Nano-sized BiFeO3 powders were prepared by co-precipitation and then the obtained powders with a density higher than 90% of the theoretical density were fabricated by sintering at 825 degrees C. The structural and micro-structural studies were investigated by the X-ray diffraction, field emission scanning electron microscope and transmission electron microscope. The dielectric constant and dissipation factor of the bulk samples were tested between 100 Hz and 5 MHz at several temperatures by an inductance-capacitance-resistance (LCR) meter. The magnetic properties of nanoparticles were measured by a vibrating sample magnetometer (VSM). As compared to bulk samples, the nanoparticles (36 nm) exhibit small magnetization (weak ferromagnetism) as a result of the spiral spin structure collapse. The electrical properties show the acceptable values for the sintered sample with a relatively high density at 825 degrees C and high amounts of BiFeO3, as compared to the other samples. (C) 2012 Elsevier B.V. All rights reserved.