{
  "spore": "profile",
  "id": "germanium-telluride",
  "spore_version": "0.2",
  "family": "phase-change-chalcogenides",
  "name": "Germanium telluride (GeTe)",
  "abbreviation": "GeTe",
  "role": "phase-change memory material and thermoelectric",
  "category": "energy",
  "type": "thermoelectrics",
  "summary": "GeTe is germanium telluride, one germanium atom bonded to one tellurium atom, with a rhombohedral crystal structure at room temperature. Its density is 6.14 g/cm3 in the Wikipedia infobox and 6.2 g/cc as a theoretical density on an evaporation-material datasheet, and both sources give a melting point of 725 °C. Gwin and Coutu report a transition at approximately 200 °C that they use for electronic memory. Calculations give a room-temperature zT of 0.39 for n-type cross-plane GeTe; these are calculated values, not measurements.\n",
  "best_for": "Phase-change memory research and thermoelectric modelling, where the sources give a switching transition near 200 °C and calculated zT figures",
  "weakest_at": "Few measured transport values for pure GeTe in the sources read here: the thermoelectric figures are calculated, and no corrosion or space test was found",
  "identity": {
    "formula": "GeTe",
    "cas": "12025-39-7",
    "crystal_system": "rhombohedral",
    "space_group": "R3m",
    "designations": [],
    "source": "wikipedia-gete",
    "where": "Infobox: crystal structure rhombohedral (Pearson symbol hR6), space group R3m, No. 160; chemical formula GeTe; CAS number 12025-39-7"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "electronics-and-chips",
      "optics-and-cameras"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density",
      "value": 6.14,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "basis": "standard-state conditions printed in the infobox: 25 °C and 100 kPa"
      },
      "method": "Value printed in the Wikipedia infobox (Density field)",
      "status": "ground",
      "source": "wikipedia-gete",
      "where": "Infobox, Density",
      "source_detail": {
        "title": "Germanium telluride (Wikipedia article: infobox, body text and references)",
        "id": "Wikipedia, read 2026-11-02",
        "url": "https://en.wikipedia.org/wiki/Germanium_telluride",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "density",
      "label": "Theoretical density",
      "value": 6.2,
      "bound": "exact",
      "unit": "g/cc",
      "scope": "material",
      "conditions": {
        "basis": "printed as Theoretical Density on the product page; not stated whether measured or calculated"
      },
      "method": "Value printed on the AEM Deposition product page as Theoretical Density",
      "status": "ground",
      "source": "aem-gete",
      "where": "Product table, Theoretical Density row",
      "source_detail": {
        "title": "Germanium Telluride Pellet Evaporation Material (GeTe), AEM Deposition product page",
        "id": "AEM Deposition product page, undated; read 2026-11-02",
        "url": "https://www.aemdeposition.com/compound-evaporation-material/germanium-telluride-evaporation-material.html",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier page, cited not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point",
      "value": 725,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "basis": "printed in the Wikipedia infobox as 725 °C (1,337 °F; 998 K)"
      },
      "method": "Value printed in the Wikipedia infobox (Melting point field)",
      "status": "ground",
      "source": "wikipedia-gete",
      "where": "Infobox, Melting point",
      "source_detail": {
        "title": "Germanium telluride (Wikipedia article: infobox, body text and references)",
        "id": "Wikipedia, read 2026-11-02",
        "url": "https://en.wikipedia.org/wiki/Germanium_telluride",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point",
      "value": 725,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "basis": "printed on the product page as Melting Point; no pressure stated"
      },
      "method": "Value printed on the AEM Deposition product page",
      "status": "ground",
      "source": "aem-gete",
      "where": "Product table, Melting Point row",
      "source_detail": {
        "title": "Germanium Telluride Pellet Evaporation Material (GeTe), AEM Deposition product page",
        "id": "AEM Deposition product page, undated; read 2026-11-02",
        "url": "https://www.aemdeposition.com/compound-evaporation-material/germanium-telluride-evaporation-material.html",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier page, cited not reproduced"
      }
    },
    {
      "benchmark": "band_gap",
      "label": "Band gap",
      "value": 0.6,
      "bound": "exact",
      "unit": "eV",
      "scope": "material",
