Cadmium sulfide
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| Names | |||
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| Other names | |||
| Identifiers | |||
3D model (
JSmol ) |
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| ChEBI | |||
| ChemSpider | |||
ECHA InfoCard
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100.013.771 | ||
| EC Number |
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| 13655 | |||
PubChem CID
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RTECS number
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| UNII | |||
| UN number | 2570 | ||
CompTox Dashboard (EPA)
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| Properties | |||
| CdS | |||
| Molar mass | 144.47 g·mol−1 | ||
| Appearance | Yellow-orange to brown solid. | ||
| Density | 4.826 g/cm3, solid. | ||
| Melting point | 1,750 °C (3,180 °F; 2,020 K) 10 MPa | ||
| Boiling point | 980 °C (1,800 °F; 1,250 K) ( sublimation )
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| insoluble[1] | |||
| Solubility | soluble in acid very slightly soluble in ammonium hydroxide
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| Band gap | 2.42 eV | ||
| -50.0·10−6 cm3/mol | |||
Refractive index (nD)
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2.529 | ||
| Structure | |||
Hexagonal, Cubic
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| Thermochemistry | |||
Std molar
entropy (S⦵298) |
65 J·mol−1·K−1[2] | ||
Std enthalpy of (ΔfH⦵298)formation |
−162 kJ·mol−1[2] | ||
| Hazards | |||
| GHS labelling: | |||
 
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| Danger | |||
| H302, H341, H350, H361, H372, H413 | |||
| P201, P202, P260, P264, P270, P273, P281, P301+P312, P308+P313, P314, P330, P405, P501 | |||
| NFPA 704 (fire diamond) | |||
| Flash point | Non-flammable | ||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose)
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7080 mg/kg (rat, oral) | ||
| NIOSH (US health exposure limits): | |||
PEL (Permissible)
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[1910.1027] TWA 0.005 mg/m3 (as Cd)[3] | ||
REL (Recommended)
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Ca[3] | ||
IDLH (Immediate danger) |
Ca [9 mg/m3 (as Cd)][3] | ||
| Safety data sheet (SDS) | ICSC 0404 | ||
| Related compounds | |||
Other anions
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Cadmium oxide Cadmium selenide | ||
Other cations
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Zinc sulfide Mercury sulfide | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Cadmium sulfide is the inorganic compound with the formula CdS. Cadmium sulfide is a yellow salt.[4] It occurs in nature with two different crystal structures as the rare minerals greenockite and hawleyite, but is more prevalent as an impurity substituent in the similarly structured zinc ores sphalerite and wurtzite, which are the major economic sources of cadmium. As a compound that is easy to isolate and purify, it is the principal source of cadmium for all commercial applications.[4] Its vivid yellow color led to its adoption as a pigment for the yellow paint "cadmium yellow" in the 18th century.
Production
Cadmium sulfide can be prepared by the precipitation from soluble cadmium(II) salts with sulfide ion. This reaction has been used for gravimetric analysis and
Pigment production usually involves the precipitation of CdS, the washing of the solid precipitate to remove soluble cadmium salts followed by calcination (roasting) to convert it to the hexagonal form followed by milling to produce a powder.[7] When cadmium sulfide selenides are required the CdSe is co-precipitated with CdS and the cadmium sulfoselenide is created during the calcination step.[7]
Cadmium sulfide is sometimes associated with sulfate reducing bacteria.[8][9]
Routes to thin films of CdS
Special methods are used to produce films of CdS as components in some photoresistors and solar cells. In the chemical bath deposition method, thin films of CdS have been prepared using thiourea as the source of sulfide anions and an ammonium buffer solution to control pH:[10]
- Cd2+ + H2O + (NH2)2CS + 2 NH3 → CdS + (NH2)2CO + 2 NH4+
Cadmium sulfide can be produced using
- Cd(CH3)2 + Et2S → CdS + CH3CH3 + C4H10
Other methods to produce films of CdS include
- Sol–gel techniques[12]
- Sputtering[13]
- Electrochemical deposition[14]
- Spraying with precursor cadmium salt, sulfur compound and dopant[15]
- Screen printing using a slurry containing dispersed CdS[16]
Reactions
Cadmium sulfide can be dissolved in acids.[17]
- CdS + 2 HCl → CdCl2 + H2S
When solutions of sulfide containing dispersed CdS particles are irradiated with light, hydrogen gas is generated:[18]
- H2S → H2 + S ΔfH = +9.4 kcal/mol
The proposed mechanism involves the electron/hole pairs created when incident light is absorbed by the cadmium sulfide[19] followed by these reacting with water and sulfide:[18]
- Production of an electron–hole pair
- CdS + hν → e− + h+
- Reaction of electron
- 2e− + 2H2O → H2 + 2OH−
- Reaction of hole
- 2h+ + S2− → S
Structure and physical properties
Cadmium sulfide has, like
Cadmium sulfide is a direct band gap semiconductor (gap 2.42 eV).[19] The proximity of its band gap to visible light wavelengths gives it a coloured appearance.[4]
As well as this obvious property other properties result:
- the conductivity increases when irradiated,[19] (leading to uses as a photoresistor)
- when combined with a
- when
- both pyroelectric[24]
- electroluminescence[25]
- CdS crystals can act as a gain medium in
- In thin-film form, CdS can be combined with other layers for use in certain types of solar cells.[28] CdS was also one of the first semiconductor materials to be used for thin-film transistors (TFTs).[29] However interest in compound semiconductors for TFTs largely waned after the emergence of amorphous silicon technology in the late 1970s.
