Quantitative microanalysis techniques for magnetic nanostructures

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dc.contributor Acoff, Viola L.
dc.contributor Janowski, Gregg M.
dc.contributor Mankey, Gary J.
dc.contributor Weaver, Mark Lovell
dc.contributor.advisor Thompson, Gregory B.
dc.contributor.author Henry, Karen Torres
dc.date.accessioned 2017-02-28T22:31:07Z
dc.date.available 2017-02-28T22:31:07Z
dc.date.issued 2010
dc.identifier.other u0015_0000001_0000358
dc.identifier.other Henry_alatus_0004D_10459
dc.identifier.uri https://ir.ua.edu/handle/123456789/864
dc.description Electronic Thesis or Dissertation
dc.description.abstract Microanalysis techniques are used to characterize magnetic nanostructures. To advance these materials in many applications, it is necessary to understand the microstructure. For example, subtle compositional fluctuations within a nanostructure can significantly influence the material properties. In this work, microanalysis techniques have been used to quantify composition, volume fraction, and long-range order parameter in magnetic nanostructures. A methodology for determining an optimal voxel dimension range was developed using a model system for the experimentally collected atom probe tomography data. The influence of voxel dimension on volume fraction and composition of chemically partitioned phases is examined. Atom probe tomography is used to understand the influence of Pt enrichment at grain boundaries in the A1 to L10 polymorphic phase transformation. The Pt enrichment at grain boundaries in atom probe tomography analysis provides experimental verification of modeling predictions of Pt surface segregation. It is also observed that upon phase transformation to L10, the Pt grain boundary enrichment decreased. Field ion microscopy and atom probe tomography is used to evaluate the field evaporation behavior of (001) planes in ordered FePt. Both experimental and simulation results have shown that the difference in evaporation field between the two components of the alloy contributed to the trajectory aberrations near the (002) pole and zone axes. The model system shows that chemical order within a structure introduces aberrations in the reconstruction of the atomic planes limiting the spatial and chemical fidelity of characterizing such structures using current reconstruction methodologies. Finally, a comparison of the experimental results to simulations is used to assess the viability of electron diffraction in the quantification of S in FePt thin films and nanoparticles. A multislice approach was used to simulate CBED patterns of FePt films with various thicknesses, compositions, orientations, and S values. In general, electron diffraction provides a technique to determine order parameter of small volumes with the implementation of multislice simulations.
dc.format.extent 126 p.
dc.format.medium electronic
dc.format.mimetype application/pdf
dc.language English
dc.language.iso en_US
dc.publisher University of Alabama Libraries
dc.relation.ispartof The University of Alabama Electronic Theses and Dissertations
dc.relation.ispartof The University of Alabama Libraries Digital Collections
dc.relation.hasversion born digital
dc.rights All rights reserved by the author unless otherwise indicated.
dc.subject.other Nanoscience
dc.subject.other Engineering, Metallurgy
dc.title Quantitative microanalysis techniques for magnetic nanostructures
dc.type thesis
dc.type text
etdms.degree.department University of Alabama. Dept. of Metallurgical and Materials Engineering
etdms.degree.discipline Metallurgical Engineering
etdms.degree.grantor The University of Alabama
etdms.degree.level doctoral
etdms.degree.name Ph.D.

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