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|Title:||Studies on graphite based magnetic nano-composites|
|Publisher:||G.B. Pant University of Agriculture and Technology, Pantnagar (Uttarakhand)|
|Abstract:||Synthesis of composite systems with superparamagnetic and graphitic nanostructures is highly demanding due to their extensive applications in various fields. In the present work graphite (G) and graphene-oxide (GO) were used as fillers and magnetite (Fe3O4) NPs were used as matrix to form the graphite based magnetic nano-composites. All the samples were synthesized via the chemical coprecipitation method. Samples were characterized by XRD, FTIR, SEM, TGA/DTG, UV-Vis and VSM. The DC electrical conductivities, as a function of temperature were measured by using four probe method for various voltage compliances (1 V, 10 V and 100 V). Dielectric measurements were performed for the frequency range 500Hz-1MHz. The co-existence of both phases of G/GO and ferrite NPs were confirmed by XRD diffraction and FTIR. The addition of G and GO induced a surprising reduction in the crystallite size of ferrite NPs ranging 17.50 to 12 nm with retained cubic structure. The surface morphology of the samples were investigated by SEM. Fe3O4 NPs were found spherical in shape with a narrow particle size distribution. The grains could not be appeared clearly for the composites. TGA/DTG analysis indicated that all the samples showed the one step thermal decomposition behavior except G and GO. The thermal stability of the composite samples was found to increase with the addition of ferrite NPs into it. All the samples exhibited superparamagnetism at the room temperature. By the addition of G/GO into the ferrite NPs, the saturation magnetization was found to be reduced. The dielectric constant (ε’), loss tangent (tanδ) and loss factor (ε’’) rapidly decreased for the lower frequency range and reached a constant value for the high frequency range. The dielectric constant for composites get enhanced with the ferrite NPs. DC electrical conductivities for all the samples were found to increase with the increasing temperature. Composite samples showed the semiconducting nature. By adding G/GO, optical band gap of the samples were found to decrease. These results remark that graphitic nanocomposites have great potential for magnetic, capacitive and microwave absorption applications.|
|Appears in Collections:||Theses|
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