{
  "spore": "profile",
  "id": "zinc-selenide",
  "spore_version": "0.2",
  "family": "optical-crystals",
  "name": "Zinc selenide (polycrystalline optical material)",
  "abbreviation": "ZnSe",
  "role": "infrared optical window and lens for CO2 lasers at 10.6 µm",
  "category": "glasses-optics",
  "type": "optical-crystals",
  "summary": "Zinc selenide is a zinc and selenium compound with a cubic zinc blende structure. The optical grade is polycrystalline. Crystran says it is produced from zinc vapour and hydrogen selenide gas, forming as sheets on graphite susceptors. Crystran gives a transmission range of 0.6 to 21 µm and a refractive index of 2.4028 at 10.6 µm, where two uncoated surfaces reflect 29.1% of the light. LASER COMPONENTS calls it the standard material for CO2 laser lenses and windows, with about 70% transmission uncoated. The material is soft, with a Knoop hardness of 120 and a rupture modulus of 55.1 MPa. Its supplier safety sheet classes it as toxic if swallowed or inhaled, and it should not be used above 250 °C in normal air.\n",
  "best_for": "Lenses and windows that must pass 10.6 µm CO2 laser light with very low absorption, and infrared windows that need transmission out to about 21 µm",
  "weakest_at": "Softness and toxicity: Knoop hardness of 120 and a rupture modulus of 55.1 MPa (Crystran and Coherent), and a supplier safety sheet that lists it as toxic if swallowed or inhaled (Angstrom Sciences)",
  "identity": {
    "formula": "ZnSe",
    "cas": "1315-09-9",
    "crystal_system": "cubic zinc blende (Crystran); a hexagonal wurtzite polymorph also exists (Wikipedia)",
    "space_group": "F43m",
    "designations": [],
    "source": "crystran-znse",
    "where": "Product Data table, Class/Structure row (FCC Cubic, F43m (#216), Zinc Blende structure, polycrystalline); CAS 1315-09-9 from the Wikipedia infobox and Angstrom Sciences SDS section 1"
  },
  "tags": {
    "environments": [
      "low-earth-orbit"
    ],
    "stresses": [],
    "applications": [
      "optics-and-cameras",
      "electronics-and-chips"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density at 300 K (manufacturer)",
      "value": 5.27,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "temperature": "300 K"
      },
      "method": "Value printed as Density @ 300 K in the Tydex CVD zinc selenide table",
      "status": "ground",
      "source": "tydex-cvd-znse",
      "where": "Density @ 300 K line",
      "source_detail": {
        "title": "Tydex: Zinc Selenide (CVD-ZnSe) properties",
        "id": "Tydex optics materials page (undated; read 2026-10-26)",
        "url": "https://tydexoptics.com/materials1/for_transmission_optics/cvd_znse",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density (supplier safety sheet)",
      "value": 5.42,
      "bound": "exact",
      "unit": "g/cc",
      "scope": "material",
      "conditions": {
        "basis": "temperature not stated"
      },
      "method": "Value printed in the Angstrom Sciences SDS. It differs from the manufacturer figure of 5.27 g/cm3 and both are kept",
      "status": "ground",
      "source": "angstrom-znse-sds",
      "where": "Section 9, Density row",
      "source_detail": {
        "title": "Zinc Selenide: Safety Data Sheet (Angstrom Sciences, Inc.)",
        "id": "CAS 1315-09-9; EC 215-259-7; last revised 07/07/15",
        "url": "https://angstromsciences.com/wp-content/uploads/files/SDS/Zinc%20Selenide.pdf",
        "year": 2015,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point",
      "value": 1525,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "basis": "value as printed, no test condition given"
      },
      "method": "Printed in the Crystran Product Data table; the row points to notes that were not found in the page text",
      "status": "ground",
      "source": "crystran-znse",
      "where": "Product Data table, Melting Point row",
      "source_detail": {
        "title": "Zinc Selenide (ZnSe): Crystran product data (Product Data table, safety notes)",
        "id": "Crystran product page (undated; read 2026-10-26)",
        "url": "https://www.crystran.co.uk/optical-materials/zinc-selenide-znse",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "refractive_index",
      "label": "Refractive index at 10.6 µm",
      "value": 2.4028,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "wavelength": "10.6 µm"
      },
      "method": "Printed in the Crystran Product Data table; Tydex prints the same 2.4028 at 10.6 µm",
      "status": "ground",
      "source": "crystran-znse",
      "where": "Product Data table, Refractive Index row (2.4028 at 10.6 µm)",
      "source_detail": {
        "title": "Zinc Selenide (ZnSe): Crystran product data (Product Data table, safety notes)",
        "id": "Crystran product page (undated; read 2026-10-26)",
        "url": "https://www.crystran.co.uk/optical-materials/zinc-selenide-znse",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "transmission_range",
      "label": "Transmission range, uncoated",
      "value": 0.6,
      "value_high": 21,
      "bound": "range",
      "unit": "µm",
      "scope": "material",
      "conditions": {
        "basis": "uncoated optical material; thickness not stated"
      },
      "method": "Printed as a range in the Crystran Product Data table. The Tydex page prints 0.5 to 19 with a unit that is probably a typo, so it is not used",
