spore: profile
id: zinc-sulphide
spore_version: 0.2
family: optical-crystals
name: Zinc sulphide (CVD multispectral and IR grades)
abbreviation: ZnS
role: infrared window and dome material, and electroluminescent phosphor base
category: glasses-optics
type: optical-crystals
summary: |
  Zinc sulphide is made by reacting zinc vapour with hydrogen sulphide gas, which deposits it as sheets on graphite substrates (chemical vapour deposition, CVD). Crystran gives a transmission range of 0.37 to 13.5 µm and a density of 4.09 g/cm3 for its multispectral grade. Tydex says its water-clear multispectral grade is hot isostatically pressed (HIP) and transmits from 0.4 to 12 µm, while its IR grade is used in the 8 to 12 µm region. Crystran's safety sheet lists the solid as harmful if swallowed or inhaled, while its own section 15 says it is not classified under EU CLP. Copper-activated zinc sulphide is also the basis of electroluminescent phosphors used in LCD backlights and dashboard lighting.
best_for: IR windows and lenses in the 8 to 12 µm thermal band that must also pass visible light (water-clear multispectral grade transmits 0.4 to 12 µm)
weakest_at: 'Softness and a 250 °C use limit in air: Crystran says windows should not be used above 250 °C in normal atmosphere, and the material oxidises at 300 °C'
identity:
  formula: ZnS
  cas: 1314-98-3
  crystal_system: cubic (zinc blende) for the CVD material; wurtzite is the hexagonal form
  space_group: F42m (printed by Crystran as HIP polycrystalline cubic, ZnS, F42m)
  source: crystran-zns-product
  where: Product data table, Class/Structure row; CAS 1314-98-3 from crystran-zns-msds section 3.1; cubic and wurtzite forms from the Wikipedia infobox and text
tags:
  environments:
    - low-earth-orbit
  stresses: []
  applications:
    - optics-and-cameras
    - electronics-and-chips
properties:
  - benchmark: density
    label: Density, multispectral grade
    value: 4.09
    unit: g/cm3
    scope: material
    conditions:
      form: CVD, HIP multispectral grade
      temperature: not stated
    method: Value printed on a manufacturer product data page as 4.09 g/cc
    status: ground
    source: crystran-zns-product
    where: Product data table, Density row
  - benchmark: density
    label: Specific gravity, multispectral safety sheet
    value: 4.08
    unit: g/cm3
    scope: material
    conditions:
      form: zinc sulphide, multispectral grade
    method: Value printed in a safety data sheet as 4.08 g/mL
    status: ground
    source: crystran-zns-msds
    where: Section 9.1, SPECIFIC GRAVITY row
  - benchmark: melting_point
    label: Melting point, product data page
    value: 1827
    unit: °C
    scope: material
    conditions:
      form: multispectral grade
    method: Value printed on a manufacturer product data page
    status: ground
    note: The page cross-references a References and Notes section that has no melting-point note. The safety sheet prints 1830 C and notes that the material sublimes at 1185 C.
    source: crystran-zns-product
    where: Product data table, Melting Point row
  - benchmark: melting_point
    label: Melting point, safety sheet
    value: 1830
    unit: °C
    scope: material
    conditions:
      form: zinc sulphide, multispectral grade
    method: Value printed in a safety data sheet
    status: ground
    note: The same row says 1185 C sublimes. The footnote says it oxidises at 300 C, plastically deforms at 500 C and dissociates at about 700 C.
    source: crystran-zns-msds
    where: Section 9.1, MELTING POINT row and footnote
  - benchmark: knoop_hardness
    label: Knoop hardness, multispectral grade (50 g indenter)
    value: 160
    unit: kg/mm2
    scope: material
    conditions:
      indenter: 50 g
      grade: MS-ZnS, CVD then HIP
    method: Value printed in a manufacturer characteristics table
    status: ground
    note: Crystran prints Knoop 240 for the same grade, but with no unit, so that value is not entered. Tydex gives 160 for MS-ZnS and 200 to 230 for IR-ZnS.
