Cadmium sulfide

Cadmium sulfide is an inorganic compound with the formula CdS. Cadmium sulfide is a yellow solid. 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. Its vivid yellow color led to its adoption as a pigment for the yellow paint "cadmium yellow" in the 18th century.

Chemical properties

Cadmium sulfide can be prepared by the precipitation from soluble cadmium(II) salts with sulfide ions. This reaction has been used for gravimetric analytical methods for the quantification of cadmium, for example in food testing.

Physical properties

Cadmium sulfide is a direct band gap semiconductor (gap 2.42 eV). The proximity of its band gap to visible light wavelengths gives it a colored appearance. Both wurtzite and cubic (sphalerite/zincblende) forms of CdS occur naturally. The cubic form is more prevalent in the crystal lattice.

Applications

Cadmium sulfide is used as pigment in plastics, and as a semiconductor in photovoltaic cells. It is also used in photocells where it converts light into electricity and in photoresistors where it increases resistance with light exposure.

Health effects

Cadmium sulfide is a known carcinogen. Exposure to cadmium sulfide can cause lung and prostate cancer. It can also cause kidney damage, bone loss, and other health problems.

See also

• Cadmium
• Sulfide
• Cadmium(II) sulfide
• Cadmium sulfide pigments