Interactions between dislocations and 180° domain walls in single-crystal LiNbO3

Lithium niobate (LN), first synthesized 70 years ago, has been widely used in diverse applications ranging from communications to quantum optics.[1,2] We have demonstrated that dislocations ensured the ferroelectric BaTiO3 crystal to have a domain structure that enhanced the piezoelectric coefficient by 19 times.[3] In this regard, dislocations in ferroelectrics offer a new avenue for property engineering, as the material is doped with its own line defects without relying on additional elements. Yet, to boost the dislocation engineering in ferroelectrics, a detailed structure-microstructure-property correlation is warranted, which this project aims to provide through fundamental scientific understanding of dislocation-tuned functionalities in a ferroelectric system of LiNbO3. We have chosen this material because it is a uniaxial ferroelectric, meaning that only 180° domain switching is possible. This feature prevents any stress-induced ferroelastic reorientation of the polarization, thus simplifying the analysis. The present project aims to investigate the influence of dislocations on dielectric and piezoelectric properties in LiNbO3 single crystals.