Synthesis and characterization of multiferroic BiFeO3 powders fabricated by hydrothermal method

The influence of processing parameters on the phase formation and particle size of hydrothermally synthesised BiFeO3 powders was investigated. BiFeO3 powders were synthesised by dissolving bismuth nitrate and iron nitrate in KOH solution at temperatures ranging from 150 to 225 C. XRD and SEM indicated that the rod-like alpha-Bi2O3 phase was formed at the initial stage of the reaction and dissolved into ions to form a thermodynamically stable BiFeO3 phase. Single-phase perovskite BiFeO3 was formed using a KOH concentration of 8 M at a temperature of 175 C or above, for a 6 h reaction period. BiFeO3 particle growth was promoted by lowering the KOH concentration, or increasing the duration time or reaction temperature. The effects of processing conditions on the formation of crystalline BiFeO3 powders are discussed in terms of a dissolution-precipitation mechanism. The magnetisation of the BiFeO3 powders at room temperature showed a weak ferromagnetic nature.