      "conditions": {
        "basis": "printed in the infobox without a temperature"
      },
      "method": "Value printed in the Wikipedia infobox (Band gap field)",
      "status": "ground",
      "source": "wikipedia-gete",
      "where": "Infobox, Band gap",
      "source_detail": {
        "title": "Germanium telluride (Wikipedia article: infobox, body text and references)",
        "id": "Wikipedia, read 2026-11-02",
        "url": "https://en.wikipedia.org/wiki/Germanium_telluride",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "band_gap",
      "label": "Direct band gap (as cited)",
      "value": 0.6,
      "bound": "exact",
      "unit": "eV",
      "scope": "material",
      "conditions": {
        "basis": "described as a direct bandgap; the paper gives this as the experimental value it compares against"
      },
      "method": "Value stated in the abstract of an arXiv preprint that models a GeTe thermophotovoltaic cell",
      "status": "ground",
      "source": "abir-2023",
      "where": "Abstract",
      "source_detail": {
        "title": "Exploring the potential of GeTe for the application in Thermophotovoltaic (TPV) cell",
        "id": "arXiv:2301.08896 (v1)",
        "url": "https://arxiv.org/pdf/2301.08896",
        "year": 2023,
        "kind": "paper",
        "license": "arXiv preprint (license as listed on arXiv)"
      }
    },
    {
      "benchmark": "curie_temperature",
      "label": "Ferroelectric Curie temperature",
      "value": 397,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "basis": "printed as approximately 670 K (746 °F; 397 °C); below this temperature the alpha phase is the dominant form of pure GeTe"
      },
      "method": "Value printed in the body text of the Wikipedia article",
      "status": "ground",
      "source": "wikipedia-gete",
      "where": "Body text, ferroelectric Curie temperature paragraph",
      "source_detail": {
        "title": "Germanium telluride (Wikipedia article: infobox, body text and references)",
        "id": "Wikipedia, read 2026-11-02",
        "url": "https://en.wikipedia.org/wiki/Germanium_telluride",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "rhombohedral_to_cubic_transition_temperature",
      "label": "Rhombohedral to cubic transition",
      "value": 640,
      "bound": "exact",
      "unit": "K",
      "scope": "material",
      "conditions": {
        "basis": "printed as above approximately 640 K (with a tilde); the paper gives it as the temperature at which the rhombohedral phase changes to a cubic rock-salt structure"
      },
      "method": "Value stated in the introduction of an arXiv preprint on GeTe thermoelectric transport",
      "status": "ground",
      "source": "askarpour-maassen-2019",
      "where": "Introduction, first paragraph",
      "source_detail": {
        "title": "Unusual thermoelectric transport anisotropy in quasi-2D, rhombohedral GeTe",
        "id": "arXiv:1904.06439 (v2)",
        "url": "https://arxiv.org/pdf/1904.06439",
        "year": 2019,
        "kind": "paper",
        "license": "arXiv preprint (license as listed on arXiv)"
      }
    },
    {
      "benchmark": "memory_transition_temperature",
      "label": "Transition temperature in memory devices",
      "value": 200,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "basis": "printed as approximately 200 °C; the abstract gives no film thickness, pressure or time"
      },
      "method": "Value stated in the abstract of a SPIE conference paper on electronic control of the GeTe phase transition",
      "status": "ground",
      "source": "gwin-coutu-2015",
      "where": "Abstract",
      "source_detail": {
        "title": "Electronic control of Germanium Telluride (GeTe) phase transition for electronic memory applications",
        "id": "doi:10.1117/12.2079359 (Proc. SPIE 9364, 93640G)",
        "url": "https://epublications.marquette.edu/electric_fac/404",
        "year": 2015,
        "kind": "paper",
        "license": "repository record (abstract read)"
      }
    },
    {
      "benchmark": "lattice_parameter_a",
      "label": "Lattice constant a",
      "value": 4.1719,
      "bound": "exact",
      "unit": "Å",
      "scope": "material",
      "conditions": {
        "phase": "rhombohedral alpha phase (Pearson symbol hR6)"
      },
      "method": "Value printed in the Wikipedia infobox (lattice constants)",
      "status": "ground",
      "source": "wikipedia-gete",
      "where": "Infobox, Lattice constants",
      "source_detail": {
        "title": "Germanium telluride (Wikipedia article: infobox, body text and references)",
        "id": "Wikipedia, read 2026-11-02",
        "url": "https://en.wikipedia.org/wiki/Germanium_telluride",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "lattice_parameter_c",
