A novel method for the direct determination of the activation enthalpy in tracer diffusion studies with applications to 'low'-temperature self-diffusion in silver

A method is described for the direct determination of the activation energy of diffusion. It avoids the depth calibration of the penetration curves and is therefore particularly appropriate for tracer diffusion studies using microsectioning. The technique requires two radio isotopes of the same element which are diffused into the specimen during two diffusion anneals at nearby temperatures. Its application to self-diffusion in silver at 'low' temperatures using the isotope pair 105Ag and sup(110m)Ag gives an activation energy of (1.73 +- 0.06) eV which agrees within the limits of error with the value deduced from the temperature dependence of the diffusion coefficient. It pertains to the monovacancy mechanism which is the only contribution to volume diffusion in silver at low enough temperatures. (author)