Mechanical properties of PZT ceramics with tailored microstructure

PZT ceramics with tailored microstructure were fabricated using 3 and 5 val ence ions as dopants. It was shown that the type of additive does not influ ence the microstructural development. Vacancies in the Pb-lattice are being formed for all dopants to assure charge equilibrium. Thus, Pb-vacancies ar e identified to dominate the microstructural development of PZT ceramics. S amples with 2 mol% additive which were sintered to near theoretrical densit y exhibit a homogeneous microstructure with an average grain size of 2 mu m The morphotropic phase boundary (MPB) of doped PZT is shifted towards high er PbZrO3 content as compared to undoped PZT. This effect is explained in t erms of crystallographic considerations. The investigations on the mechanic al properties are focused on the area of the MPB that is relevant for indus trial applications due to the extraordinary high electrical properties. For the first time an entire evaluation of the mechanical properties have been conducted considering the fracture toughness of poled and unpoled samples, R-curve behavior, temperature dependent bending strength and ferroelastic behavior. From these measurements the influence of domain switching process es on the mechanical properties are deduced and a correlation between mecha nical, ferroelastic and ferroelectric behavior and the microstructure is su pposed. (C) 1999 Elsevier Science S.A. All rights reserved.