This paper presents an investigation on the effect of Yb and Nd substituents on the piezoelectric properties and vibration velocity of 0.05Pb(Mn1/3Sb2/3)O-3-0.95Pb(Zr0.52Ti0.48)O-3 piezoelectric ceramics. The X-ray diffraction (XRD) measurements were performed on the doped samples and the results indicate that all the Yb-doped samples exhibit a single phase of perovskite structures in tetragonal symmetry and pyrochlore phases are found in specimens with high Nd dopant. The "soft" characteristic is improved by adding small amount of Yb2O3 and the optimum properties of Yb-doped PMSZ5 ceramics are achieved at x = 2 mol% (d(33) = 390 pC/N, epsilon(r) = 1380, K-p = 0.61, tan delta = 0.41%, Q(m) = 800). Meanwhile, the piezoelectric properties of all Nd2O3-doped specimens are found deteriorating. Vibration velocity at Delta T=20 degrees C, one of the most important factors for high-power piezoelectric application, is found as high as 1100 mm/s for 2 mol% Yb-doped specimens, which is about 2.7 times higher than that of the conventional hard PZT ceramics. (C) 2007 Elsevier Ltd and Techna Group S.r.l. All rights reserved.