Time-resolved x-ray diffraction study of the relaxation process of electric-field-induced strain in KD2PO4

In this article, we report on measurements of the strain relaxation process in KD2PO4. The application of a static electric field to a piezoelectric crystal generates stresses, which are released by the introduction of strain. Time-resolved x-ray diffraction experiments on square platelike samples indicated that the strain relaxation process strongly depends on the rise time of the electric field. In the case of an instantaneously applied electric field (rise time 30 ns, i.e., much shorter than the response time of the crystal), the induced strain waves were only weakly damped and still present 400 mus after activating the external electric field (which corresponds to roughly 50 round trips of the strain wave). The strain waves can be suppressed completely by employing a rise time equivalent to the intrinsic response time of the crystal. Measurements on a bar-shaped crystal indicated that the strain waves are generated at the edges of the crystal and propagate along the length of the crystal at the speed of sound. This was concluded from the time of arrival of the strain waves, as well as from the measured vibration frequency. (C) 2003 American Institute of Physics.