Sol–gel synthesis and physical properties of Ni–Cu based spinel ferrites nanoparticles

Sol–gel method has been used to synthesize copper substituted nickel ferrite CuxNi1−xFe2O4 nanoparticles with different concentration of copper as x = 0.0, 0.1, 0.2, 0.3, and 0.4. The crystallinity was confirmed through the powder X-ray diffraction method with single phase face-centred cubic structure for all CuxNi1−xFe2O4 samples having preferred orientation along (311) plane. The crystallite size was estimated through Scherrer’s formula and observed to be in the range from 21 to 38 nm. The microstructure of ferrite nanoparticles was characterized by the scanning electron microscopy. The existence of functional groups and copper substitution in CuxNi1−xFe2O4 nanoparticles was investigated by Fourier transform infrared spectroscopy. Impedance analyser was employed to investigate the dielectric properties of copper substituted nickel ferrites. The high value of dielectric constant at low frequency and low impedance at high frequency would make these nanoparticles a potential candidate for microwave device applications.