Investigation of the large magnetic moment in nano-sized Cu0.25Co0.25Zn0.5Fe2O4

Using a combination of x-ray diffraction, transmission electron microscopy, room temperature (RT) and in-field Mossbauer studies and dc magnetization, the structural and magnetic properties of nano-sized Cu0.25Co0.25Zn0.5Fe2O4, prepared by the chemical co-precipitation method, have been studied. Although the crystallite sizes are only of about 40 nm, these samples show a very large magnetic moment at RT. The moment of 81 A m(2) kg(-1) obtained in one of the samples is comparable to one of the largest reported values in spinel ferrites as that found in bulk CoFe2O4. This can be explained in terms of the enhancement in the B-B interaction because of the distortion in the octahedral B site due to the presence of the Jahn-Teller cation Cu at this site. The dependence of magnetic properties on the alpha-Fe2O3 content has also been investigated.