Ferroelectric materials history

Fig. 27 indicates the apparent piezoelectric constant e of roll-drawn PVDF as a function of static bias field E0 (Oshiki and Fukada, 1972). The value of e at E0=0 represents the true piezoelectric constant e. The curve exhibits a hysteresis and the polarity of e changes according to the poling history. If the piezoelectricity in /)-form PVDF originates from the polarization charge due to spontaneous polarization, inversion of polarity of e would mean the inversion of the polarization by the external field and hence /S-form PVDF may be a ferroelectric material, as was first suggested by Nakamura and Wada (1971). 

Apart from nonlinearities in their D(E) characteristics, the dielectric displacement D of ferroelectric materials also depends on the electric field history, a phenomenon known as ferroelectric hysteresis. The common approach to measure D(E) or P(E) hysteresis curves utilizes the Sawyer-Tower circuit (Sawyer and Tower 1930) (cf Fig. 9a) that operates in the voltage-voltage mode. 

Ionic conduction in perovskite-type oxides was first a source of interest in ferroelectric materials. S. Swanson showed that DC conductivity of BaTiOs ceramics was significantly influenced by their fabrication history, which suggests that there would be an intimate relationship between the solid-state reactions of raw materials and ionic conduction [3]. In the 1960s, when research and development of perovskite-type oxides as a dielectric or ferroelectric material such as BaTiOs and PbTii xZrxOs had become active, some of the researchers paid attention to the conduction behavior of these perovskite-type oxides. They... 

In order to anticipate problems and to interpret observations under the extreme conditions of shock compression, it is necessary to consider structural and electronic characteristics of PVDF. Although the phenomenological piezoelectric properties of PVDF are similar to those of the piezoelectric crystals, the structure of the materials is far more complex due to its ferroelectric nature and a heterogeneous mixture of crystalline and amorphous phases which are strongly dependent on mechanical and electrical history. 

The physical phenomenon of ferroelectricity-initially termed Seignette electric-ity-was first discovered in sodium potassium tartrate tetrahydrate (Rochelle or Seignette salt), and later in analogy to ferromagnetic behavior coined ferroelectricity by Valasek (1924). Its history is listed in Table 8.4, which shows the impressive change from a curious isolated property to a widespread and economically enormously important and promising ceramic engineering material (Cross and Newnham, 1987). 

The synthesis of nonchiral smectic liquid crystals is a broad topic for discussion, however, it can be divided into subsections in two different ways. For example, smectic systems can be split into metallomesogens and nonmetallomesogens, alternatively, they can be divided into materials for (1) meso-phase structure elucidation and classification [ 1 ], (2) property-structure correlations [2] and (3) host systems for ferroelectric and antiferroelectric mixtures. In the following sections template structures used for the synthesis of smectic materials will be described, followed by discussions of the syntheses of materials that have extensive histories in the elucidation of smectic phase structures, and finally of the syntheses of smectogens that are useful in applications. 

Actually, the first solid antiferroelectric material had been discovered at Tokyo Institute of Technology [40]. The discovery of the first antiferroelectric liquid crystal at the very same university was quite unintentional, but can be considered quite fortunate. In this chapter, I will introduce some details of what led to the discovery of antiferroelectric liquid crystals from the study of ferroelectric liquid crystals and also discuss the history of the discovery of the ferroelectric phase. 

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