Diffusion processes in quasiternary systems are described by a diffusion matrix composed of a matrix covering the kinetic properties and a matrix describing thermodynamic influences by interaction parameters. The interdiffusion processes were simulated by a computer program and the calculated diffusion profiles and reaction paths were compared with earlier reported experimental data. It can be shown that thermodynamics governs the principal reaction paths, whereas the individual diffusion behavior is controlled by the kinetic matrix composed of tracer diffusion coefficients depending on the type of intrinsic doping. Regions of uphill diffusion are determined predominantly by thermodynamic coupling effects. (c) 2005 Elsevier B.V. All rights reserved.