User:Graeme Bartlett/thiogallate

Thiogallates are chemical compounds which contain anionic units of sulfur connected to gallium. They can be considered as gallates where sulfur substitutes for oxygen. Similar compounds include the selenogallates and thiostannates. They are in the category of chalcogenotrielates or more broadly chalcogenometallates.

Formation
Thiogallates may be produced by heating a metal azide with gallium monosulfide and sulfur in a sealed tube.

Thiogallates containing Se2 units are formed by heating with selenium. Conversely, by heating, extra sulfur vapour can be lost forming a compound with less sulfur.

Properties
Most thiogallates are semiconductors. Their resistance drops on exposure to light. Also thiogallates are often coloured, most often red.

Thiogallate structures can include rings such as the four-membered ring: [GaSGaS] or the five-membered [GaSSGaS]. These can be linked into chains.

Use
Thiogallates are primarily of research interest. They are being researched for photovoltaic cells where efficiencies over 20% are possible, and for photoconductors, and infrared non-linear optical devices.