Cadmium selenide (infrared optical crystal) CdSe

spore: profile
id: cadmium-selenide
spore_version: 0.2
family: optical-crystals
name: Cadmium selenide (infrared optical crystal)
abbreviation: CdSe
role: birefringent infrared crystal for waveplates and long-wave optics, also used in quantum dots and photoconductors
category: glasses-optics
type: optical-crystals
summary: |
  Cadmium selenide is a black, hexagonal (wurtzite) compound of cadmium and selenium with a density of 5.81 g/cm3, printed the same by Tydex, Wikipedia and the supplier safety sheet. Tydex makes polished optical parts from monocrystalline CdSe and gives a transparent range from 0.75 µm to 24.5 to 25.5 µm. It says the crystal is birefringent for some orientations, so it can make waveplates, and that it is virtually the only material birefringent between 16 and 24 µm. Wikipedia notes limited use in light-sensitive resistors and in infrared windows, and the USGS names CdSe as an optoelectronic material and a quantum-dot precursor. The supplier safety sheet classes it as toxic if swallowed or inhaled, with a repeated-exposure hazard (H373), and Mohs hardness is only 3.25 (Tydex). The related section covers lead selenide (PbSe), a grey cubic compound used in mid-infrared photodetectors.
best_for: Polished, birefringent infrared parts and waveplates from 0.75 µm to about 25 µm, where a crystal is needed rather than a film
weakest_at: 'Toxicity and softness: the supplier safety sheet and Wikipedia classify it as toxic if swallowed or inhaled with a repeated-exposure hazard, and Mohs hardness is 3.25 (Tydex)'
identity:
  formula: CdSe
  cas: 1306-24-7
  crystal_system: hexagonal wurtzite (Tydex, Wikipedia); a cubic sphalerite form is also noted by Wikipedia
  space_group: P63mc
  source: tydex-cdse
  where: Table 1, Crystal structure row (hexagonal, P63mc); CAS 1306-24-7 from the Stanford Advanced Materials SDS section 1 and the Wikipedia infobox
tags:
  environments: []
  stresses: []
  applications:
    - optics-and-cameras
    - electronics-and-chips
    - solar-arrays
properties:
  - benchmark: density
    label: Density (manufacturer)
    value: 5.81
    unit: g/cm3
    scope: material
    conditions:
      basis: temperature not stated
    method: Printed as Density, g/cm 3 in Table 1 of the Tydex sheet
    status: ground
    source: tydex-cdse
    where: Table 1, Density row
  - benchmark: density
    label: Density (supplier safety sheet)
    value: 5.81
    unit: g/cm3
    scope: material
    conditions:
      temperature: 20 °C
    method: Printed as Density at 20 °C (68 °F) in the safety sheet. It agrees with the Tydex figure
    status: ground
    source: stanford-cdse-sds
    where: Section 9, Density row
  - benchmark: melting_point
    label: Melting point (manufacturer)
    value: 1537
    unit: °C
    scope: material
    conditions:
      basis: value as printed, no test condition given
    method: Printed in Table 1 of the Tydex sheet. Wikipedia gives 1240 °C and the safety sheet gives more than 1350 °C, so the sources conflict and both Wikipedia and the Tydex value are kept with their sources
    status: ground
    source: tydex-cdse
    where: Table 1, Melting point row
  - benchmark: melting_point
    label: Melting point (Wikipedia)
    value: 1240
    unit: °C
    scope: material
    conditions:
      basis: value as printed in the infobox
    method: Printed in the Wikipedia infobox as 1,240 °C (2,260 °F; 1,510 K). It differs from the Tydex value of 1537 °C
    status: ground
    source: wiki-cdse
    where: Infobox, Melting point field
  - benchmark: refractive_index
    label: Refractive index, ordinary ray at 10 µm
    value: 2.431
    unit: '-'
    scope: material
    conditions:
      wavelength: 10 µm
      polarization: ordinary ray (no)
    method: Printed in Table 1 as no=2.431 at 10 µm. The extraordinary index at the same wavelength is in the next property
    status: ground
    source: tydex-cdse
    where: Table 1, Refractive indices row (no=2.431, ne=2.452 @10 µm)
  - benchmark: refractive_index
    label: Refractive index, extraordinary ray at 10 µm
    value: 2.452
    unit: '-'
    scope: material
    conditions:
      wavelength: 10 µm
      polarization: extraordinary ray (ne)
    method: Printed in Table 1 as ne=2.452 at 10 µm
    status: ground
    source: tydex-cdse
    where: Table 1, Refractive indices row (no=2.431, ne=2.452 @10 µm)
  - benchmark: refractive_index
    label: Refractive index (n_D)
    value: 2.5
    unit: '-'
    scope: material
    conditions:
      wavelength: not stated on the page (printed as n_D)
    method: Printed in the Wikipedia infobox as n_D = 2.5. The page gives no wavelength or polarisation, so this is a single rounded value and is shown for comparison only
    status: ground
    source: wiki-cdse
    where: Infobox, Refractive index (n_D) field
  - benchmark: transmission_range
