Synthesis of BiFeO₃-Powders by Sol-Gel Process

The present work aims to design and study novel functional materials with multiferroic properties required in electric applications, such as magnetic and magnetoresistive sensors, actuators, microwave electronic devices, phase shifters, mechanical actuators etc. Complex oxides BiFeO₃ for analysis of its magnetic properties were synthesized by sol-gel method as powders. The size, shape and degree of crystallinity of the nanoparticles formed by sol-gel method can be controlled by varying the temperature and the ratio of the concentrations of the initial reactants and the stabilizer. To stop the growth of particles in all cases, it is usually enough to cool quickly the reaction mixture. To isolate the nanoparticles, the precipitating solvent is added, which mixes with the reaction system, but poorly dissolves the “protective shells” of the nanoparticles and, therefore, destabilizes the suspension. As a result, the nanoparticles precipitate as powder, which can be separated by centrifugation. The sol-gel method makes it possible to obtain practically monodisperse nanoparticles of various metals oxides.