Investigation of effect of Ni–Mg co-substitution on structural, optical, and magnetic properties of BiFeO3 nanoparticles grown by a sol–gel method

Abstract

In this research work, the Ni, Mg, and Ni–Mg co-doped BiFeO3 nanoparticles were synthesized via a sol–gel method. X-ray diffraction analysis confirmed that all samples had a rhombohedral distorted perovskite structure. The field emission scanning electron microscopy images revealed a change in the particle size and shape in the Ni, Mg, and Ni–Mg co-doped BiFeO3 samples compared with the undoped sample. Optical investigation showed an increase in the dielectric constant with substitution of Ni and/or Mg at the Fe sites but the value for the co-doped sample was smaller than the values for the other two samples. The calculated direct band gaps for the undoped and co-doped samples were 1.94 and 2 eV, respectively. The results obtained from the magnetic hysteresis loop measurements at room temperature indicated a ferromagnetic behavior for the doped samples. The higher magnetization value with the optical band gap value in the visible light range, make the Ni–Mg co-doped BiFeO3 multi-ferroic material a promising candidate for opto-electromagnetic applications.