Multiple ferroelectric nematic phases of a highly polar liquid crystal compound

ABSTRACT

Ferroelectric nematic liquid crystals represent not only fascinating, fundamental science, but they also hold promise for new technologies including high-density power storage or sub-millisecond switching information displays. In this work, we describe the synthesis and measurements of the physical properties of a new compound, 4-nitrophenyl 4-[(2,4-dimethoxylbenzoyl)oxy]-2-fluorobenzoate (RT11001). This material exhibits multiple, highly polar, ferroelectric nematic phases that have not been previously reported. We employ a wide range of physical characterisation methods including differential scanning calorimetry (DSC), mass density measurement, optical birefringence, polarising optical microscopy (POM), dielectric spectroscopy, electric current analysis, electro-optical switching, small-angle and wide-angle x-ray scattering measurements to show that RT11001 has multiple, distinct ferroelectric phases. We argue that the highest temperature phase is a polar nematic fluid with non-polar smectic clusters. Directly below appears to be a transition to another polar nematic phase containing polar positionally ordered clusters. Lastly, there are indications of an additional, polar biaxial liquid crystal phase at lower temperatures.

GRAPHICAL ABSTRACT

KEYWORDS:

• Ferroelectric nematic
• phase transitions
• smectic clusters
• electric polarization

Acknowledgement

This research was supported by the National Science Foundation under grant DMR-1904167. Part of the research used the 11-BM CMS beamline of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract DE-SC0012704.

Disclosure statement

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

Additional information

Funding

The work was supported by the National Science Foundation, USA [DMR-1904167]; Department of Energy (DOE) [DE-SC0012704].