DIFFUSION OF BORON IN COPPER BY DIRECT-EXCHANGE MECHANISM

The behavior of B impurities implanted into Cu single crystals has bee n investigated by means of beta radiation detected nuclear magnetic re sonance and cross-relaxation spectroscopy. Diffusion of substitutional B (B-s) in Cu is observed in the temperature range of T = 600-750 K. By combining information from new and formerly published data it is sh own that this diffusion is not mediated by any other defect; it rather takes place by a direct site exchange between B-s and neighboring Cu atoms. To our knowledge B-s in Cu is the first system for which this l ong discussed diffusion mechanism has been established experimentally.