{ "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.\n", "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", "designations": [], "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, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "density", "label": "Density (supplier safety sheet)", "value": 5.81, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "melting_point", "label": "Melting point (manufacturer)", "value": 1537, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "melting_point", "label": "Melting point (Wikipedia)", "value": 1240, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "refractive_index", "label": "Refractive index, ordinary ray at 10 µm", "value": 2.431, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "refractive_index", "label": "Refractive index, extraordinary ray at 10 µm", "value": 2.452, "bound": "exact", "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)", "source_detail": { "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" } }, { "benchmark": "refractive_index", "label": "Refractive index (n_D)", "value": 2.5, "bound": "exact", "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", "source_detail": { "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)" } }, { "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)", "source_detail": { "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" } }, { "benchmark": "band_gap", "label": "Band gap", "value": 1.74, "bound": "exact", "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", "source_detail": { "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)" } }, { "benchmark": "mohs_hardness", "label": "Mohs hardness", "value": 3.25, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity, parallel to c axis", "value": 6.9, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity, perpendicular to c axis", "value": 6.2, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "cte", "label": "Thermal expansion coefficient, parallel to c axis", "value": 2.45, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "cte", "label": "Thermal expansion coefficient, perpendicular to c axis", "value": 4.4, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "specific_heat", "label": "Specific heat capacity", "value": 258, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "dielectric_constant", "label": "Dielectric constant, clamped, perpendicular to c axis", "value": 9.7, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "dielectric_constant", "label": "Dielectric constant, clamped, parallel to c axis", "value": 10.65, "bound": "exact", "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", "source_detail": { "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" } } ], "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." ], "story": { "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", "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.", "benchmark": "transmission_range", "scope": "material", "value": "0.75 to 25.5 µm" }, { "label": "Birefringence", "line": "Tydex prints the ordinary and extraordinary indices at 10 µm, which gives the birefringence that waveplates need.", "benchmark": "refractive_index", "scope": "material", "value": "no 2.431, ne 2.452 at 10 µm" }, { "label": "Band gap", "line": "Wikipedia gives 1.74 eV for both the hexagonal and sphalerite forms, with no temperature stated.", "benchmark": "band_gap", "scope": "material", "value": "1.74 eV" } ], "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", "scope": "material" }, { "label": "Refractive index", "benchmark": "refractive_index", "scope": "material" }, { "label": "Thermal conductivity", "benchmark": "thermal_conductivity", "scope": "material" } ], "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.", "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", "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)." } ], "level": 0, "verdict": "Toxic if swallowed or inhaled" }, { "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)." } ] } ] }, "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." }, "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", "url": "https://spacemushroom.com/profiles/cadmium-selenide/" }