Kinetic Demixing of Heterovalently Doped CoO in an Electrical Field

摘要

The steady state demixing of an initially homogeneous heterovalently doped transition metal oxide (A, B)O in an electrical field is studied theoretically and experimentally. Experimental results for the demixing of gallium-doped cobalt oxide, (Co_1-x Ga_x)O, where the dopant becomes enriched at the anode side are presented. By using a defect model for the doped oxide and the five-frequency model for impurity diffusion, it can be shown that the enrichment of Ga at the anode is due to a negative apparent effective charge of the Ga~3+ ions, which is caused by defect-dopant interactions.