{
  "spore": "profile",
  "id": "bismuth-telluride",
  "spore_version": "0.2",
  "family": "semiconductor-materials",
  "name": "Bismuth telluride (with antimony telluride)",
  "abbreviation": "Bi2Te3, Sb2Te3",
  "role": "thermoelectric alloy base and layered topological insulator",
  "category": "energy",
  "type": "thermoelectrics",
  "summary": "Bismuth telluride (Bi2Te3) is a grey layered semiconductor and the base of the room-temperature thermoelectric alloys used in solid-state coolers and generators. Commercial n-type Bi2Se0.21Te2.79 and p-type Bi0.4Sb1.6Te3 reached zT values of 0.97 and 1.24 at room temperature before storage (Xiao et al., 2023). Its surface is a topological insulator with a single Dirac cone, and its bulk indirect gap is about 150 meV (Hsieh et al., arXiv 2009). Antimony telluride (Sb2Te3), the companion compound in the same family, is described here by its supplier SDS for density and melting point only. Hot, humid storage oxidises Bi2Te3 alloys (85 degC, 85% RH, 600 h), so the modules need sealing.\n",
  "best_for": "Room-temperature thermoelectric coolers and generators, where the p-type alloy reached zT 1.24 before storage",
  "weakest_at": "Humid, hot storage: 600 h at 85 degC and 85% RH oxidised the surface and cut zT by 19 and 22 percent (authors)",
  "identity": {
    "formula": "Bi2Te3",
    "cas": "1304-82-1",
    "designations": [],
    "source": "sam-bi2te3-sds",
    "where": "Section 1 (Identification), CAS"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "thermal-control",
      "electronics-and-chips"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density of bismuth telluride powder at 20 degC (supplier SDS)",
      "value": 7.642,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "material": "bismuth telluride powder, Bi2Te3",
        "temperature": "20 degC (68 degF) as printed"
      },
      "method": "Value printed in the supplier SDS, Section 9",
      "status": "ground",
      "source": "sam-bi2te3-sds",
      "where": "Section 9, Density at 20 degC line",
      "source_detail": {
        "title": "Stanford Advanced Materials SDS, Bismuth Telluride (CAS 1304-82-1), revised 01/11/2022",
        "url": "https://samaterials.com/tds/1697119060-2060-bismuth-telluride-powder-sds.pdf",
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density of bismuth telluride (second supplier SDS)",
      "value": 7.642,
      "bound": "exact",
      "unit": "g/cc",
      "scope": "material",
      "conditions": {
        "material": "bismuth telluride, Angstrom Sciences product",
        "temperature": "not stated in the copy read"
      },
      "method": "Value printed in the Angstrom Sciences SDS, physical properties table",
      "status": "ground",
      "source": "angstrom-bi2te3-sds",
      "where": "Physical properties table, Density line",
      "source_detail": {
        "title": "Angstrom Sciences SDS, Bismuth Telluride",
        "url": "https://angstromsciences.com/wp-content/uploads/files/SDS/Bismuth%20Telluride.pdf",
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point of bismuth telluride (supplier SDS)",
      "value": 573,
      "bound": "exact",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "material": "bismuth telluride powder, Bi2Te3",
        "basis": "single value printed as melting point or range"
      },
      "method": "Value printed in the supplier SDS, Section 9",
      "status": "ground",
      "note": "The Wikipedia infobox gives 580 degC, but Wikipedia is not used for property values in this profile.",
      "source": "sam-bi2te3-sds",
      "where": "Section 9, Melting point/Melting range line",
      "source_detail": {
        "title": "Stanford Advanced Materials SDS, Bismuth Telluride (CAS 1304-82-1), revised 01/11/2022",
        "url": "https://samaterials.com/tds/1697119060-2060-bismuth-telluride-powder-sds.pdf",
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point of bismuth telluride (second supplier SDS)",
      "value": 573,
      "bound": "exact",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "material": "bismuth telluride, Angstrom Sciences product"
      },
      "method": "Value printed in the Angstrom Sciences SDS, physical properties table",
      "status": "ground",
      "source": "angstrom-bi2te3-sds",
      "where": "Physical properties table, Melting Point line",
      "source_detail": {
        "title": "Angstrom Sciences SDS, Bismuth Telluride",
        "url": "https://angstromsciences.com/wp-content/uploads/files/SDS/Bismuth%20Telluride.pdf",
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density of antimony telluride (supplier SDS, 2012)",
      "value": 6.5,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "material": "antimony telluride, Sb2Te3, grey powder and pieces"
      },
      "method": "Value printed in the Stanford Advanced Materials MSDS, Section III",
      "status": "ground",
      "source": "sam-sb2te3-msds",
      "where": "Section III, Melting Point and Density line",
      "source_detail": {
        "title": "Stanford Advanced Materials MSDS, Antimony Telluride (CAS 1327-50-0), revision 2.0, 5 Sep 2012",
        "url": "https://www.sputtertargets.net/Public/pdf/antimony-telluride-msds.pdf",
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point of antimony telluride (supplier SDS, 2012)",
      "value": 629,
      "bound": "exact",
      "unit": "degC",
      "scope": "material",
      "conditions": {
        "material": "antimony telluride, Sb2Te3"
      },
      "method": "Value printed in the Stanford Advanced Materials MSDS, Section III (printed as 629.00 C)",
      "status": "ground",
      "note": "Wikipedia gives 620 degC for Sb2Te3 and is not used here. The SDS revision date is 2012.",
      "source": "sam-sb2te3-msds",
      "where": "Section III, Melting Point line",
      "source_detail": {
        "title": "Stanford Advanced Materials MSDS, Antimony Telluride (CAS 1327-50-0), revision 2.0, 5 Sep 2012",
        "url": "https://www.sputtertargets.net/Public/pdf/antimony-telluride-msds.pdf",
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, n-type Bi2Se0.21Te2.79, before storage",
