications (J. Electron. Mater., 2012, NASA Glenn)",
      "type": "paper",
      "url": "https://ntrs.nasa.gov/api/citations/20120012922/downloads/20120012922.pdf",
      "year": 2012
    }
  ],
  "gaps": [
    "Heavy and light rare earths: the USGS chapters report rare earths and heavy rare earths as groups, so the producer shares for ytterbium are for all rare earths. Yb-specific mine output and reserves were not found in the sources read.",
    "Critical-mineral listing: the USGS 2025 critical minerals list and the EU critical raw materials list were not opened for ytterbium, so critical_lists is empty. The USGS heavy chapter does not print a critical-mineral status.",
    "Space flight of ytterbium metal: no flown ytterbium metal part was found. The LISA fibre laser is a laboratory development. The Yb14MnSb11 thermoelectric material (JPL and NASA Glenn, 2012) is a compound, not the metal, and it was studied as a candidate for radioisotope generators. Its sublimation rate at 1000 °C was about three orders of magnitude above the target, and the 2012 paper does not show a flight. The paper is cited as context only, and no property or use row uses it.",
    "Uses not entered: the Wikipedia uses of Yb-169 in portable X-ray sources, Yb-171 ions as trapped-ion qubits, ytterbium in stress gauges, and a proposed magnesium replacement in infrared decoy flares do not fit the listed application values or a space use. They are not entered.",
    "Density: three values differ, 6.977 g/cm3 (Goodfellow, 20 °C), 6.97 g/cm3 (Samat, 20 °C), 6.54 g/cm3 (Trace Sciences, 25 °C) and 6570 kg/m3 (WebElements, no temperature). Wikipedia gives 6.967 g/cm3 at 20 °C. All are entered with their conditions.",
    "Bulk modulus: the Goodfellow value of 13.5 GPa conflicts with the 30.5 GPa (Wikipedia, beta form) and 31 GPa (WebElements) values. All three are entered.",
    "Electrical resistivity and thermal conductivity differ by about 11 % and 15 % between the supplier and Wikipedia figures. Both are entered with their conditions.",
    "Vickers hardness is entered under the new name vickers_hardness, because the property file has no canonical name for it. The hardness is printed in MPa by WebElements and as a range by Wikipedia. The Goodfellow Brinell figure has no unit printed and is not entered.",
    "Mechanical strength is for a 99.9 % pellet, and its temper is not printed. No annealed, cast or wrought ytterbium strength was found in an opened source.",
    "Corrosion data are qualitative (Wikipedia and SDSs). No measured weight-gain or corrosion-rate figure for ytterbium in air or water was found.",
    "Fire medium conflict: the Trace Sciences SDS Section 5.2 lists water spray as a suitable extinguishing medium, while the Samat SDS says not to use water. The handling entry follows the Samat SDS, and the conflict should be checked with the supplier before any fire response.",
    "Hazard classification differs by source: PubChem records H250 (pyrophoric, 10 % of notifications), which the two SDSs do not give. The classes also vary by form (powder, pellet, chips). The form was not separated in every source.",
    "Environment: no source tested ytterbium metal in vacuum, radiation or thermal cycling, so no environment tags are set.",
    "The Ereztech SDS (YB2694) covers ytterbium(III) isopropoxide, a different compound, and was excluded. The ChemicalBook and American Elements pages were seen only as search results and were not read, and PubChem's experimental melting and density rows were not in the fetched record.",
    "The Wikipedia page was read to its first 100,000 characters only. The remaining text was not read."
  ],
  "story": {
    "why": "Ytterbium is a rare-earth metal with several technical uses. One of them is the Yb-doped fibre laser, and NASA Goddard has built one at 1064 nm for the LISA mission. Its density of 6.977 g/cm3 and melting point of 819 °C are supplier values for a 99.9 % pellet. The metal itself is reactive, which makes handling its form (powder or fines) the main safety issue.",
    "uses": [
      {
        "where": "Space optics research",
        "line": "NASA Goddard built a linearly polarized Yb-doped fibre ring laser at 1064 nm for LISA and other space applications. The gain fibre is doped glass, and the paper is a laboratory development."
      },
      {
        "where": "Stainless steel",
        "line": "Wikipedia says ytterbium is added to stainless steel to improve grain refinement, strength and other mechanical properties."
