Caesium_sesquioxide
Caesium sesquioxide
Chemical compound
Caesium sesquioxide is a chemical compound with the formula Cs2O3 or more accurately Cs4O6. It is an oxide of caesium containing oxygen in different oxidation states. It consists of caesium cations Cs+, superoxide anions O−2 and peroxide anions O2−2. Caesium in this compound has an oxidation state of +1, while oxygen in superoxide has an oxidation state of −1/2 and oxygen in peroxide has an oxidation state of −1. This compound has a structural formula of (Cs+)4(O−2)2(O2−2).[1][2] Compared to the other caesium oxides, this phase is less well studied,[3] but has been long present in the literature.[4] It can be created by thermal decomposition of caesium superoxide at 290 °C.[5]
- 4 CsO2 → Cs4O6 + O2
The compound is often studied as an example of a Verwey type charge ordering transition at low temperatures.[6][7][8] There were some theoretical suggestions that Cs4O6 would be a ferromagnetic half metal,[9] but along with the closely related rubidium sesquioxide, experimental results found a magnetically frustrated system.[1] Below about 200 K, the structure changes to tetragonal symmetry.[10] Electron paramagnetic resonance and nuclear magnetic resonance measurements show a complicated low temperature magnetic behavior that depends on the orientation of the oxygen dimers and superexchange through the caesium atoms.[11]