Dislocation - tuned domain switching in deformed BaTiO3 single crystals

The dislocations—one-dimensional crystal defects made by lattice disorder—act as the nucleation center of new domains or/and pinning the motion of domain walls, which play a critical role in the ferroelectric switching and also offer the opportunity for tailoring functionalities of ferroelectrics. However, the interactions between dislocations and domain structures have not been satisfactorily understood.

Materials

Undeformed and deformed BaTiO3 single crystals with <001> and <110> crystallographic orientations.

Methods

Dislocations will be introduced by plastic deformation at high temperature.

Characterization: In-situ temperature and electric field dependence of optical microscopy will be used to investigate the domain switching of undeformed and deformed samples. Reflection, transmission, differential interference contrast, and polarized light modes will be employed to observe and distinguish domains and dislocation lines.

Piezoresponse force microscopy will be performed to establish local switching behaviour at micro-/nanoscale.

Characterize temperature dependent large and small signal properties – polarization and strain hysteresis, d33, and permittivity.

Supervisor & Contract: Dr. Fangping Zhuo,

Domain patterns of <110>-oriented BaTiO3 single crystal recorded using optical microscopy (size: 2 mm × 2 mm)
Domain patterns of <110>-oriented BaTiO3 single crystal recorded using optical microscopy (size: 2 mm × 2 mm)