Date of Award

5-2018

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Mechanical Engineering

Major Professor

Dibyendu Mukherjee

Committee Members

Gerd J. Duscher, Bamin Khomami, Zhili Zhang

Abstract

Nanomaterials have, over the years, generated tremendous interests of scientists and engineers from nearly all disciplines. This interest has been due to a large number of desired physico-chemical properties such as magneto-optic properties, mechanical strength, melting points, charge transport behavior, and surface reactivity exhibiting unique size-dependent characteristics at the nanoscale. The unique interfacial properties are widely believed to be a result of high ratio of surface to bulk atoms as well as, bridging states in which nanoparticles exist between atomic and bulk materials. Thus, in the world of material processing and engineering, recent years have seen a surge in the use of wide classes of nanostructured materials as novel energetic, catalytic, semiconductor, and biomedical materials with engineered functionalities that find use in industrial, technological and defense applications. Therefore, it becomes imperative to develop fundamental understanding on the manufacturing and characterization routes that can allow the systematic tuning of the interfacial-property characteristics of advanced nanomaterials by tailoring their sizes and architectures. The current PhD thesis aims to address this grand-challenge engineering problem by investigating early-stage formations theoretically, synthesis and novel spectrochemical characterizations of advanced metal/intermetallic and composite nanoparticles (NPs) with engineered surface properties. Specifically, the thesis is categorized into two broad sections, namely laser-based synthesis studies and laser-based spectroscopic characterizations of NPs. The synthesis section presents theoretical investigations into the inception stage of NP formations, namely nucleation via numerical simulations. Briefly, this section aims to reveal the processing-structure-property relations of metal NPs synthesized via gas phase routes in an effort to relate the processing parameters to the size and morphology of the NPs, which in turn, dictates their interfacial energetic and catalytic behaviors. Then, using the obtained fundamental understandings a laser-based synthesis technique is presented for generating novel energetic metallic nanocomposites. The size, morphology and energetic activities of these materials are analyzed and tuned to improve the energetic properties. Finally, the laser spectroscopic characterization section focuses on experimental investigations by introducing laser induced breakdown spectroscopy (LIBS) as a relatively non-destructive and robust spectrochemical technique for the structural and chemical composition characterizations of composite NPs in a facile, yet effective manner.

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