    source: tydex-cvd-zns
    where: Physical and Chemical Properties table, Hardness (Knoop, indentor 50 g) row, MS-ZnS column
  - benchmark: knoop_hardness
    label: Knoop hardness, IR grade (50 g indenter), range
    value: 200
    value_high: 230
    bound: range
    unit: kg/mm2
    scope: material
    conditions:
      indenter: 50 g
      grade: IR-ZnS, CVD
    method: Range printed in a manufacturer characteristics table
    status: ground
    source: tydex-cvd-zns
    where: Physical and Chemical Properties table, Hardness (Knoop, indentor 50 g) row, IR-ZnS column
  - benchmark: elastic_modulus
    label: Young's modulus, product data page
    value: 74.5
    unit: GPa
    scope: material
    conditions:
      form: multispectral grade
      temperature: not stated
    method: Value printed on a manufacturer product data page
    status: ground
    source: crystran-zns-product
    where: Product data table, Youngs Modulus (E) row
  - benchmark: elastic_modulus
    label: Young's modulus, Tydex
    value: 74.5
    unit: GPa
    scope: material
    conditions:
      form: CVD zinc sulphide, one value printed across both grades
    method: Value printed in a manufacturer characteristics table
    status: ground
    source: tydex-cvd-zns
    where: Physical and Chemical Properties table, Youngs Modulus (E) row
  - benchmark: poissons_ratio
    label: Poisson's ratio, product data page
    value: 0.28
    unit: '-'
    scope: material
    conditions:
      form: multispectral grade
    method: Value printed on a manufacturer product data page
    status: ground
    source: crystran-zns-product
    where: Product data table, Poisson Ratio row
  - benchmark: poissons_ratio
    label: Poisson's ratio, MS-ZnS (Tydex)
    value: 0.28
    unit: '-'
    scope: material
    conditions:
      grade: MS-ZnS
    method: Value printed in a manufacturer characteristics table
    status: ground
    source: tydex-cvd-zns
    where: Physical and Chemical Properties table, Poisson Ratio row, MS-ZnS column
  - benchmark: poissons_ratio
    label: Poisson's ratio, IR-ZnS (Tydex)
    value: 0.29
    unit: '-'
    scope: material
    conditions:
      grade: IR-ZnS
    method: Value printed in a manufacturer characteristics table
    status: ground
    source: tydex-cvd-zns
    where: Physical and Chemical Properties table, Poisson Ratio row, IR-ZnS column
  - benchmark: flexural_strength
    label: Modulus of rupture, MS-ZnS at 298 K
    value: 68.9
    unit: MPa
    scope: material
    conditions:
      temperature: 298 K
      grade: MS-ZnS
    method: Value printed in a manufacturer characteristics table as Modulus of Rupture; the test method is not stated
    status: ground
    note: The Tydex table also prints 160 MPa at 933 K for both grades. That value is not used here.
    source: tydex-cvd-zns
    where: Physical and Chemical Properties table, Modulus of Rupture row at 298 K, MS-ZnS column
  - benchmark: flexural_strength
    label: Modulus of rupture, IR-ZnS at 298 K
    value: 103.4
    unit: MPa
    scope: material
    conditions:
      temperature: 298 K
      grade: IR-ZnS
    method: Value printed in a manufacturer characteristics table as Modulus of Rupture; the test method is not stated
    status: ground
    source: tydex-cvd-zns
    where: Physical and Chemical Properties table, Modulus of Rupture row at 298 K, IR-ZnS column
  - benchmark: thermal_conductivity
    label: Thermal conductivity, multispectral grade at 298 K
    value: 27.2
    unit: W/(m·K)
    scope: material
    conditions:
      temperature: 298 K
      grade: multispectral
    method: Value printed on a manufacturer product data page as 27.2 W m-1 K-1 @ 298 K
    status: ground
    source: crystran-zns-product
    where: Product data table, Thermal Conductivity row
  - benchmark: cte
    label: Thermal expansion, multispectral grade at 273 K
    value: 6.5
    unit: ppm/K
    scope: material
    conditions:
      temperature: 273 K
      grade: multispectral
    method: Value printed on a manufacturer product data page as 6.5 x 10-6 per °C @ 273 K
    status: ground
    source: crystran-zns-product
    where: Product data table, Thermal Expansion row
  - benchmark: specific_heat
    label: Specific heat capacity, product data page
    value: 515
    unit: J/(kg·K)
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on a manufacturer product data page
    status: ground
    note: Tydex prints 0.124 J/(g K) for MS-ZnS, which is 124 J/(kg K). The two sources disagree by more than a factor of four, so both are kept with their source.
