Synthesis and Characterization of Superparamagnetic Co3O4@ZnO Nanocomposite

We report the sequential polyol synthesis of Co3O4@ZnO nanocomposite. Firstly, Co3O4 was synthesized and ZnO was produced on the surface of the as synthesized Co3O4 NPs in the same pot. The nanoparticles have been investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), and physical properties measurement system (PPMS) of Quantum Design. The weight percentage of phases were found as 26.3 % for ZnO and 73.5 % Co3O4 (crystal thickness ratio \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$D_{\mathrm{Co}_{3}\mathrm{O}_{4}}/ D_{\mathrm{ZnO}}= 1.38$\end{document}) by using the generalized reference intensity ratios (RIRs) method. Superparamagnetism in Co3O4@ZnO nanocomposite at room temperature was first detected with high Ms value of 10 emu/g, and the non-hysteric curve with nearly saturated nature at high fields. This non-hysteric and nearly saturated nature at 15 kOe is the nature of superparamagnetic structures.