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DF: Fachverband Dielektrische Festkörper

DF 8: Electrical and mechanical properties

DF 8.4: Vortrag

Dienstag, 23. März 2010, 15:00–15:20, H9

Planar defects and dislocations in perovskite materials — •Pierre Hirel¹, Matous Mrovec^1,2, and Christian Elsaesser^1,2 — ¹Institut für Zuverlässigkeit von Bauteilen und Systemen (IZBS), Universität Karlsruhe (Germany) — ²Fraunhofer Institut für Werkstoffmechanik IWM, Wöhlerstr. 11, 79108 Freiburg im Breisgau (Germany)

Plastic deformation, which depend on extended defects properties, can have dramatic influence on the electronic, optical and mechanical behavior of materials. In perovskite-type ceramics, which are functional components of electroactive devices, lattice dislocations are known to have an important influence on the devices’ performance and lifetime. In the case of confined systems (e.g. epitaxial thin films, superlattices, nanoparticles) the influence of defects such as stacking faults and misfit dislocations is even more pronounced. Therefore, the determination of extended defects properties in these materials is of prime importance.

This study investigates the structure and energetics of extended defects in these materials by means of atomistic and electronic calculations. The simulations are performed using both quantum mechanics first-principles (or ab initio) calculations, and classical interatomic potentials using ridig-ions or shell model. Planar defects are investigated (through the computation of γ-surfaces) for a number of perovskite materials such as SrTiO₃, PbTiO₃, and BaTiO₃. The structure of dissociated dislocations in strontium titanate will also be addressed, with a comparison with experimental results and the elastic theory of dislocations.