Date of Award

12-2016

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Materials Science and Engineering

Committee Member

Dr. Fei Peng, Committee Chair

Committee Member

Dr. Konstantin Kornev

Committee Member

Dr. Rajendra K. Bordia

Committee Member

Dr. Igor Luzinov

Committee Member

Dr. Huijuan Zhao

Abstract

Ceramic thin films embedded with oriented magnetic nanofibers or nanorods are highly demanded for the applications in remote sensing, electromagnetic shielding, and thermal management at high temperatures. The general strategy for developing ceramic composite thin films with aligned magnetic nanorods or nanofibers has not been developed yet. This dissertation is centered on fundamentally understanding a sol-gel and polymer-based route towards creation of ceramic thin films with aligned magnetic nanostructures. The topics cover fabrication and properties of ceramic and ceramic-based nanofibers, precipitating magnetic nanoparticles within ceramic fibers, aligning and embedding nanofibers or nanorods within ceramic films, and preventing cracking during the sol-gel film dip-coating processing on flat substrates or on substrates with protrusions such as nanorods or nanofibers. The recent status and challenges in developing ceramic based nanocomposite and its potential applications are reviewed in chapter I. The feasible methodologies and general approaches are described. In chapter II and chapter III, we present the development of mullite and mullite-based composite nanofibers as potential fillers in ceramic thin films. The detailed schemes of materials formation and approaches for microstructure control are discussed in detail. The mechanical and magnetic properties of the mullite-based fibers are studied. In chapter IV, the high temperature in situ precipitation of nickel nanoparticles within the mullite fiber host is studied, to fundamentally understand the processing mechanism and its potential for high temperatures applications. In chapter V, we present the fundamental understanding of processing crack-free mullite thin films by sol-gel method. In chapter VI, the scientific approach is described for processing macroscopic ceramic thin films embedded with magnetic nanorods of controlled alignment. In chapter VII, the ceramic thin film formation with embedded nanorods is studied both theoretically and experimentally. The mechanism and criterion of microscopic cracking within the thin film composites is discussed.

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