Optical properties of fe based perovskite and oxygen deficient perovskite structured compounds: A comparison

Abstract

In this work we synthesize BiFeO3 and KBiFe2O5 compounds by chemical route and analyze the bandgap reduction in KBiFe2O5. When alternate layers of corner sharing FeO6 octahedra in BiFeO3 is replaced with FeO4 tetrahedra by introducing [(K,Bi)O2] blocks into the perovskite structure, the structure modifies to brownmillerite structure. An increase in covalency and lower bond lengths of Fe–O bonds in FeO4 tetrahedra as compared to FeO6 octahedra leads to bandgap narrowing in KBiFe2O5. The morphological, structural and optical properties of KBiFe2O5 and BiFeO3 are investigated by Scanning electron microscope, X-ray diffraction and UV-visible spectroscope respectively.