      "label": "Lattice constant c",
      "value": 10.71,
      "bound": "exact",
      "unit": "Å",
      "scope": "material",
      "conditions": {
        "phase": "rhombohedral alpha phase (Pearson symbol hR6)"
      },
      "method": "Value printed in the Wikipedia infobox (lattice constants)",
      "status": "ground",
      "source": "wikipedia-gete",
      "where": "Infobox, Lattice constants",
      "source_detail": {
        "title": "Germanium telluride (Wikipedia article: infobox, body text and references)",
        "id": "Wikipedia, read 2026-11-02",
        "url": "https://en.wikipedia.org/wiki/Germanium_telluride",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "molar_mass",
      "label": "Molar mass",
      "value": 200.21,
      "bound": "exact",
      "unit": "g/mol",
      "scope": "material",
      "conditions": {
        "basis": "printed as molar mass of the GeTe formula"
      },
      "method": "Value printed in the Wikipedia infobox (Molar mass field)",
      "status": "ground",
      "source": "wikipedia-gete",
      "where": "Infobox, Molar mass",
      "source_detail": {
        "title": "Germanium telluride (Wikipedia article: infobox, body text and references)",
        "id": "Wikipedia, read 2026-11-02",
        "url": "https://en.wikipedia.org/wiki/Germanium_telluride",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "refractive_index",
      "label": "Refractive index (TPV model input)",
      "value": 5.5,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "basis": "printed as a parameter in the device table with its reference [37]; no wavelength stated"
      },
      "method": "Input value printed in the parameter table of an arXiv preprint on a GeTe thermophotovoltaic cell",
      "status": "ground",
      "source": "abir-2023",
      "where": "Simulation parameter table, refractive index row",
      "source_detail": {
        "title": "Exploring the potential of GeTe for the application in Thermophotovoltaic (TPV) cell",
        "id": "arXiv:2301.08896 (v1)",
        "url": "https://arxiv.org/pdf/2301.08896",
        "year": 2023,
        "kind": "paper",
        "license": "arXiv preprint (license as listed on arXiv)"
      }
    },
    {
      "benchmark": "refractive_index",
      "label": "Refractive index (n_D)",
      "value": 5,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "basis": "printed as 5 without a unit or wavelength in the infobox (n_D)"
      },
      "method": "Value printed in the Wikipedia infobox; it differs from the 5.5 used in the TPV preprint",
      "status": "ground",
      "source": "wikipedia-gete",
      "where": "Infobox, Refractive index (n_D)",
      "source_detail": {
        "title": "Germanium telluride (Wikipedia article: infobox, body text and references)",
        "id": "Wikipedia, read 2026-11-02",
        "url": "https://en.wikipedia.org/wiki/Germanium_telluride",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (cited, not reproduced)"
      }
    },
    {
      "benchmark": "dielectric_constant",
      "label": "Dielectric constant",
      "value": 40,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "basis": "printed without a frequency or temperature; the preprint cites its reference [6] for the value"
      },
      "method": "Value stated in the body text of an arXiv preprint on a GeTe thermophotovoltaic cell",
      "status": "ground",
      "source": "abir-2023",
      "where": "Introduction, paragraph on GeTe properties",
      "source_detail": {
        "title": "Exploring the potential of GeTe for the application in Thermophotovoltaic (TPV) cell",
        "id": "arXiv:2301.08896 (v1)",
        "url": "https://arxiv.org/pdf/2301.08896",
        "year": 2023,
        "kind": "paper",
        "license": "arXiv preprint (license as listed on arXiv)"
      }
    },
    {
      "benchmark": "seebeck_coefficient",
      "label": "Seebeck coefficient at the band edges",
      "value": 200,
      "bound": "exact",
      "unit": "µV/K",
      "scope": "material",
      "conditions": {
        "basis": "absolute value at the band edges of rhombohedral GeTe, 300 K, from a density-functional transport calculation (not measured)"
      },
      "method": "Calculated value stated in the Results of an arXiv preprint (Askarpour and Maassen); the paper states the absolute value approximately",
      "status": "calculated",
      "source": "askarpour-maassen-2019",
      "where": "Section on thermoelectric transport properties",
      "source_detail": {
        "title": "Unusual thermoelectric transport anisotropy in quasi-2D, rhombohedral GeTe",
        "id": "arXiv:1904.06439 (v2)",
        "url": "https://arxiv.org/pdf/1904.06439",
        "year": 2019,
        "kind": "paper",