      "status": "ground",
      "source": "crystran-znse",
      "where": "Product Data table, Transmission Range row",
      "source_detail": {
        "title": "Zinc Selenide (ZnSe): Crystran product data (Product Data table, safety notes)",
        "id": "Crystran product page (undated; read 2026-10-26)",
        "url": "https://www.crystran.co.uk/optical-materials/zinc-selenide-znse",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "absorption_coefficient",
      "label": "Bulk absorption at 10.6 µm",
      "value": 0.0005,
      "bound": "exact",
      "unit": "cm-1",
      "scope": "material",
      "conditions": {
        "wavelength": "10.6 µm",
        "bound": "less than, as printed",
        "temperature": "20 °C"
      },
      "method": "Coherent prints a bulk absorption coefficient of less than 0.0005 cm-1 at 10.6 µm in its ZnSe material properties table",
      "status": "ground",
      "source": "coherent-znse",
      "where": "ZnSe Material Properties (at 20 °C), Bulk Absorption Coefficient row",
      "source_detail": {
        "title": "Coherent: ZnSe material properties (ZnSe Material Properties table at 20 °C)",
        "id": "Coherent bulk optical materials page (undated; read 2026-10-26)",
        "url": "https://www.coherent.com/optics/crystals/bulk-optical-materials/zinc-selenide",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "reflection_loss",
      "label": "Reflection loss, two uncoated surfaces",
      "value": 29.1,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "wavelength": "10.6 µm",
        "surfaces": "two uncoated surfaces"
      },
      "method": "Printed in the Crystran Product Data table",
      "status": "ground",
      "source": "crystran-znse",
      "where": "Product Data table, Reflection Loss row",
      "source_detail": {
        "title": "Zinc Selenide (ZnSe): Crystran product data (Product Data table, safety notes)",
        "id": "Crystran product page (undated; read 2026-10-26)",
        "url": "https://www.crystran.co.uk/optical-materials/zinc-selenide-znse",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity",
      "value": 18,
      "bound": "exact",
      "unit": "W m-1 K-1",
      "scope": "material",
      "conditions": {
        "temperature": "298 K"
      },
      "method": "Printed in the Crystran Product Data table",
      "status": "ground",
      "source": "crystran-znse",
      "where": "Product Data table, Thermal Conductivity row",
      "source_detail": {
        "title": "Zinc Selenide (ZnSe): Crystran product data (Product Data table, safety notes)",
        "id": "Crystran product page (undated; read 2026-10-26)",
        "url": "https://www.crystran.co.uk/optical-materials/zinc-selenide-znse",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity",
      "value": 0.339,
      "bound": "exact",
      "unit": "J/(g K)",
      "scope": "material",
      "conditions": {
        "temperature": "298 K"
      },
      "method": "Printed as heat capacity in the Tydex CVD zinc selenide table",
      "status": "ground",
      "source": "tydex-cvd-znse",
      "where": "Heat capacity @ 298 K line",
      "source_detail": {
        "title": "Tydex: Zinc Selenide (CVD-ZnSe) properties",
        "id": "Tydex optics materials page (undated; read 2026-10-26)",
        "url": "https://tydexoptics.com/materials1/for_transmission_optics/cvd_znse",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Linear thermal expansion at 273 K",
      "value": 7.1,
      "bound": "exact",
      "unit": "x10-6/K",
      "scope": "material",
      "conditions": {
        "temperature": "273 K"
      },
      "method": "Printed as thermal expansion in the Tydex table; Crystran prints 7.1 x 10-6/°C at 273 K",
      "status": "ground",
      "source": "tydex-cvd-znse",
      "where": "Thermal expansion (1/K) line, @ 273 K",
      "source_detail": {
        "title": "Tydex: Zinc Selenide (CVD-ZnSe) properties",
        "id": "Tydex optics materials page (undated; read 2026-10-26)",
        "url": "https://tydexoptics.com/materials1/for_transmission_optics/cvd_znse",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Linear thermal expansion at 473 K",
      "value": 8.3,
      "bound": "exact",
      "unit": "x10-6/K",
      "scope": "material",
      "conditions": {
        "temperature": "473 K"
      },
      "method": "Printed as thermal expansion in the Tydex table; it rises with temperature (7.8 at 373 K)",
      "status": "ground",
      "source": "tydex-cvd-znse",
      "where": "Thermal expansion (1/K) line, @ 473 K",
      "source_detail": {
        "title": "Tydex: Zinc Selenide (CVD-ZnSe) properties",
        "id": "Tydex optics materials page (undated; read 2026-10-26)",
        "url": "https://tydexoptics.com/materials1/for_transmission_optics/cvd_znse",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Linear expansion coefficient at 20 °C",
      "value": 7.57,
      "bound": "exact",
      "unit": "x10-6/°C",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C"
      },
      "method": "Printed in the Coherent ZnSe material properties table",
      "status": "ground",
      "source": "coherent-znse",
      "where": "Linear Expansion Coefficient row, @ 20 °C",
      "source_detail": {
        "title": "Coherent: ZnSe material properties (ZnSe Material Properties table at 20 °C)",
        "id": "Coherent bulk optical materials page (undated; read 2026-10-26)",
