Abstract: The invention provides a novel type of piezoelectric element. This element comprises a number of piezoelectric layers of a ceramic material and a number of electrode layers of a silver-palladium alloy. The piezoelectric layers and the electrode layers are stacked alternately to form a multilayer. This multilayer is also provided with at least two external electrical connections which are in contact with a number of said electrode layers. In accordance with the invention, the composition of the main component of the ceramic material corresponds to the formula:?Pb.sub.1-u-x Ag.sub.u RE.sub.x !?Ti.sub.1-y-z Zr.sub.y (W.sub.1/2 Mg.sub.1/2).sub.z !O.sub.3,where RE is at least one element selected from the group formed by La, Nd, Sm and Gd, and in which 0<u.ltoreq.0.025; 0.005.ltoreq.x.ltoreq.0.05; 0.44.ltoreq.y.ltoreq.0.52 and 0.015.ltoreq.z.ltoreq.0.1. Preferably, RE stands for La and 0.005<u<0.020. This material can be sintered at a low temperature and has a relatively high Curie temperature.

Abstract: A torsional actuator consisting of multilayers of monolithic piezo-electric ceramic material, with planar electrodes between the successive layers and external contacts for supplying control voltages to the electrodes which cause the actuator to twist about its longitudinal axis by a torsion angle dependent on the control voltages. Viewed in cross-section, and with respect to a reference potential supplied to alternate ones of the electrodes, the remaining electrodes are in four respective quadrants and are supplied with control voltages of polarities dependent on the quadrants in which they are located.