Evaluación de coeficientes de difusión e intercambio por termogravimetría en muestras de GdBaCo2O5+d.

SCALISE B. ; BAILLY N.; DJURADO E.; CANEIRO A.; L. MOGNI

Mar del Plata

Congreso; Hyfusen - 4° Congreso Nacional - 3° Congreso Iberoamericano –Hidrogeno y Fuentes Sustentables de Energía; 2011

IEDS

In this work, thermogravimetric relaxation curves were used to evaluate the surface kinetics of the oxygen reduction reaction on GdBaCo2O5+δ layered perovskites. In this technique kinetics parameters, are obtained from the relaxation behavior of oxygen non stoichiometry, after a sudden change of oxygen partial pressure. The fitting of the experimental data with different models, assuming oxygen diffusion control, surface exchange control or both simultaneously, makes possible to obtain macroscopic values of the oxygen exchange and the diffusion coefficients  using a  simple experimental method. Samples of GdBaCo2O5+δ obtained by spray pyrolisis and solid state reaction were evaluated separately obtaining in both cases exchange coefficients varying between 10-7 and 10-9 cm/s and oxygen diffusion coefficient between 10-10 and 10-13 cm2/seg in a wide range of  temperatures (400 to 900 °C).