Oxygen stoichiometry of Sr0.97(Ti,Fe)O3−δ materials

Thermogravimetric analysis and a coulometric titration technique were used to measure the relative changes in oxygen stoichiometry of Sr0.97(Ti,Fe)O3−δ materials with temperature and oxygen partial pressure, and these results were used to re-examine the defect chemistry. These materials undergo significant weight gain on cooling which was attributed to changes in valence of Fe ions. The oxygen gain attained on cooling from 1300°C to room temperature indicates that Fe3+ and Fe4+ coexist in these materials, and that the concentration of oxygen vacancies remains relatively high in wide ranges of working conditions but may vary with temperature, and/or oxygen partial pressure.