Regensburg 2016 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 5: SYCE: Caloric effects in ferroic materials (MM with MA, DF)
DF 5.3: Hauptvortrag
Montag, 7. März 2016, 16:00–16:30, H1
Optimizing the electrocaloric effect by first-principles simulations: The role of strain and defects — •Anna Grünebohm — University of Duisburg-Essen and Cenide, Germany
The electrocaloric effect (ECE) is the adiabatic tempearture change of a material in a varying external electrical field. The ECE is promising for novel cooling devices [1]. However, in many ferroelectrics the large ECE is restricted to a narrow temperature interval.
To model modifications of the ferroelectric and electrocaloric properties of BaTiO3 by defects and epitaxial strain we have combined ab initio-based molecular dynamics simulations with a simple model for defects [2]. For polar defects the temperature range of the large caloric response is broadened. Still more striking, a giant inverse caloric effect has been observed for the first time.
Additionally, epitaxial strain can be used to enhance the caloric response and shift the operation range [3,4]. In particular tensile strain is promising to enhance the ECE of BaTiO3 around room temperature.
[1] X. Moya, et al., Nature Mater. 13,439 (2014)
[2] A. Grünebohm, et al., arXiv:1502.05201
[3] M. Marathe, et al., APL 104, 212902 (2014)
[4] A. Grünebohm, et al., APL 107, 102901 (2015).