Oxygen diffusion and surface exchange studies on (La_0.75Sr_0.25)_0.95Cr_0.5Mn_0.5O_3-δ

Oxygen tracer diffusion coefficient (D*) and surface exchange coefficient (k*) have been measured for (La0.75Sr0.25)(0.95-)Cr0.5Mn0.5O3-delta using isotopic exchange and depth profiling by secondary ion mass spectrometry technique as a function of temperature (700-1000 degrees C) in dry oxygen and in a water vapour-forming gas mixture. The typical values of D* under oxidising and reducing conditions at similar to 1000 degrees C are 4 x 10(-10) cm(2) s(-1) and 3 x 10(-8) cm(2) s(-1) respectively, whereas the values of k* under oxidising and reducing conditions at 1000 degrees C are 5 x 10(-8) cm s(-1) and 4 x 10(-8) cm s(-1) respectively. The apparent activation energies for D* in oxidising and reducing conditions are 0.8 eV and 1.9 eV respectively. (c) 2006 Elsevier B.V. All rights reserved.