Unmixing of a mixed oxide (A,B)O in an electric field: numerical solution of the time evolution of the unmixing process

The time evolution of the unmixing process in a semiconducting mixed oxide, (A,B)O, under an electric field was calculated by establishing the continu ity equations in a phenomenological way and solving them numerically by mea ns of a finite difference method. Temporal variations of composition and de fect distribution, and boundary motions were obtained, and therefrom, the d istribution of oxygen chemical potential inside the oxide was evaluated. It was found that, sluggish defect relaxation during the unmixing process mig ht induce a gradient of the oxygen chemical potential in addition to the el ectrotransport-induced composition gradient. General aspects of an electrot ransport-induced unmixing process are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.