The diffusion of zinc-65 in dense sintered zinc oxide heated at temperatures between 800 and 1400C in oxygen, argon and oxygen+argon mixtures was measured by a sectioning method. Autoradiography and the shape of the diffusion profile showed that the diffusion was predominantly along the grain-boundaries. The parameter D1/2/δD′, where D and D′ were respectively average volume and grain-boundary diffusion coefficients and δ was the width of the grain-boundary, was evaluated. In 1atm oxygen,

D1/2/δD′ s1/2/cm2 = 104.0exp[24(kcal/mol)/RT]

The parameter decreased with decreasing partial pressure of oxygen and was sensitive to the history of the specimen.

Diffusion of Zinc in Polycrystalline Zinc Oxide. Roberts, J.P., Wheeler, C.: Transactions of the Faraday Society, 1960, 56, 570-80