Magnetic materials are used in many applications such as credit cards, hard drives, electric motors, sensors, etc. Although a vast range of magnetic solids is available for these purposes, our ability to improve their efficiency and discover new materials remains paramount to the sustainable progress and economic profitability in many technological areas. The search for magnetic solids with improved performance requires fundamental understanding of correlations between the structural, electronic, and magnetic properties of existing materials, as well as active exploratory synthesis that targets the development of new magnets. Some of the strongest permanent magnets, Nd2Fe14B, SmCo5, and Sm2Co17, combine transition and rare-earth metals, benefiting from the strong exchange between the 4f and 3d magnetic sublattices. Although these materials have been studied in great detail, the development of novel magnets requires thorough investigation of other 3d-4f intermetallics, in order to gain further insights into correlations between their crystal structures and magnetic properties. Among many types of intermetallic materials, ternary pnictides RCo2Pn2 (R = La, Ce, Pr, Nd; Pn = P, As) are of interest because, despite their simple crystal structures, they contain two magnetic sublattices, exchange interactions between which may lead to rich and unprecedented magnetic behavior. Nevertheless, magnetism of these materials was studied only to a limited extent, especially as compared to the extensive studies of their silicide and germanide analogues. The ThCr2Si2 structure type, to which these ternary pnictides belong, is one of the most ubiquitous atomic arrangements encountered among intermetallic compounds. It accounts for over 1000 known intermetallics and has received increased attention due to the recently discovered FeAs-based superconductors. This dissertation is devoted to the investigation of magnetostructural relationships and anomalous magnetic behaviors in rare earth-cobalt pnictides with the ThCr2Si2 structure type, as well as to the development of new synthetic approaches to the preparation of such materials. We use iso- and aliovalent substitutions as effective tools to probe magnetostructural correlations and establish general trends in the magnetic behavior of RCo2Pn2 phases. The modification of the electronic band structure, which correlates with the changes in the crystal structure of the material, is found to act as the driving force that dictates the magnetic properties of these itinerant systems. We demonstrate how this knowledge can be used effectively to achieve diverse magnetic properties and relate them to specific structural characteristics of materials. / A Dissertation submitted to the Department of Chemistry and Biochemistry in partial fulfillment of the requirements for the degree of Doctor of
Philosophy. / Summer Semester, 2012. / June 7, 2012. / Includes bibliographical references. / Michael Shatruk, Professor Directing Dissertation; Theo Siegrist, University Representative; Susan Latturner, Committee Member; Naresh Dalal, Committee Member.
Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_183153 |
Contributors | Thompson, Corey M. (Corey Mitchell) (authoraut), Shatruk, Michael (professor directing dissertation), Siegrist, Theo (university representative), Latturner, Susan (committee member), Dalal, Naresh (committee member), Department of Chemistry and Biochemistry (degree granting department), Florida State University (degree granting institution) |
Publisher | Florida State University, Florida State University |
Source Sets | Florida State University |
Language | English, English |
Detected Language | English |
Type | Text, text |
Format | 1 online resource, computer, application/pdf |
Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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