Rubidium sesquioxide

Rubidium sesquioxide is a chemical compound with the formula Rb2O3 or more accurately Rb4O6. In terms of oxidation states, Rubidium in this compound has a nominal charge of +1, and the oxygen is a mixed peroxide (O2(2-)) and superoxide (O2−) for a structural formula of (Rb+)4(O2−)2(O2(2-)). It has been studied theoretically as an example of a strongly correlated material.

The compound was predicted to be a rare example of a ferromagnetic compound that is magnetic due to a p-block element, and a half-metal that was conducting in the minority spin band. However, while the material does have exotic magnetic behavior, experimental results instead showed an electrically insulating magnetically frustrated system. Rb4O6 also displays a Verwey transition where charge ordering appears at 290 K.

Rubidium sesquioxide can be prepared by reacting the peroxide Rb2O2 and the superoxide RbO2:


 * Rb2O2 + 2 RbO2 → 2 Rb2O3

It is initially discovered in 1907, and more thoroughly characterized in 1939. The compound crystallizes in a body-centered cubic form with the same crystal structure as Pu2C3 and Cs4O6.