      "value": 1.4,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "material": "commercial n-type Bi2Se0.21Te2.79",
        "storage": "0 h, as received",
        "temperature": "room temperature"
      },
      "method": "Value printed in Table 1 (room-temperature thermoelectric performance)",
      "status": "ground",
      "source": "xiao2023",
      "where": "Table 1, kappa row, n-type 0 h column",
      "source_detail": {
        "title": "Xiao et al., Hygrothermal Stability of Bi2Te3-based Thermoelectric Materials, Journal of Inorganic Materials 38(7), 2023",
        "url": "https://www.researching.cn/ArticlePdf/m00097/2023/38/7/800.pdf",
        "kind": "paper",
        "license": "cited, not reproduced (Chinese journal, English abstract and Table 1 values quoted)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, n-type Bi2Se0.21Te2.79, after 600 h at 85 degC and 85% RH",
      "value": 1.48,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "material": "commercial n-type Bi2Se0.21Te2.79",
        "storage": "600 h at 85 degC, 85% RH",
        "temperature": "room temperature"
      },
      "method": "Value printed in Table 1 (room-temperature thermoelectric performance)",
      "status": "ground",
      "source": "xiao2023",
      "where": "Table 1, kappa row, n-type 600 h column",
      "source_detail": {
        "title": "Xiao et al., Hygrothermal Stability of Bi2Te3-based Thermoelectric Materials, Journal of Inorganic Materials 38(7), 2023",
        "url": "https://www.researching.cn/ArticlePdf/m00097/2023/38/7/800.pdf",
        "kind": "paper",
        "license": "cited, not reproduced (Chinese journal, English abstract and Table 1 values quoted)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, p-type Bi0.4Sb1.6Te3, before storage",
      "value": 1.31,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "material": "commercial p-type Bi0.4Sb1.6Te3",
        "storage": "0 h, as received",
        "temperature": "room temperature"
      },
      "method": "Value printed in Table 1 (room-temperature thermoelectric performance)",
      "status": "ground",
      "source": "xiao2023",
      "where": "Table 1, kappa row, p-type 0 h column",
      "source_detail": {
        "title": "Xiao et al., Hygrothermal Stability of Bi2Te3-based Thermoelectric Materials, Journal of Inorganic Materials 38(7), 2023",
        "url": "https://www.researching.cn/ArticlePdf/m00097/2023/38/7/800.pdf",
        "kind": "paper",
        "license": "cited, not reproduced (Chinese journal, English abstract and Table 1 values quoted)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, p-type Bi0.4Sb1.6Te3, after 600 h at 85 degC and 85% RH",
      "value": 1.29,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "material": "commercial p-type Bi0.4Sb1.6Te3",
        "storage": "600 h at 85 degC, 85% RH",
        "temperature": "room temperature"
      },
      "method": "Value printed in Table 1 (room-temperature thermoelectric performance)",
      "status": "ground",
      "source": "xiao2023",
      "where": "Table 1, kappa row, p-type 600 h column",
      "source_detail": {
        "title": "Xiao et al., Hygrothermal Stability of Bi2Te3-based Thermoelectric Materials, Journal of Inorganic Materials 38(7), 2023",
        "url": "https://www.researching.cn/ArticlePdf/m00097/2023/38/7/800.pdf",
        "kind": "paper",
        "license": "cited, not reproduced (Chinese journal, English abstract and Table 1 values quoted)"
      }
    },
    {
      "benchmark": "figure_of_merit_zt",
      "label": "Thermoelectric figure of merit zT, n-type Bi2Se0.21Te2.79, before storage",
      "value": 0.97,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "material": "commercial n-type Bi2Se0.21Te2.79",
        "storage": "0 h",
        "temperature": "room temperature"
      },
      "method": "Value printed in Table 1 and in the English abstract",
      "status": "ground",
      "source": "xiao2023",
      "where": "English abstract; Table 1, ZT row, n-type 0 h column",
      "source_detail": {
        "title": "Xiao et al., Hygrothermal Stability of Bi2Te3-based Thermoelectric Materials, Journal of Inorganic Materials 38(7), 2023",
        "url": "https://www.researching.cn/ArticlePdf/m00097/2023/38/7/800.pdf",
        "kind": "paper",
        "license": "cited, not reproduced (Chinese journal, English abstract and Table 1 values quoted)"
      }
    },
    {
      "benchmark": "figure_of_merit_zt",
      "label": "Thermoelectric figure of merit zT, n-type Bi2Se0.21Te2.79, after 600 h at 85 degC and 85% RH",
      "value": 0.79,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "material": "commercial n-type Bi2Se0.21Te2.79",
        "storage": "600 h at 85 degC, 85% RH",
        "temperature": "room temperature"
      },
      "method": "Value printed in Table 1 and in the English abstract",
      "status": "ground",
      "source": "xiao2023",
      "where": "English abstract; Table 1, ZT row, n-type 600 h column",
      "source_detail": {
        "title": "Xiao et al., Hygrothermal Stability of Bi2Te3-based Thermoelectric Materials, Journal of Inorganic Materials 38(7), 2023",
        "url": "https://www.researching.cn/ArticlePdf/m00097/2023/38/7/800.pdf",
        "kind": "paper",
        "license": "cited, not reproduced (Chinese journal, English abstract and Table 1 values quoted)"
      }
    },
    {
      "benchmark": "figure_of_merit_zt",
      "label": "Thermoelectric figure of merit zT, p-type Bi0.4Sb1.6Te3, before storage",
      "value": 1.24,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "material": "commercial p-type Bi0.4Sb1.6Te3",
        "storage": "0 h",
        "temperature": "room temperature"
      },
      "method": "Value printed in Table 1 and in the English abstract",
      "status": "ground",
      "source": "xiao2023",
      "where": "English abstract; Table 1, ZT row, p-type 0 h column",
      "source_detail": {
        "title": "Xiao et al., Hygrothermal Stability of Bi2Te3-based Thermoelectric Materials, Journal of Inorganic Materials 38(7), 2023",
        "url": "https://www.researching.cn/ArticlePdf/m00097/2023/38/7/800.pdf",
