Dresden 2014 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 18: Dielectric and ferroelectric thin films

DF 18.3: Vortrag

Mittwoch, 2. April 2014, 16:40–17:00, GER 37

First principles study of the electrocaloric effect in strained BaTiO₃ — •Madhura Marathe and Claude Ederer — Materials Theory, ETH-Zurich, Switzerland

The electrocaloric (EC) effect – a reversible change in temperature of a material by applying an external electric field – has been known for a very long time [1]. Recently however, the discovery of a “giant electrocaloric effect” [2] has stimulated extensive work on the EC effect, due to its huge potential to increase the efficiency of cooling devices. We have studied how misfit strain affects the EC temperature change in bulk BaTiO₃.

We have performed molecular dynamics simulations for an effective Hamiltonian based on first-principles density functional theory [3]. The calculated EC temperature change Δ T reduces when BaTiO₃ is only clamped but not strained, but increases again with increasing misfit strain. Further with increasing misfit strain, there is a shift in the Δ T peak towards higher temperatures. Therefore the misfit strain can be utilized in two ways – (i) to enhance the EC temperature change and (ii) to achieve a maximal effect in the temperature range of interest for a given application.

[1] J. F. Scott, Annu. Rev. Mater. Sci. 41, 229 (2011).

[2] A. S. Mischenko, et al., Science 311, 1270 (2006).

[3] T. Nishimatsu, et al., Phys. Rev. B 82, 134106 (2010).