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Title: Study of Optical, Electrical and Magnetic Properties of Ferrite-Polymer Nano-Composites
Authors: Ajmal, Muhammad
Keywords: Physical Sciences
Issue Date: 2020
Publisher: Bahauddin Zakariya University Multan
Abstract: Spinel ferrites and some of their composites are commonly used in electrical industry where complicated tiny parts are required, in microwave for shielding as core materials and photocatalytic purposes. It is known that Y-type hexaferrites depict physical properties like those of soft ferrites so they can suitably replace spinels for high frequency microwave device applications. Keeping in mind this fact, this thesis was proposed, which involves the synthesis and characterization of composite materials based on Y-type hexaferrites and polyaniline (PANI). To enhance properties such as an increase in resistivity, the reduction of dielectric losses, and improvement in saturation magnetization, transition metals (X = Al, In and Ga) were also incorporated into hexaferrites matrix. For this purpose, Y-type hexagonal ferrites CaBaCo2X0.5Fe11.5O22 were prepared by sol gel technique sintered at 1000-1100°C for 5 hours. In-situ polymerization method was used to synthesize ferrite-PANI composites with general formula (1-x)Y-ferrite+(x)PANI. These composites were characterized by XRD, SEM, optical, magnetic and electrical measurements. XRD patterns reveal broad peak for polyaniline indicating amorphous nature of PANI, and single-phase structure of CaBaCo2X0.5Fe11.5O22 Y-type ferrites. Results demonstrate a significant rise in resistivity of nanocomposites with increasing ferrite filler (decreases PANI) ~ 104 to 106 Ω-cm due to more resistive nature of ferrite particles. Real and imaginary parts of complex permittivity of these PANI-ferrite composites follow Maxwell-Wagner model. Dielectric constant, dielectric loss and tangent loss are noted to decrease substantially with rise of ferrite content in the nanocomposites. The decrease of dielectric constant with increasing concentration of ferrite filler is predominantly caused by exchange of electrons between Fe+2 and Fe+3 ions enhancing polarization. Jonscher law-based AC conductivity of PANI-ferrite composites experiences a rise with increasing frequency. Optical band gap calculated using Tauc relation improves with rising amount of ferrite except for Ga+3 doped nanocomposite. Field dependent magnetic properties studied at room temperature using vibrating sample magnetometer illustrate that with increasing ferrite filler, coercivity decreases while both saturation magnetization and remanence increase. Such decrease of coercivity and increase in saturation magnetization may be associated with Brown’s relation. High electrical resistivity, low dielectric losses, low coercivity and x enhanced saturation magnetization of these nanocomposites (particularly 0.75[CaBaCo2X0.5Fe11.5O22]+0.25PANI) make them suitable candidates for microwave absorption, as core materials and for photocatalytic purposes.
Gov't Doc #: 21212
Appears in Collections:PhD Thesis of All Public / Private Sector Universities / DAIs.

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