Electric-field-induced reorientation of ferroelectric micro- and nano-platelets in the nematic liquid crystal

ABSTRACT

We demonstrate that ferroelectric layered perovskite Bi_3.8Nd_0.2Ti₃O₁₂ micro-platelets can be reoriented in the nematic liquid crystal by the linear coupling to an external electric field. The electric dipole moment of platelets is perpendicular to the plane of platelets and provides torque that rotates the platelets. The experiments were made in dispersions of ferroelectric platelets in a zero dielectric anisotropy nematic liquid crystal (LC), which excludes the reorientation of the dispersion via the dielectric coupling of a LC. Typical reorientation times for micrometre-size ferroelectric platelets are of the order of 100 ms for 0.5 V/μm applied electric field. The electric dipole moment in the absence of external field is very small and does not contribute to the force between the platelets. This could be either due to very narrow hysteresis loop of the ferroelectric material, or screening of dipolar electric field by ions in the LC. A stable and homogenous dispersion of ferroelectric nano-platelets could not be observed in any range of platelets’ concentration. To create a ferroelectric LC the shape and thickness of the nano-platelets has to be controlled, and the electrostatic screening of dipolar field should be minimised.

Graphical abstract

KEYWORDS:

• Ferroelectric platelets
• nematic liquid crystal
• ferroelectric nematic
• colloids

Acknowledgments

The authors thank Dr Hana Nemevšek Uršič for performing PFM measurements and Dr Jure Aplinc for Landau de Gennes numerical calculations. MMK and DS acknowledge the M-era.Net project 3184 HarvEnPiez for financial support.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the M-era.net [3184 HarvEnPiez].