INFLUENCE OF COHERENCY STRESS ON KINETIC DEMIXING

The influence of coherency stress, arising from differences in the partial molar volumes of the cations or an imposed displacement boundary condition, on composition profiles during kinetic demixing in ternary oxides subjected to a gradient in oxygen chemical potential is investigated. Coherency stresses can either enhance or diminish the magnitude of the kinetic demixing and shifts in interfacial composition owing to coherency stress on the order of several atomic percent, measured with respect to the case where stress is neglected, can be expected. For (Co,Mg)O subjected to displacement boundary conditions, steady-state and time-dependent demixing profiles are calculated and compared with experimental measurements, Although the composition profiles in the demixed solids are modified because of coherency stress, the main features of kinetic demixing remain unchanged.