Chelating Agents Assisted Rapid Synthesis of High Purity BiFeO3: Remarkable Optical, Electrical, and Magnetic Characteristics

Abstract

In this study, we presented two reliable methods, the sol–gel and autocombustion, to synthesis a high purity BiFeO3 single phase with low calcination time using glycine as chelating agent. The glycine-autocombustion method produced a high purity BiFeO3 phase using either low or high concentrations of the reactants (Bi(NO3)3 + Fe(NO3)3), while the glycine-sol–gel method delivered a high purity BiFeO3 phase using low concentrations of reactants. In the case of using tartaric acid and urea as chelating agents, mixtures of BiFeO3 and Bi25FeO40 phases were formed. The morphology, size, and porosity of the particles were obviously changed by varying the synthesis method and chelating agents. The high purity BiFeO3 samples exhibit a visible light band gap of 2.05 eV with long absorption tail extending to the infrared region, suggesting the suitability of the synthesized powders in the solar photocatalytic applications. A weak hysteresis ferromagnetic loop was observed for BiFeO3 (glycine method) and BiFeO3/Bi25FeO40 (urea method) with large contribution from the paramagnetic behavior. On contrast, robust ferromagnetic loops were found for BiFeO3/Bi25FeO40 sample synthesized by tartaric acid with saturation magnetization reaching to 2.5 emu/g. Remarkably, the pure single phase BiFeO3 powders synthesized by sol–gel and auto-combustion methods using glycine possess room temperature dielectric constant values of 622 and 845 respectively at a frequency of 42 Hz. In the case of BiFeO3 powders prepared by using tartaric acid, the dielectric constant exhibits values of 401 and 1118 for sol–gel and auto-combustion assisted samples, at the same frequency, respectively. At low frequency, the values of the real part of the complex permittivity tend to be zero which confirms a negligibly small contribution of the electrode effect.