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MM: Fachverband Metall- und Materialphysik

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

MM 29.5: Vortrag

Mittwoch, 9. März 2016, 11:15–11:30, H39

Electrocaloric Effect in BaZr_xTi_1−xO₃: Simulation vs Experiment — •Yang-Bin Ma¹, Christian Molin², Vladimir Shvartsman³, Doru Constantin Lupascu³, Sylvia Gebhardt², Bai-Xiang Xu¹, and Karsten Albe¹ — ¹Technischen Universität Darmstadt — ²Fraunhofer-Institut für Keramische Technologien und Systeme IKTS — ³Universität Duisburg-Essen

The electrocaloric effect (ECE) and the relaxor behavior of BaZr_xTi_1−xO₃ (BZT) are investigated as function of Zr content, computationally and experimentally. A lattice-based Ginzburg-Landau-type Hamiltonian is used. A multi-well Landau-type term is applied for unit cells containing Ti, and a single well for Zr. The high-frequency permittivity entering the dipole-dipole interaction is assumed composition-dependent. In experiment, the ECE in BaTiO₃ and BZT (x=0.12 and 0.2) ceramics is studied. The domain patterns are revealed by Piezoresponse Force Microscopy, together with the hysteresis and the ECE at various temperatures. The relaxor behavior is related to the relative standard deviation of the internal field distribution. With increasing Zr content, the domain size becomes smaller, and the hysteresis becomes slimmer. For Zr contents ranging from 0 to 0.3 there is a sharp drop of the ECE peak value, while the drop becomes moderate when Zr contents are larger. Meanwhile, the ECE peak shifts to lower temperature with increasing Zr content, and the temperature change decreases. The phenomena are interpreted explicitly by the domain patterns. It presents a good qualitative consistence between the phenomena observed in simulation and experiment.