        "kind": "paper",
        "license": "cited, not reproduced (Chinese journal, English abstract and Table 1 values quoted)"
      }
    },
    {
      "benchmark": "figure_of_merit_zt",
      "label": "Thermoelectric figure of merit zT, p-type Bi0.4Sb1.6Te3, after 600 h at 85 degC and 85% RH",
      "value": 0.97,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "material": "commercial p-type Bi0.4Sb1.6Te3",
        "storage": "600 h at 85 degC, 85% RH",
        "temperature": "room temperature"
      },
      "method": "Value printed in Table 1 and in the English abstract",
      "status": "ground",
      "source": "xiao2023",
      "where": "English abstract; Table 1, ZT row, p-type 600 h column",
      "source_detail": {
        "title": "Xiao et al., Hygrothermal Stability of Bi2Te3-based Thermoelectric Materials, Journal of Inorganic Materials 38(7), 2023",
        "url": "https://www.researching.cn/ArticlePdf/m00097/2023/38/7/800.pdf",
        "kind": "paper",
        "license": "cited, not reproduced (Chinese journal, English abstract and Table 1 values quoted)"
      }
    },
    {
      "benchmark": "electrical_conductivity",
      "label": "Electrical conductivity, n-type Bi2Se0.21Te2.79, before storage",
      "value": 9.45,
      "bound": "exact",
      "unit": "10^4 S/m",
      "scope": "material",
      "conditions": {
        "material": "commercial n-type Bi2Se0.21Te2.79",
        "storage": "0 h",
        "temperature": "room temperature",
        "unit_in_source": "printed as 9.45 x 10^4 S m-1 (Table 1 header: x10^4, S m-1)"
      },
      "method": "Value printed in Table 1; the unit is kept as printed, with the x10^4 factor in the unit",
      "status": "ground",
      "source": "xiao2023",
      "where": "Table 1, sigma row, n-type 0 h column; Results text on conductivity",
      "source_detail": {
        "title": "Xiao et al., Hygrothermal Stability of Bi2Te3-based Thermoelectric Materials, Journal of Inorganic Materials 38(7), 2023",
        "url": "https://www.researching.cn/ArticlePdf/m00097/2023/38/7/800.pdf",
        "kind": "paper",
        "license": "cited, not reproduced (Chinese journal, English abstract and Table 1 values quoted)"
      }
    },
    {
      "benchmark": "electrical_conductivity",
      "label": "Electrical conductivity, n-type Bi2Se0.21Te2.79, after 600 h at 85 degC and 85% RH",
      "value": 7.79,
      "bound": "exact",
      "unit": "10^4 S/m",
      "scope": "material",
      "conditions": {
        "material": "commercial n-type Bi2Se0.21Te2.79",
        "storage": "600 h at 85 degC, 85% RH",
        "temperature": "room temperature",
        "unit_in_source": "printed as 7.79 x 10^4 S m-1"
      },
      "method": "Value printed in Table 1; the unit is kept as printed, with the x10^4 factor in the unit",
      "status": "ground",
      "source": "xiao2023",
      "where": "Table 1, sigma row, n-type 600 h column; Results text on conductivity",
      "source_detail": {
        "title": "Xiao et al., Hygrothermal Stability of Bi2Te3-based Thermoelectric Materials, Journal of Inorganic Materials 38(7), 2023",
        "url": "https://www.researching.cn/ArticlePdf/m00097/2023/38/7/800.pdf",
        "kind": "paper",
        "license": "cited, not reproduced (Chinese journal, English abstract and Table 1 values quoted)"
      }
    },
    {
      "benchmark": "seebeck_coefficient",
      "label": "Seebeck coefficient, p-type Bi0.4Sb1.6Te3, before storage",
      "value": 243,
      "bound": "exact",
      "unit": "μV/K",
      "scope": "material",
      "conditions": {
        "material": "commercial p-type Bi0.4Sb1.6Te3",
        "storage": "0 h",
        "temperature": "room temperature"
      },
      "method": "Value printed in Table 1 and in the English abstract",
      "status": "ground",
      "source": "xiao2023",
      "where": "English abstract (Seebeck sentence); Table 1, Seebeck row, p-type 0 h column",
      "source_detail": {
        "title": "Xiao et al., Hygrothermal Stability of Bi2Te3-based Thermoelectric Materials, Journal of Inorganic Materials 38(7), 2023",
        "url": "https://www.researching.cn/ArticlePdf/m00097/2023/38/7/800.pdf",
        "kind": "paper",
        "license": "cited, not reproduced (Chinese journal, English abstract and Table 1 values quoted)"
      }
    },
    {
      "benchmark": "seebeck_coefficient",
      "label": "Seebeck coefficient, p-type Bi0.4Sb1.6Te3, after 600 h at 85 degC and 85% RH",
      "value": 220,
      "bound": "exact",
      "unit": "μV/K",
      "scope": "material",
      "conditions": {
        "material": "commercial p-type Bi0.4Sb1.6Te3",
        "storage": "600 h at 85 degC, 85% RH",
        "temperature": "room temperature"
      },
      "method": "Value printed in Table 1 and in the English abstract",
      "status": "ground",
      "source": "xiao2023",
      "where": "English abstract (Seebeck sentence); Table 1, Seebeck row, p-type 600 h column",
      "source_detail": {
        "title": "Xiao et al., Hygrothermal Stability of Bi2Te3-based Thermoelectric Materials, Journal of Inorganic Materials 38(7), 2023",
        "url": "https://www.researching.cn/ArticlePdf/m00097/2023/38/7/800.pdf",
        "kind": "paper",
        "license": "cited, not reproduced (Chinese journal, English abstract and Table 1 values quoted)"
      }
    },
    {
      "benchmark": "band_gap",
      "label": "Bulk indirect band gap of Bi2Te3 (spin-orbit induced)",
      "value": 150,
      "bound": "exact",
      "unit": "meV",
      "scope": "material",
      "conditions": {
        "material": "Bi2Te3 single crystal",
        "type": "indirect bulk gap",
        "basis": "photoemission and first-principles calculations"
      },
      "method": "Value printed in the abstract (delta approximately 150 meV, printed with a tilde)",
      "status": "ground",
      "source": "hsieh2009",
      "where": "Abstract, sentence on the indirect bulk band gap",
      "source_detail": {
        "title": "Hsieh et al., Time-reversal-protected single-Dirac-cone topological-insulator states in Bi2Te3 and Sb2Te3, arXiv:0909.4804 (2009)",
