Correlation Between Structural, Magnetic and Dielectric Properties of Microwave Sintered Ni-Zn-Al Nanoferrites

A series of diamagnetic aluminum (Al3+) substituted Ni-Zn Nanoferrites have been synthesized using sol-gel auto combustion route. Structural, magnetic, and dielectric properties were systematically studied and reported with respect to Al3+ substitution in host Fe3+ ions. X-ray diffraction (XRD) and infrared spectroscopy (IR) measurements confirm the presence of Al3+ ions at both A and B sites. Cation distribution proposed from XRD and IR correlates with magnetic and dielectric results. It is observed that Al3+ ions are distributed in to tetrahedral and octahedral sub-lattices. The saturation magnetization varies between 58.5 and 44.2 emu/g with increasing Al3+ substitution. This decrease in magnetization is ascribed to presence of the non-collinear spin (canted spin) structure in octahedral sub-lattice. Dielectric constant decreased and a significant improvement in AC resistivity is observed with Al3+ substitution. The observed variations are accounted on the basis of cation distribution in spinel ferrite.