Conventional mixed oxide preparation of lead scandium tantalate, PbSc0.5Ta0.5O3 (PST) powder, requires two calcinations steps, the first of which is to form a Wolframite precursor and the resulting PST phase is structurally long-range ordered. In this work, we report the synthesis of perovskite PST via a novel one-step mechanical activation route, which leads to a long-range disordered structure as verified by X-ray diffraction. Sintered PSTs from the mechanically activated powders also retain the long-range disordered perovskite structure up to 1250degreesC, while >95% theoretical density was achieved. They exhibit a spontaneous ferroelectric-relaxor transition at 15degreesC with a maximum dielectric constant of similar to13,850 and dielectric loss of <0.04. (C) 2002 Elsevier Science B.V. All rights reserved.