Temperature-Dependent Activation Volumes in Zinc

Abstract

Precision measurements of self-diffusion in zinc as a function of pressure indicate that the activation volumes $\Delta V_c$ and $\Delta V_b$ respectively associated with the nonbasal and basal vacancy jumps have a temperature dependence given by ${\left(\frac{\partial \Delta V_c}{\partial T}\right)}_p=(6.2\mathrm{}\pm 1.9)\times {10}^{-3\mathrm{}}$ ${\mathrm{cm}}^3$/mole °K and ${\left(\frac{\partial \Delta V_b}{\partial T}\right)}_p=(7.6\mathrm{}\pm 3.4)\times {10}^{-3\mathrm{}}$ ${\mathrm{cm}}^3$/mole °K. A model calculation based on a Morse-like potential indicates that the frequencies of atomic vibrations in the vicinity of the defect vary with pressure in a way that is consistent with these experimentally measured quantities.