Understanding the Scientific Basis of Electrocaloric Effect in Defects Modified Ferroelectric Polymers.

摘要

Materials with large electrocaloric effect (ECE) is attractive for Army and DoD applications such as for the thermal management of soldier s in battle field, cooling of electronic systems, and mobile cooling units with high cooling power, compact size, and high efficiency. Recent experiments have demonstrated large ECE in the relaxor ferroelectrics (defects modified ferroelectrics) over broad temperatures. Ferroelectrics provide a strong coupling of polarization to the applied field (easy to induce a large polarization) and the defects structures can be employed to the ployed to facially tailor the randomness of dipoles to achieve large ECE. This program develops fundamental understanding of large ECE in the relaxor ferroelectrics.Through experimental study and thermodynamics analysis, we intend to address these questions: (a) what are the polarization responses in these complex and highly coupled polar-materials that control the entropy change in the materials and (b) how to influence these polarization responses and consequently ECE via various molecular and nanocomposite approaches.