Synthesis, Characterization and Applications of Ferrite Nanomaterials and Composites

Abstract

Iron oxide is one of the most available iron compound in nature and it has wide range of applications in day-to-day life. The 3d electrons of Fe in the ferrites are the reason for the electrical, magnetic and electrochemical properties of ferrite. Doping of ferrites with different cation influence these properties and enhances their performance in many electrochemical applications. The present thesis focused on the study of electrical and magnetic properties of doped ferrites and their applications in electrochemical supercapacitors and sensors. The electrochemical properties of ferrites are enhanced by the incorporating graphene oxide and multiwall carbon nanotubes. The preparation of nickel and tin doped hematite nanoparticles using microwave assisted method has been discussed. The variation in the electrical and magnetic properties of nickel doped ferrite on different concentration of nickel and annealing temperature has been studied. XRD and TGA studies showed a phase transition from hematite phase to magnetite phase on nickel doping. They form hematite phase at high temperature. In these ferrite both Fe ions and Ni ions contribute for the conduction mechanism and dielectric behaviour. Magnetic studies show the magnetization increases with increase in the nickel concentration. Tin doped ferrites prepared using microwave assisted method have rhombohedral structure. AC conductivity and dielectric constant increases with increase in tin concentration. Tin doped hematite nanoplates are antiferromagnetic in nature with high coercivity. Stannous ferrite microbes prepared using microwave assisted method has a high specific capacitance and specific sensitivity towards the H2O2 sensor with lowest limit of detection. The electrical properties of magnetite, zinc ferrite, tin ferrite and nickel ferrite nanoparticles prepared using hydrothermal method have been studied. Zinc ferrite and tin ferrite have higher ac conductivity and lower loss factor than that of magnetite and nickel ferrite. Also, zinc ferrite and tin ferrite have high performance of sensing towards H2O2 than magnetite and nickel ferrite. Nanocomposite of SnFe2O4@rGO/MWCNT is studied as anode of lithium ion battery. It revealed a specific capacity of 1992 mAh/g at initial cycles and 91% coulombic efficiency. It retained 50 % of its initial capacity even after 250 cycles.