Abstract
The thermal treatment method was employed to prepare nickel-cobalt oxide (NiO/Co3O4) nanoparticles. This method was attempted to achieve the higher homogeneity of the final product. Specimens of nickel-cobalt oxide were characterized by various experimental techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). X-ray diffraction results showed that there was no crystallinity in the predecessor, and it still had the amorphous phase. The formations of the crystalline phases of the nickel-cobalt oxide nanoparticles started from 350–500 °C, and the final products had different crystallite sizes ranging from 11–35 nm. Furthermore, the variation of DC conductivity (σdc), impedance, tangent loss (tgδ) and dielectric constant (ε′) of the calcined specimens with frequency in the range of 102–106 Hz was investigated. σdc showed a value of 1.9 × 10−6 S/m, 1.3 × 10−6 S/m and 1.6 × 10−6 S/m for the specimens calcined at 350, 400 and 450 °C, respectively. Additionally, a decrease in tgδ values with an increase in temperature was observed. Finally, the formed nanoparticles exhibited ferromagnetic behaviors, which were confirmed by using a vibrating sample magnetometer (VSM).
Highlights
Nanocrystalline materials have attracted much attention because of their different magnetic, electric, dielectric, thermal, optical and catalytic properties in comparison to their bulk counterparts [1].Nanostructured metal oxides have been extensively studied due to both scientific interests and potential applications [2]
Poly(vinyl pyrrolidone) (PVP) and deionized water were used as precursors, a capping agent to reduce the agglomeration of particles and a solvent, respectively
The results show an increase in particle size with the increase of calcination temperatures
Summary
Nanocrystalline materials have attracted much attention because of their different magnetic, electric, dielectric, thermal, optical and catalytic properties in comparison to their bulk counterparts [1]. Nanostructured metal oxides have been extensively studied due to both scientific interests and potential applications [2]. Metal oxide nanoparticles (NPs) can adopt a large variety of structural geometries. They incur electronic structures that may exhibit metallic, semiconducting or insulating characteristics, endowing them with diverse chemical and physical properties. Metals 2016, 6, 181 oxides are among the most important functional materials used for chemical and biological sensing and transduction. We implemented a simple thermal treatment method for preparing magnetic metal oxide nanoparticles; the method is a much more convenient procedure and is completely environmental friendly. The nickel and cobalt oxide material has several applications, such as being active electro catalysts for oxygen evolution, as well as reduction in alkaline electrolytes [3,4], being used for the cathode material of rechargeable batteries [5] or in supercapacitor applications [6]
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