Caesium sesquioxide
3D model (JSmol)
  • InChI=1S/4Cs.2HO2.O2/c;;;;3*1-2/h;;;;2*1H;/q4*+1;;;-2/p-2
  • [Cs+].[Cs+].[Cs+].[Cs+].[O-][O].[O-][O].[O-][O-]
Molar mass 627.616 g·mol−1
Appearance black powder[1]
Pu2C3 structure type (body-centered cubic)
I43d (no. 220)
a = 984.6 pm
Related compounds
Other cations
Rubidium sesquioxide
Related caesium oxides
Caesium suboxides
Caesium monoxide
Caesium peroxide
Caesium superoxide
Caesium ozonide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Caesium sesquioxide is a chemical compound with the formula Cs2O3 or Cs4O6. In terms of oxidation states, Caesium 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 (Cs+)4(O2)2(O2−2).[1] Compared to the other caesium oxides, this phase is less well studied,[2] but has been long present in the literature.[3] It can be created by thermal decomposition of caesium superoxide at 290 °C.[4]

4 CsO2 → Cs4O6 + O2

The compound is often studied as an example of a Verwey type charge ordering transition at low temperatures.[5][6][7] There were some theoretical suggestions that Cs4O6 would be a ferromagnetic half metal,[8] but along with the closely related rubidium sesquioxide, experimental results found a magnetically frustrated system.[1] Below about 200 K, the structure changes to tegragonal symmetry.[9] 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.[10]


  1. ^ a b c d Winterlik, Jürgen; Fecher, Gerhard H.; Jenkins, Catherine A.; Medvedev, Sergey; Felser, Claudia; et al. (2009-06-09). "Exotic magnetism in the alkali sesquioxides Rb4O6 and Cs4O6". Physical Review B. 79 (21): 214410. arXiv:0904.4338. Bibcode:2009PhRvB..79u4410W. doi:10.1103/physrevb.79.214410. ISSN 1098-0121. S2CID 118706339.
  2. ^ Band, A.; Albu-Yaron, A.; Livneh, T.; Cohen, H.; Feldman, Y.; Shimon, L.; Popovitz-Biro, R.; Lyahovitskaya, V.; Tenne, R. (2004-07-27). "Characterization of Oxides of Cesium". The Journal of Physical Chemistry B. American Chemical Society (ACS). 108 (33): 12360–12367. doi:10.1021/jp036432o. ISSN 1520-6106.
  3. ^ Helms, Alfred; Klemm, Wilhelm (1939-08-29). "Über die Kristallstrukturen der Rubidium- und Cäsiumsesquioxyde". Zeitschrift für anorganische und allgemeine Chemie (in German). Wiley. 242 (2): 201–214. doi:10.1002/zaac.19392420210. ISSN 0863-1786.
  4. ^ Merz, Patrick; Schmidt, Marcus; Felser, Claudia; Jansen, Martin (2017-03-24). "Thermo-analytical Investigations on the Superoxides AO2 (A = K, Rb, Cs), Revealing Facile Access to Sesquioxides A4O6". Zeitschrift für anorganische und allgemeine Chemie. Wiley. 643 (8): 544–547. doi:10.1002/zaac.201700013. ISSN 0044-2313.
  5. ^ Max Planck Society (2018-01-19). "Charge order and electron localization in a molecule-based solid". Retrieved 2021-11-26.
  6. ^ Adler, Peter; Jeglič, Peter; Reehuis, Manfred; Geiß, Matthias; Merz, Patrick; Knaflič, Tilen; Komelj, Matej; Hoser, Andreas; Sans, Annette; Janek, Jürgen; Arčon, Denis; Jansen, Martin; Felser, Claudia (2018-01-17). "Verwey-type charge ordering transition in an open-shell p -electron compound". Science Advances. American Association for the Advancement of Science (AAAS). 4 (1): eaap7581. Bibcode:2018SciA....4.7581A. doi:10.1126/sciadv.aap7581. ISSN 2375-2548. PMC 5775027. PMID 29372183.
  7. ^ Colman, Ross H.; Okur, H. Esma; Kockelmann, Winfried; Brown, Craig M.; Sans, Annette; Felser, Claudia; Jansen, Martin; Prassides, Kosmas (2019-10-21). "Elusive Valence Transition in Mixed-Valence Sesquioxide Cs4O6". Inorganic Chemistry. American Chemical Society (ACS). 58 (21): 14532–14541. doi:10.1021/acs.inorgchem.9b02122. ISSN 0020-1669. PMC 7880551. PMID 31633914.
  8. ^ Attema, J J; Wijs, G A de; Groot, R A de (2007-04-05). "Spintronic materials based on main-group elements" (PDF). Journal of Physics: Condensed Matter. IOP Publishing. 19 (16): 165203. Bibcode:2007JPCM...19p5203A. doi:10.1088/0953-8984/19/16/165203. ISSN 0953-8984.
  9. ^ Okur, H. Esma; Colman, Ross H.; Ohishi, Yasuo; Sans, Annette; Felser, Claudia; Jansen, Martin; Prassides, Kosmas (2020-01-06). "Pressure-Induced Charge Disorder–Order Transition in the Cs4O6 Sesquioxide". Inorganic Chemistry. American Chemical Society (ACS). 59 (2): 1256–1264. doi:10.1021/acs.inorgchem.9b02974. ISSN 0020-1669. PMID 31904961. S2CID 210041198.
  10. ^ Arčon, D.; Anderle, K.; Klanjšek, M.; Sans, A.; Mühle, C.; Adler, P.; Schnelle, W.; Jansen, M.; Felser, C. (2013-12-10). "Influence of O2 molecular orientation on p-orbital ordering and exchange pathways in Cs4O6". Physical Review B. American Physical Society (APS). 88 (22): 224409. Bibcode:2013PhRvB..88v4409A. doi:10.1103/physrevb.88.224409. ISSN 1098-0121.