|About this Abstract
||2010 TMS Annual Meeting & Exhibition
||Computational Thermodynamics and Kinetics
||Diffusion on Al-Type Sites in Intermetallic Phases Having the Tetragonal Al4Ba Structure
||Gary S. Collins, Randal Newhouse, Samantha Cawthorne
|On-Site Speaker (Planned)
The Al<sub>4</sub>Ba structure is very common. It has two inequivalent Al-sites, each with two atoms per formula unit. Each site is surrounded by atoms of the other site, so that diffusion carries atoms between the two sublattices. Due to differing, but collinear, electric field gradients (EFG) at the two sites, the EFGs at jumping atoms fluctuate in magnitude. For large jump frequencies, this leads to motional averaging of quadrupole interaction frequencies that we have studied in many phases using perturbed angular correlation spectroscopy (PAC). At low temperature, one observes two quadrupole interaction frequencies. With increasing temperature, the apparent frequencies approach and then merge, above which temperature one observes only a single signal. The jump frequency at the temperature of mergence is approximately equal to the difference in the static quadrupole interaction frequencies. An overview of results for many phases and their interpretation will be given.
||Definite: A CD-only volume