        "url": "https://arxiv.org/pdf/0909.4804",
        "kind": "paper",
        "license": "arXiv preprint, cited as published"
      }
    },
    {
      "benchmark": "seebeck_coefficient",
      "label": "Seebeck coefficient, electrodeposited Bi2Te3 thin film at room temperature",
      "value": 51.7,
      "bound": "exact",
      "unit": "μV/K",
      "scope": "material",
      "conditions": {
        "material": "electrodeposited Bi2Te3 thin film from dichloromethane, transferred to an insulating layer",
        "temperature": "room temperature (300 K in the Results)",
        "sign": "printed as negative (n-type); the magnitude is stored here"
      },
      "method": "Value printed in the abstract (room-temperature coefficient)",
      "status": "ground",
      "source": "cicvaric2020",
      "where": "Abstract, last sentences (room-temperature coefficient)",
      "source_detail": {
        "title": "Cicvaric et al., Thermoelectric Properties of Bismuth Telluride Thin Films Electrodeposited from a Nonaqueous Solution, ACS Omega 5, 14679 (2020)",
        "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7315573/",
        "kind": "paper",
        "license": "CC BY 4.0"
      }
    },
    {
      "benchmark": "leg_thickness",
      "label": "Minimum leg thickness of conventional Bi2Te3 alloy modules",
      "value": 100,
      "value_high": 200,
      "bound": "range",
      "unit": "μm",
      "scope": "material",
      "conditions": {
        "device": "conventional Bi2Te3-alloy thermoelectric module",
        "basis": "limit set by mechanical and manufacturing constraints"
      },
      "method": "Range printed in the abstract (the scan prints the unit as an OCR form of micrometre)",
      "status": "ground",
      "source": "ntrs-fleurial2000",
      "where": "Abstract, first paragraph (leg dimensions, 100-200 thick minimum)",
      "source_detail": {
        "title": "Fleurial and Borshchevsky, Development of Thick-Film Thermoelectric Microcoolers Using Electrochemical Deposition, NASA NTRS 20000048809",
        "url": "https://ntrs.nasa.gov/citations/20000048809",
        "kind": "report",
        "license": "public domain (NASA)"
      }
    },
    {
      "benchmark": "heat_flux_pumped",
      "label": "Projected heat pumping of a thick-film Bi2Te3 microcooler",
      "value": 200,
      "bound": "lower",
      "unit": "W/cm2",
      "scope": "cell",
      "conditions": {
        "device": "projected thick-film microcooler with thousands of thermocouples on diamond substrate",
        "temperature_difference": "30 to 60 K"
      },
      "method": "Projection printed in the abstract (more than 200 W/cm2); not a measured result",
      "status": "prediction",
      "note": "The paper says this is anticipated for a device still in development. It is a design target, not a measured value.",
      "source": "ntrs-fleurial2000",
      "where": "Abstract, sentence on pumping more than 200 W/cm2",
      "source_detail": {
        "title": "Fleurial and Borshchevsky, Development of Thick-Film Thermoelectric Microcoolers Using Electrochemical Deposition, NASA NTRS 20000048809",
        "url": "https://ntrs.nasa.gov/citations/20000048809",
        "kind": "report",
        "license": "public domain (NASA)"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Hot humid storage (85 degC, 85% RH, 600 h)",
      "headline": "Surface oxidised to bismuth oxide and tellurium oxide; zT fell by about a fifth.",
      "effect": "Commercial n-type Bi2Se0.21Te2.79 and p-type Bi0.4Sb1.6Te3 stored 600 h at 85 degC and 85% RH formed Bi2O3 and TeO2 (the p-type also Sb2O3), with nanoscale holes and microcracks in the surface. The authors report zT falling from 0.97 to 0.79 (n-type) and from 1.24 to 0.97 (p-type), and they conclude that devices need strict encapsulation.",
      "rating": "severe",
      "conditions": {
        "temperature": "85 degC",
        "humidity": "85% RH",
        "time": "600 h",
        "material": "commercial Bi2Te3-based alloys, not pure Bi2Te3"
      },
      "source": "xiao2023",
      "where": "English abstract; Table 1; Fig. 1 and Fig. 2 (XRD and XPS after storage)"
    },
    {
      "environment": "Air, porous electrodeposited films",
      "headline": "Porous films oxidise significantly; smooth films and tellurium-terminated surfaces resist it.",
      "effect": "Porous electrodeposited Bi2Te3 films oxidised significantly and their thermoelectric properties degraded. Smoother films with a smaller surface-to-volume ratio oxidised less, and films with a Te(O) surface termination showed no oxygen below the surface layer (XPS). The paper says that MBE-grown films are stable and surface oxidation takes months.",
      "rating": "moderate",
      "conditions": {
        "environment": "air storage",
        "exposure_time": "not stated for the porous films",
        "film": "electrodeposited from dichloromethane"
      },
      "source": "cicvaric2020",
      "where": "Abstract; Oxidation of Bismuth Telluride Films section"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "Harmful if swallowed, in contact with skin or if inhaled (H302+H312+H332). Causes skin irritation (H315), serious eye irritation (H319) and may cause respiratory irritation (H335). Signal word Warning.",
        "ghs": [
          "H302",
          "H312",
          "H332",
          "H315",
          "H319",
          "H335"
        ],
        "source": "sam-bi2te3-sds",
        "where": "Section 2, Hazard statements"
      },
      {
        "text": "A second SDS for the same compound gives signal word Danger, with H302+H312, H331 (toxic if inhaled), H319 and H335. The two SDS copies disagree, so check the supplier's SDS for the batch you handle.",
        "ghs": [
          "H302",
          "H312",
          "H331",
          "H319",
          "H335"
        ],
        "source": "angstrom-bi2te3-sds",
        "where": "Section 2, Hazard Statements"
      },
      {
        "text": "US exposure limits printed in the SDS for undoped bismuth telluride: PEL 15 mg/m3 total dust and 5 mg/m3 respirable; REL 10 mg/m3 total dust and 5 mg/m3 respirable; TLV 10 mg/m3 total dust and 5 mg/m3 respirable (selenium-doped material has its own limits).",
