Phase-field model simulation of ferroelectric/antiferroelectric materials microstructure evolution under multiphysics loading

dc.contributor.advisor Wei Hong
dc.contributor.author Zhang, Jingyi
dc.contributor.department Materials Science and Engineering
dc.date 2018-08-11T16:11:46.000
dc.date.accessioned 2020-06-30T02:52:04Z
dc.date.available 2020-06-30T02:52:04Z
dc.date.copyright Wed Jan 01 00:00:00 UTC 2014
dc.date.embargo 2001-01-01
dc.date.issued 2014-01-01
dc.description.abstract <p>Ferroelectric (FE) and closely related antiferroelectric (AFE) materials have unique electromechanical properties that promote various applications in the area of capacitors, sensors, generators (FE) and high density energy storage (AFE). These smart materials with extensive applications have drawn wide interest in the industrial and scientific world because of their reliability and tunable property. However, reliability issues changes its paradigms and requires guidance from detailed mechanism theory as the materials applications are pushed for better performance. A host of modeling work were dedicated to study the macro-structural behavior and microstructural evolution in FE and AFE material under various conditions.</p> <p>This thesis is focused on direct observation of domain evolution under multiphysics loading for both FE and AFE material. Landau-Devonshire time-dependent phase field models were built for both materials, and were simulated in finite element software Comsol. In FE model, dagger-shape 90 degree switched domain was observed at preexisting crack tip under pure mechanical loading. Polycrystal structure was tested under same condition, and blocking effect of the growth of dagger-shape switched domain from grain orientation difference and/or grain boundary was directly observed. AFE ceramic model was developed using two sublattice theory, this model was used to investigate the mechanism of energy efficiency increase with self-confined loading in experimental tests. Consistent results was found in simulation and careful investigation of calculation results gave confirmation that origin of energy density increase is from three aspects: self-confinement induced inner compression field as the cause of increase of critical field, fringe leak as the source of elevated saturation polarization and uneven defects distribution as the reason for critical field shifting and phase transition speed. Another important affecting aspect in polycrystalline materials is the texture of material, textured materials have better alignment and the alignment reorganization is associated with inelastic strain. We developed a vector field of alignment to describe texture degree and introduced the alignment vector into our FE and AFE model. The model with alignment field gave quantatively results for the well-recognized irreversible strain in AFE virgin ceramics during the first poling process. The texture field also shows a shielding zone under mechanical loading around existing crack tip.</p> <p>In conclusion, this thesis developed working models of FE and AFE material and systematically studied their behavior under multiphysics loading in a finite element analysis approach. Materials structure of polycrystal materials including grain orientation, grain boundary, defects and materials texture were tested for their effect on hysteresis and switched domain growth. Detailed microstructure development in domain switching and alignment was directly observed in this simulation.</p>
dc.format.mimetype application/pdf
dc.identifier archive/lib.dr.iastate.edu/etd/13775/
dc.identifier.articleid 4782
dc.identifier.contextkey 5777478
dc.identifier.doi https://doi.org/10.31274/etd-180810-621
dc.identifier.s3bucket isulib-bepress-aws-west
dc.identifier.submissionpath etd/13775
dc.identifier.uri https://dr.lib.iastate.edu/handle/20.500.12876/27962
dc.language.iso en
dc.source.bitstream archive/lib.dr.iastate.edu/etd/13775/Zhang_iastate_0097M_14186.pdf|||Fri Jan 14 20:00:31 UTC 2022
dc.subject.disciplines Mechanics of Materials
dc.title Phase-field model simulation of ferroelectric/antiferroelectric materials microstructure evolution under multiphysics loading
dc.type article
dc.type.genre thesis
dspace.entity.type Publication
relation.isOrgUnitOfPublication bf9f7e3e-25bd-44d3-b49c-ed98372dee5e
thesis.degree.level thesis
thesis.degree.name Master of Science
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