Ferroelectric Nanoparticles in Liquid Crystals: The Role of Ionic Transport at Small Concentrations of the Nanoparticles

TL;DR

This study investigates how tiny concentrations of ferroelectric BaTiO3 nanoparticles affect ionic transport and dielectric properties in liquid crystals, revealing that ionic screening influences electrical characteristics even at minimal nanoparticle levels.

Contribution

It demonstrates that ultra-small concentrations of ferroelectric nanoparticles alter ionic transport and dielectric responses in liquid crystals through ionic-electronic screening effects.

Findings

Reduced current and capacitance in nanoparticle-filled cells

Ionic screening by nanoparticles affects dielectric properties

Minimal nanoparticle concentration significantly influences ionic transport

Abstract

We reveal the visible influence of the ultra-small concentrations (1 wt.% or less) of the BaTiO3 nanoparticles (average size 24 nm) on the current-voltage characteristics and capacitance of the dielectric liquid crystal (LC) 5CB. The pure LC cell demonstrates higher current (and thus smaller resistance) than the LC cells filled with a very small concentration (0.5-1) wt.% of BTO nanoparticles. The same trend is observed for the charge-voltage characteristics: the capacitance loop is the widest for the pure LC cell and becomes noticeably thinner in the presence of (0.5-1) wt.% of BaTiO3 nanoparticles. This seems counterintuitive, because 1 wt.% of ferroelectric nanoparticles very slightly modify the effective dielectric response and should not influence on the director distribution and elastic properties of the LC. We conclude that a possible physical reason of this observation is the influence of the ionic-electronic screening charges, which cover the ferroelectric nanoparticles and become polarized in the external field, on the ionic transport in the LC.