Group members

Dr. Paul Chekhonin
Michael Mietschke
Stefan Engelhardt
Hagen Bryja

Cooperative activities

SPP1599 "Ferroic Cooling"

Electrocaloric Thin Films

Electrocaloric materials, which gain increasing interest for novel solid state cooling devices, show a diffusionless phase transition, which is induced by electric fields. However, the interplay between the microstructural changes and the electrocaloric effect at such phase transitions is not completely understood so far. The main aim of our work is to use epitaxial films to study these correlations in more detail.

Therefore, epitaxial (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) are grown on single crystalline substrates using pulsed laser deposition. The influence of different deposition parameters as well as the substrate orientation is investigated in order to realize PMN-PT films with a pure perovskite phase. The structure of the grown film is characterized in detail by X-ray diffraction and surface microscopy. Electric polarization measurements are used to determine the temperature dependant ferroelectric properties and to estimate the electrocaloric effect indirectly. Besides the work on the model system PMN-PT, we started with the preparation of lead-free epitaxial thin films focusing on the BaTiO3-BaZrO3 system.

Recent publications:

M. Mietschke, S. Engelhardt, S. Fähler, C. Molin, S. Gebhardt, L. Schultz, R. Hühne
Structural and ferroelectric properties of 0.9PMN-0.1PT thin films
Ferroelectrics (2015) accepted.

M. Mietschke, S. Oswald, S. Fähler, L. Schultz, R. Hühne
Tuning structure in epitaxial Pb(Mg1/3Nb2/3)O3-PbTiO3 thin films by using miscut substrates
Thin Solid Films 589 (2015) 792.

M. Mietschke, S. Fähler, L. Schultz, R. Hühne
Influence of the deposition geometry on structural and ferroelectric properties of epitaxial PMN-PT films
Proc. 2014 IEEE Int. Symp. on Applications of Ferroelectrics, Int. Workshop on Acoustic Transduction Materials and Devices & Workshop on Piezoresponse Force Microscopy (ISAF/IWATMD/PFM) (2014) 153-156.