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Cadmium sulfide

Cadmium sulfide


Other names	Cadmium(II) sulfide
Identifiers
CAS number	1306-23-6
EINECS number	215-147-8
RTECS number	EV3150000
Properties
Molecular formula	CdS
Molar mass	144.46 g/mol
Appearance	Yellow-orange solid.
Density	4.82 g/cm³, solid.
Melting point	1750°C at 100 bar
Boiling point	980°C subl.
Solubility in water	Insoluble
Structure
Crystal structure	Hexagonal
Hazards
EU classification	Toxic Carc. Cat. 2 Muta. Cat. 3 Repr. Cat. 3 Dangerous for the environment
Flash point	non flammable
Related Compounds
Other anions	Cadmium oxide Cadmium selenide
Other cations	Zinc sulfide Mercury sulfide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Cadmium sulfide is a chemical compound with the formula CdS. It exists in nature as two different minerals, greenockite and hawleyite.

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Greenockite forms hexagonal crystals with the wurtzite structure. It has a yellowish colour with specific gravity of 4.7 and Mohs hardness of 3.8. Hawleyite has the sphalerite (zinc blende) structure.

Synthetic cadmium pigments based on cadmium sulfide are valued for their good thermal stability in many polymers, for example in engineering plastics. By adding selenium in its formula its possible to obtain colors ranging from a greenish yellow to red violet pigment. The weather resistance for this pigment is 8 in full tone, which means that it is a good pigment for UV.

Cadmium sulfide is a direct bandgap semiconductor with a bandgap of 2.42 eV. It has useful properties for optoelectronics, being used in both photosensitive and photovoltaic devices. One simple use is as a photoresistor whose electrical resistance changes with incident light levels.

Mixed with zinc sulfide, cadmium sulfide acts as a phosphor with long afterglow.

Cadmium sulfide was used as a pigment in paints as far back as 1819, but in small quantities due to its scarcity. Most cadmium sulfide used in paints is manufactured in chemical laboratories.

Such a painter as Claude Monet used it extensively due to its appealing shade of yellow well suited to his paintings.