MULTICOMPONENT EXCHANGE AND DIFFUSION IN SILICATES

The treatment of multicomponent diffusion and exchange in silicates is developed. An ionic diffusion model, similar to one proposed by workers in ceramics, is described and applied to the evaluation of diffusion coefficients, Dij, from tracer diffusion values. The general problem of cation exchange between complex silicates is then solved exactly, with particular emphasis on 1. (a) useful approximations to the exact solutions; 2. (b) the influence of the kinetic and thermodynamic parameters on the diffusion process; and 3. (c) the limiting cases, which enable the complex silicates to be treated as binary systems, for the purposes of computing diffusion profiles. © 1979.