A new five-ring banana-shaped compound is presented which does not exhibit a mesophase but a high-temperature crystalline phase with unexpected electro-optical properties. By application of a sufficiently high electric field (15 V µm−1) this solid modification can be clearly switched where the texture of the switched state is different for an opposite sign of the applied electric field. This switching is accompanied by a current response which indicates an antiferroelectric ground state. The switching polarisation was found to be 700 nC cm−2. It is interesting that the polar switching takes place only below a frequency of 5 Hz. The crystalline nature of the solid modification was proved by X-ray diffraction measurements on partially oriented samples. The mechanism of the polar switching is not yet clear. It can be assumed that the switchable modification has a structure with sufficient free volume which enables the collective rotation of at least parts of the molecules.
一种新的五环香蕉形化合物被提出,它不呈现中间相,而是呈现具有意想不到的电光特性的高温结晶相。通过施加足够高的电场(15 V µm-1),这种固体改性可以被清晰地切换,其中切换状态的纹理对于施加的电场的相反符号是不同的。这种切换伴随着电流响应,表明反
铁电基态。切换极化被发现在5 Hz以下的频率下发生。有趣的是,极性切换仅在5 Hz以下的频率下发生。通过对部分取向的样品进行X射线衍射测量,证实了固体改性的结晶性质。极性切换的机理尚不清楚。可以假设可切换的改性具有足够的自由体积的结构,使得至少部分分子的集体旋转成为可能。