Microstructural design of PZT ceramics

PZT ceramics, Pb(Zr1−xTix)O3, are good dielectrics and piezoelectric materials. These properties reach a maximum in the morphotropic phase boundary (MPB), where phase coexistence occurs. The width of this coexistence region was found to be dependent on the size of the ferroelectric domain, through the size of the grains, within the relation that the larger the domain size, the shorter the coexistence region 1[Soares, M. R., Senos, A. M. R. and Mantas, P. Q., Phase coexistence region and dielectric properties of PZT ceramics. J. Eur. Ceram. Soc., 2000, 20, 321–334].1 In turn, a shorter coexistence region means a higher dielectric permittivity in compositions near the MPB zone 1[Soares, M. R., Senos, A. M. R. and Mantas, P. Q., Phase coexistence region and dielectric properties of PZT ceramics. J. Eur. Ceram. Soc., 2000, 20, 321–334]1 and therefore, PZT ceramics with high densities and large mean grain size are necessary to obtain materials with better electrical properties. Here, a sintering additive of PbO–SiO2 was investigated to produce high dense materials with a good microstructural development, i.e., large grain sizes, at low sintering temperatures. Using 3 wt% of glassy phases, high densities are already observed at 800 °C, 82–85%. Above 950 °C, the higher the SiO2 content in the glassy phase, the lower the densities. Larger amounts of the glassy phase increases the density at low temperatures and the microstructures are uniform, even after 12 h of sintering time.