Fundamental Study on Electroclinic Effect in Smectic A Liquid Crystals and the Application for Fast Optical Modulator

在这个项目的第一年，我们得到了在电斜效应中不仅会引起分子倾斜，还会引起层变形的结果。利用层与玻璃表面垂直的电池，进行了x射线衍射实验。在电场作用下，将探测器固定在层间距的布拉格角，旋转电池，测量x射线衍射强度。随着电场的增大，对称位置出现两个峰，间距变宽。这一事实表明，雪佛龙层结构是通过施加磁场形成的。结果表明，在低场区，层倾角与分子倾角基本相等。上面的实验给出了垂直于玻璃表面的层变形的信息。然而，显微镜观察表明，存在平行于表面的层变形。为了证实这一点，有必要观察传播规律。为此，我们正试图用由非常薄的玻璃组成的细胞来检测劳厄模式。在这个时刻，由于玻璃的漫射散射阻止了对劳厄点的观察。由于电斜效应相当于准电相中软模的激发，因此我们应该观察到介电常数随着温度接近相变点而发散增加。研制了介电常数自动测定系统，并对其性能进行了验证。

In the first year of this project, we obtained the results that not only the molecular tilt but also the layer deformation are induced in the electroclinic effect.1. Using the cells whose layers are perpendicular to the glass surfaces, the X-ray diffraction experiments were carried out. The X-ray diffraction intensity was measured under an electric field as rotating the cell with the detector fixed at the Bragg angle of the inter layer spacing. With increasing the field, two peaks appeared at the symmetry positions and the separation became wide. This fact suggests that the chevron layer structure is formed by applying the field. It was confirmed that the layer tilt angle is nearly equal to the molecular tilt angle in the low field region.2. The above experiment gives information about the layer deformation perpendicular to the glass surfaces. The microscope observation, however, suggests the existence of the layer deformation parallel to the surfaces. To confirm this, it is necessary to observe the transmission Laue pattern. For this purpose, we are trying to detect the Laue pattern using the cells composed with very thin glasses. At this moment, the diffuse scattering due to the glasses prevents the observation of the Laue spot.3. Since the electroclinic effect is equivalent to the excitation of the soft mode in the paraelectric phase, we should observe the divergent increase of the dielectric constant as the temperature approaches to the phase transition point. We developed the automatic system for determining dielectric constant and confirmed the behavior.