Sol-gel derived multiferroic BiFeO3 ceramics with large polarization and weak ferromagnetism

Insulating BiFeO3 ceramics of single perovskite phase were prepared by rapid sintering using sol-gel derived fine powders. The ceramics are dense and consist of grains of 2-6 mu m in diameter. Their leakage current density remains lower than 3.02x10(-4) A/cm(2) under the poling field below 119 kV/cm. The main conduction mechanism from 15 to 119 kV/cm is space-charge-limited current relating to oxygen vacancies. The ceramics exhibit a saturated ferroelectric hysteresis loop with a large remanent polarization (2P(r)=56 mu C/cm(2)) under the applied field of 180 kV/cm. Weak ferromagnetism with remanent magnetization of 1.5x10(-5)mu(B)/Fe is observed at 10 K. (c) 2006 American Institute of Physics.