Shunsuke Kobayashi

Barium titanate stabilized by γ-cyclodextrin nanoparticles were prepared by using a microwave reactor equipped with ultrasonic nozzle mixing at 240°C in a tetraethylene glycol solution of barium ethoxide and titanium ethoxide in the presence of γ-cyclodextrin. Particles in γ-cyclodextrin-stabilized BaTiO₃ nanoparticles had an average diameter of 2.1 nm and mainly distributed within the range of about 1 to 4 nm. The γ-cyclodextrin-stabilized BaTiO₃ nanoparticles were mixed with 4-cyano-4′-pentylbiphenyl at room temperature resulting in a liquid crystal sol of 4-cyano-4′-pentylbiphenyl. The response time of liquid crystal devices in the presence of γ-cyclodextrin-stabilized BaTiO₃ nanoparticles was faster than that in the absence.

In this research, we focus on the polymer-stabilized V-mode FLC (PSV-FLC) in which a doped monomer is photocured in the SmA phase. PSV-FLC may show monostable and V-shaped electrooptical characteristics with a grayscale capability. In this paper, we investigate the dependence of the monostable capability on the fabricating conditions such as monomer materials, polymer concentration, and UV energy. Furthermore, in order to increase the contrast ratio, we introduce a photo-alignment technique. As a result, it is found that the monostable capability of PSV-FLC strongly depends on their conditions. Furthermore, the more uniform molecular alignment without rubbing scratch pattern was obtained by using the photo-alignment film.

We focus on vertical alignment ferroelectric liquid crystal (FLC) cells fabricated without the rubbing technique to realize FLC displays having high contrast ratio. In this study, we research the conditions for the fabrication of uniformly vertical alignment FLC cells in terms of the tilt angle of FLC and the anchoring strength of alignment film materials. As a result, the uniformly vertical alignment of FLC can be obtained in the case of the small tilt angle and the strong anchoring strength. Furthermore, we investigate the effect of the application of electric field on the vertical alignment.

Herein, we report the dielectric properties of liquid crystal cells embedded with the nanoparticles of Pd, where each of which is covered with a diffusion cloud. It is shown that an amplification of the capacitors with these media occurs with the gain, A_c = 12.5, when the concentration of nanoparticles is 0.3 wt% and in the frequency region below the dielectric relaxation frequency, 158.5 Hz. This phenomenon is explained by an equivalent circuit model together with a compatible explanation of the dielectric strength and the relaxation time. It is claimed that the occurrence of the capacitance amplification may be attributed to a special nature of the oscillating extra charges, which appear in the region between the host medium and inclusion, and produces an effective negative dielectric constant of the special nanoparticles. This explanation was made by formulating an independent auxiliary equivalent circuit equation that enables to determine the numerical condition of the production of the negativity in the dielectric constant of inclusions (nanoparticles), and, thus, we succeeded in getting the numerical value of this dielectric constant and that of the gain of the capacitance amplification.