        "ghs": [],
        "source": "sam-bi2te3-sds",
        "where": "Section 8, Control parameters"
      },
      {
        "text": "Antimony telluride: OSHA PEL and ACGIH TLV of 0.1 mg(Te)/m3. The SDS says most antimony compounds are poisonous by ingestion and inhalation and irritate the skin and mucous membranes.",
        "ghs": [],
        "source": "sam-sb2te3-msds",
        "where": "Section II, Section VI"
      }
    ],
    "failure_risks": [
      {
        "mode": "Oxidation in hot humid storage",
        "trigger": "Storage at 85 degC and 85% RH for 600 h without encapsulation",
        "consequence": "Surface oxidation to Bi2O3 and TeO2 cut zT by about 19 percent (n-type) and 22 percent (p-type) in the authors' test, through lower mobility and conductivity.",
        "severity": "moderate",
        "source": "xiao2023",
        "where": "English abstract; Table 1"
      },
      {
        "mode": "Explosive reaction with chlorates and perchlorates",
        "trigger": "Contact of antimony telluride with chlorates or perchlorates, or with strong oxidising agents",
        "consequence": "The SDS says the material is moderately explosive by chemical reaction with chlorates and perchlorates and flammable by spontaneous reaction with strong oxidising agents.",
        "severity": "high",
        "source": "sam-sb2te3-msds",
        "where": "Section IV (Unusual Fire and Explosion Hazards); Section V (Incompatibility)"
      },
      {
        "mode": "Supply interruption for bismuth and tellurium",
        "trigger": "Chinese export controls and production concentrated in China",
        "consequence": "USGS reports that China produced 88 percent of world bismuth (2025) and 80 percent of refined tellurium (2025). European tellurium prices rose 84 percent in 2025 after China required export documents that verify end use.",
        "severity": "high",
        "source": "usgs-te-2026",
        "where": "Production and Events, Trends and Issues sections"
      }
    ],
    "side_effects": [
      {
        "text": "Heating or decomposition gives off tellurium dioxide and bismuth oxide fumes.",
        "affects": "Firefighters and anyone near a fire or hot process",
        "source": "sam-bi2te3-sds",
        "where": "Section 5 (Special hazards arising from the substance)"
      },
      {
        "text": "Decomposition on heating or on contact with acid gives off toxic tellurium and antimony fumes from antimony telluride.",
        "affects": "Anyone near a fire or an acid spill",
        "source": "sam-sb2te3-msds",
        "where": "Section IV and Section V (Hazardous Decomposition)"
      }
    ],
    "handling": [
      {
        "text": "Store in a cool, dry place in tightly closed containers, under dry inert gas. The SDS calls bismuth telluride moisture sensitive.",
        "source": "sam-bi2te3-sds",
        "where": "Section 7, Further information about storage conditions"
      },
      {
        "text": "Keep away from acids, oxidising agents and water. For antimony telluride, also keep away from chlorates and perchlorates.",
        "source": "sam-bi2te3-sds",
        "where": "Section 7 and Section 10 (incompatible materials)"
      },
      {
        "text": "Avoid breathing dust and use eye and skin protection. Use a respirator or local exhaust where dust forms.",
        "source": "sam-bi2te3-sds",
        "where": "Section 2 (P261, P280) and Section 8"
      }
    ],
    "mitigations": [
      {
        "text": "Encapsulate micro-thermoelectric devices strictly against humidity. The authors conclude that Bi2Te3-based materials have extremely poor hygrothermal stability without it.",
        "source": "xiao2023",
        "where": "Abstract, conclusion sentence"
      }
    ]
  },
  "uses": [
    {
      "application": "thermal-control",
      "device": "Bi2Te3-based thermoelectric modules for cooling and energy generation",
      "example": "USGS says bismuth telluride is used in thermoelectric devices for cooling and energy generation, and it estimates that thermoelectric devices took 15 percent of global tellurium end use in 2025.",
      "source": "usgs-te-2026",
      "where": "Domestic Production and Use, first and second paragraphs"
    },
    {
      "application": "electronics-and-chips",
      "device": "Thick-film thermoelectric microcoolers electrodeposited on diamond substrates (projected)",
      "example": "NASA JPL reported electrochemically deposited Bi2Te3 films of 10 to 50 micrometres for microcoolers with thousands of thermocouples, projected to pump more than 200 W/cm2 over 30 to 60 K. The record describes development work, not a flight unit.",
      "source": "ntrs-fleurial2000",
      "where": "Abstract"
    }
  ],
  "supply": [
    {
      "subject": "Bismuth (40 percent of the bismuth telluride formula)",
      "abundance": "No crustal abundance read. USGS says bismuth minerals rarely occur in mineable quantities; it is mostly a byproduct of lead ore processing.",
      "producers": [
        {
          "country": "China",
          "share_percent": 88,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "USGS: recycled bismuth-containing alloy scrap was up to 10 percent of US apparent consumption for 2021 to 2025.",
      "substitutes": [],
      "source": "usgs-bi-2026",
      "where": "Salient Statistics; Import Sources (2021 to 2024); Events, Trends, and Issues; World Refinery Production table, 2025 column"
    },
    {
      "subject": "Tellurium (60 percent of the bismuth telluride formula)",
      "abundance": "No crustal abundance read. USGS says reserves are not reported at mine or country level, and more than 90 percent of tellurium comes from copper anode slimes.",
      "producers": [
        {
          "country": "China",
          "share_percent": 80,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "USGS: tellurium was recycled from CdTe solar cells in the US, but the quantity was limited.",
      "substitutes": [
        "USGS: bismuth selenide and organic polymers can substitute for BiTe in some thermoelectric devices."
