Dresden 2026 – wissenschaftliches Programm
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FM: Fachverband Funktionsmaterialien
FM 16: Topical Session: Dislocations in Functional Materials II (joint session MM/FM)
FM 16.4: Vortrag
Mittwoch, 11. März 2026, 16:45–17:00, SCH/A251
Generating a “ferroelectric metal” by preferential reduction of dislocations in BaTiO3 — •Christian Rodenbücher1, Gustav Bihlmayer2, Carsten Korte1, and Kristof Szot3 — 1Forschungszentrum Jülich GmbH, Institute of Energy Technologies (IET-4), 52425 Jülich, Germany — 2Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-1), 52425 Jülich, Germany — 3University of Silesia, Institute of Physics, 41-500 Chorzów, Poland
Redox processes in transition metal oxides are of high relevance for sensors, information technology, superconductivity, and energy conversion. Perovskites with mixed ionic-electronic conductivity, such as BaTiO3, are of particular interest because oxygen nonstoichiometry controls electronic charge carriers and thus conductivity. Surprisingly, thermal reduction in vacuum can induce metallic behaviour with conductivities far exceeding predictions from point-defect chemistry. To clarify the origin of this metallic state, we investigate the electronic transport, electronic structure, and chemical composition of BaTiO3 single crystals during annealing and cooling under ultrahigh vacuum. Surface-sensitive techniques such as XPS and LC-AFM allow us to correlate electronic structure changes with the insulator-to-metal transition. We find that surface-layer dislocations act as preferential reduction sites, forming conducting filaments that yield macroscopic metallic behaviour despite minimal overall oxygen loss. Metallic behaviour persists into the ferroelectric phase. Nanoscale mapping shows that metallic filaments and piezoelectrically active regions coexist thus explaining how a “ferroelectric metal” can exist.
Keywords: Dislocations; Perovskites; Insulator-metal transition; Solid oxides; Ferroelectrics