Joe Lomax

Research Interests:

Associate Professor Lomax's research interests include the synthesis and characterization of solid state electronic materials, such as ion conductors and molecular metals.

Particular interest has been concentrated on the B"-aluminas which are a technologically interesting class of solid state ion conductors used in high temperature batteries, sensors and have potential as laser hosts. The B"-aluminas are part of a group of compounds which have highly mobile cations which can move to conduct charge or can be ion exchanged to impart new properties to the materials. A new class of the B"-aluminas has been discovered in this lab by reacting the sodium B"-alumina with group(IV) chlorides. The group(IV) ions (e.g. Zr+4) displace 4 sodium ions (4 Na+).

From collaborative work with Professors Mary Wintersgill and John Fontanella of the Physics Department the ion movement behavior of these new compounds was ascertained. It was found that the new compounds had a reduced activation energy of ion motion which most likely resulted from the reduced sodium ion-ion repulsion that resulted from the ion exchange. The structure of these new compounds was determined by Assistant Professor Wayne Pearson of the Chemistry Department; the results showed that the Zirconiums sit in a site similar to that of the remaining sodiums.

Further investigation into the limits of ion exchange in these compounds along with their crystallographic and ion movement properties is ongoing.

It has been recently reported that C60 (a.k.a. Buckminsterfullerene) shows a dielectric relaxation at around 240 K. This is quite unusual in that a dielectric relaxation implies a permanent dipole moment which is impossible for a spherically symmetrical molecule such as C60, so some longer range ordering of molecules must be responsible. The Fontanella/Wintersgill laboratory is uniquely suited for investigating the dielectric properties of these compounds.

They have a diamond pressure cell fitted to measure dielectric properties at high pressure and a dilution refrigeration system to work at ultra-low temperature (>8mK) to look at quantum effects. The chemistry of this collaboration would involve the synthesis and crystal growth for these experiments and the student would be involved in the measurements and analysis of the resulting data.

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Joel

Address:
Chemistry Department

U. S. Naval Academy
572 Holloway Rd.
Annapolis, MD 21402-5026

Michelson Hall Room 307

Telephone: 410-293-4701

Phone (alt): 410-293-6641

FAX: 410-293-2218

Email: lomax@usna.edu

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