      ],
      "source": "usgs-te-2026",
      "where": "Salient Statistics; World Refinery Production table; Substitutes; Events, Trends, and Issues"
    },
    {
      "subject": "Antimony (Sb2Te3 companion compound)",
      "abundance": "No crustal abundance read.",
      "producers": [
        {
          "country": "China",
          "share_percent": 36.4,
          "year": 2025
        },
        {
          "country": "Russia",
          "share_percent": 29.1,
          "year": 2025
        },
        {
          "country": "Tajikistan",
          "share_percent": 20,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "USGS: recycling supplied 12 percent of estimated US apparent consumption in 2025.",
      "substitutes": [],
      "source": "usgs-sb-2026",
      "where": "World Mine Production and Reserves table (2025e); Salient Statistics; Import Sources; Recycling"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Stanford Advanced Materials SDS, Bismuth Telluride (CAS 1304-82-1), revised 01/11/2022",
      "type": "sds",
      "url": "https://samaterials.com/tds/1697119060-2060-bismuth-telluride-powder-sds.pdf",
      "year": 2022
    },
    {
      "title": "Angstrom Sciences SDS, Bismuth Telluride",
      "type": "sds",
      "url": "https://angstromsciences.com/wp-content/uploads/files/SDS/Bismuth%20Telluride.pdf",
      "year": 2015
    },
    {
      "title": "Stanford Advanced Materials MSDS, Antimony Telluride (CAS 1327-50-0), revision 2.0, 5 Sep 2012",
      "type": "sds",
      "url": "https://www.sputtertargets.net/Public/pdf/antimony-telluride-msds.pdf",
      "year": 2012
    },
    {
      "title": "Xiao et al., Hygrothermal Stability of Bi2Te3-based Thermoelectric Materials, Journal of Inorganic Materials 38(7), 2023",
      "type": "paper",
      "url": "https://www.researching.cn/ArticlePdf/m00097/2023/38/7/800.pdf",
      "year": 2023
    },
    {
      "title": "Cicvaric et al., Thermoelectric Properties of Bismuth Telluride Thin Films Electrodeposited from a Nonaqueous Solution, ACS Omega 5, 14679 (2020)",
      "type": "paper",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7315573/",
      "year": 2020
    },
    {
      "title": "Hsieh et al., Time-reversal-protected single-Dirac-cone topological-insulator states in Bi2Te3 and Sb2Te3, arXiv:0909.4804 (2009)",
      "type": "paper",
      "url": "https://arxiv.org/pdf/0909.4804",
      "year": 2009
    },
    {
      "title": "Fleurial and Borshchevsky, Development of Thick-Film Thermoelectric Microcoolers Using Electrochemical Deposition, NASA NTRS 20000048809",
      "type": "report",
      "url": "https://ntrs.nasa.gov/citations/20000048809",
      "year": 2000
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026, Bismuth",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bismuth.pdf",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026, Tellurium",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tellurium.pdf",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026, Antimony",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-antimony.pdf",
      "year": 2026
    },
    {
      "title": "PubChem compound record, Bismuth telluride (CID 6379155)",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/6379155",
      "year": 2026
    }
  ],
  "gaps": [
    "Crystal structure (trigonal, space group R-3m) for Bi2Te3 is not in the identity block: the only sources read with it are Wikipedia, which this profile uses for composition only.",
    "Melting point and density of bismuth telluride from a source other than the two SDS copies: the Wikipedia infobox values (580 degC, 7.74 g/cm3) were not used. The two SDS copies agree on density 7.642 and melting 573 degC.",
    "Thermal conductivity, zT and Seebeck values for pure, undoped Bi2Te3 at a stated temperature: not found in a non-Wikipedia source read in this run. The thermoelectric values above are for commercial Bi2Se0.21Te2.79 and Bi0.4Sb1.6Te3 alloys.",
    "Sb2Te3 band gap, thermal conductivity and thermoelectric figures: only in Wikipedia, which is not used for property values here. Not in the file.",
    "Antimony telluride hazard classes: the American Elements and Alfa Aesar H-statements (H302, H332, H411) appeared only in search snippets and were not read from a fetched SDS. Not in the file.",
    "Critical-mineral status of bismuth, tellurium and antimony on the USGS 2025 list: the USGS page returned HTTP 403 and was not read. Secondary search snippets disagree on whether bismuth and antimony were newly added. Left out. EU critical raw materials status not checked.",
    "NIOSH Pocket Guide (npgd0056) for bismuth telluride returned HTTP 403 and was not read. The exposure limits above come from the SDS copy only.",
    "Atomic weights are not in the sources used here, so the recipe uses each element's share of the bismuth telluride formula (40 and 60 percent) instead.",
    "The two Bi2Te3 SDS copies disagree on signal word (Warning against Danger) and on hazard classes (H332 against H331). Both are reported in risks.hazards.",
    "Space, vacuum, radiation and thermal-cycling flight data for Bi2Te3 modules: none found in a source read in this run. The NASA NTRS record is a 2000 development report with a projection, not a flight result.",
    "Property names not in spores/property-canon.yaml and used here: figure_of_merit_zt, electrical_conductivity, seebeck_coefficient, band_gap, leg_thickness, heat_flux_pumped.",
    "Electrical conductivity is printed as 9.45 x 10^4 S/m (Xiao et al.); it is kept in the printed unit with the factor in the unit field.",
    "Sb2Te3 supplier SDS is from 2012 (revision 2.0). Its PEL and TLV are for tellurium (0.1 mg(Te)/m3), not antimony.",
    "Wet-chemical and acid corrosion of Bi2Te3 not read. Oxidation rate constants not given in the sources read.",
    "The Xiao et al. paper is in Chinese; the English abstract, Table 1 and the Table 1 values were read from the Chinese layout. Values match the English abstract on zT and Seebeck."
