When 3:30 PM - 5:00 PM Jan 13, 2012
Where 1670 CSE
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Engineering Thermal-Electrical Responses in Complex Oxides: Enhanced Dielectric and Pyroelectric Response in Epitaxially Strained Ferroelectric Thin Films

Lane Martin
University of Illinois at Urbana-Champaign, Department of Materials Science and Engineering

Motivated by the need to more efficiently utilize our energy resources there has been much work on direct thermal-to-electrical energy conversion and low-power thermal management systems. Here we will investigate recent advances in the understanding of thermal properties and responses of complex oxide thin films, with special attention to how epitaxial constraints can enhance dielectric/pyroelectric/electrocaloric responses in ferroelectrics. Through a combination of thermodynamic analyses, phenomenological models, and experimental approaches the potential of modern oxide materials for energy conversion and solid state cooling will be examined. We will report on the study of dielectric, pyroelectric, electrocaloric, and ferroelectric properties of highly engineered ferroic thin films (i.e., PbZr1-xTixO3 and others). Highly-strained, epitaxial thin films have been produced on a wide range of substrates by pulsed laser deposition. Optimization of enhanced responses in these films has been aided by the study of epitaxial strain, film thickness, composition, and more using Ginzburg-Landau-Devonshire models. Aided by such models, we have optimized the experimental processing parameters and have begun studies of enhanced dielectric/pyroelectric/electrocaloric responses that make use of new effects to produce ferroelectric thin films with the large room temperature dielectric and pyroelectric responses. In particular we will examine the importance of domain walls and so-called extrinsic contributions to these results. These observations have implications for dielectric, piezoelectric, pyroelectric, electrocaloric, and emission properties in these materials.

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