Temperature dependence of poling strain and strain under high electric fields in LaSr-doped morphotropic PZT and its relation to changes in structural characteristics

The performance of ferroelectric devices when operated over a wide temperature range is subject to considerable changes resulting from the temperature dependence of strain characteristics of the functional materials. The effects of temperature on poling strain and strain under unipolar cycling at electric fields of 2.5 kV mm(-1) have been investigated for morphotropic donor doped lead zirconate titanate (PZT) with various Zr/Ti ratios between 20 and 160 degrees C. Remanent strain and strain under electric field show opposite behaviors with respect to their temperature dependence for all materials. The remanent strain was found to decrease at high temperature, whereas the field-induced strain under unipolar cycling increases. Depending on composition, there are marked differences with respect to the quantitative temperature behavior and the non-linearity of strain-temperature (S-E-T) characteristics. From corresponding X-ray diffraction patterns the differences in strain behavior can be related to the specific temperature-induced structural changes in the materials. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.