  ],
  "story": {
    "why": "Bismuth telluride is a layered narrow-gap semiconductor. Bi2Te3-based alloys are the working material of room-temperature thermoelectric coolers and generators, and they reached zT of 1.24 for p-type material before storage (Xiao et al., 2023). Its surface also hosts a single Dirac cone and is classed as a topological insulator (Hsieh et al., arXiv 2009). The same layered family includes antimony telluride, which has its own supplier SDS for density and melting point. Hot, humid storage is the main ageing risk, so the material is used sealed.",
    "uses": [
      {
        "where": "Thermoelectric cooling and power",
        "line": "USGS says Bi2Te3 is used in thermoelectric devices for cooling and energy generation, and that thermoelectric devices took an estimated 15 percent of global tellurium end use in 2025."
      },
      {
        "where": "Micro-coolers for electronics (projected)",
        "line": "NASA JPL proposed thick-film Bi2Te3 microcoolers, electrodeposited on diamond substrates, with thousands of thermocouples, projected to pump more than 200 W/cm2 over 30 to 60 K. The 2000 record is a development report."
      }
    ],
    "can_do": [
      {
        "label": "Room-temperature zT",
        "line": "The p-type Bi0.4Sb1.6Te3 alloy reached zT 1.24 at room temperature before storage, and 0.97 after 600 h at 85 degC and 85% RH (Xiao et al., 2023).",
        "benchmark": "figure_of_merit_zt",
        "scope": "material",
        "value": "1.24 (p-type, before storage)"
      },
      {
        "label": "Bulk band gap",
        "line": "Bi2Te3 is an indirect semiconductor with a bulk gap of about 150 meV, and its surface carries a single Dirac cone (Hsieh et al., arXiv 2009).",
        "benchmark": "band_gap",
        "scope": "material",
        "value": "about 150 meV"
      },
      {
        "label": "Module leg size",
        "line": "Conventional Bi2Te3-alloy modules are limited by a minimum leg thickness of 100 to 200 micrometres and by 100 to 200 legs (Fleurial, NASA NTRS 2000).",
        "benchmark": "leg_thickness",
        "scope": "material",
        "value": "100 to 200 micrometres"
      },
      {
        "label": "Projected pumping",
        "line": "A thick-film microcooler is projected to pump more than 200 W/cm2 over a 30 to 60 K difference. This is a design target, not a measured result (Fleurial, NASA NTRS 2000).",
        "benchmark": "heat_flux_pumped",
        "scope": "material",
        "value": "more than 200 W/cm2"
      }
    ],
    "compare": "Bismuth telluride is denser than antimony telluride in the SDS copies read: 7.642 g/cm3 against 6.5 g/cm3. Its melting point is lower, 573 degC against 629 degC. Among the Bi2Te3-based alloys tested before storage, the p-type Bi0.4Sb1.6Te3 has the higher zT (1.24 against 0.97 for the n-type Bi2Se0.21Te2.79), and it keeps more zT after 600 h at 85 degC and 85% RH (0.97 against 0.79). The sources read here give no thermoelectric figures for pure Sb2Te3.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Melting point",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "zT at room temperature",
        "benchmark": "figure_of_merit_zt",
        "scope": "material"
      }
    ],
    "handling": [
      "Keep it dry and closed under dry inert gas. The SDS calls it moisture sensitive.",
      "Keep it away from acids, oxidising agents and water. For antimony telluride, keep it away from chlorates and perchlorates.",
      "Avoid dust. Use local exhaust and a respirator where dust forms, and wear eye and skin protection.",
      "Encapsulate finished devices against humidity. The authors conclude that the alloys have extremely poor hygrothermal stability without it."
    ],
    "good_for": [
      "Room-temperature thermoelectric coolers and generators. The p-type alloy reached zT 1.24 before storage (Xiao et al., 2023).",
      "Micro-coolers in development. NASA JPL projected more than 200 W/cm2 pumping from thick films (NASA NTRS 2000)."
    ],
    "watch_out": [
      "Humid heat: 600 h at 85 degC and 85% RH cut zT by 19 and 22 percent and oxidised the surface.",
      "Supply: China produced 88 percent of bismuth and 80 percent of refined tellurium in 2025 (USGS).",
      "Antimony telluride: moderately explosive in contact with chlorates and perchlorates, per its SDS."
