Study of anneal-tuned dielectric properties, AC conductivity, complex impedance, and modulus of cobalt ferrite nanoparticles

Abstract The frequency-dependent electrical behavior of CoFe2O4 nanoparticles prepared using the chemical co-precipitation technique is investigated. The crystallite size of as-prepared particles was found to be 14.11 nm which increased to 20.32 nm, 23.78 nm, and 34.69 nm on annealing at 573 K, 773 K, and 973 K respectively. The influence of annealing temperature on electrical properties is analyzed using dielectric response, impedance spectroscopy and modulus spectroscopy in the range 1 kHz to 1 MHz. A strong dependence of electrical properties on structural parameters is observed. The real part of the dielectric constant lied in the range of 1.54–3.12, the imaginary part of the dielectric constant varied from 0.06 to 0.41, and the value of dielectric loss varied from 0.04 to 0.13 at 1 MHz for different annealing temperature. All the samples possess excellent insulating properties. Annealing CoFe2O4 nanoparticles yield ferrites with an ultra-low dielectric constant, reduced dielectric loss with high resistivity at high frequencies making them suitable in high-frequency applications.