Structure and magnetic properties of copper(II) hexacyanoferrate(III) compound

Abstract

Molecular magnet copper(II) hexacyanoferrate(III) powder, Cu1.5[Fe(CN)6]·6H2O was prepared by coprecipitation method where the particle size is in the nanoscale range. It possessed a face-centered cubic (FCC) crystal structure with lattice parameter of around 10 angstroms. This ferromagnetic powder has a Curie temperature of 19 K. The effects of annealing on its physical as well as magnetic properties were studied. The FeIII-CN-CuII structure is the major structure in the freeze-dried Fe-Cu cyanide. As the cyanide was annealed at higher temperature, two other structures appeared, namely FeII-CN-CuIII and CuII-CN-FeIII as probed by Fourier-transform infrared (FTIR) and Moessbauer techniques. After annealing at 140 °C, FeIII-CN-CuII structure disappeared while FeII-CN-CuIII structure appeared to be the dominant structure. Complete decomposition of the cyanide phase occurred at around 370 °C, whereby nanoscale Fe-Cu particles were found, as well as significant amount of amorphous carbon particles. These soft magnetic Fe-Cu particles have Ms value of 32 emu/g and coercivity of 0.5 kOe.