Oxygen transport in La1-xSrxMn1-yCoyO3 +/-delta perovskites part II. Oxygen surface exchange

The kinetics of oxygen surface exchange are discussed for selected composit ions in the perovskite oxide system La1-xSrxMn1-yCoyO3=delta. In particular the relationship between the two parameters measured by the O-18/O-16 Isot ope Exchange Depth Profile (IEDP) method, the oxygen surface exchange coeff icient, k*, and the oxygen tracer diffusion coefficient, D*, is examined. T he strong correlation observed between k* and D* is interpreted in terms of oxygen vacancies playing a major role in the surface exchange process for these materials. The relationship between k* and D* for La1-xSrxMn1-yCoyO3= delta compositions is compared to that seen for other acceptor-doped perovs kites and some acceptor doped fluorites. Such comparisons yield important i mplications for electrochemical devices utilising such acceptor-doped oxide s, (C) 1999 Published by Elsevier Science BN. All rights reserved.