Oxygen exchange and mechanism of oxygen intake by complex oxides with a swedenborgite structure

The kinetics of oxygen sorption from air by Y0.8Ca0.2BaCo4-xFexO7+δ (x = 0, 1) is studied by nonisothermal thermogravimetric measurements. The activation energy is calculated by model-free methods of Friedman, Starink and Vyazovkin. The master plot and Coates–Redfern methods are applied to determine the mechanism of oxygen intake. The results show the activation energies and frequency factors are 189 and 197 kJ mol–1 and 4.7 × 1013 and 2.3 × 1014 min–1 in Y0.8Ca0.2BaCo4O7+δ and Y0.8Ca0.2BaCo3FeO7+δ, respectively. The arguments are given in proof of oxygen sorption determined by the volume random nucleation and growth of the oxygen-rich nuclei.