The effect of PbO excess on the sintering and piezoelectric properties of 12Pb(Ni1/3Sb2/3)O-3-40PbZrO(3)-48PbTiO(3) ceramics has been investigated on specimens produced from PbO, TiO2, ZrO2, NiO, and Sb2O3 powders as starting materials. When the PbO excess content was below 3.0 wt.% and the mixture of starting materials calcined at 850 degreesC for 2 h, no amount of PbO phase was detected after sintering. On the other hand, as the PbO excess content was greater than 3.0 wt.%, residual PbO phase was found. When the sample sintered at 1280degreesC for 2 h, the main crystalline phase was of a perovskite structure and the minor crystalline phase of pyrochlore was also present. When the PbO excess increased from 5.0 to 7.0 wt.%, the bulk density of the sintered samples increased with increasing the PbO content. When the PbO excess content reached 7.0 wt.%, the bulk density approached 7.8 g cm (-3) (approximate to98.0% of theoretical). The planar coupling coefficient (K-p) and mechanical quality factor (Q(m)) reached their maximum values, 0.53 and 314, respectively, when the PbO excess content was 3.0 wt.%. (C) 2002 Elsevier Science B.V. All rights reserved.