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.
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
  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
    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
  - benchmark: density
    label: Density of bismuth telluride (second supplier SDS)
    value: 7.642
    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
  - benchmark: melting_point
    label: Melting point of bismuth telluride (supplier SDS)
    value: 573
    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
  - benchmark: melting_point
    label: Melting point of bismuth telluride (second supplier SDS)
    value: 573
    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
  - benchmark: density
    label: Density of antimony telluride (supplier SDS, 2012)
    value: 6.5
    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
  - benchmark: melting_point
    label: Melting point of antimony telluride (supplier SDS, 2012)
    value: 629
    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
  - benchmark: thermal_conductivity
    label: Thermal conductivity, n-type Bi2Se0.21Te2.79, before storage
    value: 1.4
    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
  - benchmark: thermal_conductivity
    label: Thermal conductivity, n-type Bi2Se0.21Te2.79, after 600 h at 85 degC and 85% RH
    value: 1.48
    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
  - benchmark: thermal_conductivity
    label: Thermal conductivity, p-type Bi0.4Sb1.6Te3, before storage
    value: 1.31
    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
  - benchmark: thermal_conductivity
    label: Thermal conductivity, p-type Bi0.4Sb1.6Te3, after 600 h at 85 degC and 85% RH
    value: 1.29
    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
  - benchmark: figure_of_merit_zt
    label: Thermoelectric figure of merit zT, n-type Bi2Se0.21Te2.79, before storage
    value: 0.97
    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
  - 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
    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
  - benchmark: figure_of_merit_zt
    label: Thermoelectric figure of merit zT, p-type Bi0.4Sb1.6Te3, before storage
    value: 1.24
    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
  - 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
    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
  - benchmark: electrical_conductivity
    label: Electrical conductivity, n-type Bi2Se0.21Te2.79, before storage
    value: 9.45
    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
  - benchmark: electrical_conductivity
    label: Electrical conductivity, n-type Bi2Se0.21Te2.79, after 600 h at 85 degC and 85% RH
    value: 7.79
    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
  - benchmark: seebeck_coefficient
    label: Seebeck coefficient, p-type Bi0.4Sb1.6Te3, before storage
    value: 243
    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
  - benchmark: seebeck_coefficient
    label: Seebeck coefficient, p-type Bi0.4Sb1.6Te3, after 600 h at 85 degC and 85% RH
    value: 220
    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
  - benchmark: band_gap
    label: Bulk indirect band gap of Bi2Te3 (spin-orbit induced)
    value: 150
    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
  - benchmark: seebeck_coefficient
    label: Seebeck coefficient, electrodeposited Bi2Te3 thin film at room temperature
    value: 51.7
    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)
  - 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)
  - 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
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
    us_position: 'USGS: estimated world refinery production was 16,000 t in 2025, and China accounted for 88 percent. US net import reliance was 92 percent of apparent consumption in 2025e. Import sources 2021 to 2024: China 56 percent, Republic of Korea 22 percent, Germany 13 percent.'
    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
    us_position: 'USGS: China accounted for 80 percent of estimated global refined production in 2025. US imports were 14 t in 2025e. The US warehouse price rose 60 percent to an estimated 120 USD/kg in 2025, and the Rotterdam price rose 84 percent to an estimated 150 USD/kg.'
    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
    us_position: 'USGS: world mine production was 110,000 t in 2025e, with China 40,000 t, Russia 32,000 t and Tajikistan 22,000 t. Shares are calculated by Space Mushroom from the USGS table. US net import reliance was 91 percent of apparent consumption in 2025e. China supplied 55 percent of US total antimony metal and oxide imports in 2021 to 2024. The 2025 average price was 25 USD/lb.'
    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.
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
    license: public domain (USGS)
  usgs-sb-2026:
    title: USGS Mineral Commodity Summaries 2026, Antimony
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-antimony.pdf
    kind: report
    license: public domain (USGS)
  pubchem-bi2te3:
    title: PubChem compound record, Bismuth telluride (CID 6379155)
    url: https://pubchem.ncbi.nlm.nih.gov/compound/6379155
    kind: database
    license: public domain (NCBI)
license: CC-BY-4.0
checked_values: 22
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 22
  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.
story:
  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
        share_percent: 40
        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.
      - name: Tellurium
        symbol: Te
        share_percent: 60
        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.
  risk_groups:
    - title: For people
      level: 1
      verdict: Harmful if swallowed or inhaled (SDS)
      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.
    - title: If it fails
      level: 2
      verdict: Oxidises in humid heat; zT drops
      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).
    - title: Handling
      level: 1
      verdict: Keep dry, away from acids and oxidisers
      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.
  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
      value: 1.24 (p-type, before storage)
      benchmark: figure_of_merit_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).
    - label: Bulk band gap
      value: about 150 meV
      benchmark: 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).
    - label: Module leg size
      value: 100 to 200 micrometres
      benchmark: leg_thickness
      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).
    - label: Projected pumping
      value: more than 200 W/cm2
      benchmark: heat_flux_pumped
      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).
  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
    - label: Melting point
      benchmark: melting_point
    - label: zT at room temperature
      benchmark: figure_of_merit_zt
  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.