Study of Mossbauer and Magnetic Properties of Al~(3+) ions Doped Superparamagnetic Nano Ferrites

摘要

Nanocrystalline Al~(3+) ions doped Mg_(0.2)Mn_(0.5)Ni_(0.3)Al_yFe_(2-y)O_4 compositions, where y=0.0 and 0.10 have been synthesized by citrate precursor method. Crystal structure and magnetic properties have been investigated at room temperature by means of X-ray diffraction, TEM, LCR meter, VSM and Mossbauer spectroscopy. Particle size and lattice parameter has been found to decrease as non-magnetic Al content increased. Relative loss factor has very low value in range of 10~(-6)-10~(-5) which is three orders of magnitude less than samples prepared by conventional method. The Mossbauer spectroscopy results shows superparamagnetism. The isomer shift corresponding to Fe~(3+) ions do not show any significant variation which indicates that replacement of Fe~(3+) ions do not affect significantly the d-electrons density which in turn affects the s-electrons density around Fe~(3+) nuclei. The nuclear hyperfine magnetic fields have been found to decrease at A-site and B-site with increasing substitution of Al~(3+) ions in Mg-Mn-Ni ferrite.