Magnetic properties of multi-metal Prussian Blue analogue Co0.75Ni0.75[Fe(CN)6]•6.8H2O

We have studied magnetic properties of the ternary metal Prussian Blue analogue Co0.75Ni0.75[Fe(CN)(6)] center dot 6.8H(2)O. Room temperature Mossbauer and IR spectra give the evidence of two Fe-III sites in the compound. It undergoes a paramagnetic to ferromagnetic phase transition at 15.9 K. Field dependent magnetization data correspond to a ferromagnetic ordering of the spin only moments of Fe-III, Co-II and Ni-II ions. Approximately 87.45% Fe-III ions are in low spin (S = 1/2) and 12.55% Fe-III ions are in high spin (S = 5 state. On the other hand, 100% Coll ions are in low spin (S = 1/2) and 100% Ni-II ions are in (t(2g)) (e(h))(2) spin state (S = 1). The observed very large coercive field at lower temperatures is an indication of the presence of magnetic hardness in the compound. Non-saturation of magnetization at 1.5 K even under 100 kOe field and a bifurcation in the field cooled and zero field cooled magnetization curves indicate the presence of some spin glass type component in the compound. (c) 2005 Elsevier B.V. All rights reserved.