    label: Transmission range, uncoated optical part
    value: 0.75
    value_high: 25.5
    bound: range
    unit: µm
    scope: material
    conditions:
      basis: monocrystalline optical grade; thickness not stated
    method: Printed in the Tydex text as transparent between 0.75 µm and 24.5 to 25.5 µm. The upper edge is printed as a band, so 25.5 is shown as value_high. The limit is set by lattice absorption, as stated by Tydex
    status: ground
    source: tydex-cdse
    where: Text, first paragraph (transparency range)
  - benchmark: band_gap
    label: Band gap
    value: 1.74
    unit: eV
    scope: material
    conditions:
      temperature: not stated
      form: hexagonal and sphalerite, as printed
    method: Printed in the Wikipedia infobox as 1.74 eV for both the hexagonal and sphalerite forms, with no temperature given
    status: ground
    source: wiki-cdse
    where: Infobox, Band gap field
  - benchmark: mohs_hardness
    label: Mohs hardness
    value: 3.25
    unit: '-'
    scope: material
    conditions:
      basis: as printed
    method: Printed as Mohs hardness in Table 1 of the Tydex sheet. No Knoop or Vickers value was read for CdSe in this run
    status: ground
    source: tydex-cdse
    where: Table 1, Mohs hardness row
  - benchmark: thermal_conductivity
    label: Thermal conductivity, parallel to c axis
    value: 6.9
    unit: W/(m × K)
    scope: material
    conditions:
      axis: parallel to c (||c)
      temperature: not stated
    method: Printed in Table 1 of the Tydex sheet as ||c = 6.9
    status: ground
    source: tydex-cdse
    where: Table 1, Thermal conductivity row
  - benchmark: thermal_conductivity
    label: Thermal conductivity, perpendicular to c axis
    value: 6.2
    unit: W/(m × K)
    scope: material
    conditions:
      axis: perpendicular to c (⊥c)
      temperature: not stated
    method: Printed in Table 1 of the Tydex sheet as ⊥c = 6.2
    status: ground
    source: tydex-cdse
    where: Table 1, Thermal conductivity row
  - benchmark: cte
    label: Thermal expansion coefficient, parallel to c axis
    value: 2.45
    unit: x10-6/K
    scope: material
    conditions:
      axis: parallel to c (||c)
      temperature: 25 °C
    method: Printed in Table 1 of the Tydex sheet as ||c = 2.45 x 10-6 K-1 at 25 °C
    status: ground
    source: tydex-cdse
    where: Table 1, Thermal expansion coefficients row
  - benchmark: cte
    label: Thermal expansion coefficient, perpendicular to c axis
    value: 4.4
    unit: x10-6/K
    scope: material
    conditions:
      axis: perpendicular to c (⊥c)
      temperature: 25 °C
    method: Printed in Table 1 of the Tydex sheet as ⊥c = 4.4 x 10-6 K-1 at 25 °C. The two axes expand differently, so orientation matters in a mount
    status: ground
    source: tydex-cdse
    where: Table 1, Thermal expansion coefficients row
  - benchmark: specific_heat
    label: Specific heat capacity
    value: 258
    unit: J/(kg × K)
    scope: material
    conditions:
      temperature: not stated
    method: Printed as Specific heat capacity, J/(kg × K) 258 in the Tydex property block
    status: ground
    source: tydex-cdse
    where: Property block beside the text, Specific heat capacity row
  - benchmark: dielectric_constant
    label: Dielectric constant, clamped, perpendicular to c axis
    value: 9.7
    unit: '-'
    scope: material
    conditions:
      temperature: 300 K
      axis: perpendicular to c (εT11/ε0)
    method: Printed in the Tydex property block as εT11/ε0 = 9.7 at 300 K
    status: ground
    source: tydex-cdse
    where: Property block, Dielectric constants (@300 K) row
  - benchmark: dielectric_constant
    label: Dielectric constant, clamped, parallel to c axis
    value: 10.65
    unit: '-'
    scope: material
    conditions:
      temperature: 300 K
      axis: parallel to c (εT33/ε0)
    method: Printed in the Tydex property block as εT33/ε0 = 10.65 at 300 K
    status: ground
    source: tydex-cdse
    where: Property block, Dielectric constants (@300 K) row
corrosion:
  - environment: Water
    headline: Insoluble in water.
    effect: Both the Tydex sheet and the safety sheet call cadmium selenide insoluble in water. Neither gives a solubility figure or a humidity ageing test.
    rating: low
    conditions:
      temperature: not stated
    source: stanford-cdse-sds
    where: Section 9, Solubility row (water insoluble)
  - environment: Hot nitric and phosphoric acid
    headline: Dissolves in hot nitric and phosphoric acid.
    effect: Tydex says the material is soluble in hot nitric and phosphoric acid. The safety sheet lists acids as incompatible, so acids can attack the surface and the bulk.
    rating: moderate
    conditions:
      temperature: hot, as printed; acid concentration not stated
    source: tydex-cdse
    where: Table 1, Solubility row
  - environment: Strong oxidising agents
    headline: Reacts with strong oxidising agents.
