The Department of Physics and Astronomy invites all to a colloquium featuring Dr. Gary Collins, Department of Physics & Astronomy at Washington State University. Dr. Collins will present his talk, “Atom-scale Studies of Interactions between Solute Atoms in Solids”, Tuesday, April 4, at 4:10 p.m. in Webster 17.
Meet for refreshments before the lecture at 3:45 – 4:10 p.m. in the foyer on floor G above the lecture hall.
Abstract: An important topic in the theory of solutions is the interaction between solute atoms. Attractive interactions promote clustering or even phase separation whereas repulsive interactions stabilize ordering and formation of superlattices. For samples in thermal equilibrium, interactions can be studied using a local probe technique to measure the relative concentrations of isolated solute atoms and solute-atom pairs. From measurements made as a function of temperature, one can determine interaction enthalpies.
The PAC technique (perturbed angular correlation of gamma rays) extensively used by my group was applied in the 1980’s by Krystof Krolas and coworkers to measure interactions between pairs of solutes in noble metals. Typical interaction enthalpies found were in the range ±0.20 eV. A phenomenology was developed to explain many of the observations, which will be reviewed. At WSU, we [1] are applying the same approach to study such interactions in intermetallic compounds. For intermetallics, the interactions have been found to vary according to the sublattices occupied by the solutes. Results will be presented for pairs of 111In probe atoms and Cu, Ag, Au, and natural In solutes atoms in the compound GdAl2.