        "url": "https://www.coherent.com/optics/crystals/bulk-optical-materials/zinc-selenide",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus",
      "value": 67.2,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "form": "polycrystalline optical grade, as printed"
      },
      "method": "Printed in the Crystran Product Data table (9.75 x 10^6 psi in the Coherent table)",
      "status": "ground",
      "source": "crystran-znse",
      "where": "Product Data table, Youngs Modulus (E) row",
      "source_detail": {
        "title": "Zinc Selenide (ZnSe): Crystran product data (Product Data table, safety notes)",
        "id": "Crystran product page (undated; read 2026-10-26)",
        "url": "https://www.crystran.co.uk/optical-materials/zinc-selenide-znse",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "poissons_ratio",
      "label": "Poisson's ratio",
      "value": 0.28,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "basis": "dimensionless"
      },
      "method": "Printed in the Crystran Product Data table",
      "status": "ground",
      "source": "crystran-znse",
      "where": "Product Data table, Poisson Ratio row",
      "source_detail": {
        "title": "Zinc Selenide (ZnSe): Crystran product data (Product Data table, safety notes)",
        "id": "Crystran product page (undated; read 2026-10-26)",
        "url": "https://www.crystran.co.uk/optical-materials/zinc-selenide-znse",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "bulk_modulus",
      "label": "Bulk modulus",
      "value": 40,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "basis": "as printed"
      },
      "method": "Printed in the Crystran Product Data table",
      "status": "ground",
      "source": "crystran-znse",
      "where": "Product Data table, Bulk Modulus (K) row",
      "source_detail": {
        "title": "Zinc Selenide (ZnSe): Crystran product data (Product Data table, safety notes)",
        "id": "Crystran product page (undated; read 2026-10-26)",
        "url": "https://www.crystran.co.uk/optical-materials/zinc-selenide-znse",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "flexural_strength",
      "label": "Rupture modulus (apparent elastic limit)",
      "value": 55.1,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grain_size": "under 100 µm (Coherent)",
        "note": "Coherent calls this rupture modulus; Crystran prints the same 55.1 MPa as apparent elastic limit"
      },
      "method": "Printed in the Coherent ZnSe material properties table as 55.1 MPa (8,000 psi)",
      "status": "ground",
      "source": "coherent-znse",
      "where": "Rupture Modulus row",
      "source_detail": {
        "title": "Coherent: ZnSe material properties (ZnSe Material Properties table at 20 °C)",
        "id": "Coherent bulk optical materials page (undated; read 2026-10-26)",
        "url": "https://www.coherent.com/optics/crystals/bulk-optical-materials/zinc-selenide",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "knoop_hardness",
      "label": "Knoop hardness",
      "value": 105,
      "value_high": 120,
      "bound": "range",
      "unit": "kg/mm2",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C",
        "note": "range as printed; Crystran prints 120 with a 500 g indenter"
      },
      "method": "Printed as a range in the Coherent ZnSe material properties table",
      "status": "ground",
      "source": "coherent-znse",
      "where": "Knoop Hardness row",
      "source_detail": {
        "title": "Coherent: ZnSe material properties (ZnSe Material Properties table at 20 °C)",
        "id": "Coherent bulk optical materials page (undated; read 2026-10-26)",
        "url": "https://www.coherent.com/optics/crystals/bulk-optical-materials/zinc-selenide",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "thermo_optic_coefficient",
      "label": "Thermo-optic coefficient dn/dT at 10.6 µm",
      "value": 6.1,
      "bound": "exact",
      "unit": "x10-5/°C",
      "scope": "material",
      "conditions": {
        "wavelength": "10.6 µm"
      },
      "method": "Printed in the Coherent ZnSe material properties table",
      "status": "ground",
      "source": "coherent-znse",
      "where": "Thermo-Optic Coefficient (dn/dT) row",
      "source_detail": {
        "title": "Coherent: ZnSe material properties (ZnSe Material Properties table at 20 °C)",
        "id": "Coherent bulk optical materials page (undated; read 2026-10-26)",
        "url": "https://www.coherent.com/optics/crystals/bulk-optical-materials/zinc-selenide",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "water_solubility",
      "label": "Solubility in water",
      "value": 0.001,
      "bound": "exact",
      "unit": "g/100 g water",
      "scope": "material",
      "conditions": {
        "temperature": "not stated"
      },
      "method": "Printed in the Crystran Product Data table; the Angstrom SDS calls it insoluble",
      "status": "ground",
      "source": "crystran-znse",
      "where": "Product Data table, Solubility row",
      "source_detail": {
        "title": "Zinc Selenide (ZnSe): Crystran product data (Product Data table, safety notes)",
        "id": "Crystran product page (undated; read 2026-10-26)",
        "url": "https://www.crystran.co.uk/optical-materials/zinc-selenide-znse",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "band_gap",
