Ferroelectric thin films develop large residual stresses and preferred crystallographic orientation during processing which can effect electromechanical properties and performance. The present work investigates the effects of stress on field-induced polarization switching in ferroelectric PZT (52/48) thin films. Film response is measured as a function of externally applied mechanical stress using a double-beam laser-Doppler heterodyne interferometer. This apparatus successfully eliminates any displacement contribution from flexural vibration of the substrate and enables measurement of the strain-electric field hysteresis loops as a function of applied stress. The field-induced strain in the PZT film increases with increasing compressive stress, while the opposite trend is observed for applied tensile stress. The dependence of electromechanical response on the external stress is attributed to the initial tensile residual stress state in the film. Tensile stress creates an in-plane clamping effect on the domains in the film, hindering polarization switching. The application of a compressive stress reduces tensile residual stress in the film and the constraint on the domains; hence more 90° polarization switches are allowed to occur under applied electric field, leading to higher field-induced strains. Applied tensile stress amplifies the clamping effect, leading to lower field-induced strains. Experimental observations are consistent with numerical simulations based on existing micromechanical models of polarization switching.
Publisher
Department of Theoretical and Applied Mechanics. College of Engineering. University of Illinois at Urbana-Champaign
Series/Report Name or Number
TAM R 974
2001-6013
ISSN
0073-5264
Type of Resource
text
Language
eng
Permalink
http://hdl.handle.net/2142/112677
Copyright and License Information
Copyright 2001 Board of Trustees of the University of Illinois
TAM technical reports include manuscripts intended for publication, theses judged to have general interest, notes prepared for short courses, symposia compiled from outstanding undergraduate projects, and reports prepared for research-sponsoring agencies.
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