    effect: The safety sheet says the material reacts with strong oxidising agents and should be stored away from them. Decomposition in a fire gives toxic metal oxide fume and hydrogen selenide.
    rating: moderate
    conditions:
      basis: safety sheet reactivity statements
    source: stanford-cdse-sds
    where: Section 10 (Stability and reactivity) and Section 7 (storage)
  - environment: Air and long-term storage
    headline: No air, humidity or UV ageing data for bulk cadmium selenide was found in the sources read.
    effect: The safety sheet says the material is stable under recommended storage conditions. No oxidation rate, humidity test or long-term ageing result for bulk CdSe was read in this run.
    rating: unknown
    conditions:
      basis: recommended storage conditions only
    source: stanford-cdse-sds
    where: Section 10 (Chemical stability, stable under recommended storage conditions)
  - environment: Oxygen during heat treatment of PbSe films (related section)
    headline: Heat treatment in oxygen deliberately oxidises lead selenide layers, and the products depend on temperature.
    effect: A 2022 study says heat treatment in an oxygen-containing medium is needed to make lead chalcogenide photodetectors. It reports that the oxidation products depend on the starting composition and annealing temperature, and that metallic lead can form alongside PbO.
    rating: moderate
    conditions:
      basis: thermodynamic analysis and XRD and Raman study of chemical-bath PbSe layers, 20 to 500 °C
    source: pbse-micromachines-2022
    where: Abstract
  - environment: Air at room temperature (PbSe films and detectors)
    headline: No long-term air or humidity ageing test for PbSe detectors was found in the sources read.
    effect: The 2022 iodine-sensitisation study reports no ageing, long-term air-exposure or stability tests. The study cites excellent chemical stability as a general property of PbSe, but gives no test result for it.
    rating: unknown
    conditions:
      basis: no ageing data reported
    source: pbse-nanomaterials-2022
    where: Introduction and Section 3.1 (no ageing tests reported)
risks:
  hazards:
    - text: 'Signal word Danger. H301 and H331: toxic if swallowed or inhaled. H373: may cause damage to organs through prolonged or repeated exposure. Route of exposure: oral and inhalation.'
      ghs:
        - H301
        - H331
        - H373
      source: stanford-cdse-sds
      where: Section 2 (Hazard identification)
    - text: The Wikipedia infobox also lists H312 and H410, with GHS06, GHS08 and GHS09 pictograms. The safety sheet does not print H312 or H410, so the two sources differ on these codes.
      ghs:
        - H312
        - H410
      source: wiki-cdse
      where: Infobox (GHS hazard statements)
    - text: The safety sheet lists IARC group 1 (carcinogenic to humans), ACGIH A2 (suspected human carcinogen) and OSHA carcinogen status for the material.
      ghs: []
      source: stanford-cdse-sds
      where: Section 11 (Carcinogenicity)
    - text: Exposure limit of 0.2 mg/m3 as Se (PEL and REL, long-term). The safety sheet asks for a properly operating chemical fume hood designed for hazardous chemicals.
      ghs: []
      source: stanford-cdse-sds
      where: Section 8 (Exposure controls)
  failure_risks:
    - mode: Reaction with oxidising agents or acids
      trigger: Contact with strong oxidisers, or hot nitric or phosphoric acid
      consequence: The surface and bulk can be attacked. The safety sheet says it reacts with strong oxidisers, and Tydex says it dissolves in hot nitric and phosphoric acid.
      severity: moderate
      source: stanford-cdse-sds
      where: Section 10 (Reactivity) and Table 1 solubility row (Tydex)
    - mode: Toxic fume in a fire
      trigger: Heating in a fire, or thermal decomposition
      consequence: Decomposition gives toxic metal oxide fume and hydrogen selenide, according to the safety sheet.
      severity: high
      source: stanford-cdse-sds
      where: Section 10 (Hazardous decomposition products)
    - mode: Surface scratching and abrasion
      trigger: Contact with hard particles, clamps or polishing grit
      consequence: Mohs hardness is 3.25 (Tydex), so the faces mark easily and a scratched optic loses transmission.
      severity: moderate
      source: tydex-cdse
      where: Table 1, Mohs hardness row
    - mode: Strain from unequal expansion
      trigger: Heating or cooling a part that is bonded or clamped in a mount
      consequence: The two axes expand by 2.45 and 4.4 x10-6/K at 25 °C (Tydex), so a rigid mount can strain the crystal. This is an inference from the printed coefficients, not a tested failure.
      severity: low
      source: tydex-cdse
      where: Table 1, Thermal expansion coefficients row
  side_effects:
    - text: Dust from powder handling or cutting is an exposure route, and the safety sheet asks for fume-hood use and exposure control (section 8).
      affects: People working near machining or spills, and the work area
      source: stanford-cdse-sds
      where: Section 8 (Exposure controls)
  handling:
    - text: Work in a properly operating chemical fume hood designed for hazardous chemicals, with an average face velocity of at least 100 feet per minute (safety sheet section 8).