        "license": "arXiv preprint (license as listed on arXiv)"
      }
    },
    {
      "benchmark": "figure_of_merit_zt",
      "label": "Room-temperature zT, n-type cross-plane",
      "value": 0.39,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "basis": "n-type, cross-plane direction, 300 K, optimal carrier concentration; density-functional transport calculation (not measured)"
      },
      "method": "Calculated value stated in the Discussion of an arXiv preprint (Askarpour and Maassen); the paper's in-plane n-type value is 0.13",
      "status": "calculated",
      "source": "askarpour-maassen-2019",
      "where": "Discussion, first list of optimal room-temperature zT values",
      "source_detail": {
        "title": "Unusual thermoelectric transport anisotropy in quasi-2D, rhombohedral GeTe",
        "id": "arXiv:1904.06439 (v2)",
        "url": "https://arxiv.org/pdf/1904.06439",
        "year": 2019,
        "kind": "paper",
        "license": "arXiv preprint (license as listed on arXiv)"
      }
    }
  ],
  "corrosion": [],
  "risks": {
    "hazards": [
      {
        "text": "PubChem's GHS summary lists H302 (100%): Harmful if swallowed, with signal word Warning, from 56 company reports to the ECHA C&L Inventory (2 notifications).",
        "ghs": [
          "H302"
        ],
        "source": "pubchem-gete",
        "where": "Safety and Hazards, GHS Classification (CID 16213264)"
      },
      {
        "text": "PubChem lists precautionary statement codes P264, P270, P301+P317, P330 and P501; the statement texts are behind links on that page and were not read in this run.",
        "ghs": [],
        "source": "pubchem-gete",
        "where": "Safety and Hazards, GHS Classification, Precautionary Statement Codes"
      }
    ],
    "failure_risks": [
      {
        "mode": "Phase change at the memory transition temperature",
        "trigger": "Heating a GeTe film to its transition temperature",
        "consequence": "The abstract gives the transition temperature as approximately 200 °C and does not state what happens to stored data above it.",
        "severity": "moderate",
        "source": "gwin-coutu-2015",
        "where": "Abstract"
      },
      {
        "mode": "Rhombohedral to cubic phase change",
        "trigger": "Heating GeTe above approximately 640 K",
        "consequence": "The calculations model only the rhombohedral phase, the room-temperature form, so the calculated Seebeck and zT values do not describe the material above this temperature.",
        "severity": "low",
        "source": "askarpour-maassen-2019",
        "where": "Introduction and Section on thermoelectric transport properties"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "No supplier safety data sheet for GeTe was read in this run, so the hazard entries above rest on PubChem's GHS summary alone.",
        "source": "pubchem-gete",
        "where": "Safety and Hazards (CID 16213264)"
      },
      {
        "text": "AEM Deposition sells GeTe as pellets, pieces and powder for thermal evaporation; its product page gives no storage or handling text.",
        "source": "aem-gete",
        "where": "Product description and availability"
      }
    ],
    "mitigations": []
  },
  "uses": [
    {
      "application": "electronics-and-chips",
      "device": "Phase-change electronic memory (research)",
      "example": "Gwin and Coutu's paper is titled 'Electronic control of Germanium Telluride (GeTe) phase transition for electronic memory applications'. Its abstract reports a transition temperature of approximately 200 °C.",
      "source": "gwin-coutu-2015",
      "where": "Title and abstract"
    },
    {
      "application": "electronics-and-chips",
      "device": "Single-junction thermophotovoltaic cell (theoretical)",
      "example": "Abir and co-authors model a GeTe thermophotovoltaic cell, a device that converts radiated heat into electricity, using a direct bandgap of 0.6 eV. The work is a theoretical calculation.",
      "source": "abir-2023",
      "where": "Abstract and Introduction"
    }
  ],
  "supply": [
    {
      "subject": "Germanium",
      "producers": [],
      "critical_lists": [
        {
          "list": "USGS 2025 List of Critical Minerals (germanium named on the list)",
          "listed": true
        }
      ],
      "recycling": "USGS: the United States can recycle new and old germanium scrap, but available information was inadequate to make reliable estimates of the amount of secondary germanium produced.",
      "substitutes": [
        "USGS: silicon or gallium arsenide can substitute for germanium in certain electronic applications, and chalcogenide glass has been used as a substitute for germanium metal in infrared applications."