    ],
    "verdict": "Bi2Te3 is the established room-temperature thermoelectric base material, with zT near 1 for commercial alloys. Its weak points are humid heat and a supply chain concentrated in China. The file has 22 sourced values and two supplier SDS copies that disagree on hazard classes. Pure-compound thermoelectric data and the Sb2Te3 band gap are not sourced here.",
    "recipe": {
      "line": "Bismuth telluride is a compound of bismuth and tellurium in a 2 to 3 ratio, Bi2Te3 (Wikipedia, composition). Thermoelectric material is an alloy of it with antimony or selenium: the 2023 commercial samples were n-type Bi2Se0.21Te2.79 and p-type Bi0.4Sb1.6Te3. Thin films can be electrodeposited from a dichloromethane solution with a short nucleation pulse (Cicvaric et al., 2020), and thick films of Bi2Te3 and its solid solutions by electrochemical deposition for microcoolers (Fleurial, NASA NTRS, 2000). Antimony telluride, Sb2Te3, is the companion compound with two antimony and three tellurium in the formula (Wikipedia, composition).",
      "parts": [
        {
          "name": "Bismuth",
          "symbol": "Bi",
          "role": "Two of the five positions in the Bi2Te3 formula (share of the formula). Bismuth is also the main element in the n-type and p-type alloys.",
          "share_percent": 40
        },
        {
          "name": "Tellurium",
          "symbol": "Te",
          "role": "Three of the five positions in the Bi2Te3 formula (share of the formula). Tellurium makes up the layered framework that gives the material its cleavage.",
          "share_percent": 60
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The supplier SDS classes bismuth telluride as harmful and irritant. Two copies disagree on the signal word.",
        "points": [
          {
            "label": "Acute hazard",
            "line": "H302+H312+H332 (harmful if swallowed, in contact with skin or inhaled); H315 and H319 irritant; H335 may irritate the airways."
          },
          {
            "label": "Dust",
            "line": "The SDS quotes US limits of 15 mg/m3 total dust and 5 mg/m3 respirable dust for undoped material. Avoid dust."
          },
          {
            "label": "Antimony telluride",
            "line": "The SDS for Sb2Te3 quotes 0.1 mg(Te)/m3 for OSHA and ACGIH, and says most antimony compounds are poisonous."
          }
        ],
        "level": 1,
        "verdict": "Harmful if swallowed or inhaled (SDS)"
      },
      {
        "title": "If it fails",
        "lead": "The two failure routes in the sources are humid heat and contact with chlorates and perchlorates.",
        "points": [
          {
            "label": "Humidity",
            "line": "600 h at 85 degC and 85% RH oxidised the surface, and zT fell by about a fifth (Xiao et al., 2023)."
          },
          {
            "label": "Chemical",
            "line": "Antimony telluride is moderately explosive by chemical reaction with chlorates and perchlorates, per its SDS."
          },
          {
            "label": "Supply",
            "line": "China produced 88 percent of bismuth and 80 percent of refined tellurium in 2025 (USGS)."
          }
        ],
        "level": 2,
        "verdict": "Oxidises in humid heat; zT drops"
      },
      {
        "title": "Handling",
        "lead": "The SDS calls bismuth telluride moisture sensitive.",
        "points": [
          {
            "label": "Storage",
            "line": "Store dry, in closed containers, under dry inert gas, away from acids, oxidising agents and water (SDS Section 7)."
          },
          {
            "label": "Encapsulation",
            "line": "The authors conclude that the modules need strict encapsulation against humidity."
          }
        ],
        "level": 1,
        "verdict": "Keep dry, away from acids and oxidisers"
      }
    ]
  },
  "updated": "2026-10-26",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 22,
    "unreachable": 0,
    "caveats": 0,
    "note": "Written by an AI assistant on 2026-10-26 from pages read in this run. Values come from two supplier SDS copies per Bi2Te3, one SDS for Sb2Te3, Xiao et al. 2023, Cicvaric et al. 2020, Hsieh et al. 2009, a NASA NTRS record and three USGS 2026 chapters. Wikipedia is used for composition only."
  },
  "sources": {
    "sam-bi2te3-sds": {
      "title": "Stanford Advanced Materials SDS, Bismuth Telluride (CAS 1304-82-1), revised 01/11/2022",
      "url": "https://samaterials.com/tds/1697119060-2060-bismuth-telluride-powder-sds.pdf",
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "angstrom-bi2te3-sds": {
      "title": "Angstrom Sciences SDS, Bismuth Telluride",
      "url": "https://angstromsciences.com/wp-content/uploads/files/SDS/Bismuth%20Telluride.pdf",
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "sam-sb2te3-msds": {
      "title": "Stanford Advanced Materials MSDS, Antimony Telluride (CAS 1327-50-0), revision 2.0, 5 Sep 2012",
      "url": "https://www.sputtertargets.net/Public/pdf/antimony-telluride-msds.pdf",
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "xiao2023": {
      "title": "Xiao et al., Hygrothermal Stability of Bi2Te3-based Thermoelectric Materials, Journal of Inorganic Materials 38(7), 2023",
      "url": "https://www.researching.cn/ArticlePdf/m00097/2023/38/7/800.pdf",
      "kind": "paper",
      "license": "cited, not reproduced (Chinese journal, English abstract and Table 1 values quoted)"
    },
    "cicvaric2020": {
      "title": "Cicvaric et al., Thermoelectric Properties of Bismuth Telluride Thin Films Electrodeposited from a Nonaqueous Solution, ACS Omega 5, 14679 (2020)",
      "url": "https://pmc.ncbi.nlm.nih.gov/articles/PMC7315573/",
      "kind": "paper",
      "license": "CC BY 4.0"
    },
    "hsieh2009": {
      "title": "Hsieh et al., Time-reversal-protected single-Dirac-cone topological-insulator states in Bi2Te3 and Sb2Te3, arXiv:0909.4804 (2009)",
      "url": "https://arxiv.org/pdf/0909.4804",
      "kind": "paper",
      "license": "arXiv preprint, cited as published"
    },
    "ntrs-fleurial2000": {
      "title": "Fleurial and Borshchevsky, Development of Thick-Film Thermoelectric Microcoolers Using Electrochemical Deposition, NASA NTRS 20000048809",
      "url": "https://ntrs.nasa.gov/citations/20000048809",
      "kind": "report",
      "license": "public domain (NASA)"
    },
    "usgs-bi-2026": {
      "title": "USGS Mineral Commodity Summaries 2026, Bismuth",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-bismuth.pdf",
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "usgs-te-2026": {
      "title": "USGS Mineral Commodity Summaries 2026, Tellurium",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tellurium.pdf",
      "kind": "report",
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}