1314-12-1

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.

Toxic by ingestion.