      ],
      "source": "usgs-mcs2026-germanium",
      "where": "Events, Trends, and Issues (China named as the leading producer and exporter of germanium metal in 2025, without a share); World Refinery Production and Reserves; Recycling; Substitutes"
    },
    {
      "subject": "Tellurium",
      "producers": [
        {
          "country": "China",
          "share_percent": 80,
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 List of Critical Minerals (tellurium named on the list)",
          "listed": true
        }
      ],
      "recycling": "USGS: tellurium was recycled from CdTe solar cells in the United States, but the quantity was limited because most of these cells were relatively new.",
      "substitutes": [
        "USGS: bismuth selenide and organic polymers can substitute for bismuth telluride in some thermoelectric devices."
      ],
      "source": "usgs-mcs2026-tellurium",
      "where": "Summary: China accounted for 80% of estimated global production in 2025; Recycling; Substitutes"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "AEM Deposition: Germanium Telluride pellet evaporation material (product page)",
      "type": "datasheet",
      "url": "https://www.aemdeposition.com/compound-evaporation-material/germanium-telluride-evaporation-material.html",
      "year": 2026
    },
    {
      "title": "PubChem: Germanium telluride (GeTe), CID 16213264, GHS classification",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/16213264",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Germanium",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-germanium.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": "Electronic control of Germanium Telluride (GeTe) phase transition for electronic memory applications (Gwin and Coutu)",
      "type": "paper",
      "url": "https://epublications.marquette.edu/electric_fac/404",
      "year": 2015
    },
    {
      "title": "Unusual thermoelectric transport anisotropy in quasi-2D, rhombohedral GeTe (arXiv:1904.06439)",
      "type": "paper",
      "url": "https://arxiv.org/abs/1904.06439",
      "year": 2019
    },
    {
      "title": "Exploring the potential of GeTe for the application in Thermophotovoltaic (TPV) cell (arXiv:2301.08896)",
      "type": "paper",
      "url": "https://arxiv.org/abs/2301.08896",
      "year": 2023
    }
  ],
  "gaps": [
    "Corrosion, oxidation and ageing of GeTe were not found in any source read in this run; the failure modes cover the phase-transition temperatures only.",
    "The thermoelectric figures are calculated (density-functional theory). No measured zT for undoped GeTe was read in this run. A higher measured zT for an alloyed GeTe is cited in the 2019 preprint and is left out because it is a different composition.",
    "The TPV preprint's electrical resistivity figure is printed with an exponent, so it is left out under the rule for exponent values.",
    "No measured Seebeck coefficient, thermal conductivity or electrical resistivity for undoped GeTe, with units, was found in any source read in this run.",
    "No supplier safety data sheet for GeTe was read; the only hazard source is PubChem's GHS summary, which lists no pictograms in the text read.",
    "The USGS germanium summary names China as the leading producer and exporter of germanium metal in 2025 but gives no production share, so no producer percentages are recorded for germanium.",
    "Lattice constants, molar mass, band gap, refractive index, Seebeck coefficient and zT use snake_case benchmark names because they are not in property-canon; the refractive index differs between the Wikipedia infobox and the TPV preprint and both are kept.",
    "Two sources could not be read by the script: the FUSNano product page returned no content, and the MDPI and American Elements pages returned HTTP 403."
