Observation of the Fixed Fe–CN–Mn Cluster in Cesium Manganese Hexacyanoferrate

The temperature-induced phase transition of cesium manganese hexacyanoferrate is based on the charge transfer between transition metal ions, and the behavior is complex. To clarify the mechanism for the phase transition, X-ray absorption and magnetic susceptibility were measured. The magnetic susceptibility behavior was different from that of rubidium manganese hexacyanoferrate. X-ray data analyses suggested that the phase transition of cesium manganese hexacyanoferrate is the result of a local charge transfer in the fixed Fe–CN–Mn cluster and the interaction among the clusters. Calculation of the Gibbs free energy of the mean-field model indicates that the cluster interaction influences the phase transition behavior of cesium manganese hexacyanoferrate.