Characterization of BiFeO3–Al2O3 nano-composites: A study of structural, microstructural, electrical, and magnetic properties

Abstract

Results: of the studies on the structural, magnetic, and electrical properties of BiFeO3–Al2O3 nanocomposites prepared using the sol-gel method have been reported. The X-ray diffraction results confirm bi-phase structure of the composites with the presence of some impurity phases of Bi25FeO40 and Bi24A12O39. Field emission scanning electron microscopy images revealed the crystalline nature composed of grain and grain boundaries of both the pure and composite samples. Energy-dispersive X-ray spectroscopy confirms the absence of unwanted components. Magnetic characterization reveals weak ferromagnetic behaviour of BiFeO3 and composites while diamagnetic behaviour of Al2O3. The maximum saturation magnetization in the pure BFO sample is ∼ 6 emu/gm, but this magnetization is lowered by up to 63% and is determined to be ∼ 3.8 emu/gm with the 30% addition of Al2O3 in the BFO matrix. Electrical measurements demonstrate that the addition of Al2O3 nanoparticles leads to a reduction in the dielectric constant, loss tangent, and ac conductivity. A.C. conductivity was found to follow Jonscher's universal power law and to be dominated by the correlated barrier hopping mechanism in the conduction process, according to frequency-dependent ac conductivity analysis. Additionally, impedance analysis reveals a field-induced excitation of charge carriers, resulting in a noteworthy reduction in sample impedance. Overall electrical properties have been discussed in the context of oxygen vacancies, secondary phases, defects, and disorder in details