Untersuchungen Zur Elektrostriktion und Piezoelektrizität der Ferroelektrika

Abstract

The electromechanical effects of ferroelectric crystals are shown on the basis of the thermodynamical theory. A piezoelectric resonator is most frequently used to determine the piezoelectric constants. In some cases, however, it was found that direct measurement of the deformation as a function of the electric displacement was useful since quadratic effects can be investigated in the same way. The electrostriction constants can also be found by the dynamic method. This method (an electrostriction resonator) also provides the possibility of exciting and investigating mechanical oscillations without the superposition of a linearizing d.c. field. A survey of the experimental results is given for some ferroelectrics. In the neighbourhood of the Curie point, in particular, some considerable deviations from the expected results can be observed.