Advanced doping strategies, defect states and electronic structure of functional oxides

Chemical substitution, iso- or heterovalent, is fundamental to tailoring material properties. While such strategies are well-established for classical semiconductors, they are only poorly understood in functional oxides due to the higher complexity of defect formation and charge compensation mechanisms. A broad scientific community exchange is needed to foster the understanding of the underlying physics and chemistry to achieve a control of material properties.

Scope:

Functional oxides play a crucial role in many fields of energy transition and efficient energy conversion and storage. This includes e.g., the reversible ex-solution/segregation of oxide-based heterogeneous catalysts for 3-way-catalysis or water (photo)electrolysis, reversible lithium uptake/release in cathode active materials, di-/piezoelectrics for sensors and actuators, high-temperature thermoelectrics for electricity generation from waste heat, and mixed ionic-electronic conducting ceramic membranes for O₂ or H₂ separation/transport. The typical strategy to adjust their functional properties is the application of iso- or heterovalent (partial) substitution. The latter is also called doping. However, all these materials share a common challenge – their doping is mostly defined empirically and that it is yet unclear how to a priori select and process the right host materials and dopants to reproducibly achieve the intended material properties, as already vastly established for classical semiconductors. The reasons behind this complication are the various ways how a material can react to doping, e.g., electronic compensation, ionic compensation, valence changes of cations or anions, or the segregation or neutralization of the dopant. This symposium is therefore aiming at bringing together a broad range of different expertise, crucial to work towards an overarching, potentially predictive concept. Vital requirements for success are the close interaction and unification of vocabulary currently used to describe the same phenomena from different viewpoints. This includes competences in solid-state and defect chemistry, semiconductor physics, materials and defect modelling, and spectroscopic techniques, in particular X-ray photoelectron spectroscopy, but also the typical application fields of functional oxides.

Hot topics to be covered by the symposium:

• New synthesis routes for dopedoxides with defined & reproducible properties
• Doping concepts for oxides to advance material properties
• Cationic versus anionic substitution
• Interface properties of electroceramics
• Ex-solution & segregation behavior of catalysts/electrodes
• Latest developments in defect modelling on different length & time scales
• Transport and surface reaction kinetics of mixed ionic-electronic/triple-conducting ceramics, e.g., oxygen & hydrogen separation/transport membranes
• Recent advances of spectroscopic characterization methods including in-situ & operando approaches

List of invited speakers (confirmed):

• Saiful Islam (Oxford University, GB)
• Hiroshi Kageyama (Kyoto University, Japan)
• Susana Garcia Martin (Universidad Complutense Madrid, Spain)
• Igor Lubomirsky (Weizmann Institute, Israel)
• Edith Bucher (University of Leoben, Austria)
• Armin Feldhoff (Leibniz University Hanover, Germany)
• Guiditta Perversi (Maastricht University, Netherlands)
• Andreas Klein (TU Darmstadt, Germany)
• Emre Erdem (Sabanci University Istanbul, Turkey)
• Roger A. DeSouza (RWTH Aachen, Germany)