    source: crystran-zns-product
    where: Product data table, Specific Heat Capacity row
  - benchmark: specific_heat
    label: Specific heat capacity, MS-ZnS (Tydex)
    value: 0.124
    unit: J/(g·K)
    scope: material
    conditions:
      temperature: 298 K
      grade: MS-ZnS
    method: Value printed in a manufacturer characteristics table
    status: ground
    note: Disagrees with the Crystran value of 515 J/(kg K). Tydex gives 0.112 J/(g K) for IR-ZnS.
    source: tydex-cvd-zns
    where: Physical and Chemical Properties table, Heat Capacity at 298 K row, MS-ZnS column
  - benchmark: refractive_index
    label: Refractive index at 10 µm, product data page
    value: 2.20084
    unit: '-'
    scope: material
    conditions:
      wavelength: 10 µm
    method: Value printed on a manufacturer product data page
    status: ground
    note: Crystran cites the 1984 Applied Optics paper by Debenham (NPL) for the refractive index of zinc sulphide from 0.405 to 13 µm.
    source: crystran-zns-product
    where: Refractive index table, row 10.00 µm
  - benchmark: refractive_index
    label: Refractive index at 10 µm, MS-ZnS (Tydex)
    value: 2.2008
    unit: '-'
    scope: material
    conditions:
      wavelength: 10.0 µm
      grade: MS-ZnS
    method: Value printed in a manufacturer refractive index table
    status: ground
    source: tydex-cvd-zns
    where: Refractive Index table, 10.0 row, MS-ZnS column
  - benchmark: optical_transmission_range
    label: Transmission range, multispectral grade
    value: 0.37
    value_high: 13.5
    bound: range
    unit: µm
    scope: material
    conditions:
      grade: multispectral
      note: Crystran says the range depends on thickness and coating
    method: Range printed on a manufacturer product data page
    status: ground
    source: crystran-zns-product
    where: Product data table, Transmission Range row
  - benchmark: optical_transmission_range
    label: Transmission range, MS-ZnS water-clear grade (Tydex)
    value: 0.4
    value_high: 12
    bound: range
    unit: µm
    scope: material
    conditions:
      grade: MS-ZnS, HIP water-clear
    method: Range printed in a manufacturer characteristics text
    status: ground
    source: tydex-cvd-zns
    where: 'Text beside the Physical and Chemical Properties table: transmission characteristics from 0.4 to 12 microns'
  - benchmark: water_solubility
    label: Solubility in water
    value: 0.000065
    unit: g/100 g water
    scope: material
    conditions:
      temperature: not stated
    method: Value printed on a manufacturer product data page as 65 x 10-6 g/100g water
    status: ground
    note: Tydex describes ZnS as insoluble in water, which agrees.
    source: crystran-zns-product
    where: Product data table, Solubility row
  - benchmark: max_service_temp
    label: Maximum use temperature in normal atmosphere
    value: 250
    unit: °C
    scope: material
    conditions:
      atmosphere: normal atmosphere
      note: a safety advice for windows, not a measured limit
    method: Advice printed under the data tables of a manufacturer product data page
    status: ground
    source: crystran-zns-product
    where: 'Text under the data tables: For safety, Zinc Sulphide windows should not be used above 250°C in normal atmosphere'
  - benchmark: apparent_elastic_limit
    label: Apparent elastic limit
    value: 26.9
    unit: MPa
    scope: material
    conditions:
      grade: multispectral
    method: Value printed on a manufacturer product data page (26.9 MPa, 3900 psi)
    status: ground
    source: crystran-zns-product
    where: Product data table, Apparent Elastic Limit row
corrosion:
  - environment: Strong mineral acids and strong oxidising materials
    headline: Strong mineral acids react with zinc sulphide, so keep it away from acids and strong bases.
    effect: The safety sheet says the product reacts with strong mineral acids and strong oxidising materials, and lists them as incompatible. The Crystran safety sheet also lists keeping it away from acids and strong bases in storage.
    rating: moderate
    conditions:
      basis: general reactivity statements in a safety data sheet; no corrosion rate given
    source: crystran-zns-msds
    where: Section 10.1 and 10.5; Section 7.2
  - environment: Air at 300 °C and above
    headline: Zinc sulphide oxidises at 300 °C in air and decomposes around 700 °C.
