Self-diffusion along dislocations in single-crystal Au films

Abstract

Self-diffusion measurements over the temperature range 247-352°C have been made on single-crystal Au films of 2-μ thickness grown epitaxially onto (001) MgO substrates, using Au195 radioactive tracer and rf sputter-etching techniques for serial sectioning. The penetration profiles revealed shallow lattice diffusion and a much deeper tracer penetration down dislocations; the former is significantly enhanced by diffusion in dislocations. The activation energy Qd and the combined preexponential factor AdDd0 for self-diffusion along dislocations are found to be 1.16 ± 0.02 eV and 5 × 10-16 cm4/sec, respectively. From the enhanced lattice diffusion observed in the first stage of the penetration profiles, a dislocation density of ∼1011 lines/cm2 could also be evaluated for the single-crystal films. The data compare well with other fcc metals and appear to favor a vacancy diffusion mechanism. © 1973 The American Physical Society.