Terahertz properties of liquid crystals doped with ferroelectric BaTiO₃ nanoparticles

ABSTRACT

In this paper, we present the results of the terahertz measurements of liquid crystal (LC) ferroelectric BaTiO₃ nanoparticles (nps) suspensions in the range of frequency from 0.3 up to 3.0 THz. Two different sol-gel methods and the harvesting technique were used to fabricate the nanoparticles. Five LC materials served as hosts for the suspensions: two single compounds: 6CHBT and 2,3′,5′-trifluoro-4-(4-pentylcyclohexyl)-4′-(trifluoromethoxy)-1,1′-biphenyl, and three mixtures: 1867, 2037 and 2020. We characterise, for the first time, the refractive indices and absorption parameters of suspensions with harvested nps in the terahertz range and show how the process of the nps’ preparation affects their response. We observed the increase of birefringence for few LC suspensions in comparison with the pure LCs. The highest increase of birefringence was for 2020 suspension with one kind of ferroelectric nps. On the other hand in most cases the addition of ferroelectric nps to LC causes the increase of its absorption in the THz range. The measurements of LCs terahertz properties by using time-pulsed spectrometer were performed.

Graphical Abstract

KEYWORDS:

• Liquid crystal
• nematic
• terahertz spectroscopy
• ferroelectric nanoparticles

Acknowledgements

This work was supported by the National Centre of Science under Grant PRELUDIUM no. DEC-2013/09/N/ST8/01777 and by the DSTL-DGA joint PhD grant DSTLX-100074647.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Centre of Science under Grant PRELUDIUM no. DEC-2013/09/N/ST8/01777 and by the DSTL-DGA joint PhD grant DSTLX-100074647.