Sol-gel synthesis and properties of multiferroic BiFeO3

High purity multiferroic BiFeO3 (BFO) powders were synthesized by sol-gel process using bismuth nitrate and iron nitrate as sources. The BFO powders annealed at 600 degrees C in nitrogen environment were mainly composed of a rhombohedral BiFeO3 phase (R-phase) with a minor impurity phase of Bi2O3. A pure BFO R-phase has been obtained by leaching out the minor Bi2O3 phase using diluted nitric acid. A reversible phase transformation of the BFO R-phase has been detected at 836 degrees C by a differential thermal analysis. The powders of BFO R-phase exhibits a uniform feature with the particle size of similar to 200 nm, The dielectric constant of the BFO R-phase is measured to be similar to 15 in the frequency range of 10(4)similar to 10(6) Hz at room temperature. (C) 2005 Elsevier B.V. All rights reserved.