Abstract: In piezoceramic multilayer actuators, the head region and the foot region consist of inactive, that is to say electrode-free, piezoceramic layers. Due to the arrangement of the metallic electrodes and the layers of the piezoceramic materials, the shrinkage of the piezoceramic material, in particular in the passive head region and foot region, is influenced during the sintering process and can cause the formation of cracks. Different expansion behavior of the active and of the passive region during operation also lead to stresses which favor crack formation, in particular at the boundary between both regions. According to the invention, it is therefore proposed that a transition region (11), whose shrinkage and expansion behavior lies between the shrinkage and expansion behavior of the active region (10) and the shrinkage and expansion behavior of an inactive region (8, 9) which are electrode free, adjoins the active region (10) up to the inactive head region (8) and up to the inactive foot region (9).

Abstract: The invention relates to piezoelectric ceramic materials consisting of lead zirconate titanate and (1) at least one of an alkaline earth pyrochlore and an alkali metal perovskite having the formula AB5+O3, where B is Nb, Ta, or Sb; or (2) an alkaline earth alkali metal perovskite having the formula A(T1+0.25B5+0.75)O3, where A is the alkaline earth metal, T is the alkali metal, and B is Nb, Ta, or Sb. The materials are characterized by excellent heat and time stability.

Abstract: The Invention relates to piezoelectric ceramic materials with a base consisting of lead zirconate titanate. Said materials are characterised by the excellent heat- and time-stability of the functional characteristics.