SFB 1548:  FLAIR - Fermi Level Engineering Applied to Oxide Electroceramics

• Subject Area: Materials Science and Engineering ; Chemistry
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 463184206

Electroceramic materials exhibit a variety of properties and are increasingly used, for example, in energy conversion, energy storage, and electronics. For developing advanced electroceramic materials with novel and/or enhanced properties, which are compatible with major societal challenges as climate-neutrality, health-protection, and resource and energy efficiency, it is highly desirable to be able to predict how their properties depend on composition and on the way the material is made. While this is possible to large extent in semiconductor technology, it is currently prohibited for electroceramic oxides by the lack of a generalized understanding of how chemical substitution (doping) is affecting material properties. The collaborative research center FLAIR proposes to overcome this deficiency by using the Fermi energy as a common parameter to describe the different possible charge compensation mechanisms, which are decisive for material properties. In doing so, FLAIR explores Fermi level engineering as a new avenue towards the design of oxide electroceramics and also provides an advanced understanding of space-charge regions at surfaces, grain boundaries, heterointerfaces. The relation between the Fermi energy and phase stability is applied further to derive novel synthesis routes and to control microstructure evolution. Eventually, Fermi level engineering shall become a toolkit for designing a variety of oxide electroceramic materials for different applications. The long-term vision is to provide a simulation tool, which, starting with given compositions and processing parameters, can predict phase distribution, microstructures, and resulting material properties. This CRC develops the concept for the example of three different application fields of electroceramics: (I) Mixed ionic-electronic conductors for ion exchange membranes and fuel cells, (II) photo- and electrocatalysts for electrolytic water splitting, and (III) piezoelectrics and dielectrics for actuators and capacitors. The materials of interest include oxides, oxynitrides, oxyfluorides, and oxyhydroxides with perovskite or a related crystal structure. This CRC addresses current technological bottlenecks such as i) the tradeoff between oxygen ion conductivity, in- and excorporation of ions, and CO2 resistance of oxygen transport membranes, ii) the visible-light sensitivity of photocatalysts, iii) noble-metal-free electro-catalysts for the oxygen evolution reactions, iv) hardening phenomena of lead-free piezoelectrics, and v) the temperature stability of high-permittivity dielectrics. The proposed research program is executed by combining leading expertise and scientific equipment in electronic structure analysis, surface science, solid-state chemistry, defect chemistry, electrochemistry, ceramic processing, microstructure analysis, and multiscale modelling of oxide electroceramics.

• DFG Programme: Collaborative Research Centres

Current projects

• A01 - Fermi level engineering of doped perovskites: From the dilute limit to phase formation (Project Heads Albe, Karsten ;  Zhang, Ph.D., Hongbin )
• A02 - Polaronic contributions to Fermi level tolerance in perovskite-type oxide electroceramics (Project Head Albe, Karsten )
• A03 - Fermi level engineering in oxygen transport membranes (Project Head Weidenkaff, Anke )
• A04 - Fermi level engineering in (non)-degenerate semiconducting perovskite-type oxynitride photoabsorbers (Project Head Weidenkaff, Anke )
• A05 - Fermi energy guided topochemical reaction strategies for electrocatalytically active Ba-rich transition metal oxyfluorides, oxyhydroxides and their combination (Project Head Clemens, Oliver )
• A07 - Charge transition levels and Fermi energy limits in functional oxides (Project Head Klein, Andreas )
• B01 - Fermi level engineering of grain boundaries in perovskite oxides by first-principles calculations (Project Head Albe, Karsten )
• B02 - Understanding dopant-controlled modification of electronic structure and reactivity of perovskite surfaces using ab initio calculations (Project Head Rohrer, Jochen )
• B03 - Impact of Fermi energy on microstructure evolution: An electro-chemo-mechanical phase-field study (Project Head Xu, Bai-Xiang )
• B04 - Influence of bulk electronic structure on grain boundary properties in perovskite oxides (Project Heads Klein, Andreas ;  Rheinheimer, Wolfgang )
• B05 - Probing the electrical activity of grain boundaries in acceptor-doped perovskite oxides through ion transport experiments (Project Head De Souza, Ph.D., Roger )
• B06 - Real-space structure and electronic structure of grain boundaries in perovskites (Project Head Kübel, Christian )
• B07 - Perovskite-based high performance electrocatalysts for the oxygen evolution reaction: Fundamental insight into bulk and interface electronic structure towards materials design (Project Head Hofmann, Jan Philipp )
• B08 - Enhancing oxygen and hydrogen surface exchange reactions by Fermi level engineering (Project Heads Hofmann, Jan Philipp ;  Klein, Andreas )
• Z01 - Central Tasks of the Collaborative Research Center (Project Head Klein, Andreas )
• Z02 - Near-ambient pressure photoelectron spectroscopy for Fermi level engineering (Project Heads Hofmann, Jan Philipp ;  Klein, Andreas )
• Z03 - Structural characterization using 2D and 3D electron diffraction (Project Head Kolb, Ute )
• Z04 - Integrated Research Training Group “Junior FLAIR” (Project Head Xu, Bai-Xiang )
• Z05 - Sustainable Research Data Management (Project Heads Kübel, Christian ;  Zhang, Ph.D., Hongbin )

• Applicant Institution: Technische Universität Darmstadt
• Participating University: Rheinisch-Westfälische Technische Hochschule Aachen; Technische Universität Graz; Universität Stuttgart
• Participating Institution: Forschungszentrum Jülich GmbH ; Institut für Energie- und Klimaforschung (IEK), until 8/2023
• Spokesperson: Professor Dr. Andreas Klein