0.55Pb(Ni1/3Nb2/3)O-3-0.45Pb(Zr0.3Ti0.7)O-3 (abbreviated as PNN-PZT) piezoelectric ternary ceramics were prepared by conventional solid-state reaction techniques and sintered at 1200-1275 degrees C for 2 h. The influence of sintering temperature on phase structures, microstructures, and electrical properties of the PNN-PZT ceramics was systematically investigated. The PNN-PZT ceramics sintered at 1250 degrees C for 2 h have optimal piezoelectric, dielectric, and ferroelectric properties: d(33) = 887 pC/N, k(p)= 0.621, Q(m) =31, epsilon(r) = 8763 (1 kHz), tan delta = 0.034 (1 kHz), P-r= 27.55 mu/cm(2) (20Hz), and E-c = 3.32 kV/cm (20Hz). The sintering temperature causes the change of ferroelectric phase structure in the PNN-PZT ceramics. The dielectric and piezoelectric properties are dependent on the tetragonal phase content (7P) which is closely associated with the sintering temperature. The tetragonal phase in the PNN-PZT ceramics has lower activation energy which is responsible for the correlation between the sintering temperatures and the dielectric and piezoelectric properties. (C) 2017 Elsevier Ltd. All rights reserved.