Magnetic Properties in Multiferroic Bi1-xFe1+xO3 (x ≤ 0.5) of Nanoparticles

Magnetic properties have been studied in the Bi1-xFe1+xO3 (x <= 0.5) series in order to establish how a partial Bi3+ -> Fe3+ substitution can be explored in tuning the functional magnetic and multiferroic properties. A self-propagating combustion of a solid precursor comprising the nitrates in the presence of camphor (as a fuel) has been used to synthesize this compound Bi1-xFe1+xO3 as nanoparticles at low temperature such as 550 degrees C in open air. An almost single phase compound has formed easily during burning the precursor in air. The 550 degrees C temperature is an optimized value to get ideal single magnetic domain particles without undergoing a significant disintegration. The X-ray diffraction patterns reveal a rhombohederally distorted perovskite with a space group R3c. The observed lattice parameters are a = 0.5586 nm and c = 1.3903 nm with cell density rho = 7.2 g/cm(3), assuming a crystal lattice of z = 6 formula units. An average crystallite size was found using the Debye-Scherrer formula, which varies from 36 to 42 nm for the different compositions. Different samples studied by varying the x-value in small steps of 0, 0.1, 0.2, 0.5 and 0.8 reveal a maximum magnetization 8.23 emu/g in the bismuth ferrite phase on an optimal x = 0.5 substitution. A maximum coercivity of 172 Oe is achieved at lower x = 0.2. The sintered pellet (at 550 degrees C for 4 h) of sample Bi0.5Fe1.5O3 (x = 0.5), measures a wide ferroelectric hysteresis loop at room temperature, showing a polarization of 0.07 mu C/cm(2), remnant polarization of 0.06 mu C/cm(2), and coercivity 39.2 kV/cm for an applied electric field up to 60 kV/cm.