The dispersion of ferroelectric nanomaterials in liquid crystals has recently emerged as a promising way for the design of advanced and tunable electro-optical materials. The goal of this paper is a broad overview of the current technology, basic physical properties, and applications of ferroelectric nanoparticle/liquid crystal colloids. By compiling a great variety of experimental data and discussing it in the framework of existing theoretical models, both scientific and technological challenges of this rapidly developing field of liquid crystal nanoscience are identified. They can be broadly categorized into the following groups: (i) the control of the size, shape, and the ferroelectricity of nanoparticles; (ii) the production of a stable and aggregate-free dispersion of relatively small (~10 nm) ferroelectric nanoparticles in liquid crystals; (iii) the selection of liquid crystal materials the most suitable for the dispersion of nanoparticles; (iv) the choice of appropriate experimental procedures and control measurements to characterize liquid crystals doped with ferroelectric nanoparticles; and (v) the development and/or modification of theoretical and computational models to account for the complexity of the system under study. Possible ways to overcome the identified challenges along with future research directions are also discussed.

In this article we describe electro-optical properties of recently discovered ferroelectric particles/liquid crystal colloids. We show that the presence of ferroelectric particles in a liquid crystal changes its birefringence and dielectric anisotropy. In contrast to the traditional time consuming and expensive chemical synthetic methods, this method to create liquid crystals with enhanced properties is relatively simple and has a great potential. We also demonstrate the performance of these new materials in various devices, including displays, light modulators, and beam steering devices.

Liquid crystal technology has a long well-established history of applications in visible light, primarily in the display industry. In contrast, applications at lower frequencies (microwave through infrared) are less common. In this paper, we examine non-display applications and review the use of liquid crystal materials for tunable signal processing devices operating at microwave and millimeter wave frequencies. These devices include tunable phase shifters, filters (bandpass and bandstop), antennas and antenna arrays, resonators, and frequency selective surfaces. We also give a short review of the typical characteristics of liquid crystals in these frequency ranges.

Conventional display applications of liquid crystals utilize thin layers of mesogenic materials, typically less than 10 µm. However, emerging non-display applications will require thicker, i.e., greater than 100 µm, layers of liquid crystals. Although electro-optical performance of relatively thin liquid crystal cells is well-documented, little is known about the properties of thicker liquid crystal layers. In this paper, the electro-optical response of dual-frequency nematic liquid crystals is studied using a broad range (2–200 µm) of the cell thickness. Two regimes of electro-optical switching of dual-frequency nematics are observed and analyzed.

In this paper, we will explore how optical and ferroelectric properties of the stressed ferroelectric nanoparticles prepared through ball milling set a limit on the performance of optical and electro-optical devices based on such materials. It was found that suspensions of ${\mathrm{BaTiO}}_3$ nanoparticles exhibit a blue shift in the optical band gap with a decrease in particle size. The optical band gap of ${\mathrm{PbTiO}}_3$ nanoparticles is not affected by the milling time. Polarization switching is composed of slow and fast components. A slow component is threshold-less and is caused by the particle reorientation while a fast component has a threshold, and its rise time is inversely proportional to the electric field. The absorption edge of these suspensions accounts for the applications in the near UV range, while kinetics of the polarization switching governs the speed of electro-optical devices.