As green technology advances, the need for cheaper, stronger permanent magnets becomes more and more vital everyday. Electric motors,
like those used in wind turbines and electric cars, rely heavily on Dy doped Nd2Fe14B in order to achieve the required efficiencies to be
successful, however both Nd and Dy are expensive rare-earth elements that the field is trying to move away from relying on. In order to
approach this issue, many are trying to combine these powerful permanent magnets with cheaper and more abundant soft magnetic materials in
order to create exchange-spring magnets. While exchange coupling behavior has been studied for several decades now, there are major issues
with controlling the uniformity in the generated materials leading to a limited understanding of the properties of these assemblies. In order
to address both of these issues at the same time, we devised an approach to create a hard magnetic nanoparticle of fcc-FePt, which was then
shelled with the soft magnet Co. In order to gain the desired control of the final core@shell particles, a mix and round bottom and microwave
heating was utilized, the synthetic details of which are laid out in Chapter 2. Chapter 3 lays out the results from applying a layer-by-layer
shell of Co onto a constant 5 nm FePt particle. From this shelling, the transition from hard-exchange to exchange-spring to decoupling of the
core@shell system can be observed. The limit of these regions were found to be very small, with the hard-exchange regime only being in the
case of shell sizes smaller than 1.4 nm and decoupling occurring in the materials with >2nm of Co shelled on. This limited range is due to
cobalt’s short range coupling, which can not support strong coupling beyond 3-4 layers of Co. / A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the
requirements for the degree of Doctor of Philosophy. / Fall Semester 2017. / November 20, 2017. / Exchange-spring, Materials Synthesis, Nanomaterials / Includes bibliographical references. / Michael Shatruk, Professor Co-Directing Dissertation; Geoffrey F. Strouse, Professor Co-Directing
Dissertation; Peng Xiong, University Representative; Joseph Schlenoff, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_604955 |
| Contributors | Carnevale, David J. (David John) (author), Shatruk, Mykhailo (professor co-directing dissertation), Strouse, Geoffrey F. (professor co-directing dissertation), Xiong, Peng (university representative), Schlenoff, Joseph B. (committee member), Florida State University (degree granting institution), College of Arts and Sciences (degree granting college), Department of Chemistry and Biochemistry (degree granting departmentdgg) |
| Publisher | Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text, doctoral thesis |
| Format | 1 online resource (95 pages), computer, application/pdf |
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