Monophasic (greater than or equal to 99.4%) perovskite powders of a Pb(Mg1/3Nb2/3)O-3-PbTiO3 system were prepared by a B-site precursor method. Phase developments and lattice parameter chan.-cs in the perovskite system were examined by X-ray diffraction. Weak-field dielectric responses of the ceramic system were investigated as functions of PbTiO3 concentration and measurement frequency. Phase transition modes in the dielectric spectra were analyzed in terms of diffuseness characteristics. Ferroelectric hysteresis behaviors were monitored with respect to temperature changes. (C) 2001 Published by Elsevier Science Ltd. All rights reserved.