      }
    ],
    "can_do": [
      {
        "label": "Weight",
        "line": "Density is 6.977 g/cm3 at 20 °C for a 99.9 % pellet (Goodfellow). Samat gives 6.97 g/cm3 at 20 °C, and Wikipedia gives 6.967 g/cm3 at 20 °C.",
        "benchmark": "density",
        "scope": "material",
        "value": "6.977 g/cm3"
      },
      {
        "label": "Melting",
        "line": "Melting point is 819 °C for the pellet and the Samat powder. Wikipedia and the Trace SDS give 824 °C.",
        "benchmark": "melting_point",
        "scope": "material",
        "value": "819 °C"
      },
      {
        "label": "Heat conduction",
        "line": "Thermal conductivity is 32.9 W/(m·K) from 0 to 100 °C (Goodfellow), and 38.5 W/(m·K) in the Wikipedia infobox.",
        "benchmark": "thermal_conductivity",
        "scope": "material",
        "value": "32.9 W/(m·K)"
      },
      {
        "label": "Stiffness",
        "line": "The tensile modulus of the 99.9 % pellet is 17.8 GPa (Goodfellow). WebElements gives Young's modulus as 24 GPa.",
        "benchmark": "elastic_modulus",
        "scope": "material",
        "value": "17.8 GPa"
      }
    ],
    "compare": "Ytterbium is a rare-earth metal with a density of 6.977 g/cm3 for the Goodfellow pellet, and a melting point of 819 °C. Its thermal conductivity of 32.9 W/(m·K) is modest for a metal, and its tensile strength of 68.9 MPa for a pellet is low for a structural metal. It is also reactive in air, water and acids, so it needs dry, inert handling. No comparison profile is carried in this file, so the rows below list ytterbium values only.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Melting point",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      }
    ],
    "handling": [
      "Handle and store under inert gas, and keep away from moisture (Trace SDS, Samat SDS).",
      "Keep containers sealed and store away from water, acids, oxidizers and halogens (Samat SDS).",
      "Avoid forming dust, and use exhaust ventilation where dust is formed (Trace SDS).",
      "Use special powder for metal fires, or dry sand, and do not use water (Samat SDS, Trace SDS)."
    ],
    "good_for": [
      "Optical sources: an Yb-doped fibre ring laser at 1064 nm has been built for LISA (NASA Goddard, arXiv 1003.3687).",
      "Stainless steel: ytterbium is added to improve grain refinement and strength (Wikipedia)."
    ],
    "watch_out": [
      "Powder and fines are flammable, and PubChem records spontaneous ignition in air in 10 % of its notifications (PubChem, Trace SDS).",
      "Water releases flammable gas that may ignite spontaneously (Samat SDS).",
      "Supply is concentrated: China produced about 69 % of world rare-earth mine output in 2025, and China's October 2025 export controls included ytterbium, which were then suspended for one year (USGS).",
      "Most figures come from one supplier, one encyclopedia and one data site, and the density and bulk modulus conflict between sources."
    ],
    "verdict": "Ytterbium is a rare-earth metal with a density of 6.977 g/cm3 and a melting point of 819 °C for a 99.9 % pellet. One documented technical use is the Yb-doped fibre laser that NASA Goddard built for LISA, and its space use is still laboratory work. The metal needs dry, inert handling, because powder ignites and water releases flammable gas.",
    "recipe": {
      "line": "Ytterbium is a single-element metal (Yb). Wikipedia says it is separated from the other rare earths by ion exchange or by reduction with sodium amalgam, and the oxide is reduced to metal by heating with lanthanum, aluminium, cerium or zirconium in high vacuum.",
      "parts": [
        {
          "name": "Ytterbium",
          "symbol": "Yb",
          "role": "The whole material. The Goodfellow pellet is 99.9 % pure, and the Samat and Trace SDSs describe the metal as a powder.",
          "atoms": 1,
          "atomic_weight": 173.045
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The hazard is in the metal's form. The SDSs classify the powder as a flammable solid that can ignite in air, and the metal releases flammable gas with water.",
        "points": [
          {
            "label": "Powder and fines",
            "line": "The SDSs classify the metal as a flammable solid (H228), and PubChem records H250, catches fire spontaneously if exposed to air, in 10 % of its notifications."
          },
          {
            "label": "Water",
            "line": "Contact with water releases flammable gas that may ignite spontaneously (H260, Samat SDS)."
          },
          {
            "label": "Health",
            "line": "The SDSs give harmful classes (H302, H312, H332) and irritation, and PubChem says the acute toxic rating is low. Its toxicity summary lists fibrogenic effects for rare-earth metals in general."
          }
        ],
        "level": 1,
        "verdict": "Form-dependent"
      },
      {
        "title": "If it fails",
        "lead": "The sources give four failure routes: a fire in powder, flammable gas on contact with water, surface oxidation in air, and violent reaction with acids and halogens.",
        "points": [
          {
            "label": "Fire",
            "line": "Use special powder for metal fires, dry sand, dry chemical or alcohol-resistant foam (Samat and Trace SDSs). The Samat SDS says do not use water."
