Phase formations in Pb(Zn1/3Ta2/3)O-3, with Ba partially/fully substituted for Pb as a perovskite stabilizer, were studied. Ceramic powders were prepared by a B-site precursor method in order to enhance the perovskite yields. Lattice parameters of the pyrochlore and perovskite structures were determined. Weak-field low-frequency dielectric properties of the ceramics were measured, and diffuseness characteristics reflected in the dielectric spectra were evaluated. Microstructures of the fracture surfaces were examined. (C) 2000 Elsevier Science Ltd. All rights reserved.