Effect of codoping of rare earth elements and Cr on multiferroic, optical and photocatalytic properties of BiFeO3

In the present work, first principle calculations have been performed to study the combined effect of A (Bi) and B (Fe) site doping on the structural, multiferroic, optical and photocatalytic properties of BiFeO3 (BFO). Rare earth elements (La, Ce, Gd, Nd, Er and Eu) are doped at the A-site while Cr is doped at the B-site in perovskite BFO. A variation in total magnetic moments and spontaneous polarization of the doped systems is observed that are governed by the introduction of the rare earth elements. A maximum polarization of 110 mu C/cm2 is obtained for (Gd,Cr) doped BFO and the maximum magnetization of 5.1 mu B/cell is obtained for (Nd,Cr) doped BFO. From the study of partial electronic density of states it has been observed that amongst all the dopants incorporated as rare earth elements, the (Er,Cr)BFO system exhibits the minimum bandgap of 1.94 eV and thus shifts the absorption edge deep into the visible region which has been confirmed through the optical spectra. The band-edge alignment of the pure and codoped systems has revealed that (Er,Cr)BFO exhibits the maximum potential to be a promising photocatalyst with improved efficiency as compared to pristine BFO.