    effect: The safety sheet says it oxidises at 300 °C, exhibits plastic deformation at 500 °C and dissociates at about 700 °C. In a fire it decomposes above 400 °C in air, and above 800 °C in an inert atmosphere it sublimes into zinc and sulphur fumes.
    rating: moderate
    conditions:
      atmosphere: air, and inert atmosphere for the sublimation statement
      note: a safety-sheet statement, not an oxidation rate
    source: crystran-zns-msds
    where: Section 9.2 footnote; Section 5.3
  - environment: Water at 20 °C and room temperature
    headline: Zinc sulphide is insoluble in water.
    effect: Crystran prints a solubility of 65 x 10-6 g per 100 g of water, and its safety sheet calls it insoluble. Tydex also calls it insoluble. No corrosion rate in water was reported.
    rating: low
    conditions:
      temperature: not stated (solubility figure)
      note: solubility, not a corrosion rate
    source: crystran-zns-product
    where: Product data table, Solubility row; crystran-zns-msds section 9.1
  - environment: Low Earth orbit, LDEF experiment, zinc sulphide based mirrors
    headline: Zinc sulphide mirrors on LDEF were less stable than the other coated optics, with contamination and dendrite formation.
    effect: The 1992 NASA-linked paper says zinc sulphide based mirrors showed less stable behaviour, with contamination effects and related dendrite formation, and that the samples on the leading and trailing edges also had interesting impact sites. The paper concerns mirrors, not windows, and gives no numbers.
    rating: moderate
    conditions:
      test: Long Duration Exposure Facility, flight exposure
      note: mirror coatings, not bulk windows
    source: ntrs-ldef-donovan1992
    where: Abstract, space environmental effects on coated optics
  - environment: Rain and high-speed dust and particulate abrasion
    headline: Tydex says the IR grade resists rain erosion and dust abrasion well.
    effect: Tydex states that the IR grade has a high resistance to rain erosion and to high-speed dust and particulate abrasion, which makes it suitable for exterior IR windows. This is a supplier claim with no test numbers given.
    rating: low
    conditions:
      grade: IR-ZnS, CVD
      basis: supplier statement, no test data
    source: tydex-cvd-zns
    where: Introduction paragraph on IR-ZnS
risks:
  hazards:
    - text: 'Crystran''s safety sheet, revision 2026 issued 6 July 2026, lists the hazard statements H302 (harmful if swallowed), H315 (causes skin irritation), H319 (causes serious eye irritation) and H332 (harmful if inhaled), with signal word Warning. Section 15 of the same sheet says EU CLP: Not classified.'
      ghs:
        - H302
        - H315
        - H319
        - H332
      source: crystran-zns-msds
      where: Sections 2.1, 2.2 and 15.1
    - text: PubChem reports that zinc sulfide (CID 9833931) is Not Classified, and that it does not meet GHS hazard criteria for 91.4% (829 of 907) of all reports.
      ghs: []
      source: pubchem-zns
      where: Safety and Hazards, GHS Classification
    - text: The safety sheet says the product is harmful if swallowed, possibly liberating toxic hydrogen sulphide in contact with gastric juices, and harmful by inhalation of dust.
      ghs: []
      source: crystran-zns-msds
      where: Sections 2.1 and 11.1
    - text: The occupational exposure limit is 10 mg/m3 total particulate, as an 8 hour time-weighted average.
      ghs: []
      source: crystran-zns-msds
      where: Section 8.1
  failure_risks:
    - mode: Oxidation and softening at high temperature in air
      trigger: Use or heating above 250 °C in normal atmosphere, and oxidation from 300 °C
      consequence: Crystran advises against using windows above 250 °C in normal atmosphere, and its safety sheet says the material oxidises at 300 °C and deforms plastically at 500 °C.
      severity: moderate
      source: crystran-zns-product
      where: Text under the data tables; crystran-zns-msds section 9.2
    - mode: Contamination and dendrite formation on zinc sulphide mirrors in orbit
      trigger: Long duration exposure in low Earth orbit (LDEF)
      consequence: The LDEF paper says the zinc sulphide based mirrors were less stable and showed contamination and related dendrite formation. It is a mirror result, not a window result.
