The primary focus of this research is to investigate the non-linear behavior of
single crystal and polycrystalline relaxor ferroelectric PMN-xPT and PZN-xPT through
experimentation and modeling.
Characterization of single crystal and polycrystalline specimens with similar
compositions was performed. These data give experimental insight into the differences
that may arise in a polycrystal due to local interaction with inhomogeneities. Single
crystal specimens were characterized with a novel experimental technique that reduced
clamping effects at the boundary and gave repeatable results. The measured
experimental data was used in conjunction with electromechanical characterizations of
other compositions of single crystal specimens with the same crystallographic orientation
to study the compositional effects on material properties and phase transition behavior.
Experimental characterization provided the basis for the development of a model
of the continuous phase transformation behavior seen in PMN-xPT single crystals. In the
modeling it is assumed that a spatial chemical and structural heterogeneity is primarily
responsible for the gradual phase transformation behavior observed in relaxor
ferroelectric materials. The results are used to simulate the effects of combined electrical
and mechanical loading.
An improved rate-independent micromechanical constitutive model based on the
experimental observations of single crystal and polycrystalline specimens under large
field loading is also presented. This model accounts for the non-linear evolution of
variant volume fractions. The micromechanical model was calibrated using single crystal data. Simulations of the electromechanical behavior of polycrystalline ferroelectric materials are presented. These results illustrate the effects of non-linear single crystal behavior on the macroscopic constitutive behavior of polycrystals.
| Identifer | oai:union.ndltd.org:GATECH/oai:smartech.gatech.edu:1853/22695 |
| Date | 17 March 2008 |
| Creators | Webber, Kyle Grant |
| Publisher | Georgia Institute of Technology |
| Source Sets | Georgia Tech Electronic Thesis and Dissertation Archive |
| Detected Language | English |
| Type | Dissertation |
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