      source: stanford-cdse-sds
      where: Section 8 (Additional information about design of technical systems)
    - text: Store away from oxidising agents (safety sheet section 7).
      source: stanford-cdse-sds
      where: Section 7 (Storage)
    - text: Transport and disposal are under UN3077, environmentally hazardous substances, solid, n.o.s. (cadmium selenide), according to the safety sheet.
      source: stanford-cdse-sds
      where: Section 14 (Transport information)
  mitigations:
    - text: Use a fume hood, keep the material away from acids and oxidising agents, and control dust (safety sheet sections 8 and 10).
      source: stanford-cdse-sds
      where: Sections 8 and 10
uses:
  - application: optics-and-cameras
    device: Near- and mid-infrared optical parts and waveplates
    example: Tydex says parts of cadmium selenide can be used in the near and mid-infrared, and that the hexagonal crystal is birefringent for some orientations, so it can make waveplates of various orders. It also says the material is virtually the only one birefringent between 16 and 24 µm.
    source: tydex-cdse
    where: Text, opening paragraphs
  - application: optics-and-cameras
    device: Nonlinear optical converters and parametric oscillators at high radiation load
    example: Tydex says the low absorption of cadmium selenide makes its crystals suitable for nonlinear optical converters and parametric oscillators where the radiation load is high.
    source: tydex-cdse
    where: Text, paragraph after the transmission figure
  - application: electronics-and-chips
    device: Optoelectronic devices and quantum-dot displays and imaging
    example: The USGS says CdSe is used in optoelectronic applications, and that quantum dots made from CdSe were used in displays and medical imaging equipment.
    source: usgs-mcs2026-cadmium
    where: Events, Trends, and Issues
  - application: solar-arrays
    device: n-type layer in photovoltaic cells
    example: Wikipedia says CdSe can serve as the n-type semiconductor layer in photovoltaic cells. The article adds that pigment uses are declining because of environmental concerns.
    source: wiki-cdse
    where: Article, uses section (paraphrased)
supply:
  - subject: Cadmium
    producers:
      - country: China
        share_percent: 41.3
        year: 2025
      - country: Korea
        share_percent: 18.7
        year: 2025
      - country: Japan
        share_percent: 5.7
        year: 2025
      - country: Canada
        share_percent: 5.7
        year: 2025
      - country: Kazakhstan
        share_percent: 4.8
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (cadmium not named)
        listed: false
      - list: EU critical raw materials list of 34 (cadmium not named)
        listed: false
    recycling: 'USGS: secondary cadmium is mainly recovered from spent consumer and industrial NiCd batteries. Other scrap includes CdTe solar panels and cadmium-containing electric-arc furnace dust.'
    substitutes:
      - 'USGS, for cadmium uses generally (not for CdSe optics): other battery chemistries such as lithium-ion can replace NiCd, zinc-nickel can replace cadmium plating, and cerium sulfide can replace cadmium pigments.'
    source: usgs-mcs2026-cadmium
    where: World Refinery Production and Reserves table, 2025e (world total 23000 t, rounded; shares calculated by Space Mushroom); Recycling; Substitutes. Critical lists from the USGS 2025 list page and the EU page
  - subject: Selenium
    abundance: 0.05 ppm in the Earth's crust (USGS PP 1802-A, Table A1)
    producers:
      - country: China
        share_percent: 52.6
        year: 2025
      - country: Japan
        share_percent: 16.8
        year: 2025
      - country: Russia
        share_percent: 8.4
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (selenium not named)
        listed: false
      - list: EU critical raw materials list of 34 (selenium not named)
        listed: false
    recycling: 'USGS: recycling is insignificant. Most scrap from electronic materials was exported for recovery of its selenium.'
    substitutes:
      - 'USGS: amorphous silicon and cadmium telluride compete with CIGS in thin-film solar cells; silicon replaces selenium in low- and medium-voltage rectifiers; bismuth and tellurium replace selenium in free-machining alloys.'
    source: usgs-mcs2026-selenium
    where: World Refinery Production and Capacity table, 2025e (world total 3800 t, selenium content; shares calculated by Space Mushroom); Recycling; Substitutes
  - subject: Lead (for the related PbSe section)
    producers:
      - country: China
        share_percent: 42.2
        year: 2025
      - country: Australia
        share_percent: 10.7
        year: 2025
      - country: Peru
        share_percent: 6.4
        year: 2025
      - country: United States
        share_percent: 6.2
        year: 2025
      - country: Russia
        share_percent: 5.8
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals (lead named)
        listed: true
      - list: EU critical raw materials list of 34 (lead not named)
        listed: false
    recycling: 'USGS: about 1 million tons of secondary lead was produced in 2025, equal to 70% of apparent domestic consumption. Nearly all of it came from old scrap, mostly lead-acid batteries.'
    substitutes:
      - 'USGS: plastics have replaced lead in cable covering and cans, tin has replaced lead in potable-water solder, lead-free solders are used in electronics, and steel and zinc replace lead in wheel weights.'
