Experimental and first principles investigation of Bi1-xCexFeO3: Structure, electronic and optical properties

Abstract

The effects of Ce substitution on the structural, electronic and optical properties of BiFeO3 (BFO) powders using a simple hydrothermal method were investigated. X-ray diffraction data and scanning electron microscope images reveal the lattice contraction and decrease of grain size for the Bi1-xCexFeO3 (BCFO) powders. The absorption in ranges of 250–900 nm is enhanced with the increase of Ce dopant. The optical band gap of BCFO powders extrapolated by the UV–Vis absorption data decreases from 2.69 (x = 0, pure BFO) to 2.39 eV (x = 15%), in good agreement with the first principles calculation. We further demonstrated that the tunable gaps were mainly attributed to the doped Ce-4f states. An additional peak shifted from 1.45 to 1.65 eV in the calculated absorption spectrum is owing to the intraband transition between the Ce-4f impurity band and Fe-3d states or O-2p states in the conduction band, indicating that the band gap can be adjusted in another band range. The two tunable bands will open a new avenue to discover and design optimal BFO compounds for optical applications.