Competitive Occupying of Fe^3+ and Co^3+ Ions into the Lattice B-Sites of Perovskite Crystalline Structure

Perovskite-type oxide has a general formula ABO3. Both the lattice A- and lattice B-sites can be occupied by two kinds of metallic ions, forming substituted perovskites such as La（1-x）SrxCoO3-d and LaFexCo（1-x）O3. In the present work, we aim to investigate competitive occupying of Fe（3＋） and Co（3＋） ions into the lattice B-sites of perovskite LaFexCo（1-x）O3 formed under the condition of excess feeding of Fe（3＋） and Co（2＋） ions relative to the La（3＋） ions. For this purpose, standard curve of normalized cell volumes（NCVs） of a defined series of perovskites LaFexCo（1-x）O3 versus the x values was plotted. Lattice occupancy of Fe（3＋） ions at the B-sites of the perovskite LaFexCo（1-x）O3 was then determined from the standard curve. It is proved that Fe（3＋） ions were capable of occupying preferentially into the lattice B-sites of the perovskite crystalline structure.