Enhancement in conductivity and dielectric properties of rare-earth (Gd³⁺) substituted nano-sized CoFe₂O₄

Cobalt ferrites nanoparticles doped with gadolinium CoFe_2−xGd_xO₄, referred to as CFGO (x = 0.0, 0.1, 0.3, 0.5 and 0.7) was achieved by glycine nitrate process. The phase confirmation and crystallite size were obtained from X-ray diffraction spectra and their variation with dopants content was determined. The Williamson–Hall plot was used to investigate the individual contributions of crystallite sizes and lattice strain on the peak broadening of the CFGO nanoparticles. Further confirmation of the spinel structure was done by Fourier transform infrared spectra. Dielectric properties such as dielectric constant (ε′) and dielectric loss (ε″) have been investigated in the frequency range 100 Hz–1 MHz. The dielectric constant (ε′) dispersion for CFGO nanoferrites is fitted in accordance with the modified Debye’s function. The complex impedances and complex modulus analysis confirm a grain interior mechanism contributing to the dielectric properties. The electrical behaviour of the CFGO nanoferrites exhibited small polaron conduction mechanism. From the temperature dependence curve of dielectric relaxation, activation energies for CFGO samples have been calculated. The low loss dielectric makes these samples promising materials to be used at high frequencies.