- Thin films of CdS can be piezoelectric and have been used as transducers which can operate at frequencies in the GHz region.
- Nanoribbons of CdS show a net cooling due annihilation of phonons, during anti-Stokes luminescence at ~510 nm. As a result, a maximum temperature drop of 40 and 15 K has been demonstrated when the nanoribbons are pumped with a 514 or 532 nm laser.[30]
Applications
Pigment
CdS is used as
Historical use in art
The general commercial availability of cadmium sulfide from the 1840s led to its adoption by artists, notably Van Gogh, Monet (in his London series and other works) and Matisse (Bathers by a River 1916–1919).[33] The presence of cadmium in paints has been used to detect forgeries in paintings alleged to have been produced prior to the 19th century.[34]
CdS-CdSe solutions
CdS and CdSe form solid solutions with each other. Increasing amounts of cadmium selenide, gives pigments verging toward red, for example CI pigment orange 20 and CI pigment red 108.[31]
Such solid solutions are components of photoresistors (light dependent resistors) sensitive to visible and near infrared light.[citation needed]
Safety
Cadmium sulfide is toxic, especially dangerous when inhaled as dust, and cadmium compounds in general are classified as
References
- ISBN 978-0-8493-0594-8.
- ^ ISBN 978-0-618-94690-7.
- ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0087". National Institute for Occupational Safety and Health (NIOSH).
- ^ ISBN 0-12-352651-5
- ISBN 1-4067-8113-4
- ISBN 0-8247-8468-5
- ^ ISBN 978-3-527-30204-8.
- ISBN 0-306-44857-2
- PMID 15556006.
- .
- .
- .
- .
- .
- ^ U.S. patent 4,086,101 Photovoltaic cells, J.F. Jordan, C.M. Lampkin Issue date: April 25, 1978
- ^ U.S. patent 3,208,022, High performance photoresistor, Y.T. Sihvonen, issue date: September 21, 1965
- .
- ^ ISBN 90-277-1946-2
- ^ ISBN 1-56677-433-0
- ^ ISBN 0-19-855370-6
- ISBN 0-471-49196-9
- .
- ISBN 0-471-93620-0
- .
- .
- .
- S2CID 651903.
- .
- S2CID 51650159.
- S2CID 4426843.
- ^ ISBN 0-85404-573-2
- .
- ISBN 0-309-06556-9
- ISBN 0-387-98722-3
- ^ "CDC - CADMIUM SULFIDE - International Chemical Safety Cards - NIOSH". June 26, 2018. Archived from the original on 2018-06-26.
- PMID 14043617.
- ^ "Sicherheitsdatenblatt" (PDF). Archived from the original (PDF) on 24 July 2015.
External links
- Cadmium(II) sulphide information at Webelements
- IARC Monograph: "Cadmium and Cadmium Compounds" Last access November 2005.
- International Chemical Safety Card 0404
- National Pollutant Inventory - Cadmium and compounds
- Defence Internet | About Defence | Zinc Cadmium Sulphide Dispersion Trials Report by the Academy of Medical Sciences to the Chief Scientific Adviser, Ministry of Defence on the zinc cadmium sulphide dispersion trials undertaken in the United Kingdom between 1953 and 1964.