Elusive Valence Transition in Mixed-Valence Sesquioxide Cs₄O₆.

ABSTRACT: Cs₄O₆ is a mixed-valence molecular oxide with a cubic structure, comprising valency-delocalized O₂^4/3- units and with properties highly sensitive to cooling protocols. Here we use neutron powder diffraction to authenticate that, while upon deep quenching the cubic phase is kinetically arrested down to cryogenic temperatures, ultraslow cooling results in an incomplete structural transition to a contracted tetragonal phase. Two dioxygen anions in a 1:2 ratio are identified, providing evidence that the transition is accompanied by charge and orbital order and stabilizes a Robin-Day Class II mixed-valence state, comprising O₂^2- and O₂^- anions. The phenomenology of the phase change is consistent with that of

SUBMITTER: Colman RH 

PROVIDER: S-EPMC7880551 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature