Award Date

2009

Degree Type

Thesis

Degree Name

Master of Science in Physics

Department

Physics and Astronomy

Advisor 1

Lon Spight, Committee Chair

Advisor 2

Oliver Tschauner, Committee Chair

First Committee Member

Stephen Lepp

Second Committee Member

David Schiferl

Graduate Faculty Representative

Clemens Heske

Number of Pages

116

Abstract

X-ray diffraction is the basis of crystallography, the study of the structure of crystals. It uses X-rays of a wavelength on the order of the size of atoms, so it can resolve the positions of individual atoms in a crystal. Illuminating the crystal with a well-collimated X-ray beam produces X-rays diffracted in a certain direction for a specific crystal orientation. By analyzing the relative phase of the incoming and outgoing scattered X-rays, the unique arrangements of atoms can be determined and the structure of the crystal can be solved.

There is a long standing controversy regarding the crystal structures and densities of high pressure (HP) phases of rear-earth metals. Over the last couple of decades the dysprosium (Dy) structure has been obtained by polycrystalline diffraction from samples in the DACs (Diamond Anvil Cells). Due to HP powder diffraction issues of deviatoric stress and pressure gradient, the structures found are controversial. These experimental controversies have as a present consequence lack of accurate lanthanides phase diagram.

In the experimental work conducted for this thesis, dysprosium was studied using high pressure single crystal X-ray diffraction method. Single crystals of Dy were flux grown. The experiment was conducted at Advanced Photon Source (APS) synchrotron radiation beam line at Argonne National Lab (ANL). The experimental results reported were for the twinned crystal symmetry indexed in 0.7-3.8 GPa pressure region.

Keywords

Crystal growth; Crystallography; Crystalline structure; Diamond Anvil Cells (DACs); Dysprosium (Dy); High pressure densities; Rare earth metals; Single crystal X-ray diffraction

Disciplines

Condensed Matter Physics | Mineral Physics

Language

English


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