The Study on Physical and Optical Properties of Ferroelectric Polymers Applying Crystal Technology

偏氟乙烯和三氟乙烯共聚物（P(VDF/TrFE)）是铁电聚合物。P（VDF/TrFE）晶体表现出点群C_<2v>对称性，因此具有5个Pockels系数（PCFs）。最近，Ohigashi等人报道了P（VDF/TrFE）形成了一种高度双取向的晶体膜（HDCF），没有非晶区或片层晶体。首次观察到hdcf的宏观轴（拉伸轴和极化轴）与P（VDF/TrFE）晶体的各个晶轴直接对应。也就是说，利用晶体技术对铁电聚合物的光学行为进行进一步的研究是值得期待的。在这项研究中，我们首次提出了一个新的实验系统来测量聚合物薄膜（PTFs）的光学行为。在此基础上，重点研究了HDCF的Pockels效应（PEFs）。我们研制了测量ptf折射率、双折射和光场的实验系统。该系统的更重要的特点如下。在保持偏振度的同时减小了激光束的直径，使得激光束可以在垂直于ptf厚度方向的方向上引入，便于在ptf的各个方向上测量PEF。此外，利用该系统，我们可以在测量ptf双折射的温度依赖性时同时获得薄膜厚度的变化。也就是说，我们可以通过修正表观结果来估计内在价值。使用该系统测量hdcf的pef得到了许多结果，其中最重要的结果如下。1) HDGF满足单晶铁电物质的现象学理论。2) HDCF的最大PCF为20 pm/V，明显大于常规聚合物铁电薄膜（片层晶体薄膜）。3) HDCF具有与单晶相似的结构和光学行为。少

Vinylidene fluoride and trifluoroethylene copolymers (P(VDF/TrFE)) are ferroelectric polymers. P(VDF/TrFE) crystals exhibit the point group C_<2v> symmetry, hence they have five Pockels coefficients (PCFs). Recently, Ohigashi et al. reported that P(VDF/TrFE) formed a highly double-oriented crystalline film (HDCF) with no noncrystalline areas or lamella crystals. The macroscopic axes of the HDCFs (drawing and poling axes) were observed for the first time, to directly correspond to each crystalline axis of the P(VDF/TrFE) crystals. Namely, further progress in the research on the optical behavior of ferroelectric polymers using crystal technology is expected. In this study, we propose for the first time a new experimental system for measuring the optical behavior of polymer thin films (PTFs). Furthermore, using the system, we investigate, mainly, the Pockels effects (PEFs) of HDCF.We developed the experimental system for measuring the indicatrix, double refraction and PEF of PTFs. The sig … More nificant characteristics of this system are as follows. The diameter of the laser beam is reduced while maintaining the degree of polarization so that the laser beam can be introduced in the direction perpendicular to the thickness direction of PTFs, to facilitate measurement of PEF in various directions of PTFs. Furthermore, using this system, we can obtain the change in film thickness simultaneously during measurements of the temperature dependence of double refraction for PTFs. Namely, we can estimate the intrinsic value by correcting the apparent results.Many results were obtained from measuring PEFs of HDCFs using the system, the most significant, of which, are as follows.1) The HDGF satisfies the phenomenological theory of single-crystalline ferroelectric substances.2) The maximum PCF obtained for the HDCF was 20 pm/V, which is significantly larger than that of conventional polymer ferroelectric films (lamella crystalline films).3) The HDCF exhibits structural and optical behaviors similar to those of single crystals. Less