      "label": "Band gap at 25 °C",
      "value": 2.7,
      "bound": "exact",
      "unit": "eV",
      "scope": "material",
      "conditions": {
        "temperature": "25 °C"
      },
      "method": "Stated in the Wikipedia article text; the article infobox gives 2.82 eV at 10 K",
      "status": "ground",
      "source": "wikipedia-znse",
      "where": "Article text, band gap paragraph",
      "source_detail": {
        "title": "Zinc selenide (Wikipedia article: formula, CAS, structure, band gap, uses, synthesis, hazard infobox)",
        "id": "Wikipedia (undated; read 2026-10-26)",
        "url": "https://en.wikipedia.org/wiki/Zinc_selenide",
        "year": 2026,
        "kind": "web",
        "license": "CC BY-SA 4.0 (Wikipedia)"
      }
    },
    {
      "benchmark": "max_service_temp",
      "label": "Maximum window temperature in air",
      "value": 250,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "atmosphere": "normal atmosphere"
      },
      "method": "Stated as a safety limit for windows in the Crystran product text, not in the table",
      "status": "ground",
      "source": "crystran-znse",
      "where": "Product text, safety note on window temperature",
      "source_detail": {
        "title": "Zinc Selenide (ZnSe): Crystran product data (Product Data table, safety notes)",
        "id": "Crystran product page (undated; read 2026-10-26)",
        "url": "https://www.crystran.co.uk/optical-materials/zinc-selenide-znse",
        "year": 2026,
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Air at high temperature",
      "headline": "Oxidizes significantly at 300 °C. Windows should not go above 250 °C in normal atmosphere.",
      "effect": "Crystran says ZnSe oxidizes significantly at 300 °C, shows plastic deformation at about 500 °C and dissociates at about 700 °C. Its safety advice is not to use windows above 250 °C in normal atmosphere.",
      "rating": "moderate",
      "conditions": {
        "atmosphere": "normal air, as stated",
        "exposure": "temperature limits only; exposure time not stated"
      },
      "source": "crystran-znse",
      "where": "Product text, thermal limits paragraph"
    },
    {
      "environment": "Atomic oxygen (simulated by an oxygen plasma, as in low Earth orbit)",
      "headline": "An oxygen plasma equal to about 16 years in low Earth orbit changed the mid-infrared response very little.",
      "effect": "Thin ZnSe films were exposed to an electron cyclotron resonance oxygen plasma, equal to about 16 years in low Earth orbit. The mid-infrared optical response barely changed, while the ultraviolet to near-infrared response changed a lot. The authors attribute the oxidation to a thin surface layer.",
      "rating": "low",
      "conditions": {
        "basis": "thin films, not bulk optics",
        "fluence": "about 16 years in low Earth orbit equivalent"
      },
      "source": "yan2002",
      "where": "Abstract (repository copy)"
    },
    {
      "environment": "Water",
      "headline": "Very low solubility, at 0.001 g per 100 g of water.",
      "effect": "Crystran prints a solubility of 0.001 g/100 g water. The Angstrom Sciences SDS calls the material insoluble in water. Neither source reports a humidity or ageing test.",
      "rating": "low",
      "conditions": {
        "temperature": "not stated"
      },
      "source": "crystran-znse",
      "where": "Product Data table, Solubility row"
    },
    {
      "environment": "Bases and oxidizing agents, or a fire",
      "headline": "Incompatible with bases and oxidizers. Heating in a fire gives hydrogen selenide and selenium dioxide.",
      "effect": "The Angstrom Sciences SDS lists bases and oxidizing agents as materials to avoid. Its decomposition products are hydrogen selenide, selenium dioxide and metal oxide fume.",
      "rating": "moderate",
      "conditions": {
        "basis": "SDS reactivity and decomposition statements"
      },
      "source": "angstrom-znse-sds",
      "where": "Section 10 (Stability and reactivity)"
    }
  ],
  "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. Precautionary statements include P270 (do not eat, drink or smoke when using) and P310 (call a Poison Center or doctor).",
        "ghs": [
          "H301",
          "H331",
          "H373"
        ],
        "source": "angstrom-znse-sds",
        "where": "Section 2 (Hazard identification)"
      },
      {
        "text": "The Wikipedia infobox also lists H410 with pictograms GHS06, GHS08 and GHS09. The Angstrom SDS does not print H410, though its section 12 rates aquatic toxicity as High.",
        "ghs": [
          "H410"
        ],
        "source": "wikipedia-znse",
        "where": "Infobox (hazard statements)"
      },
      {
        "text": "Exposure limit of 0.2 mg/m3 as Se, long-term value. The SDS calls for a dust respirator, rubber gloves and safety glasses or goggles, with ventilation to keep concentrations at or below the limit.",
        "ghs": [],
        "source": "angstrom-znse-sds",
        "where": "Sections 7 and 8"
      },
      {
        "text": "The SDS lists chronic selenium effects, including fatigue, loss of fingernails and hair, anaemia and weight loss.",
        "ghs": [],
        "source": "angstrom-znse-sds",
        "where": "Section 11 (Toxicological information)"
      }
    ],
    "failure_risks": [
      {
