Effect of Uniaxial Stress on the Interdiffusion in the KClKBr System

Abstract

BYDiffusion phenomena in single alkali halides are nowadays vastly studied and recently more attention has been paid to mixed alkali halides. Generally, diffusion in compound solid solutions is not well known and because mixed alkali halides possess by far the simplest defect structure they may s e r v e as good model substances to develop the basic ideas. Here we shall discuss the chemical interdiffusion which has been successfully interpreted by Manning' s theory /1, 2/ for binary metal couples. We extended it to the ionic systems /3 to 6/.The theories describe reasonably well the chemical interdiffusion coefficient 5 and the Kirkendall shift in metal systems, and 5 in the KC1-RbCl system. However, both approaches deal only with isolated vacancies although there a r e evidences for bound divacancies in metals /7/ and vacancy pairs in alkali halides /8 to lo/. As a f i r s t step to include the latter effect we have evaluated the correlation factors for vacancy-pair diffusion in NaC1-type mixed crystals /ll/, On the other hand, careful experimental data for mixed crystals are s c a r c e .