Novel iron oxides with square planar coordination from low temperature synthesis

By using new synthetic approaches, one can create new families of materials which could lead to new chemical and physical properties. From this philosophy, we have synthesized novel iron oxides by topochemically extracting oxygen from well known perovskites derivatives SrFeO3, layered Sr3Fe2O7 and brownmillerite CaFeO2.5. The new materials SrFeO2, Sr3Fe2O5 and CaFeO2 possess FeO4 square planes and derivatives. These novel materials show new structures in which exotic electronic and magnetic properties can be witnessed. They also provide clues to understand oxygen diffusion in solids. In this review, we describe the chemical and physical properties of these novel iron oxides. (author)