          },
          {
            "label": "Air",
            "line": "The metal tarnishes slowly in air, and fine metal oxidizes readily (Wikipedia). The powder is air sensitive (Samat SDS)."
          },
          {
            "label": "Acids and halogens",
            "line": "Violent reactions are possible with strong acids and halogens (Trace SDS), and the metal dissolves quickly in acids (Wikipedia)."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Keep it dry",
            "line": "Store under dry inert gas in a sealed container, away from water, acids, oxidizers and halogens (Samat and Trace SDSs)."
          },
          {
            "label": "Dust control",
            "line": "Avoid forming dust and provide exhaust ventilation where dust is formed. Use a full-face particle respirator where a risk assessment calls for one (Trace SDS)."
          }
        ]
      }
    ]
  },
  "updated": "2026-10-26",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 35,
    "unreachable": 2,
    "caveats": 6,
    "note": "Read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry. Unreachable: the PubChem web page (browser check block; the JSON record was read instead, and it has no experimental property rows), and the ChemicalBook MSDS (no PDF returned). Caveats: most physical values come from one supplier (Goodfellow), one encyclopedia (Wikipedia) and one data site (WebElements); supply shares are for all rare earths, not ytterbium; the density, bulk modulus and resistivity values conflict between sources; the mechanical strengths are for a 99.9 % pellet with the temper not printed; the fire medium conflicts between the two SDSs."
  },
  "sources": {
    "wikipedia-yb": {
      "title": "Ytterbium (Wikipedia)",
      "url": "https://en.wikipedia.org/wiki/Ytterbium",
      "year": 2026,
      "kind": "web",
      "license": "CC BY-SA 4.0 (cited, not reproduced)"
    },
    "pubchem-yb": {
      "title": "PubChem compound record: Ytterbium (CID 23992), including ECHA C&L Inventory classification",
      "id": "CAS 7440-64-4",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/23992/JSON",
      "kind": "database",
      "license": "PubChem (NCBI), public domain; sections attributed to ECHA and others"
    },
    "goodfellow-yb": {
      "title": "Ytterbium pellets, 99.9 % (Goodfellow product datasheet)",
      "url": "https://www.goodfellow.com/uk/ytterbium-pellets-1000220085",
      "kind": "datasheet",
      "license": "supplier web page (cited, not reproduced)"
    },
    "webelements-yb": {
      "title": "WebElements: Ytterbium, physical properties (University of Sheffield)",
      "url": "https://winter.group.shef.ac.uk/webelements/ytterbium/physics.html",
      "kind": "database",
      "license": "WebElements, cited not reproduced"
    },
    "usgs-ree-2026": {
      "title": "Mineral Commodity Summaries 2026: Rare Earths (USGS)",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "usgs-heavy-ree-2026": {
      "title": "Mineral Commodity Summaries 2026: Rare Earths (Heavy) (USGS)",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-rare-earths-heavy.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "trace-yb-sds": {
      "title": "Safety data sheet: Ytterbium (metal powder), Trace Sciences International",
      "url": "https://tracesciences.com/wp-content/uploads/2025/04/Ytterbium-metal-powder-SDS.pdf",
      "year": 2025,
      "kind": "datasheet",
      "license": "supplier safety data sheet, cited not reproduced"
    },
    "samat-yb-sds": {
      "title": "Safety data sheet: Ytterbium powder, Stanford Advanced Materials (revised 29/12/2022)",
      "id": "CAS 7440-64-4",
      "url": "https://samaterials.com/tds/1697121476-1098-ytterbium-metal-powder-sds.pdf",
      "year": 2022,
      "kind": "datasheet",
      "license": "supplier safety data sheet, cited not reproduced"
    },
    "lisa-yb-laser-arxiv": {
      "title": "Fiber laser development for LISA (arXiv 1003.3687, NASA Goddard)",
      "url": "https://arxiv.org/pdf/1003.3687",
      "year": 2010,
      "kind": "paper",
      "license": "arXiv preprint, cited not reproduced"
    },
    "nesbitt-yb14mnsb11-2012": {
      "title": "In Situ Growth of a Yb2O3 Layer for Sublimation Suppression for Yb14MnSb11 Thermoelectric Material for Space Power Applications (Nesbitt, Opila, Nathal; J. Electron. Mater. 41(6), 2012)",
      "url": "https://ntrs.nasa.gov/api/citations/20120012922/downloads/20120012922.pdf",
      "year": 2012,
      "kind": "paper",
      "license": "NASA NTRS public record, cited not reproduced"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/ytterbium/"
}