Influence of precursor Bi~(3 +) /Fe~(3 +) ion concentration on hydrothermal synthesis of BiFeO_3 crystallites

摘要

In this study we investigated the effect of precursor Bi~(3 +) /Fe~(3 +) ion concentration on the hydrothermal synthesis of BiFeO-3 crystallites. It is demonstrated that the phase-purity and morphology of the products is highly dependent on the metal ion concentration. Phase-pure BiFeO_3 crystals can be prepared at the Bi~(3 +) /Fe~(3 +) ion concentration ranging from 0.025 to 0.0625 M. The samples prepared at n(Bi~(3 +) /Fe~(3 +))=0.025, 0.0375, 0.05, and 0.0625 M, are composed, respectively, of cuboid-like particles (100-200 nm), regular spherical agglomerates (30-40 μm) made up of irregular grains with size about several hundred nanometers, irregular flower-like clusters formed from irregular grains of several hundred nanometers in size, and octahedron-shaped particles (500-600 nm). These samples have a similar bandgap energy of 2.20 eV and exhibit a typical antiferromagnetic behavior at room temperature.