Dresden 2006 – scientific programme

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DF: Dielektrische Festkörper

DF 10: Electric, Electromechanical and Optical Properties I

DF 10.9: Talk

Thursday, March 30, 2006, 17:30–17:50, M{\"U}L Elch

Light-induced changes of polarization dynamics in PLZT ceramics — •T. Granzow, A. Volkenborn, and J. Rödel — FB Material- und Geowissenschaften, TU Darmstadt

Due to their excellent electrooptical properties, PLZT ceramics have been investigated since the early days of electrooptics. Most investigations have focussed on the influence of electric fields on the optical properties. The opposite effect, the influence of illumination on the ferroelectric domain structure and hysteresis is still not entirely clear. It has been shown that there is an interplay between the nucleation of ferroelectric domains, motion of domain walls and light-induced free charge carriers, but there are contradictions both in theory and in experiments if free charge carriers will help or hinder ferroelectric polarization reversal.

In this talk, we will compare the polarization behavior in PLZT 8/65/35 and PLZT 9.5/65/35 with and without illumination in the visible spectral range. We will present the ferroelectric hysteresis detected by measuring the switching current as well as the integrated polarization. To obtain the domain dynamics, the development of P on a timescale between 1 µs and 10 s under a constant electric field is examined for various field amplitudes. It will be shown that, although the difference between the illuminated and unilluminated hysteresis measurement is rather small for frequencies up to 100 Hz, there is a notable decrease of the switching time constants in the ms range. This phenomenon will be discussed within the framework of conduction band electrons facilitating domain wall movement.