Degree Name

PHD, Doctor of Philosophy

Degree Type

Dissertation - Open Access

Department

Department of Chemistry and Biochemistry

Advisory Committee

Committee Chair - Susan E. Latturner

Outside Committee Member - David Lind

Committee Member - Naresh Dalal

Committee Member - Geoffrey Strouse

Date

9-25-2008

Abstract

The main emphasis of this research was to explore molten metals (flux) as a growth medium for single crystal intermetallics. The primary characterization methods included: SEM-EDS, X-ray Diffraction, and SQUID magnetometry. The main focus was on the magnetic and structural properties of the single crystal phases.

The RT2TrxZn20-x (R = Rare Earth; T = Mn, Fe; Tr = Al, In) compounds were synthesized using Al/Zn and In/Zn eutectics. These compounds form a known structure; however, the incorporation of Mn into the structure had not been previously reported. These compounds displayed paramagnetic behavior with respect to the rare earth element present; however, the Sm analogs displayed complex Van-Vleck paramagnetism.

The R6T13-xAl1+x (R = La, Nd; T = Fe, Mn) single crystal compounds were synthesized using La/Ni and Nd/Fe eutectics. These compounds form a known structure, however, the physical and magnetic properties with respect to the anisotropy present was not adequately characterized. Also, a previously unreported incorporation of Mn into these samples occurred. The iron analogs displayed type II antiferromagnetic behavior, with anisotropy effects, that can be adequately described using itinerant electron magnetism. However, the manganese analogs displayed ferromagnetic behavior, with strong and weak ferromagnetism occurring due to anisotropy. Substitution of magnetic rare earth elements, such as neodymium for lanthanum, introduces localized magnetic moments in addition to the itinerant moments.

The La21Fe8M7C12 (M = Sn, Sb, Bi, Te, Ge) single crystals were synthesized using a La/Ni eutectic. This compounds form a novel structure not reported in the literature. The magnetic properties, display spin frustration and formation of a spin glass state, with respect to the isolated tetrahedron of iron atoms within the structure. The formation of the spin glass state was confirmed, by AC susceptibility measurements, using SQUID magnetometry.

Availability

Open Access

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