A Mossbauer spectral study on heat-induced phase transformation in Ni-Fe cyanide

Molecular magnet nickel(Ⅱ) hexacyanoferrate(Ⅲ) powder,Ni3[Fe(CN)6]2·16.5H2O,was prepared by co-precipitation method,and the co-precipitated powder was treated at room temperature,100 oC and 160 oC.It possessed a face-centered cubic(FCC) crystal structure with lattice constant of around 10 .For the freeze-dried sample,the structure was mainly FeⅢ-CN-NiⅡ,with a minor amount of FeⅡ-CN-NiⅢ structure;while for the cyanide annealed at higher temperatures,the FeIII-CN-NiII structure was gradually converted to FeⅡ-CN-NiⅢ,indicating phase transformation during the annealing.