A simple co-precipitation technique has been used successfully for the preparation of pure, ultrafine, single phase BiNbO4 (BN), MgTiO3 and Mg4Ta2O9. An aqueous sodium hydroxide or ammonium hydroxide and ammonium carbonate solution was used to precipitate these cations as hydroxides and carbonates simultaneously under basic conditions. These precursors on heating at 750 degrees C, produce the respective powders. For comparison, these compounds were also prepared by the traditional solid state method. The phase purity and lattice parameters were studied by powder X-ray diffraction (XRD). Particle size and morphology was studied by transmission electron spectroscopy (TEM). (c) 2005 Elsevier Ltd. All rights reserved.