    source: usgs-mcs2026-lead
    where: World Mine Production and Reserves table, 2025e (world total 4500 thousand t, rounded; shares calculated by Space Mushroom); Recycling; Substitutes; critical lists from the USGS 2025 page and the EU page
media: []
documents:
  - title: 'Tydex: Cadmium Selenide (optical-grade monocrystalline CdSe, Table 1)'
    type: datasheet
    url: https://www.tydexoptics.com/pdf/Cadmium_Selenide.pdf
    year: 2026
  - title: 'Cadmium Selenide: Safety Data Sheet (Stanford Advanced Materials, CAS 1306-24-7)'
    type: sds
    url: https://samaterials.com/tds/1697119137-1116-cadmium-selenide-powder-sds.pdf
    year: 2022
  - title: 'Lead Selenide: Safety Data Sheet (Stanford Advanced Materials, CAS 12069-00-0)'
    type: sds
    url: https://samaterials.com/tds/1697120005-849-lead-selenide-evaporation-materials-sds.pdf
    year: 2023
  - title: 'USGS Mineral Commodity Summaries 2026: Cadmium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-cadmium.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Lead'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lead.pdf
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Selenium'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-selenium.pdf
    year: 2026
  - title: USGS Professional Paper 1802-A, Table A1 (crustal abundance)
    type: report
    url: https://pubs.usgs.gov/pp/1802/a/pp1802a.pdf
    year: 2017
  - title: Promoted Mid-Infrared Photodetection of PbSe Film by Iodine Sensitization Based on Chemical Bath Deposition (Nanomaterials, 2022)
    type: paper
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC9105836/
    year: 2022
  - title: Thermodynamic Analysis and Experimental Study on the Oxidation of PbX (X = S, Se) Nanostructured Layers (Micromachines, 2022)
    type: paper
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC9412640/
    year: 2022
gaps:
  - 'No Crystran CdSe page was read: the Crystran cadmium selenide product URL returned 404 in this run, so Tydex is the main optical source.'
  - No Knoop hardness, Young's modulus or Poisson ratio for CdSe was found. Tydex gives Mohs hardness 3.25 and elastic constants (C11 74.1 GPa, C33 83.6 GPa, C44 13.17 GPa, C12 45.2 GPa, C13 39.3 GPa at 298 K), which are not in the property list because the canonical names do not fit them.
  - No radiation, proton, UV-dose, atomic-oxygen or flight result for bulk CdSe or PbSe was found in a source read in this run.
  - 'The melting point of CdSe conflicts across sources: Tydex 1537 °C, Wikipedia 1240 °C, and the safety sheet gives more than 1350 °C. All three are kept with their sources.'
  - 'The hazard codes for CdSe differ: the safety sheet prints H301, H331 and H373 only, and Wikipedia adds H312 and H410. Neither is verified against an EU C&L or ECHA record in this run.'
  - No air, humidity or long-term ageing test for bulk CdSe was found. A 2014 RSC Advances paper on CdSe in air could not be opened (403).
  - The cadmium row was not located in the USGS PP 1802-A Table A1 text read in this run, so no cadmium crustal abundance is given.
  - No photographs were collected, so the media list is empty.
  - PubChem was not opened in this run, so no PubChem GHS summary is used.
  - The atomic weights of cadmium and selenium were not read, so the recipe gives no atomic weights.
  - The PbSe related section has no bulk PbSe optical data (refractive index, transmission, absorption) from a source read in this run.
  - The ACAL BFi PbSe detector page returned 403, so no detectivity (D*) figure is given for the PbSe detectors.
  - 'The PbSe hazard codes differ: the safety sheet prints H300 and H330 (fatal), H360 and H373, while Wikipedia lists H301, H302, H331, H332, H360, H373 and H410.'
  - No long-term air or humidity ageing test for PbSe detectors was found in the sources read.
  - The lead crustal abundance row was not located in the USGS PP 1802-A Table A1 text read in this run.
