Design of NiO @ SiO2 core shell nanocomposites and unveiling their dielectric behavior under diverse frequency and temperature regime

Abstract

NiO@SiO2 core–shell nanocomposits (CSN) were prepared using co-precipitation cum stober method. Powder XRD analysis, FT-IR and FT-Raman studieswere employed to comprehend the crystalline nature, surface functionality, and molecular structure of the title material. TEM and XPS studies were performed to confirm the formation, cationic distribution and electronic states of the title material. The impedance properties were examined with respect to frequency (1 Hz–1 MHz) at selected temperatures (323 K- 673 K) in steps of 50 K. The complex impedance plot was utilized to delineate the contribution of grain and grain boundary resistances. Nyquist plots of impedance and modulus indicatednegative temperature coefficient of resistance behaviorand non-Debye type of relaxation. The conductivity spectra were analyzed using the universal Jonscher power law σac = σdc + Aωn, and the activation energy was found to be 0.34 eV from Arrhenius plot.