  ],
  "story": {
    "why": "Germanium telluride (GeTe) is a compound of germanium and tellurium that switches between structures with very different electrical properties. Gwin and Coutu tie its phase transition to electronic memory. The same compound has also been studied as a thermoelectric material and as the absorber of a theoretical thermophotovoltaic cell. The sources read here give datasheet and reference values for density, melting point and band gap, and calculated values for its thermoelectric performance. It is the simpler two-element member of the phase-change family, to which its sibling Ge2Sb2Te5 also belongs.",
    "uses": [
      {
        "where": "Electronic memory research",
        "line": "Gwin and Coutu's 2015 paper is titled 'Electronic control of Germanium Telluride (GeTe) phase transition for electronic memory applications'. Its abstract reports a transition temperature at approximately 200 °C, and a resistivity that decreases by as much as six orders of magnitude."
      },
      {
        "where": "Thermophotovoltaic cell (theory)",
        "line": "Abir and co-authors calculate a single-junction GeTe thermophotovoltaic cell, a device that converts radiated heat into electricity, starting from a direct band gap of 0.6 eV. The work is a theoretical calculation, not a fabricated device."
      }
    ],
    "can_do": [
      {
        "label": "Electronic memory",
        "line": "Switch between two structural states whose resistivity differs strongly, which the Gwin and Coutu abstract ties to electronic memory. The abstract gives the transition temperature as approximately 200 °C.",
        "benchmark": "memory_transition_temperature",
        "scope": "material",
        "value": "200 °C"
      },
      {
        "label": "Band gap",
        "line": "Act as a semiconductor with a direct band gap of 0.6 eV (Wikipedia infobox; Abir and co-authors).",
        "benchmark": "band_gap",
        "scope": "material",
        "value": "0.6 eV"
      },
      {
        "label": "Thermoelectric zT",
        "line": "Reach a calculated room-temperature zT of 0.39 for n-type cross-plane material (Askarpour and Maassen, 2019; calculated, not measured).",
        "benchmark": "figure_of_merit_zt",
        "scope": "material",
        "value": "0.39"
      }
    ],
    "compare": "GeTe is the two-element compound of this pair: the sibling Ge2Sb2Te5 profile adds antimony to the same germanium and tellurium. Among the values in this profile, the melting point of 725 °C and the density of 6.14 g/cm3 are datasheet or reference values, while the thermoelectric figures are calculated. The band gap of 0.6 eV is the same in the infobox and in the thermophotovoltaic preprint, and the refractive index is given as 5 in one source and 5.5 in the other.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Melting point",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Band gap",
        "benchmark": "band_gap",
        "scope": "material"
      }
    ],
    "handling": [
      "No supplier safety data sheet for GeTe was read in this run, so the hazard entries rest on PubChem's GHS summary alone.",
      "AEM Deposition sells GeTe as pellets, pieces and powder for thermal evaporation; its page gives no storage or handling text.",
      "PubChem lists H302 (harmful if swallowed); the precautionary statement texts behind its codes were not read."
    ],
    "good_for": [
      "Phase-change memory research, where the Gwin and Coutu abstract describes electronic control of the GeTe transition at approximately 200 °C.",
      "Thermoelectric modelling, where the calculated room-temperature zT of 0.39 gives a baseline for n-type cross-plane GeTe."
    ],
    "watch_out": [
      "The thermoelectric figures are calculated, not measured, and the calculations model only the rhombohedral phase below approximately 640 K.",
      "The Seebeck coefficient of about 200 µV/K at the band edges is a calculated value (Askarpour and Maassen), not a measured one.",
      "The refractive index is 5 in the Wikipedia infobox and 5.5 in the TPV preprint's parameter table, and neither gives a wavelength."
    ],
    "verdict": "GeTe has enough sourced data for a phase-change and thermoelectric profile. Its thermoelectric figures are calculated, and its only hazard source is PubChem's summary.",
    "recipe": {
      "line": "GeTe is germanium telluride, formed from one germanium atom bonded to one tellurium atom. The sources read here do not describe the synthesis route used for the commercial powder or evaporation material.",
      "parts": [
        {
          "name": "Germanium",
          "symbol": "Ge",
          "role": "The group-14 element that forms one half of the compound, bonded to tellurium in the rhombohedral lattice."
        },
        {
          "name": "Tellurium",
          "symbol": "Te",
          "role": "The group-16 element that forms the other half of the compound; tellurium is also the byproduct element in the supply section."
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "PubChem's hazard summary lists H302 for GeTe, based on company notifications. No supplier safety data sheet was read in this run.",
        "points": [
          {
            "label": "Ingestion",
            "line": "PubChem's GHS summary lists H302 (100%): Harmful if swallowed, with the signal word Warning, from 56 company reports."
