The steady-state de-mixing of an initially homogeneous oxide solid solution in an electrical potential gradient was studied theoretically and experimentally. Monocrystalline (Co,Ni)O solid solutions were exposed to potential gradients of various strengths. A drift, with respect to the oxide sub-lattice, towards the cathode was observed and an enrichment of Co was found due to its higher mobility as compared to that of Ni (i.e. DCo > DNi » Do). The de-mixing increased with increasing strength of the potential gradient. A formal treatment was given, for steady state conditions, which considered the diagonal elements of the transport coefficient matrix. The predicted de-mixing profile corresponded well with the experimental one.

Steady State Demixing of Homovalent Oxide Solid Solutions in an Electrical Potential Gradient. O.Teller, M.Martin: Electrochemistry, 2000, 68[6], 478-81