      severity: moderate
      source: ntrs-ldef-donovan1992
      where: Abstract
  side_effects:
    - text: At temperatures above 800 °C in an inert atmosphere the material sublimes into zinc and sulphur fumes, and it decomposes to hydrogen sulphide gas on contact with incompatible materials.
      affects: Furnaces, vacuum coating and cleaning equipment near the part
      source: crystran-zns-msds
      where: Section 5.3 and Section 10.6
  handling:
    - text: Protective gloves made of PVA are required. Safety goggles or glasses with side shields are needed where chipping or dust may be produced. Provide local exhaust and general ventilation.
      source: crystran-zns-msds
      where: Section 8.2
    - text: Avoid generating dust, and take up pieces into containers for disposal. Keep away from heat, avoid skin and eye contact, and protect from physical damage.
      source: crystran-zns-msds
      where: Sections 6.3 and 7.1
    - text: Keep away from foodstuffs, acids and strong bases, and strong oxidising materials, which the safety sheet lists as incompatible.
      source: crystran-zns-msds
      where: Sections 7.2 and 10.5
  mitigations:
    - text: Keep windows below 250 °C in normal atmosphere, as Crystran advises.
      source: crystran-zns-product
      where: Text under the data tables
uses:
  - application: optics-and-cameras
    device: Exterior infrared windows in the 8 to 12 µm thermal band
    example: Tydex says the IR-ZnS grade is often used in the 8 to 12 micron region, and that its resistance to rain erosion and dust abrasion makes it suitable for exterior IR windows.
    source: tydex-cvd-zns
    where: Introduction paragraph on IR-ZnS
  - application: optics-and-cameras
    device: Water-clear multispectral windows and lenses that must pass visible light as well as the infrared
    example: Tydex says its hot isostatically pressed multispectral grade is water-clear, with minimal scatter and high transmission from 0.4 to 12 microns.
    source: tydex-cvd-zns
    where: Introduction paragraph on MS-ZnS and the Physical and Chemical Properties table
  - application: electronics-and-chips
    device: Copper-activated zinc sulphide electroluminescent phosphor in thick-film AC devices
    example: A US patent says ZnS:Cu electroluminescent phosphors are used for backlighting LCD displays, for automotive dashboard and control switch illumination, and for emergency egress lighting.
    source: us5702643
    where: Background of the description
supply:
  - subject: Zinc (feedstock for zinc sulphide; world mine production, 2025e)
    producers:
      - country: China
        share_percent: 31.5
        year: 2025
      - country: Peru
        share_percent: 11.5
        year: 2025
      - country: Australia
        share_percent: 8.5
        year: 2025
      - country: India
        share_percent: 6.7
        year: 2025
      - country: Mexico
        share_percent: 6
        year: 2025
    critical_lists:
      - list: USGS 2025 List of Critical Minerals
        listed: true
    recycling: 'USGS zinc chapter: refined zinc produced in the United States was recovered from secondary materials, including galvanizing residues and crude zinc oxide from electric arc furnace dust.'
    substitutes:
      - 'USGS: many elements are substitutes for zinc in chemical, electronic and pigment uses.'
    source: usgs-mcs2026-zinc
    where: 'World Mine Production and Reserves table, 2025e (world total 13,000 thousand t; shares calculated by Space Mushroom from the country values); Recycling; Substitutes. Critical-list status: usgs-crit2025 page, which lists Zinc used as a coating to protect iron and steel from rust and corrosion.'
