Hematite α-Fe2O3 induced magnetic and electrical behavior of NiFe2O4 and CoFe2O4 ferrite nanoparticles

In this paper, we have investigated the structural, magnetic and electrical properties of ferrites (NiFe2O4 and CoFe2O4), hematite alpha-Fe2O3, NiFe2O4/alpha-Fe2O3 and CoFe2O4/alpha-Fe2O3 nanoparticles. These nanoparticles were synthesized by a chemical combustion method. The cubic phase of spinel NiFe2O4 and CoFe2O4 and rhombohedral alpha-Fe2O3 is studied by X-ray diffraction technique. The Williamson-Hall plot is used to find the lattice strain and nanoparticles size of each NiFe2O4, CoFe2O4, alpha-Fe2O3 and their composites. The cation distribution on A and B-sites of NiFe2O4 and CoFe2O4 ferrites with the influence of alpha-Fe2O3 results to mixed spinel structure, is calculated by Bertaut method of X-ray diffraction intensity. The average particles size of present nanoparticles is measured with Scherrer's relation, Williamson-Hall plot and the transmission electron microscopy, which confirmed particles size that lies in 47-147 nm. The magnetic results are pointy depends on nano-size, cation distribution, content of ferrite in alpha-Fe2O3 and exchange interaction among Fe3+/Fe2+ ions. The major advantage of NiFe2O4/alpha-Fe2O3 and CoFe2O4/alpha-Fe2O3 nanocomposites is to observe stability in magnetization up to higher temperature. This may due to antiferromagnetic behavior of alpha-Fe2O3 over ferrimagnetic NiFe2O4 and CoFe2O4. The rich Fe content in alpha-Fe2O3 composite and the interfacial polarization based on Wagner-Sillar effect might be enhanced dielectric properties. In order to explore the effects of observed variations in the microstructure and cation distribution on the dielectric properties, the impedance data is used to extract grains and grain boundaries effects.