Role of chelating agents on the sol-gel synthesis of bismuth ferrite nanoparticles

Bismuth ferrite (BiFeO₃) possesses multifunctional properties pertaining to its unique crystal structure. This study presents a comprehensive investigation on the role of different chelating agents on the low temperature, sol-gel synthesis of bismuth ferrite (BFO) nanoparticles (NPs). The sol-gel process utilizes precursors (iron nitrate and bismuth nitrate), solvent (ethylene glycol), catalyst (nitric acid), and the chelating agent. In this work, different chelating agents, such as acetic acid (AA), citric acid (CA), ethylenediaminetetraacetic acid (EDTA), glycine (GLY), tartaric acid (TA), and urea are evaluated for their influence on the phase purity and morphological features of the synthesized BFO. The NPs are characterized using various techniques such as x-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, UV-Vis-NIR spectroscopy, and vibrating sample magnetometry (VSM). Among all the chelating agents, TA is found to be the most suitable candidate for BFO synthesis. Pure BFO NPs of average crystallite size 20.8 nm, 24.8 m²/g surface area, and 1.91 eV optical bandgap are obtained after the calcination of the BFO-TA gel. The results are attributed to the easy gelation capability of TA due to the formation of a well-organized heterometallic polynuclear network during the gelation process. High magnetic saturation of 6.72 emu/g and squareness ratio of 0.26 of BFO-TA NPs implies a weak ferromagnetic nature. These results demonstrate a promising route to synthesize pure BFO, which given its multiferroic nature can be used for many applications.

Graphical Abstract