Research Abstract

I recently submitted my first abstract for a materials Conference.  The first conference to which I have submitted the abstract was PACRIM8, hopefully I will still submit the abstract to ACERS and TMS.  below is the current draft of the abstract.  Research as always is continuing and the project develops as time goes on.  Check back for updates, or ask any questions you may have.

Crystallographic Characterization of Rare-Earth Hafnates

Thomas J. Anderson

Dr. Rick Ubic

The nature and degree of disorder in the Ln2Hf2O7 (Ln = La → Lu) series has never been fully quantified. The purpose of this study is to investigate the structure of such pyrohafnates and specifically to determine the degree of both cation and anion disorder, both of which have implications for ionic conductivity. Towards that end, several lanthanide pyrohafnate compounds, Ln2Hf2O7 (Ln = La, Pr, Nd, Tb, Dy, Yb, and Lu), have been synthesized via a solid-state reaction mechanism. The crystal structures were determined by electron diffraction, and Rietveld structural refinements were conducted using neutron diffraction data collected at the Los Alamos Neutron Science Center. As expected, low-Z lanthanides result in pyrochloric compounds whereas high-Z lanthanides form fully fluoritic ones. Intermediate lanthanides form partially disordered pyrochlores, and some show anionic disorder unconnected to cation disorder. As expected, the fluorite-equivalent cubic lattice constant was found to decrease as Z increases.

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