Dielectric and magnetic properties of NiFe < inf > 2-x < /inf > Bi < inf > x < /inf > O < inf > 4 < /inf > nanoparticles at microwave frequencies prepared via co-precipitation method

Abstract

NiFe2-xBixO4 (x = 0, 0.1, 0.15, 0.20 and 0.25) nanopowders were synthesized via chemical co-precipitation method. The precursor gels were sintered at 973 K in air for 2 h to obtain the single phase pure nanostructured NiFe2-xBixO4 spinel. The crystal structure and magnetic properties of the substituted spinel series of NiFe2-xBixO4 have been investigated by means x-ray diffraction and vibrating sample magnetometer. The values of the saturation magnetization and the coercive field of NiFe2-xBixO4 nanoparticles were found to decrease with increasing degree of bismuth substitution. The room temperature real and imaginary part of permittivity was measured from 1MHz to 1.8GHz. The real part of permittivity was found to increase with increase of bismuth content. The room temperature electron paramagnetic resonance was studied to investigate the magnetic properties at microwave frequency.