        "mode": "Overheating a window in normal air",
        "trigger": "Use above 250 °C in normal atmosphere (Crystran)",
        "consequence": "Oxidation becomes significant at 300 °C, plastic deformation starts at about 500 °C and dissociation at about 700 °C (Crystran).",
        "severity": "moderate",
        "source": "crystran-znse",
        "where": "Product text, thermal limits paragraph"
      },
      {
        "mode": "Surface damage or fracture under mechanical load",
        "trigger": "Contact with hard particles, clamping loads or handling",
        "consequence": "Knoop hardness is 105 to 120 kg/mm2 and the rupture modulus is 55.1 MPa (Coherent), so the surface marks easily and a stressed part can break at a low load.",
        "severity": "moderate",
        "source": "coherent-znse",
        "where": "Knoop Hardness and Rupture Modulus rows"
      },
      {
        "mode": "Toxic dust or fume from machining or a fire",
        "trigger": "Grinding, cutting or spilling the powder, or a fire near the part",
        "consequence": "Dust raises selenium exposure. In a fire it gives hydrogen selenide, selenium dioxide and metal oxide fume (Angstrom Sciences).",
        "severity": "high",
        "source": "angstrom-znse-sds",
        "where": "Sections 6, 8 and 10"
      }
    ],
    "side_effects": [
      {
        "text": "Machining and spills make dust. The SDS says take care not to raise dust, not to blow dust off clothing or skin with compressed air, and to wash thoroughly after handling.",
        "affects": "People working near machining or spills, and the work area",
        "source": "angstrom-znse-sds",
        "where": "Sections 6 and 7"
      }
    ],
    "handling": [
      {
        "text": "Handle under dry protective gas, wash thoroughly after handling and do not use food or tobacco in the work area (Angstrom SDS section 7).",
        "source": "angstrom-znse-sds",
        "where": "Section 7 (Handling and storage)"
      },
      {
        "text": "Store in a cool, dry place in a tightly sealed container, apart from bases and oxidizing agents.",
        "source": "angstrom-znse-sds",
        "where": "Section 7 and section 10"
      },
      {
        "text": "Clean up spills by vacuuming with a HEPA filter into a closed container. Take care not to raise dust.",
        "source": "angstrom-znse-sds",
        "where": "Section 6 (Accidental release measures)"
      }
    ],
    "mitigations": [
      {
        "text": "Keep windows at or below 250 °C in normal atmosphere, and use a dust respirator, gloves and eye protection when handling the powder or machining.",
        "source": "crystran-znse",
        "where": "Product text (window temperature); SDS section 8"
      }
    ]
  },
  "uses": [
    {
      "application": "optics-and-cameras",
      "device": "CO2 laser lenses and output windows at 10.6 µm",
      "example": "LASER COMPONENTS calls zinc selenide the standard material for CO2 laser lenses and windows. Uncoated, about 70% of 10.6 µm light passes through; coating both sides raises transmission above 99.4%.",
      "source": "lc-co2-optics",
      "where": "Materials for CO2 laser optics, pages 1 and 2"
    },
    {
      "application": "optics-and-cameras",
      "device": "Infrared optical coating for low Earth orbit (ground test only)",
      "example": "A ground test exposed thin ZnSe films to an oxygen plasma equal to about 16 years in low Earth orbit. The mid-infrared optical response barely changed, and the authors judged ZnSe potentially suitable for space infrared applications.",
      "source": "yan2002",
      "where": "Abstract (repository copy)"
    },
    {
      "application": "electronics-and-chips",
      "device": "X-ray and gamma-ray detectors (tellurium-activated ZnSe scintillator)",
      "example": "Tellurium-activated ZnSe is a scintillator with an emission peak at 640 nm, used in x-ray and gamma-ray detectors.",
      "source": "wikipedia-znse",
      "where": "Article text, uses paragraph"
    }
  ],
  "supply": [
    {
      "subject": "Zinc",
      "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": "Mexico",
          "share_percent": 6,
          "year": 2025
        },
        {
          "country": "United States",
          "share_percent": 5.2,
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 List of Critical Minerals (zinc named)",
          "listed": true
        },
        {
          "list": "EU critical raw materials list (34 CRMs, under Regulation (EU) 2024/1252); zinc not named",
          "listed": false
        }
      ],
      "recycling": "USGS: US refined zinc is partly recovered from secondary materials, including galvanizing residues and crude zinc oxide.",
      "substitutes": [],
      "source": "usgs-mcs2026-zinc",
      "where": "World Mine Production and Reserves table (2025e; shares calculated by Space Mushroom against the 13,000 thousand t world total, which is rounded); Recycling. Critical list 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 (selenium not named)",
          "listed": false
        }
      ],
      "recycling": "USGS: recycling is insignificant. Most scrap from electronic materials is exported for recovery of its selenium.",
      "substitutes": [
        "LASER COMPONENTS also offers CO2 laser optics in germanium and gallium arsenide on request (supplier page, not a substitute the source ranks)."
