Chemical diffusion and conductivity were studied in La1-xSrxMnO3, where x was between 0.05 and 0.20, by using direct-current 4-probe methods, and relaxation techniques in which a sudden change in O chemical potential was applied. A defect model was developed in order to explain the O partial pressure dependence of the conductivity and O non-stoichiometry. It was found that the transient conductivity behavior after a sudden change in O partial pressure could be described by a diffusion model with partial surface reaction. The chemical diffusion coefficients ranged from 10-5 to 10-4cm2/s at 1000C. It increased, with decreasing O partial pressure, due to the thermodynamic enhancement effect. This enhancement factor, and ambipolar diffusion theory, were combined so as to deduce O vacancy diffusion coefficients (table 2).

I.Yasuda, M.Hishinuma: Journal of Solid State Chemistry, 1996, 123[2], 382-90

Table 2

Oxygen Vacancy Diffusion in La1-xSrxMnO3