Equilibration kinetics of (La,Sr)MnO3

The present work reports isothermal changes of oxygen non-stoichiometry for the perovskite-type electrode material (La0.8Sr0.2)MnO3 in the temperature range 945-1255 K. A thermogravimetric method was used to monitor the rate of the gas/solid equilibration. For equilibration degrees larger than 0.5, the equilibration kinetic data can be described by a diffusion equation. Th e determined chemical diffusion coefficient depends essentially on the oxyg en partial pressure. Its temperature dependence can be expressed by the fol lowing expressions at low and high p(O-2), respectively: D (chem)=(1.9 +/- 1.6)10(-3)exp-(83.4 +/- 15.8)kJmol(-1)/RT(cm(2)s(1)) (1) D (chem)=(1.6 +/- 0.6)10(-1)exp-(121.2 +/- 8.2)kJmol(-1)/RT(cm(2)s(-1)) (2) (C) 2000 Kluwer Academic Publishers.