          },
          {
            "label": "Precautions",
            "line": "PubChem lists precautionary codes P264, P270, P301+P317, P330 and P501. The statement texts were not read."
          }
        ],
        "level": 0,
        "verdict": "Harmful if swallowed (PubChem H302)"
      },
      {
        "title": "In a device",
        "lead": "These are device-level statements from the papers read here. The sources do not report field incidents.",
        "points": [
          {
            "label": "Transition temperature",
            "line": "The memory transition is described at approximately 200 °C in the Gwin and Coutu abstract."
          },
          {
            "label": "Phase change",
            "line": "Above approximately 640 K the rhombohedral phase changes to a cubic rock-salt structure, so the room-temperature calculations no longer describe the material."
          }
        ]
      },
      {
        "title": "Handling and supply",
        "points": [
          {
            "label": "Form",
            "line": "AEM Deposition sells GeTe as pellets, pieces and powder. Its product page gives no storage or safety text."
          },
          {
            "label": "Supply",
            "line": "China accounted for 80% of estimated global tellurium production in 2025, according to the USGS summary."
          }
        ]
      }
    ]
  },
  "updated": "2026-11-02",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 17,
    "unreachable": 0,
    "caveats": 0,
    "note": "Read by an AI assistant on 2026-11-02 from pages fetched in this run: 17 of 17 benchmark values found in their cited sources by verify-values; 0 sources unreadable; 0 values not found. Thermoelectric values are calculated, not measured."
  },
  "sources": {
    "wikipedia-gete": {
      "title": "Germanium telluride (Wikipedia article: infobox, body text and references)",
      "id": "Wikipedia, read 2026-11-02",
      "url": "https://en.wikipedia.org/wiki/Germanium_telluride",
      "year": 2026,
      "kind": "web",
      "license": "CC BY-SA 4.0 (cited, not reproduced)"
    },
    "aem-gete": {
      "title": "Germanium Telluride Pellet Evaporation Material (GeTe), AEM Deposition product page",
      "id": "AEM Deposition product page, undated; read 2026-11-02",
      "url": "https://www.aemdeposition.com/compound-evaporation-material/germanium-telluride-evaporation-material.html",
      "year": 2026,
      "kind": "datasheet",
      "license": "supplier page, cited not reproduced"
    },
    "pubchem-gete": {
      "title": "PubChem compound record, Germanium telluride (GeTe), CID 16213264: identifiers and GHS classification",
      "id": "CID 16213264; CAS 12025-39-7",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/16213264/JSON",
      "year": 2026,
      "kind": "database",
      "license": "public domain (NCBI)"
    },
    "usgs-mcs2026-germanium": {
      "title": "Mineral Commodity Summaries 2026, Germanium",
      "id": "USGS MCS 2026, February 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-germanium.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "usgs-mcs2026-tellurium": {
      "title": "Mineral Commodity Summaries 2026, Tellurium",
      "id": "USGS MCS 2026, February 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tellurium.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "gwin-coutu-2015": {
      "title": "Electronic control of Germanium Telluride (GeTe) phase transition for electronic memory applications",
      "id": "doi:10.1117/12.2079359 (Proc. SPIE 9364, 93640G)",
      "url": "https://epublications.marquette.edu/electric_fac/404",
      "year": 2015,
      "kind": "paper",
      "license": "repository record (abstract read)"
    },
    "askarpour-maassen-2019": {
      "title": "Unusual thermoelectric transport anisotropy in quasi-2D, rhombohedral GeTe",
      "id": "arXiv:1904.06439 (v2)",
      "url": "https://arxiv.org/pdf/1904.06439",
      "year": 2019,
      "kind": "paper",
      "license": "arXiv preprint (license as listed on arXiv)"
    },
    "abir-2023": {
      "title": "Exploring the potential of GeTe for the application in Thermophotovoltaic (TPV) cell",
      "id": "arXiv:2301.08896 (v1)",
      "url": "https://arxiv.org/pdf/2301.08896",
      "year": 2023,
      "kind": "paper",
      "license": "arXiv preprint (license as listed on arXiv)"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/germanium-telluride/"
}