Dislocation-based functionality in single-crystal BaTiO3

The topological line defects, dislocations, in contrast to metals, had been avoided at all cost in ceramics for fear of implementing charge centers because they are often considered as a culprit for the degradation of ceramics.[1] However, recent work published in Science from our group and collaborators has demonstrated that dislocations ensured the ferroelectric BaTiO3 crystal to have a domain structure that enhanced the piezoelectric coefficient by 19 times.[2] When dislocations are interacting with topological domain walls (planar defects), they offer many new opportunities for altering functionalities by dislocation-based defect engineering.[3-6] The present project aims to investigate the influence of dislocations on dielectric and piezoelectric properties in ferroelectric BaTiO3 single crystals. These properties at both macroscopic and microscopic levels will be explored. One major aim is to understand the dynamics of the defect interactions between dislocations and domain walls and their role in determining functionalities.

The effective work will involve bulk deformation, structure and property characterizations. Dislocations will be introduced using high-temperature plastic deformation.[3,4] Advanced transmission electron microscope (TEM) will be employed to image the dislocation structures and their orientations. The obtained samples with dislocation networks will be characterized by investigating first and third harmonic dielectric and piezoelectric properties. Especially, local dislocation-domain wall interactions will be studied using piezoresponse force microscope (PFM) and scanning x-ray diffraction microscopy (SXDM) at the European Synchrotron Radiation Facility.

As an MSc student, you will be trained to use the existing state of the art setups including Zwick and Instron, different microscopes as well as basic and dedicated characterization techniques, e.g., structural and ferroelectric measurements.

If you are interested in this topic, please contact: Fangping Zhuo,

Expected starting date: as soon as possible, but can be flexible.

Reference:

[1] Hull, D. and Bacon, D. J. Introduction to dislocations. Butterworth-Heinemann, (2001).

[2] Höfling, M., Zhou, X., Zhuo, F., Rödel, J., et al. Science 372, 961 (2021).

[3] Zhuo, F., Rödel, J. et al. Nat. Commun. 13, 6676 (2022).

[4] Zhuo, F., Rödel, J. et al. Phys. Rev. Lett. 13, 01680 (2023).

[5] Zhuo, F. and Rödel, J. Appl. Phys. Lett. 122, 252902 (2023).

[6] Jiang T., Ni F., Zhuo, F., Rödel, J. et al. Appl. Phys. Lett. 123, in publication (2023).