Thallium(I) sulfide
Encyclopedia
Thallium sulfide, Tl2S, is a chemical compound of thallium
and sulfur
.
It was used in some of the earliest photo-electric detectors by T. Case
who developed the so-called thalofide (sometimes spelt thallofide) cell, used in early film projectors. Case described the detector material as consisting of thallium, oxygen and sulfur, and this was incorrectly described by others as being thallium oxysulfide, which incidentally is a compound that is not known. Case's work was then built on by R.J. Cashman who recognised that the controlled oxidation of the Tl2S film was key to the operation of the cell. Cashman's work culminated in the development of long wave infrared detectors used during the second world war. Reliable Tl2S detectors were also developed in Germany at the same time.
Tl2S is found in nature as the mineral carlinite which has the distinction of being the only sulfide mineral of thallium that does not contain at least two metals. Tl2S has a distorted anti-CdI2 structure.
Tl2S can be prepared from the elements or by precipitating the sulfide from a solution of thallium(I), e.g. the sulfate
or nitrate. Thin films have been deposited, produced from a mixture of citratothallium complex and thiourea. Heating the film in nitrogen at 300°C converts all the product into Tl2S
Thallium
Thallium is a chemical element with the symbol Tl and atomic number 81. This soft gray poor metal resembles tin but discolors when exposed to air. The two chemists William Crookes and Claude-Auguste Lamy discovered thallium independently in 1861 by the newly developed method of flame spectroscopy...
and sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
.
It was used in some of the earliest photo-electric detectors by T. Case
Theodore Case
Theodore Willard Case known for the invention of the Movietone sound-on-film sound film system, was born into a prominent family in Auburn, New York.-Family history:...
who developed the so-called thalofide (sometimes spelt thallofide) cell, used in early film projectors. Case described the detector material as consisting of thallium, oxygen and sulfur, and this was incorrectly described by others as being thallium oxysulfide, which incidentally is a compound that is not known. Case's work was then built on by R.J. Cashman who recognised that the controlled oxidation of the Tl2S film was key to the operation of the cell. Cashman's work culminated in the development of long wave infrared detectors used during the second world war. Reliable Tl2S detectors were also developed in Germany at the same time.
Tl2S is found in nature as the mineral carlinite which has the distinction of being the only sulfide mineral of thallium that does not contain at least two metals. Tl2S has a distorted anti-CdI2 structure.
Tl2S can be prepared from the elements or by precipitating the sulfide from a solution of thallium(I), e.g. the sulfate
Thallium(I) sulfate
Thallium sulfate , archaically known as thallous sulfate, is the sulfate salt of thallium. It is colorless, odorless, and tasteless, but highly toxic.-Uses:...
or nitrate. Thin films have been deposited, produced from a mixture of citratothallium complex and thiourea. Heating the film in nitrogen at 300°C converts all the product into Tl2S