Large-scale growth and shape evolution of bismuth ferrite particles with a hydrothermal method

Large-scale polyhedral bismuth ferrite (BiFeO3) particles were synthesized with a hydrothermal method under a series of experimental conditions. X-ray diffraction revealed that the BiFeO3 powders had a perovskite structure. Scanning electron microscopy images showed different BiFeO3 particles were formed, including sphere, octahedron, truncated octahedron, cubo-octahedron and truncated cube. The experimental results showed that the concentration of KOH, reaction time, heating and cooling rates had important impacts on the size and morphology of the BiFeO3 particles. The formation mechanism and change process of the large-scale polyhedral BiFeO3 particles were discussed in detail. The obtained BiFeO3 showed ferroelectric behavior and magnetic response, which approved the multiferroic property of the BiFeO3 crystallization. The optical behaviors of BiFeO3 particles revealed the band gap energy of about 2 eV, which is smaller than the BiFeO3 bulk due to the nano-crystallites.