Scale-Bridging Simulation of Functional Composites (SFC)
Ferroelectric perovskites (ABO3, with A: alkali earth metals and B: transition metals) are widely used in applications and are promising for energy harvesting devices as well as for future efficient solid-state cooling devices based on the electrocaloric effect. All these applications share the following demands on materials design: Replace toxic Pb and increase efficiency and reversibility in a broad and suitable operation range (cooling: At and below room temperature, others: At and above room temperature).
The goal of the group is the design of ferroelectric composites with superior functional properties. We will simultaneously optimize multiple responses with high technological impact for (a) harvesting of electric energy from temperature fluctuations or stress and (b) cooling by means of the electrocaloric effect. Our approach is the scale-bridging optimization of composite systems with different morphologies: (a) superlattices (b) pillars and (c) inclusions, combining the benefits of materials choice, controlled inhomogeneities, domain structure, and the boundary conditions at the interfaces. Our methods are scale-bridging simulations based on ab initio parametrization with high predictive power, which allow us to fundamentally understand and design the properties of materials systems.
Modification of phase diagram, domain structure and functional properties of BaTiO3 by the boundary conditions in films: (a) Phase diagram under biaxial strain. In the hatched T-range, the domains illustrated in (b) are stabilized by the elastic boundary conditions. (c) Electrocaloric response for the removal of different field strengths (encoded by color). The presence of domains allows for a constant electrocaloric strength (T/E) in a broad field strength. Details can be found in A. Grünebohm, Euro. Phys. Lett. 115, 47002, 2016.
- Molecular Dynamics;
- Density-Functional theory;
- Magneto- and electrocaloric effects;
- Ferroic materials;
- Functional (piezoelectric, dielectric, caloric) responses
Dr. Anna Grünebohm
Tel: +49 234 32 29377
Fax: +49 234 32 14977