Katrin Benkert

Influence of sintering conditions on doped PZT ceramics for base-metal electrode multilayer actuators

The influence of sintering atmosphere and copper addition on the microstructural and piezoelectric properties of Mn-doped lead zirconate titanate ceramics (PZT) was investigated. This ceramic powder densifies below 1000°C, enabling the use of copper inner electrodes for a multilayer actuator setup. To simulate the influence of oxidized inner electrodes during sintering, different CuO contents (0 and 1 mol.%) were mixed to the precalcined Mn-doped PZT powder. Ceramic discs were sintered at 950°C in air and analogously in N2, or in steam containing N2 (25 vol.% water vapor content). The electrical characterization of the discs showed that the piezoelectric properties are influenced by the CuO addition as well as by the sintering atmospheres. The large signal piezoelectric constant shows an improvement of at least 20% when CuO is added. CuO acts as a sintering aid, and especially when the ceramics are fired in steam-containing N2, anomalous grain growth occurs.

Accelerated processing route for KNN based piezoceramics

Abstract It is known that the properties of potassium–sodium–niobate (KNN, K0·46Na0·54NbO3) are sensitive to processing and that the most successful way of stabilising and improving material performance is proper doping of KNN. However, this leads to more complex material systems, whose synthesis is very time consuming to assess by conventional processing techniques. On the other hand, known high throughput routes impose a serious interference with conventional processing, resulting in significant differences of the findings, or inaccessibility of certain parameters. In this paper, an accelerated processing route is introduced and compared with conventional mixed oxide processing regarding the density, large signal piezoelectric charge constant, permittivity, loss tangent planar coupling factor, specific resistivity and microstructure. By means of three differently doped KNN based compositions, it is shown that the accelerated processing route yields reproducible results, which are equal or even superior to conventional techniques, while the processing time and the batch costs are significantly reduced.