Identifier

etd-04132007-093916

Degree

Doctor of Philosophy (PhD)

Department

Chemistry

Document Type

Dissertation

Abstract

Our primary research goals are to synthesize, characterize, and study the structure, dimensionality, and physical properties of new highly correlated electron materials. Intermetallic lanthanide and oxide phases are of great interest due to their fascinating array of structural features and physical property phenomena, such as heavy fermion behavior, superconductivity, and magnetism. The crystal growth, structure, and physical properties of several different classes of materials, such as the Ln-M-Ga (Ln = La, Ce, Pr, M = Ni, Pd), Yb5Pt9, and R2Ir2O7 (R = Pr, Eu) compounds, will be highlighted within. The Ln-M-Ga phases allow us to examine the influence of the lanthanide environments, dimensionality and layering on the magnetic and transport properties in these compounds. For example, CePdGa6 is a heavy fermion with ã ~ 230 mJ mol-1 K-2 and exhibits an anisotropic magnetism with TN ~ 5.5 K. The structurally related compound, Ce2PdGa10, also shows enhanced mass behavior (ã ~ 220 mJ/mol- K2), exhibits paramagnetic behavior down to 2 K, and has a large positive MR > 200 % at 2 K and 9 T. Also bearing a striking resemblance to the CePdGa6 phase, Ce2PdGa12 is an antiferromagnetic heavy fermion with ã ~ 170 mJ mol-1 K-2 and a magnetic transition at TN ~ 11 K. The crystal structures and physical properties of several new Ln2NiGa10 (Ln = La, Ce, Pr) and Ln2NiGa12 (Ln = La, Ce, Pr) compounds will also be discussed and compared to determine the role of the lanthanide and transition metal environments. The oxide pyrochlores, R2Ir2O7 (R = Pr, Eu), which show geometrically frustrated magnetism, may also offer insight into the structure-property relationships in three dimensional materials.

Date

2007

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Julia Y. Chan

DOI

10.31390/gradschool_dissertations.3109

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