documents:
  - title: 'Crystran: Zinc Sulphide (Zinc Sulfide) Multispectral (ZnS) product data page'
    type: datasheet
    url: https://www.crystran.com/optical-materials/zinc-sulphide-zinc-sulfide-multispectral-zns/
    year: 2026
  - title: 'Crystran: Safety Data Sheet, Zinc Sulphide (Zinc Sulfide) Multispectral (REACH, revision 2026 issued 6 July 2026)'
    type: sds
    url: https://www.crystran.com/wp-content/uploads/2025/09/zinc-sulphide-multispectral-zns-msds.pdf
    year: 2026
  - title: 'Tydex: CVD-ZnS (Zinc Sulphide), IR-ZnS and MS-ZnS properties (undated PDF)'
    type: datasheet
    url: https://www.tydexoptics.com/pdf/CVD-ZnS%20(Zinc%20Sulphide).pdf
    year: 2026
  - title: 'PubChem: Zinc Sulfide (CID 9833931), GHS classification summary'
    type: database
    url: https://pubchem.ncbi.nlm.nih.gov/compound/1314-98-3
    year: 2026
  - title: 'USGS Mineral Commodity Summaries 2026: Zinc'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zinc.pdf
    year: 2026
  - title: 'USGS: About the 2025 List of Critical Minerals (final list of 60 minerals)'
    type: report
    url: https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals
    year: 2025
  - title: 'Donovan et al.: Space environmental effects on coated optics (NASA NTRS, 1992)'
    type: report
    url: https://ntrs.nasa.gov/citations/19920017855
    year: 1992
  - title: 'US patent 5,702,643: ZnS:Cu electroluminescent phosphor and method of making same'
    type: report
    url: https://patents.google.com/patent/US5702643
    year: 1997
gaps:
  - No flight, radiation or thermal-vacuum result for a zinc sulphide window was found in a source we could open. The only space source is the LDEF paper, which concerns mirror coatings.
  - 'Knoop 240 from Crystran is not entered: the page prints the hardness with no unit. Tydex''s Knoop 160 (MS) and 200 to 230 (IR) are entered instead, and the two sources differ for the same grade.'
  - 'Melting point conflicts: Crystran''s product page prints 1827 °C, its safety sheet prints 1830 C, and Tydex prints 1830 K. The Tydex value is in kelvin and is not converted or entered.'
  - 'Specific heat conflicts: Crystran prints 515 J/(kg K) and Tydex prints 0.124 J/(g K) for MS-ZnS. Both are entered with their source and no value is preferred.'
  - Tydex's thermal conductivity (19.0 and 27.2) is printed in J/(K x m x s) and is not entered. The Crystran value of 27.2 W/(m K) at 298 K is used.
  - Tydex's thermal expansion (7.85 for IR-ZnS) is printed with no exponent or unit, so it is not entered.
  - Crystran's dielectric constant of 88 is printed with no unit or test condition and is not confirmed by a second source, so it is left out.
  - Young's modulus of 87.6 GPa and Poisson's ratio of 0.318 from a 1983 CVD ZnS study appear only in a search snippet. The paper is paywalled and was not read, so these are not entered.
  - The 2008 Optical Engineering paper on Cleartran (doi 10.1117/1.3006123) could not be opened. Its four-point flexure, fracture toughness and Weibull data are not entered.
  - No dome-specific source was read. Uses are limited to IR windows and water-clear windows, and the IR dome statement in the brief is not supported here.
  - The FLIR grade of zinc sulphide was not profiled. Its safety sheet and data sheet were read but describe a different grade.
  - Atomic weights of zinc and sulphur were not read in a source this run, so the recipe gives atom counts only.
  - Sulphur supply, country production shares for zinc sulphide, and the EU critical raw materials status of zinc were not found or not checked.
  - 'No UNS, EN or other grade designations were applied: CVD zinc sulphide is sold by grade (IR or multispectral) and no standard code was printed in the sources read.'
  - No moisture or humidity ageing result for zinc sulphide windows was found in a source we could open. Water solubility is the only water-related figure.
  - 'The Crystran safety sheet lists H302, H315, H319 and H332 in section 2.2, but its section 15 says EU CLP: Not classified. Both statements are kept, and the conflict is not resolved here.'
