Synthesis of BiFeO_3 Nanoparticles by a Polyacrylamide Gel Route

A new polyacrylamide gel route was used to prepare BiFeO3 nanoparticles.In this route,the solution containing the required cations was gelled by using acrylamide;during the gelation process,acrylamide was polymerized to form a polymer network,which provided a structural framework for the growth of particles.It is demonstrated that high-purity BiFeO3 powders can be prepared using ethylenediamine-tetraacetic acid(EDTA) as the chelating agent.On the other hand,it is found that adding an appropriate amount of glucose to the precursor solution can effectively suppress the gel shrinkage during drying,and consequently lead to a significant improvement of powder quality.Scanning electron microscope(SEM) observation reveals that the as-prepared BiFeO3 powder has a uniform particle size,and the particles are almost spherical without any agglomeration or adhesion.Differential scanning calorimetry(DSC) analysis reveals that the product has an antiferromagnetic phase transition at about 370℃ and a ferroelectric phase transition at about 830℃.Ferroelectric and magnetic hysteresis loop measurements show that the product exhibits clear ferroelectric property and weak ferromagnetism.