sources:
  tydex-cdse:
    title: 'Tydex: Cadmium Selenide (optical-grade monocrystalline CdSe, Table 1 and text)'
    id: Tydex CdSe sheet (undated; read 2026-10-26)
    url: https://www.tydexoptics.com/pdf/Cadmium_Selenide.pdf
    year: 2026
    kind: datasheet
    license: supplier document, linked not reproduced
  wiki-cdse:
    title: 'Cadmium selenide (Wikipedia article: infobox, uses, production, hazard statements)'
    id: Wikipedia (undated; read 2026-10-26)
    url: https://en.wikipedia.org/wiki/Cadmium_selenide
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (Wikipedia)
  stanford-cdse-sds:
    title: 'Cadmium Selenide: Safety Data Sheet (Stanford Advanced Materials, CAS 1306-24-7)'
    id: revised 26/11/2022; accessed 25/08/2023
    url: https://samaterials.com/tds/1697119137-1116-cadmium-selenide-powder-sds.pdf
    year: 2022
    kind: datasheet
    license: supplier document, linked not reproduced
  stanford-pbse-sds:
    title: 'Lead Selenide: Safety Data Sheet (Stanford Advanced Materials, CAS 12069-00-0)'
    id: revised 19/01/2023; accessed 25/08/2023
    url: https://samaterials.com/tds/1697120005-849-lead-selenide-evaporation-materials-sds.pdf
    year: 2023
    kind: datasheet
    license: supplier document, linked not reproduced
  wiki-pbse:
    title: 'Lead(II) selenide (Wikipedia article: infobox, uses, band gap, detection range, hazard statements)'
    id: Wikipedia (undated; read 2026-10-26)
    url: https://en.wikipedia.org/wiki/Lead(II)_selenide
    year: 2026
    kind: web
    license: CC BY-SA 4.0 (Wikipedia)
  pbse-nanomaterials-2022:
    title: Promoted Mid-Infrared Photodetection of PbSe Film by Iodine Sensitization Based on Chemical Bath Deposition
    id: Nanomaterials (Basel) 2022, 12(9), 1391
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC9105836/
    year: 2022
    kind: paper
    license: open access (PubMed Central)
  pbse-micromachines-2022:
    title: Thermodynamic Analysis and Experimental Study on the Oxidation of PbX (X = S, Se) Nanostructured Layers
    id: Micromachines, 2022 Jul 29
    url: https://pmc.ncbi.nlm.nih.gov/articles/PMC9412640/
    year: 2022
    kind: paper
    license: open access (PubMed Central)
  usgs-mcs2026-cadmium:
    title: Mineral Commodity Summaries 2026, Cadmium
    id: USGS MCS 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-cadmium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-lead:
    title: Mineral Commodity Summaries 2026, Lead
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-lead.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-selenium:
    title: Mineral Commodity Summaries 2026, Selenium
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-selenium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-pp1802a:
    title: Critical Mineral Resources of the United States - An Introduction (Professional Paper 1802-A), Table A1, crustal abundances
    id: USGS PP 1802-A
    url: https://pubs.usgs.gov/pp/1802/a/pp1802a.pdf
    year: 2017
    kind: report
    license: public domain (USGS)
  usgs-crit2025:
    title: About the 2025 List of Critical Minerals (USGS, final list of 60 minerals)
    id: Final 2025 List of Critical Minerals, November 2025
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
    kind: web
    license: public domain (USGS)
  ec-crm:
    title: Critical raw materials (European Commission, list of 34 critical raw materials)
    id: Regulation (EU) 2024/1252
    url: https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en
    year: 2024
    kind: web
    license: European Commission web page
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 17
  unreachable: 3
  caveats: 3
  note: 'Written by an AI assistant on 2026-10-26 from pages and PDFs read in the same run. Unreachable: the Crystran CdSe page (404), the ACAL BFi PbSe detector page (403) and the RSC Advances CdSe paper (403). Caveats: CdSe melting point differs across three sources; CdSe and PbSe hazard codes differ between sources; no bulk ageing data for CdSe or PbSe in air.'
related:
  id: lead-selenide
  name: Lead selenide (mid-infrared photodetector material)
  formula: PbSe
  cas: 12069-00-0
  role: uncooled mid-infrared photoconductive film for detectors and thermal imaging
  summary: Lead selenide is a grey compound of lead and selenium with a cubic halite (rock-salt) structure, and its molar mass is 286.16 g/mol (Wikipedia). It has a direct band gap of 0.27 eV at room temperature. Wikipedia says it is used to make infrared detectors for thermal imaging, and that it detects wavelengths from 1.5 to 5.2 µm. A 2022 study of iodine-sensitised films reports room-temperature mid-infrared response from 2250 to 5000 nm, with responsivity of 0.237 A/W at 2250 nm and 0.053 A/W at 5000 nm. Its supplier safety sheet classes it as fatal if swallowed or inhaled and as a reproductive toxicant.