      ],
      "source": "usgs-mcs2026-selenium",
      "where": "Refinery production table, 2025 column (world total 3,800 t, selenium content; shares calculated by Space Mushroom. USGS states China at 53%); Recycling; Substitutes. Abundance from USGS PP 1802-A Table A1; critical lists from the USGS 2025 list and the EU page."
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Angstrom Sciences safety data sheet: Zinc Selenide (CAS 1315-09-9), last revised 07/07/15",
      "type": "sds",
      "url": "https://angstromsciences.com/wp-content/uploads/files/SDS/Zinc%20Selenide.pdf",
      "year": 2015
    },
    {
      "title": "Crystran: Zinc Selenide (ZnSe) product data",
      "type": "datasheet",
      "url": "https://www.crystran.co.uk/optical-materials/zinc-selenide-znse",
      "year": 2026
    },
    {
      "title": "Coherent: ZnSe material properties (bulk optical materials)",
      "type": "datasheet",
      "url": "https://www.coherent.com/optics/crystals/bulk-optical-materials/zinc-selenide",
      "year": 2026
    },
    {
      "title": "Tydex: CVD zinc selenide properties",
      "type": "datasheet",
      "url": "https://tydexoptics.com/materials1/for_transmission_optics/cvd_znse",
      "year": 2026
    },
    {
      "title": "LASER COMPONENTS: Materials for CO2 laser optics (12/25 edition)",
      "type": "datasheet",
      "url": "https://www.lasercomponents.com/fileadmin/user_upload/home/Datasheets/diverse-laser-optics/co2-laseroptics/materials-co2-laser-optics.pdf",
      "year": 2025
    },
    {
      "title": "Oxygen plasma effects on optical properties of ZnSe films (J. Vac. Sci. Technol. A, 2002)",
      "type": "paper",
      "url": "https://digitalcommons.unl.edu/electricalengineeringfacpub/9",
      "year": 2002
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Zinc",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-zinc.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
    }
  ],
  "gaps": [
    "No flight or space-qualification result for ZnSe optics was found. The only space-related source is a ground test of thin films in an oxygen plasma, which gives no data for bulk windows in orbit.",
    "No radiation, proton or UV-dose result for bulk ZnSe was read in this run.",
    "The Crystran safety sheet URL returned 404, so the Crystran hazard list was not read. The H-codes come from the Angstrom Sciences SDS and the Wikipedia infobox, which disagree on H410.",
    "PubChem could not be opened (challenge page and REST 404), so no PubChem GHS summary is used.",
    "The Thorlabs and KEMET safety sheets could not be downloaded in this run.",
    "No open-access review of the CVD production route was found. The process description rests on one supplier page (Crystran) and one older description in Wikipedia (not CVD).",
    "Single-crystal ZnSe absorption: Crystran says it is reported to be lower, but gives no figure and does not say it is available.",
    "Zinc crustal abundance was not found: the zinc row was not located in the USGS PP 1802-A Table A1 text read in this run.",
    "No humidity or long-term ageing test on bulk ZnSe was found.",
    "Atomic weights of zinc and selenium were not read, so the recipe gives the molecular weight only.",
    "No photographs were collected for this profile, so the media list is empty.",
    "Sources conflict on density (5.27 and 5.42 g/cm3) and on melting point (Crystran 1525 °C; Angstrom gives more than 1100 °C, not used). Both values are kept with their sources."
