Temperature-Dependent Activation Volumes of Self-Diffusion in Cadmium

The principal-axis self-diffusion coefficients of cadmium were measured over the temperature range 250-320 °C and over the pressure range 0-8 kbar. The self-diffusion activation volumes of the basal and nonbasal vacancy mechanisms are found to be temperature dependent, isotropic, and approximately proportional to the absolute temperature. We find that the activation entropy has a pressure dependence of -0.011 ± 0.002 ${\mathrm{cm}}^3$/mole °K, whereas the activation enthalpy is independent of pressure within our experimental uncertainty.