Thallium oxide slowly oxidizes to thallic oxide, Tl2O3 on exposure to air, gradually becoming insoluble in aqueous solution.
Thallium monooxide is a black powder; orthorhombic crystals; hygroscopic; density 9.52g/cm3; melts at 596°C; vaporizes at about 1,080°C; soluble in water, alcohol and acids.
In manufacture of glass of a high coefficient of refraction for optical purposes (thallium flint glass) and for artificial gems.
Thallium oxide can be made by heating Tl metal in air or oxygen. The brown-black thallic oxide, Tl2O3 , that may also form begins to lose oxygen at about 100°C converting to thallium oxide, Tl2O.
Thallium oxide also can be prepared by thermal dissociation of thallium hydroxide, TlOH or thallium carbonate, Tl2CO3 Thallium oxide dissolves in water forming thallous hydroxide, TlOH. It reacts with carbon dioxide to form thallous carbonate, Tl2CO3.
