Electron transfer phase transition and oxidization process in NaxCo0.44Mn0.56[Fe(CN)6]0.90 (0.00 ≤ x ≤ 1.60).

We investigated the phase diagram of NaxCo0.44Mn0.56[Fe(CN)6]0.90 in the entire Na concentration range of 0.00 ≤ x ≤ 1.60. We found that the compound shows an electron transfer (ET) phase transition in a wide x range of 0.19 ≤ x ≤ 1.38. The extended ET model well reproduces the variation of the [Fe2+(CN)6]4- and [Fe3+(CN)6]3- concentration at the phase transition. The ET phase transition reverses the oxidation process of the compound; the process is in the order of Co, Mn, and Fe (Fe, Mn, and Co) in the low (high) temperature phase.