Colloidal processing of NbO2.5 and Pb(ZrTi)O-3 (PZT) powder mixtures and a study of the piezoelectric properties of sintered Nb-doped PZT (PNZT) are conducted. The PZT-based bulk samples are first prepared in various organic solvents, and then pressure-casted to form homogeneous green compacts. Results from the sedimentation and zeta (zeta)-potential measurements are used to reveal the optimum dispersive properties of PZT and NbO2.5 colloids. High temperature dilatometry, X-ray diffractometry (XRD), scanning and transmission electron microscopy (SEM and TEM) are used to analyze the sintering, microstructures, and crystalline phases of PZT and PNZT bulk samples. The test results show that green PNZT parts with green densities higher than 4.5 g/cm(3) can be sintered into high density ceramics (>= 97% theoretical density). The use of NbO2.5 doping significantly reduces the grain growth and promotes the formation of pores. The increase in Pb vacancies and NbO2.5 doping reduces the value of the coercive field. However, the creation of secondary phases due to over-doping degrades several important piezoelectric properties such as d(33), d(31), k(p), and P-r.

Keywords: PZT; NbO2.5; Nb-doped PZT; zeta-potential; colloids