Mass transport equations unifying descriptions of isothermal diffusion, thermomigration, segregation, and position-dependent diffusivity

Abstract

Via the combined use of the jump frequency and chemical force formulation methods, a set of generalized mass transport equations has been derived. This set of equations unifies the descriptions of isothermal diffusion, thermomigration induced by a thermal gradient, and segregation and the position-dependent diffusivity arising from the crystal inhomogeneity. The equations reproduce Fick's laws for the isothermal homogeneous crystal case, and the diffusion-segregation equations for the isothermal inhomogeneous crystal case. Also, a new expression for the heat of transport of thermomigration is obtained. © 1998 American Institute of Physics.