Structure and magnetic properties of iron-based cyanide compounds

The M/sub 1.5/[Fe(CN)/sub 6/]/spl middot/zH/sub 2/O powders with M=Ni, Co, Cu and Zn and z=4-7 were prepared by co-precipitation. A structural change was found after heat treatment at a temperature in the range of 100-200/spl deg/C. Mossbauer and magnetic measurements have shown that the Fe/sup III/-CN-M/sup II/ state was the major structure in the co-precipitated form, while the Fe/sup II/-CN-M/sup III/ bond was formed in the annealed samples. The stable Fe/sup II/-CN-M/sup III/ state could convert into a metastable Fe/sup III/-CN-M/sup II/ state accompanied by two peaks in UV-visible spectra. A broad peak was observed in the photo-luminescence spectra, indicating the potential for optical applications.