sources:
  crystran-zns-product:
    title: 'Crystran: Zinc Sulphide (Zinc Sulfide) Multispectral (ZnS) product data page'
    id: crystran.com/optical-materials/zinc-sulphide-zinc-sulfide-multispectral-zns (page undated)
    url: https://www.crystran.com/optical-materials/zinc-sulphide-zinc-sulfide-multispectral-zns/
    year: 2026
    kind: datasheet
    license: supplier document, linked not reproduced
  crystran-zns-msds:
    title: 'Crystran: Safety Data Sheet, Zinc Sulphide (Zinc Sulfide) Multispectral (REACH format, revision 2026)'
    id: Revision 2026, issued 6 July 2026; CAS 1314-98-3; EC 215-251-3
    url: https://www.crystran.com/wp-content/uploads/2025/09/zinc-sulphide-multispectral-zns-msds.pdf
    year: 2026
    kind: datasheet
    license: supplier document, linked not reproduced
  tydex-cvd-zns:
    title: 'Tydex: CVD-ZnS (Zinc Sulphide) product datasheet, IR-ZnS and MS-ZnS'
    id: tydexoptics.com/pdf/CVD-ZnS (Zinc Sulphide).pdf (undated)
    url: https://www.tydexoptics.com/pdf/CVD-ZnS%20(Zinc%20Sulphide).pdf
    year: 2026
    kind: datasheet
    license: supplier document, linked not reproduced
  pubchem-zns:
    title: PubChem compound record, Zinc Sulfide (CID 9833931), GHS classification
    id: CID 9833931; CAS 1314-98-3
    url: https://pubchem.ncbi.nlm.nih.gov/compound/1314-98-3
    year: 2026
    kind: database
    license: public domain (NCBI)
  usgs-mcs2026-zinc:
    title: Mineral Commodity Summaries 2026, Zinc
    id: USGS MCS 2026, February 2026
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zinc.pdf
    year: 2026
    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)
  ntrs-ldef-donovan1992:
    title: Space environmental effects on coated optics (Donovan, Bennett, Dalbey, Burge, Gyetvay; Naval Air Warfare Center and The Aerospace Corporation)
    id: NTRS 19920017855 (published 1 January 1992)
    url: https://ntrs.nasa.gov/citations/19920017855
    year: 1992
    kind: report
    license: public domain (NASA)
  us5702643:
    title: US patent 5,702,643, ZnS:Cu electroluminescent phosphor and method of making same
    id: US 5,702,643
    url: https://patents.google.com/patent/US5702643
    year: 1997
    kind: web
    license: patent document, linked not reproduced
  wikipedia-zns:
    title: 'Wikipedia: Zinc sulfide (formula, crystal forms, history and uses; used for composition and history only)'
    id: en.wikipedia.org/wiki/Zinc_sulfide (undated)
    url: https://en.wikipedia.org/wiki/Zinc_sulfide
    year: 2026
    kind: web
    license: CC BY-SA 4.0
license: CC-BY-4.0
updated: '2026-10-26'
review:
  status: draft
  method: assistant
  checked_values: 24
  unreachable: 2
  caveats: 4
  note: 'Written by an AI assistant on 2026-10-26 from pages and PDFs read in this run. Unreachable: the 2008 Optical Engineering Cleartran paper (SPIE page returned no text) and the PubChem page for CAS 1314-98-3 (browser check); the PubChem GHS summary was read for CID 9833931 through its REST view. Caveats: Crystran hazard statements conflict with its section 15; melting point and specific heat disagree between sources; the PubChem percentage was read through a summary tool, not the page text.'
story:
  recipe:
    line: Zinc sulphide is zinc and sulphur in a one-to-one ratio, ZnS. The CVD process combines zinc vapour with hydrogen sulphide gas, which deposits the material as sheets on graphite substrates. Tydex says the multispectral grade is then hot isostatically pressed (HIP), which removes defects in the lattice and makes it water-clear.
    parts:
      - name: Zinc
        symbol: Zn
        role: The metal. Zinc vapour reacts with hydrogen sulphide to build up the solid.
      - name: Sulphur
        symbol: S
        role: The non-metal. It comes from hydrogen sulphide gas during deposition and is the source of the toxic gas released on decomposition.
  risk_groups:
    - title: For people
      level: 1
      verdict: Harmful label conflicts with section 15
      lead: Crystran's safety sheet lists harmful-if-swallowed and harmful-if-inhaled statements for the solid, while its section 15 says the product is not classified under EU CLP. The PubChem record for zinc sulphide says it is Not Classified for most reports.
      points:
        - label: Dust
          line: The safety sheet sets an occupational limit of 10 mg/m3 as an 8 hour average for total particulate, and says to avoid making dust.
        - label: Acid contact
          line: The safety sheet says it may liberate toxic hydrogen sulphide in contact with gastric juices, and that it reacts with strong mineral acids.
    - title: If it overheats
      lead: These results are safety-sheet and supplier statements, not field incidents.
      points:
        - label: Oxidation
          line: Crystran says it oxidises significantly at 300 °C, deforms plastically at 500 °C and dissociates at about 700 °C. Windows should not be used above 250 °C in normal atmosphere.
