Equilibrium defect concentrations and their mobility in the crystalline lattice of cobaltous oxide

Application of Wagner's Theory to the Parabolic Growth of Oxides Containing Different Kinds of Defects: I . Pure Oxides

“…There is a general agreement that Co oxidizes according to a parabolic rate law at high temperatures, the process being controlled by the diffusion of metal vacancies in the p-type semiconducting oxide (39)(40)(41)(42)(43)(44)(45)(46). Around 1000~ and at high oxygen activities the vacancies are prevailingly singly charged (12,16,21,(47)(48)(49)(50)(51)(52), in agreement with the value of the oxygen pressure exponent in the dependence of the parabolic rate constant, the deviations from stoichiometry, and the self-diffusion coefficient of Co on P (02) (16,21,. Around 1000~ and at high oxygen activities the vacancies are prevailingly singly charged (12,16,21,(47)(48)(49)(50)(51)(52), in agreement with the value of the oxygen pressure exponent in the dependence of the parabolic rate constant, the deviations from stoichiometry, and the self-diffusion coefficient of Co on P (02) (16,21,.…”

“…--(Kr + K1Kaao)p --2K,KaKaao = 0 [16] For any value of ao, Eq. [18] gives the corresponding" concentration of the electron holes and then Eq.…”

Chemical diffusion in metal oxides. Example of TiO2

“…This results in a strong dependence of the chemical diffusion coefficient on their concentration. This is the case for CoO, of which nonstoichiometry is ∼0.1 at.% [23][24][25][26][27][28][29]. As seen in Fig.…”

“…The chemical diffusion coefficient for undoped CoO as a function of oxygen activity, p(O 2 )[18,[23][24][25][26][27][28] …”

Chemical diffusion in complex oxides with an emphasis on BaTiO3

“…9, the present diffusivity of undoped BaTiO 3 is compared at 1000 C, where the reported data are the most abundant, with those of some other perovskite oxides that are used as the interconnect or cathode of solid oxide fuel cells or oxygen membrane. [23][24][25][26][27][28][29] The data of typical binary oxides, NiO, 23 CoO [30][31][32][33][34][35][36] and TiO 2 37 are also shown (right bottom in the figure). The present system has a chemical diffusivity that is higher than any other.…”