Enhanced magnetic and ferroelectric properties in scandium doped nano Bi₂Fe₄O₉

Abstract

In this study we report the synthesis of undoped and Sc³⁺ doped Bi₂Fe₄O₉ nanoparticles using sonochemical technique. X-ray diffraction reveals that all samples are single phase with no impurities detected. EDS analysis was done to confirm the extent of Sc³⁺ doping in the samples. The size and morphology of the nanoparticles have been analyzed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Bi₂Fe₄O₉ nanoparticles show a weak ferromagnetic behavior at room temperature, which is quite different from the linear M–H relationship reported for bulk Bi₂Fe₄O₉. A magnetization of 0.144 μB/f.u. is obtained at 300 K, which is mainly attributed to the uncompensated moments at the disordered particle surface resulting from the reduced coordination of the surface spins, arising due to lattice strain or oxygen deficiency. Addition of Sc³⁺ dopant in varying concentrations in these Bi₂Fe₄O₉ nanoparticles, improves their magnetic as well as ferroelectric properties. The leakage current is considerably reduced and electric polarization increases significantly in case of Bi₂Fe₄(1−x)ScxO₉ (x = 0.1) nanoparticles. Thus it can be inferred that Sc³⁺ doped Bi₂Fe₄O₉ nanoparticles shows promise as good multiferroic materials.