Thallium(III) oxide, also known as thallic oxide, is a chemical compound of

thallium Thallium is a chemical element with the symbol Tl and atomic number 81. It is a gray post-transition metal that is not found free in nature. When isolated, thallium resembles tin, but discolors when exposed to air. Chemists William Crookes an ...

and

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

. It occurs in nature as the rare mineral

avicennite Avicennite ( thallium(III) oxide) is an oxide mineral. It was discovered around the Dzhuzumli village, Samarqand, Uzbekistan. It is named after Avicenna, a Persian doctor and polymath. See also *List of minerals *List of minerals named after peopl ...

. Its structure is related to that of Mn₂O₃ which has a

bixbyite Bixbyite is a manganese iron oxide mineral with chemical formula: (Mn,Fe)2O3. The iron/manganese ratio is quite variable and many specimens have almost no iron. It is a metallic dark black with a Mohs hardness of 6.0 - 6.5. It is a somewhat rare ...

like structure. Tl₂O₃ is metallic with high conductivity and is a degenerate n-type

semiconductor A semiconductor is a material which has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity falls as its temperature rises; metals behave in the opposite way. ...

which may have potential use in

solar cells A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect, which is a physical and chemical phenomenon.

. A method of producing Tl₂O₃ by

MOCVD Metalorganic vapour-phase epitaxy (MOVPE), also known as organometallic vapour-phase epitaxy (OMVPE) or metalorganic chemical vapour deposition (MOCVD), is a chemical vapour deposition method used to produce single- or polycrystalline thin films. ...

is known. Any practical use of thallium(III) oxide will always have to take account of thallium's poisonous nature. Contact with

moisture Moisture is the presence of a liquid, especially water, often in trace amounts. Small amounts of water may be found, for example, in the air (humidity), in foods, and in some commercial products. Moisture also refers to the amount of water vapo ...

and acids may form poisonous thallium compounds.

Production

It is produced by the reaction of thallium with oxygen or

hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%� ...

in an alkaline thallium(I) solution. Alternatively, it can be created by the oxidation of thallium(I) nitrate by chlorine in an aqueous

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which exp ...

solution.Georg Brauer; Handbuch der präparativen anorganischen Chemie, Band 2, S.884; (in German)

References

Thallium(III) compounds Sesquioxides {{inorganic-compound-stub