        - label: Fumes
          line: Above 800 °C in an inert atmosphere it sublimes into zinc and sulphur fumes.
    - title: Handling and storage
      points:
        - label: Protection
          line: PVA gloves, goggles where chipping or dust is possible, and ventilation where dust forms.
        - label: Storage
          line: Keep away from acids and strong bases, strong oxidising materials, and foodstuffs.
  why: Zinc sulphide is a polycrystalline infrared optical material made by chemical vapour deposition. It transmits from the visible into the thermal infrared, and the water-clear multispectral grade is hot isostatically pressed to remove scatter. It is not a single crystal; the sources read describe it as a cubic zinc blende deposit. Its main strengths for the designer are infrared transmission to about 12 to 13.5 µm and a moderate hardness. Its main limits are a low use temperature in air and a value that changes by grade and supplier.
  uses:
    - where: Infrared windows
      line: Tydex says the IR grade is often used in the 8 to 12 µm region and resists rain erosion and dust abrasion, which makes it suitable for exterior IR windows.
    - where: Water-clear windows
      line: The multispectral grade is made water-clear by hot isostatic pressing. Tydex gives its transmission from 0.4 to 12 µm.
    - where: Electroluminescent phosphors
      line: Copper-activated zinc sulphide is the basis of electroluminescent phosphors, which a US patent says are used in LCD backlights, automotive dashboards and emergency egress lighting.
  can_do:
    - label: Infrared transmission
      value: 0.37 to 13.5 µm
      line: Crystran gives a transmission range of 0.37 to 13.5 µm for its multispectral grade. Tydex gives 0.4 to 12 µm for its water-clear grade.
    - label: Refractive index
      value: 2.20084 at 10 µm
      line: Crystran prints a refractive index of 2.20084 at 10 µm, and Tydex prints 2.2008 for the multispectral grade at 10.0 µm.
    - label: Hardness
      value: 160 kg/mm2 (MS)
      line: Tydex prints a Knoop hardness of 160 kg/mm2 for the multispectral grade and 200 to 230 kg/mm2 for the IR grade, both at a 50 g indenter.
    - label: Stiffness
      value: 74.5 GPa
      line: Crystran and Tydex both print a Young's modulus of 74.5 GPa.
    - label: Heat conduction
      value: 27.2 W/(m·K)
      line: Crystran prints a thermal conductivity of 27.2 W/(m·K) at 298 K for the multispectral grade.
  compare: Within the sources read, the IR grade of zinc sulphide is harder than the multispectral grade (Knoop 200 to 230 against 160 kg/mm2, Tydex), and the two grades have the same Young's modulus. The water-clear multispectral grade gives the widest visible-to-infrared window, while the IR grade is quoted for the 8 to 12 µm region. No sources read compare zinc sulphide with a second IR material on cost or availability.
  compare_rows:
    - label: Heat conduction
      benchmark: thermal_conductivity
    - label: Hardness
      benchmark: knoop_hardness
    - label: Stiffness
      benchmark: elastic_modulus
  handling:
    - Wear PVA gloves, and use goggles where chipping or dust may be produced.
    - Avoid making dust, and keep the material away from heat, acids and strong bases.
    - Keep it below 250 °C in normal atmosphere when used as a window.
  good_for:
    - Infrared windows in the 8 to 12 µm band, where Tydex says the IR grade resists rain erosion and dust abrasion.
    - Water-clear windows that must pass the visible and the infrared, with a transmission range of about 0.4 to 12 µm for the multispectral grade.
  watch_out:
    - Use temperature. Crystran advises against using windows above 250 °C in normal atmosphere, and the material oxidises at 300 °C.
    - Grade and supplier. The Knoop hardness and specific heat differ between Crystran and Tydex, so the value must come from the supplier for the grade used.
    - Hazard labelling. The Crystran safety sheet lists harmful-if-swallowed and harmful-if-inhaled statements, but its section 15 says not classified.
  verdict: Zinc sulphide is a useful infrared window material for the 8 to 12 µm band and, in the water-clear grade, for the visible and infrared. Its values depend on grade and supplier, its use temperature in air is low, and no space test on a window was found in the sources read.