Development of novel magnetic core shell nanoparticles with tunable properties for pertinent applications

Abstract

This thesis deals with the development of a novel series of magnetic core/shell newlinetype nanoparticles for state of art-applications. The entire work described in the thesis newlineis divided into four assignments; first assignment is related to the development of newlinegraphitic carbon coated Ni/NiO core/shell nanoparticles. The special type of hybrid newlinecomposite nanoparticles is synthesized via a complex polymeric precursor, derived newlinethrough a sol-gel type chemical process. The process offers a precise control over the newlinesize and shape of the final products. The process involves a controlled reaction newlinebetween a Ni salt and poly-vinyl alcohol (PVA)-sucrose polymer molecules. The PVA newlinemolecule in aqueous solution forms small micelles in the shape of closed rings or newlinelaminates. The small micelles possess plenty of OH groups free from H-bonding newlinewhich can offer surface-active reaction centers. The mixing of sucrose with PVA newlinesolution provides a sufficient viscosity to the reaction medium in such a way that the newlinemicellar wall becomes enough stable during the reaction. This technique provides a newlinecontrolled nucleation and growth of the nascent nanoparticles by encapsulating in the newlinepolymer micelles. In the next assignment, graphitic carbon stabilized Ni nanoparticles newlinewere synthesized from the Ni2+-PVA/sucrose polymeric precursor powders derived in newlinethe first assignment. newlineIn the third assignment, the graphitic carbon coated and#945;-Fe2O3 nanoparticles newlinewere developed after heat treating the Fe3+-PVA/sucrose polymeric complex newlineprecursor at selected processing temperatures in ambient conditions. The last newlineassignment is related to the development of non-aligned and field-aligned newlinenanocomposite films of the graphitic carbon coated Ni/NiO core/shell nanoparticles newlinein PVA matrix. The structural, optical, electrical and magnetic properties of all the newlinesamples were evaluated in detail. newline