Single-phase perovskite lead-based ferroelectric powders-Pb(Mg1/3Nb2/3)O-3 (PMN) or 0.9Pb(Mg1/3Nb2/3)O-3- 0.1PbTiO(3) (0.9PMN-0.1PT)-were prepared using Mg(NO3)(2), instead of MgO or MgCO3, ia a mixed-oxide method and one-step calcination, The reaction proceeded via the formation of 3Pb(NO3)(2). 7PbO, Pb(OH)(2), tetragonal PbO, and then 2PbO-Nb2O5 (P2N)for PMN or 3PbO-Nb2O5 (P3N) for PMN-PT; a mixture of PMN and Pb-2(MgxNb1.33)O5.33+x then formed, followed finally by the formation of single-phase PMN or 0.9PMN-0.1PT. Such prepared powder showed excellent room-temperature dielectric constants-13800 for PMN or 22600 for 0.PMN -0.1PT-by sintering at a temperature of 900 degrees C for 2 h.