Structure and Physical Properties
Cadmium sulfide has, like zinc sulfide, two crystal forms; the more stable hexagonal wurtzite structure (found in the mineral Greenockite) and the cubic zinc blende structure (found in the mineral Hawleyite). In both of these forms the cadmium and sulfur atoms are four coordinate. There is also a high pressure form with the NaCl rock salt structure.
Cadmium sulfide is a direct band gap semiconductor (gap 2.42 eV). The magnitude of its band gap means that it appears coloured.
As well as this obvious property others properties result:
- the conductivity increases when irradiated with light(leading to uses as a photoresistor)
- when combined with a p-type semiconductor it forms the core component of a photovoltaic (solar) cell and a CdS/Cu2S solar cell was one of the first efficient cells to be reported (1954)
- when doped with for example Cu+ ("activator") and Al3+ ("coactivator") CdS luminesces under electron beam excitation (cathodoluminescence) and is used as phosphor
- both polymorphs are piezoelectric and the hexagonal is also pyroelectric
- electroluminescence
- CdS crystal can act as a solid state laser
Read more about this topic: Cadmium Sulfide
Famous quotes containing the words structure and, structure, physical and/or properties:
“Slumism is the pent-up anger of people living on the outside of affluence. Slumism is decay of structure and deterioration of the human spirit. Slumism is a virus which spreads through the body politic. As other “isms,” it breeds disorder and demagoguery and hate.”
—Hubert H. Humphrey (1911–1978)
“Why does philosophy use concepts and why does faith use symbols if both try to express the same ultimate? The answer, of course, is that the relation to the ultimate is not the same in each case. The philosophical relation is in principle a detached description of the basic structure in which the ultimate manifests itself. The relation of faith is in principle an involved expression of concern about the meaning of the ultimate for the faithful.”
—Paul Tillich (1886–1965)
“Good schools are schools for the development of the whole child. They seek to help children develop to their maximum their social powers and their intellectual powers, their emotional capacities, their physical powers.”
—James L. Hymes, Jr. (20th century)
“A drop of water has the properties of the sea, but cannot exhibit a storm. There is beauty of a concert, as well as of a flute; strength of a host, as well as of a hero.”
—Ralph Waldo Emerson (1803–1882)