  properties:
    - benchmark: melting_point
      label: Melting point (Wikipedia)
      value: 1078
      unit: °C
      scope: material
      conditions:
        basis: value as printed in the infobox
      method: Printed in the Wikipedia infobox as 1,078 °C (1,972 °F; 1,351 K). The safety sheet gives 1065 °C
      status: ground
      source: wiki-pbse
      where: Infobox, Melting point field
    - benchmark: melting_point
      label: Melting point (supplier safety sheet)
      value: 1065
      unit: °C
      scope: material
      conditions:
        basis: value as printed in the safety sheet
      method: Printed as Melting point/Melting range 1065 °C (1949 °F) in the lead selenide safety sheet. It differs from the Wikipedia value of 1078 °C
      status: ground
      source: stanford-pbse-sds
      where: Section 9, Melting point row
    - benchmark: density
      label: Density (supplier safety sheet)
      value: 8.1
      unit: g/cm3
      scope: material
      conditions:
        temperature: 20 °C
      method: Printed as Density at 20 °C (68 °F) 8.1 g/cm3 in the safety sheet
      status: ground
      source: stanford-pbse-sds
      where: Section 9, Density row
    - benchmark: band_gap
      label: Band gap, direct, at room temperature
      value: 0.27
      unit: eV
      scope: material
      conditions:
        temperature: room temperature
      method: Printed in the Introduction of the 2022 Nanomaterials study as a direct band gap of 0.27 eV at room temperature. Wikipedia also gives 0.27 eV
      status: ground
      source: pbse-nanomaterials-2022
      where: Introduction, first paragraph
    - benchmark: detection_wavelength_range
      label: Detection range (Wikipedia)
      value: 1.5
      value_high: 5.2
      bound: range
      unit: µm
      scope: material
      conditions:
        basis: detector film, no test condition given
      method: Printed in the Wikipedia article text as detecting wavelengths from 1.5 to 5.2 µm. The article says it can be extended beyond 6 µm under special conditions
      status: ground
      source: wiki-pbse
      where: Article text, detector paragraph
    - benchmark: detection_wavelength_range
      label: Mid-infrared response of iodine-sensitised film
      value: 2250
      value_high: 5000
      bound: range
      unit: nm
      scope: material
      conditions:
        basis: iodine-sensitised PbSe film by chemical bath deposition; room temperature, as stated
      method: Printed in the Introduction as a mid-infrared detection capability from 2250 to 5000 nm. Section 3.1 gives a broad absorption range of 1000 to 25000 nm for PbSe films
      status: ground
      source: pbse-nanomaterials-2022
      where: Introduction (mid-infrared detection range)
    - benchmark: responsivity
      label: Responsivity at 2250 nm (iodinated film T30)
      value: 0.237
      unit: A/W
      scope: cell
      conditions:
        wavelength: 2250 nm
        film: I2-PbSe-T30
      method: Printed in Section 3.2 as responsive at 2250 nm with a responsivity of 0.237 A/W
      status: ground
      source: pbse-nanomaterials-2022
      where: Section 3.2 (responsivity)
    - benchmark: responsivity
      label: Responsivity at 5000 nm (iodinated film)
      value: 0.053
      unit: A/W
      scope: cell
      conditions:
        wavelength: 5000 nm
      method: Printed in Section 3.2 as a responsivity of 0.053 A/W at 5000 nm
      status: ground
      source: pbse-nanomaterials-2022
      where: Section 3.2 (responsivity)
    - benchmark: rise_time
      label: Rise time of iodinated film
      value: 2.1
      unit: s
      scope: cell
      conditions:
        wavelength: 808 nm
        irradiance: 50 mW/cm2
        bias: 1 V
      method: Printed in Section 3.2 as a rise time of about 2.1 s and a decay time of about 2.3 s for the device at 808 nm, 50 mW/cm2 and 1 V
      status: ground
      source: pbse-nanomaterials-2022
      where: Section 3.2 (response speed)
    - benchmark: decay_time
      label: Decay time of iodinated film
      value: 2.3
      unit: s
      scope: cell
      conditions:
        wavelength: 808 nm
        irradiance: 50 mW/cm2
        bias: 1 V
      method: Printed in Section 3.2 with the rise time of 2.1 s, at 808 nm, 50 mW/cm2 and 1 V
      status: ground
      source: pbse-nanomaterials-2022
      where: Section 3.2 (response speed)
  hazards:
    - text: The safety sheet classes lead selenide with H300 and H330 (fatal if swallowed or if inhaled), H360 (may damage fertility or the unborn child) and H373 (may cause damage to organs through prolonged or repeated exposure).
      ghs:
        - H300
        - H330
        - H360
        - H373
      source: stanford-pbse-sds
      where: Section 2 (Hazard identification)
    - text: Wikipedia lists H301, H302, H331, H332, H360, H373 and H410, with GHS06, GHS07, GHS08 and GHS09 pictograms. The sheet and the article disagree on the acute codes.
      ghs:
        - H301
        - H302
        - H331
        - H332
        - H360
        - H373
        - H410
      source: wiki-pbse
      where: Infobox (hazard statements)
  uses:
    - application: electronics-and-chips
      device: Uncooled mid-infrared photodetectors for thermal imaging
      example: Wikipedia says lead selenide is used to make infrared detectors for thermal imaging, and that it has high detectivity at room temperature, which is the basis for uncooled operation.
      source: wiki-pbse
      where: Article, uses section (paraphrased)
    - application: optics-and-cameras
      device: Iodine-sensitised PbSe film detector, 2250 to 5000 nm
      example: A 2022 study reports a room-temperature mid-infrared film with responsivity of 0.237 A/W at 2250 nm and 0.053 A/W at 5000 nm, and a rise time of about 2.1 s.
      source: pbse-nanomaterials-2022
      where: Section 3.2
story:
  recipe:
    line: CdSe is a 1:1 compound of cadmium and selenium. Tydex says the optical crystals are grown from the vapour phase. Wikipedia says bulk crystals are grown by the high-pressure vertical Bridgman method, and that nanoparticles can be made by solution precipitation, high-temperature pyrolysis and other routes.
    parts:
      - name: Cadmium
        symbol: Cd
        role: Cation in the lattice. In the Wikipedia nanoparticle routes it is supplied as an alkylcadmium precursor.