  ],
  "story": {
    "why": "Zinc selenide is a zinc and selenium compound that transmits infrared light from about 0.6 µm to 21 µm (Crystran). That range includes the 10.6 µm line of CO2 lasers. Its refractive index is 2.4028 at 10.6 µm, and its absorption there is very low, less than 0.0005 cm-1 (Coherent). The material is used for CO2 laser lenses and windows for these reasons. Its hardness and strength are modest, and its selenium content is toxic, so handling and temperature limits matter.",
    "uses": [
      {
        "where": "CO2 laser optics",
        "line": "LASER COMPONENTS calls zinc selenide the standard material for CO2 laser lenses and windows. Uncoated, about 70% of 10.6 µm light passes through, and coating both sides raises transmission above 99.4%."
      },
      {
        "where": "Infrared optics for space (ground test)",
        "line": "A ground test exposed thin ZnSe films to an oxygen plasma equal to about 16 years in low Earth orbit. The mid-infrared optical response barely changed, and the authors judged ZnSe potentially suitable for space infrared applications."
      },
      {
        "where": "X-ray and gamma-ray detectors",
        "line": "Tellurium-activated ZnSe is a scintillator with an emission peak at 640 nm, used in x-ray and gamma-ray detectors (Wikipedia)."
      }
    ],
    "can_do": [
      {
        "label": "Infrared transmission",
        "line": "Crystran gives an uncoated transmission range of 0.6 to 21 µm, which covers the 10.6 µm line of CO2 lasers.",
        "benchmark": "transmission_range",
        "scope": "material",
        "value": "0.6 to 21 µm"
      },
      {
        "label": "Transmission at 10.6 µm",
        "line": "LASER COMPONENTS prints about 70% transmission at 10.6 µm for uncoated material. This is close to the 29.1% reflection loss from two uncoated surfaces that Crystran gives.",
        "benchmark": "reflection_loss",
        "scope": "material",
        "value": "about 70% uncoated"
      },
      {
        "label": "Absorption",
        "line": "Coherent prints the bulk absorption at 10.6 µm as less than 0.0005 cm-1. LASER COMPONENTS calls its laser-grade ZnSe suited to high-power applications.",
        "benchmark": "absorption_coefficient",
        "scope": "material",
        "value": "less than 0.0005 cm-1 at 10.6 µm"
      },
      {
        "label": "Temperature limit",
        "line": "Crystran advises against using ZnSe windows above 250 °C in normal atmosphere.",
        "benchmark": "max_service_temp",
        "scope": "material",
        "value": "250 °C in normal atmosphere"
      }
    ],
    "compare": "Against sapphire, the other optical crystal in this collection, zinc selenide transmits further into the infrared, to 21 µm (Crystran), and it is much softer, with a Knoop hardness of 120 kg/mm2 (Crystran). The sapphire record is built on different tests and units, so the two are not compared number by number here. The sources read give no cost or availability comparison.",
    "compare_rows": [
      {
        "label": "Transmission range",
        "benchmark": "transmission_range",
        "scope": "material"
      },
      {
        "label": "Refractive index",
        "benchmark": "refractive_index",
        "scope": "material"
      },
      {
        "label": "Thermal conductivity",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      }
    ],
    "handling": [
      "Handle under dry protective gas and wash thoroughly after handling, as the safety sheet directs.",
      "Store in a cool, dry place in a tightly sealed container, away from bases and oxidizing agents.",
      "Vacuum spills with a HEPA filter and avoid raising dust. Do not blow dust off with compressed air.",
      "Keep windows at or below 250 °C in normal atmosphere."
    ],
    "good_for": [
      "Low-absorption CO2 laser optics. Uncoated transmission is about 70% at 10.6 µm, and two-side coating raises it above 99.4% (LASER COMPONENTS).",
      "Long-wave infrared windows. The uncoated transmission range runs from 0.6 to 21 µm (Crystran)."
    ],
    "watch_out": [
      "Softness. Knoop hardness is 105 to 120 kg/mm2 (Coherent), so the surface marks easily.",
      "Toxicity. The safety sheet classes the material as toxic if swallowed or inhaled, with H373 for repeated exposure.",
      "Temperature. Do not use windows above 250 °C in normal atmosphere (Crystran)."
    ],
    "verdict": "Zinc selenide is the standard low-absorption material for CO2 laser optics and an infrared window out to about 21 µm. It is soft, its selenium content is toxic, and it should not run above 250 °C in air, so it suits protected optics better than hard-wearing windows.",
    "recipe": {
      "line": "ZnSe is a 1:1 compound of zinc and selenium (one atom of each per formula unit). Crystran says it is produced from zinc vapour and hydrogen selenide gas, forming as sheets on graphite susceptors. Wikipedia also lists older routes: reaction of aqueous zinc sulfate with hydrogen selenide, heating zinc oxide, zinc sulfide and selenium together, and melt growth under argon pressure.",
      "parts": [
        {
          "name": "Zinc",
          "symbol": "Zn",
          "role": "Cation in the zinc blende lattice. In the deposition route it is supplied as zinc vapour (Crystran)."
