Study of oxygen desorption from substituted perovskites: New possibilities through fast intermittent temperature-programmed desorption

A differential desorption technique, named intermittent temperature-programmed desorption (ITPD), has been used to get new insights into the properties of La1−xSrxCo0.8Fe0.2O3−δ perovskites. The apparent activation energy of desorption (Eapp) and the frequency factor (ν) were calculated from ITPD data, for the two distinct oxygen species desorbing from perovskite at temperatures lower than 400 °C. The low values (about 107–108 s−1) obtained for νapp indicated that re-adsorption occurred during the TPD process and therefore that Eapp is equal to the Heat of adsorption (E=−ΔH). The first oxygen species, related to lower desorption temperatures, exhibits a distribution of E from 105 to 125 kJ mol−1. The second one, related to higher desorption temperatures, corresponds to E=146±4 kJ mol−1 and 139±5 kJ mol−1, for x=0.2 and x=0.3, respectively. The relative amounts of these species contributing to the desorption peak are dependent upon Sr content in the perovskite.