Regensburg 2016 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 29: Topical session: Caloric effects in ferroic materials III - Electrocalorics

MM 29.4: Talk

Wednesday, March 9, 2016, 11:00–11:15, H39

Direct Electrocaloric Effect Measurements in BaTiO₃-based Ferroelectric Ceramics — •Mehmet Sanlialp, Vladimir V. Shvartsman, and Doru C. Lupascu — Universität Duisburg-Essen, Institut für Materialwissenschaft

Nowadays small size and high performance of electronic components are highly demanded. However, use of miniaturized high power electronic devices often faces large heat dissipation, which reduces the performance of these devices. Recently, solid-state refrigeration based on the electrocaloric effect (ECE) has been proposed as a promising solution of this problem. ECE is a change of temperature or entropy of a dielectric material under an applied electric field at adiabatic or isothermal conditions, respectively. ECE based refrigerators should combine high efficiency, low cost, be environmental friendly and easy scalable. Therefore, search for materials with large ECE is important. We report on development of two experimental setups to measure the ECE directly: a modified differential scanning calorimeter and a self-made quasi-adiabatic calorimeter. We performed the ECE measurements in several lead-free ferroelectric ceramics: (1-x)Ba(Zr_0.2Ti_0.8)O₃-x(Ba_0.7Ca_0.3)TiO₃, 0.55Ba(Zr_0.2Ti_0.8)O₃-0.45(Ba_0.7Ca_0.3)TiO₃ with Fe and Nb doping, (1-x)Ba(Sn_0.15Ti_0.85)O₃-x(Ba_0.7Ca_0.3)TiO₃. Temperature, electric field, and composition dependences of the electrocaloric effect have been studied. Furthermore, we compare results of the direct measurements with frequently used indirect estimations based on Maxwell relations to judge the compatibility of these measurement methods.