        },
        {
          "name": "Selenium",
          "symbol": "Se",
          "role": "Anion in the zinc blende lattice. In the deposition route it is supplied as hydrogen selenide gas (Crystran)."
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The supplier safety sheet classes zinc selenide as toxic, so dust and fume need controlling. It gives a long-term exposure limit of 0.2 mg/m3 as selenium.",
        "points": [
          {
            "label": "The powder",
            "line": "The Angstrom Sciences sheet has the signal word Danger, with H301 and H331 (toxic if swallowed or inhaled) and H373 (may cause damage to organs through prolonged or repeated exposure)."
          },
          {
            "label": "Dust",
            "line": "The sheet says to take care not to raise dust, to vacuum spills with a HEPA filter, and not to blow dust off with compressed air."
          },
          {
            "label": "In a fire",
            "line": "The decomposition products are hydrogen selenide, selenium dioxide and metal oxide fume."
          }
        ],
        "level": 0,
        "verdict": "Toxic if swallowed or inhaled"
      },
      {
        "title": "If the optic overheats",
        "lead": "These limits come from the supplier's product text, not from incident data.",
        "points": [
          {
            "label": "Window limit",
            "line": "Crystran says windows should not be used above 250 °C in normal atmosphere. Oxidation becomes significant at 300 °C, plastic deformation starts at about 500 °C, and dissociation at about 700 °C."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Storage",
            "line": "Store in a cool, dry place in a tightly sealed container, apart from bases and oxidizing agents."
          },
          {
            "label": "Protection",
            "line": "The sheet calls for a dust respirator, rubber gloves, and safety glasses or goggles."
          }
        ]
      }
    ]
  },
  "updated": "2026-10-26",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 21,
    "unreachable": 4,
    "caveats": 3,
    "note": "Written by an AI assistant on 2026-10-26 from pages and PDFs read in the same run. Unreachable: the Crystran safety sheet (404), PubChem, the Thorlabs sheet and the KEMET sheet. Caveats: density and melting point differ between suppliers; the Tydex page prints a transmission range in mm that looks like a typo, so it was not used; no open-access review of CVD production was found."
  },
  "sources": {
    "crystran-znse": {
      "title": "Zinc Selenide (ZnSe): Crystran product data (Product Data table, safety notes)",
      "id": "Crystran product page (undated; read 2026-10-26)",
      "url": "https://www.crystran.co.uk/optical-materials/zinc-selenide-znse",
      "year": 2026,
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "wikipedia-znse": {
      "title": "Zinc selenide (Wikipedia article: formula, CAS, structure, band gap, uses, synthesis, hazard infobox)",
      "id": "Wikipedia (undated; read 2026-10-26)",
      "url": "https://en.wikipedia.org/wiki/Zinc_selenide",
      "year": 2026,
      "kind": "web",
      "license": "CC BY-SA 4.0 (Wikipedia)"
    },
    "coherent-znse": {
      "title": "Coherent: ZnSe material properties (ZnSe Material Properties table at 20 °C)",
      "id": "Coherent bulk optical materials page (undated; read 2026-10-26)",
      "url": "https://www.coherent.com/optics/crystals/bulk-optical-materials/zinc-selenide",
      "year": 2026,
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "tydex-cvd-znse": {
      "title": "Tydex: Zinc Selenide (CVD-ZnSe) properties",
      "id": "Tydex optics materials page (undated; read 2026-10-26)",
      "url": "https://tydexoptics.com/materials1/for_transmission_optics/cvd_znse",
      "year": 2026,
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "lc-co2-optics": {
      "title": "LASER COMPONENTS: Materials for CO2 laser optics",
      "id": "12/25 V3 supplier PDF",
      "url": "https://www.lasercomponents.com/fileadmin/user_upload/home/Datasheets/diverse-laser-optics/co2-laseroptics/materials-co2-laser-optics.pdf",
      "year": 2025,
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "angstrom-znse-sds": {
      "title": "Zinc Selenide: Safety Data Sheet (Angstrom Sciences, Inc.)",
      "id": "CAS 1315-09-9; EC 215-259-7; last revised 07/07/15",
      "url": "https://angstromsciences.com/wp-content/uploads/files/SDS/Zinc%20Selenide.pdf",
      "year": 2015,
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "yan2002": {
      "title": "Oxygen plasma effects on optical properties of ZnSe films",
      "id": "J. Vac. Sci. Technol. A 20(3), May-June 2002 (repository copy, University of Nebraska-Lincoln Digital Commons)",
      "url": "https://digitalcommons.unl.edu/electricalengineeringfacpub/9",
      "year": 2002,
      "kind": "paper",
      "license": "repository copy, read from the abstract page"
    },
    "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-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 under Regulation (EU) 2024/1252)",
      "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",
  "url": "https://spacemushroom.com/profiles/zinc-selenide/"
}