Thallium oxide is the general name of several oxides of thallium. The most common is Tl2O in which thallium is in its +1 oxidation state. Other oxides of thallium include TlO2, Tl4O3 and Tl2O3.
Thallium(I) oxide (Tl2O) is black and produces a basic yellow solution of thallium(I) hydroxide (TlOH) when dissolved in water. It is formed by heating solid TlOH or Tl2CO3 in the absence of air. Thallium oxide is used to make special high refractive indexglass. Research is continuing into the use of thallium oxide in high temperature superconductors.
