DETERMINATION OF SIZE AND INTERFACE HYPERFINE FIELD OF CO NANOSIZED PRECIPITATES IN AG BY MOSSBAUER-SPECTROSCOPY

We induced Co to form inclusions in Ag by ion implantation of Co into Ag and by coevaporation of both elements in a MBE system. Mossbauer sp ectroscopy at 4.2 K reveals the hyperfine fields present in the bulk a nd at the interface of the precipitates. By post-implanting the Co-57 activity into the coevaporated samples, we strongly enhanced this inte rface population, which facilitates the determination of the associate d magnetic hyperfine field. The dependence of the precipitate size on the Co concentration and annealing treatment is monitored. We propose a simple model which allows to estimate the precipitate size in the ca se of preferential interface population.