Cadmium sulfide is a chemical compound that has the formula CdS. It is yellow in color and is a semiconductor of electricity. It exists as two different polymorphs, hexagonal greenockite and cubic hawleyite.
Greenockite is a hexagonal, yellowish crystal. It is a rare mineral and is the only real ore of cadmium. It is a much sought after mineral because of its beautiful color and crystal habit. It has the same structure as that of zinc iron sulfide wurtzite. The structure of Greenockite is composed of SCd4 tetrahedrons, which are stacked in a layered structure with every other layer exactly the same in an AB AB AB hexagonal sequence. Crystals of greenockite are typically of six sided pyramids. In it the hemimorphic character is easily seen because the top of the crystal is the point and the bottom of it is its base.
Cubic hawleyite, the other polymorph of Cadmium Sulfide, is a rare sulfide mineral in the sphalerite group, dimorphous and easily confused with greenockite (mentioned above). Chemically, it is cadmium sulfide, and occurs as a bright yellow coating on sphalerite or siderite in vugs, deposited by meteoric waters. It was discovered in 1955 in the Hector-Calumet mine, Keno-Galena Hill area, Yukon Territory and named in honor of mineralogist James Edwin Hawley, a professor at Queen's University in Ontario, Canada.
Properties of Cadmium Sulfide
Some basic properties of cadmium sulfide are listed below:
|Physical state and appearance
||Solid. (Solid powder.)
||Yellow or brown
||Sublimes. (980°C or 1796°F)
||Insoluble in hot and cold water
The main applications of Cadmium Sulfide is as a pigment.
Figure 1. Cadmium Sulfide courtesy of ahpmat.com. Used with permission.
Cadmium Sulfide is also used in the production of solar cells where it is used as a buffer layer in the manufacture of CIGS (Copper -Indium-Gallium-Selenide) solar cells. With an increasing interest and uptake of solar cells, this application for cadmium sulfide could also increase..
Other uses of the Cadmium Sulfide are listed below:
- Light dependent resistors/photoresistors for light sensors
- Chemical bath deposition, CBD
- Sol gel techniques
- Electrochemical deposition
- Spraying with precursor cadmium salt, sulfur compound and dopant
- Screen printing using a slurry containing dispersed CdS
Future of Cadmium Sulfide
While the main use for Cadmium Sulfide has been as pigment, it is reasonable to expect that the solar cell market will begin to consume more Cadmium Sulfide in the future as the technology becomes more widely accepted and more affordable.
This information has been sourced, reviewed and adapted from materials provided by AHP Materials.
For more information o this source, please visit AHP Materials.