Current Search: Honors Student Theses (x) » Document (PDF) (x) » Gopman, Daniel B. (x)
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Title
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Size distribution of polymer-coated magnetite nanoparticles.
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Creator
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Gopman, Daniel B., Harriet L. Wilkes Honors College
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Abstract/Description
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A method for estimating the size distribution of magnetite nanoparticles from their magnetic properties is presented. The 10 nm diameter particles were coated with poly(acrylic) acid and prepared as a water-based suspension. A vacuum-dried sample was placed in a transmission electron microscope (TEM) so that the physical sizes of the particles could be estimated. The particle magnetization was measured by a superconducting quantum interference device (SQUID) in magnetic fields up to 25...
Show moreA method for estimating the size distribution of magnetite nanoparticles from their magnetic properties is presented. The 10 nm diameter particles were coated with poly(acrylic) acid and prepared as a water-based suspension. A vacuum-dried sample was placed in a transmission electron microscope (TEM) so that the physical sizes of the particles could be estimated. The particle magnetization was measured by a superconducting quantum interference device (SQUID) in magnetic fields up to 25 kiloOersted and temperatures ranging from 5 to 370 Kelvin. The magnetic moments in the sample were estimated by fitting those measurements to a Langevin magnetization model, weighted by a log-normal distribution with unknown parameters.The best-fit procedure yielded particle volumes smaller than those observed by transmission electron microscopy, suggesting the existence of a magnetically inactive layer of atoms. In addition, our particles exhibited stronger spin-wave behavior than expected for particles of similar size, as evidenced by the lower saturation magnetization and higher Bloch coefficient.
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Date Issued
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2008
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PURL
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http://purl.flvc.org/FAU/77669
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Subject Headings
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Particles (Nuclear physics), Electromagnetic theory, Particle size determination
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Format
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Document (PDF)
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Title
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Transcendental minds and mythical strings: the emergence of platonism in modern physics.
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Creator
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Gopman, Daniel B., Harriet L. Wilkes Honors College
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Date Issued
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2008
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PURL
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http://purl.flvc.org/FAU/165336
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Format
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Document (PDF)