Investigation of frequency and temperature dependent impedance, modulus and conductivity properties of MgO@SiO2 core shell nanocomposites

Abstract

In this paper, a detailed investigation of electrical and conductivity behavior of MgO@SiO2 core shell nanocomposites (MgO@SiO2 CSN) in the frequency range between 1 Hz and 1 MHz at selected temperatures was reported. The powder XRD analysis unveiled a face-centered cubic structure with Fm-3 m space group and the FTIR spectra identified Mg-O and Si-O-Si vibrational bands. The oxidation states of the elements were studied employing XPS technique. TEM analysis confirmed the core shell formation with average particle size of 113.3 ± 3.1 nm with the shell thickness measuring 7.4 ± 1.1 nm. The existence of the dielectric dispersion is ascribed to the Maxwell–Wagner interfacial polarization. The Nyquist plots indicate the presence of grain effects with negative temperature coefficient of resistance with non-Debye type of relaxation. The activation energy of 0.388 eV with a negative slope of 4.49, indicate that oxygen vacancies may have contributed to conduction mechanism.