Project Details

Description

0114801

Weng

Ferroelectric ceramics are an important class of engineering materials that have wide applications as sensors, actuators, transducers, and ultrasonic medical imaging. This class of materials can exist or can be fabricated in several scales: single crystals, polycrystals, composites, and thin films, but their distinctive properties are not clearly known. In order to explore the full potential for each of them and to provide a guideline for material design and selection, a research project will be undertaken to study their properties, and to develop for each of them the unique constitutive models for their nonlinear, coupled electromechanical behaviors. In this process, the change of crystal structures from the high temperature paraelectric to the low temperature ferroelectric state will be considered, and domain switch from one poled state to another under application of an electric field and/or mechanical stress will be investigated. This will be carried out by consideration of the mechanics, physics, and irreversible thermodynamics involved during phase transformation and domain switch. In particular, the thermodynamics driving force arising from the change in Gibbs free energy of a heterogeneous system and the resistance force associated with the domain wall movement will be used to construct the kinetic equations. On the single crystal level, domains with lamellar structures for all potential variants will be identified under a given electromechanical field, while on the polycrystal level it will be addressed for the constituent grains considering grain interactions. For ferroelectric composites actuated with ferroelectric/piezoelectric particles or rods, or spheroidal inclusions in general, the effect of microstructural features, such as particle shape, volume concentration, and distribution, will be examined. For the thin films whose thickness direction usually contains columnar grains with some preferred texture, their distinctive characteristics from the bulks will be emphasized. The theory will be checked with experimental data, some from open literature and others from work of two collaborators. The outcome of the proposed study will be a set of physically based, experimentally verified constitutive models that reveal the unique features of the electromechanical behavior for each scale.

The proposed problems touch upon several novel aspects not commonly encountered simultaneously: micromechanics of heterogeneous materials, electric-mechanical coupling, nonlinear response, evolution of microstructures, irreversible thermodynamics, physics of phase transformation and domain switch, and scale-transition. As such, it will contribute to the basic advancement of scientific knowledge in this important field. The research program will be integrated into both graduate and undergraduate teaching at Rutgers. At the graduate level a new focus on the coupled phenomena in solids will be initiated. This will include the electromechanical coupling in piezoelectricity and ferroelectricity as proposed, and electrostriction, ferromagnetic behavior, magnetostriction, and shape-memory alloys. At the undergraduate level a project for the seniors with an interest in both mechanics and electronic materials will be offered through Rutgers' J. J. Slade Scholars program. Participants of this project will have the unique opportunity to learn both, and gain experience to write a thesis on this interdisciplinary topic. In this process, minority and under-privileged students will be actively sought to participate.

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StatusFinished
Effective start/end date9/1/018/31/05

Funding

  • National Science Foundation: $250,000.00

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