Effect of Nd substitution for Ca on crystal structure, optical and magnetic properties of multiferroic Bi_0.9Ca_0.1FeO₃

Pure and co-doped BiFeO₃ (Ca, Nd) nanoparticles with diameter in the range of 50-250 nm were synthesized through a sol-gel method. X-ray diffraction (XRD) and Raman results show that Bi-site co-doped with Ca, Nd could result in a transition of crystal structure (from single phase rhombohedral (R3c) to two phase coexistence). An apparent blue shift can be observed in the co-doped samples along with a decrease of the direct optical band gap. Moreover, the leakage current was decreased due to the introduction of nonvolatile Ca and Nd at Bi³⁺ site. Analysis of MPMS-VSM magnetic hysteresis data reveals a further enhancement in magnetism in the Nd doped Bi_0.9Ca_0.1FeO_3, which is further explained by XPS characterization.