      - name: Selenium
        symbol: Se
        role: Anion in the lattice. In the Wikipedia nanoparticle routes it is supplied as trioctylphosphine selenide.
  risk_groups:
    - title: For people
      level: 0
      verdict: Toxic if swallowed or inhaled
      lead: The supplier safety sheet classes cadmium selenide as toxic, with a repeated-exposure hazard, and lists it under several carcinogen classifications.
      points:
        - label: The powder
          line: The sheet has the signal word Danger, with H301 and H331 (toxic if swallowed or inhaled) and H373 (may cause damage to several organs through prolonged or repeated exposure).
        - label: Cancer classes
          line: The sheet lists IARC group 1 (carcinogenic to humans), ACGIH A2 (suspected human carcinogen) and OSHA carcinogen status (section 11).
        - label: In a fire
          line: Decomposition gives toxic metal oxide fume and hydrogen selenide (section 10).
    - title: Handling and storage
      points:
        - label: Ventilation
          line: Use a properly operating chemical fume hood designed for hazardous chemicals, with an average face velocity of at least 100 feet per minute (section 8).
        - label: Storage
          line: Store away from oxidising agents, and keep the material away from acids (sections 7 and 10).
    - title: Mechanical and thermal limits
      points:
        - label: Softness
          line: Mohs hardness is 3.25 (Tydex), so the faces mark easily. Keep hard particles and clamps away from the optical faces.
        - label: Expansion
          line: 'The expansion coefficient differs by axis: 2.45 x10-6/K parallel to c and 4.4 x10-6/K perpendicular to c at 25 °C (Tydex).'
  why: Cadmium selenide transmits from about 0.75 µm to about 25 µm and is birefringent in the mid-infrared, which Tydex says makes it useful for waveplates and nonlinear optics. Its band gap of 1.74 eV (Wikipedia) and its photoconductive and luminescent behaviour explain its use in light-sensitive resistors, quantum dots and photovoltaic layers. Its toxicity, softness and reactivity with oxidisers set the handling limits.
  uses:
    - where: Near- and mid-infrared optics and waveplates
      line: Tydex says CdSe is birefringent for some orientations, so it can make waveplates, and that it is virtually the only material birefringent between 16 and 24 µm.
    - where: Nonlinear optics
      line: Tydex says the low absorption suits CdSe crystals in nonlinear optical converters and parametric oscillators where the radiation load is high.
    - where: Quantum dots, displays and imaging
      line: The USGS says CdSe is used in optoelectronic applications, and that quantum dots made from CdSe were used in displays and medical imaging equipment.
  can_do:
    - label: Infrared transmission
      benchmark: transmission_range
      value: 0.75 to 25.5 µm
      line: Tydex gives transparency from 0.75 µm to a band of 24.5 to 25.5 µm, with the upper limit set by lattice absorption.
    - label: Birefringence
      benchmark: refractive_index
      value: no 2.431, ne 2.452 at 10 µm
      line: Tydex prints the ordinary and extraordinary indices at 10 µm, which gives the birefringence that waveplates need.
    - label: Band gap
      benchmark: band_gap
      value: 1.74 eV
      line: Wikipedia gives 1.74 eV for both the hexagonal and sphalerite forms, with no temperature stated.
  compare: Cadmium selenide is hexagonal and birefringent for some orientations (Tydex), so it can make waveplates, which an isotropic cubic optic cannot. Its Mohs hardness is 3.25 (Tydex), which makes it a soft material to polish and mount. Its supplier sheet classes it as toxic (H301, H331, H373). No cost or availability comparison with other infrared materials was read in this run.
  compare_rows:
    - label: Transmission range
      benchmark: transmission_range
    - label: Refractive index
      benchmark: refractive_index
    - label: Thermal conductivity
      benchmark: thermal_conductivity
  handling:
    - Work in a fume hood designed for hazardous chemicals, and keep dust out of the work area.
    - Store away from oxidising agents and acids, in a sealed container.
    - Transport and disposal are under UN3077, environmentally hazardous substances, solid (safety sheet section 14).
  good_for:
    - Birefringent infrared parts and waveplates across 0.75 µm to about 25 µm (Tydex).
    - Nonlinear optical converters and parametric oscillators where the radiation load is high (Tydex).
  watch_out:
    - Toxicity. The safety sheet classes the material as toxic if swallowed or inhaled, with H373 for repeated exposure.
    - Softness. Mohs hardness is 3.25, so the faces scratch easily (Tydex).
    - Oxidisers and acids. The material reacts with strong oxidising agents and dissolves in hot nitric and phosphoric acid (Tydex, safety sheet).
  verdict: Cadmium selenide is a birefringent infrared crystal that transmits to about 25 µm, which makes it a choice for waveplates and nonlinear optics in the long-wave infrared. Its cadmium and selenium content, soft surface and reactivity with oxidisers mean it needs fume-hood handling and protected mounting. Lead selenide, covered in the related section, is the mid-infrared photodetector counterpart.