Dislocation-based functionality in oxides

• Applicant: Professor Dr.-Ing. Jürgen Rödel
• Subject Area: Synthesis and Properties of Functional Materials
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 414179371

The traditional view of dislocations is that of a vehicle for plastic deformation in metals. In contrast, dislocations in oxides can also be heavily charged. By virtue of the low mobility of these dislocations, the charge and its compensating space charge (a quasi - one-dimensional dopant) can be locked into space, up to high temperatures. If successful, this project will offer another dimension in design space for functional ceramics. The full materials’ potential will finally be exploited, together with traditional 0-dim. (elemental doping), 2-dim. (grain boundary design), and 3-dim. (second phase inclusions) defects. Mechanically-induced doping with dislocations leads to reactive centers and conducting paths parallel to the dislocation and to electrical and thermal scattering centers perpendicular to it. An electrostatic interaction with ferroelectric domain walls provides novel opportunities for material design. These new designed properties, however, can only be harvested if processing strategies can be made available to generate dislocations in bulk oxides. Next to plastic deformation of single crystals, dislocation creep in polycrystals with electric field, as well as surface and redox techniques, will be considered.

• DFG Programme: Reinhart Koselleck Projects