Novel Iron Oxides with Square Planar Coordination from Low Temperature Synthesis

Abstract

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 CaFeO_2.5. 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.