Session G28 - DMP: DEFECTS IN MATERIALS
Mixed session, Tuesday afternoon, March 21, 14:30
Empire Room, Fairmont Hotel
A unique grain-boundary site was previously observed in high-purity Pt by us using perturbed angular correlations of gamma rays. To help identify the site, electric-field gradients at atomic sites near grain boundaries in fcc metals were calculated in the point-charge approximation. Boundaries considered were low-energy, symmetric-tilt boundaries \Sigma 3 to \Sigma 17. Lattice relaxation was not allowed for, but additional calculations were made after removing equivalent atoms from near the boundary plane that have small Wigner-Seitz volumes. It is found that efg's are appreciable only for sites within about one near-neighbor distance of the boundaries. For these sites, the asymmetry parameter of the efg is always found to be in the range 0.05 to 0.95. No sites were discovered that have zero asymmetry parameter like the unique site observed in Pt, leaving its identification open.