Thallium(I) oxide
# Thallium(I) oxide

Thallium(I) oxide is the inorganic compound of thallium and oxygen with the formula $Tl_2O$ in which thallium is in its +1 oxidation state. It 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 $Tl_2CO_3$ in the absence of air. Thallium oxide is used to make special high refractive index glass. Thallium oxide is a component of several high temperature superconductors. Thallium(I) oxide reacts with acids to make thallium(I) salts.

$Tl_2O$ adopts the anti-cadmium iodide structure in the solid state. In this way, the Tl(I) centers are pyramidal and the oxide centers are octahedral.

Thallium(I) oxide, like all thallium compounds, is highly toxic.

## Preparation

Thallium(I) oxide can be produced by decomposition of thallium(I) hydroxide at 100 °C or by heating thallium(III) oxide in the absence of air to 700 °C.

    $\mathrm {2\ TlOH\longrightarrow Tl_{2}O+H_{2}O}$
    $\mathrm {Tl_{2}O_{3}\longrightarrow Tl_{2}O+O_{2}}$
