Crystal ferroelectrics

Licjuid Crystals. Ferroelectric Hquid crystals have been appHed to LCD (Uquid crystal display) because of their quick response (239). Ferroelectric Hquid crystals have chiral components in their molecules, some of which are derived from amino acids (240). Concentrated solutions (10—30%) of a-helix poly(amino acid)s show a lyotropic cholesteric Hquid crystalline phase, and poly(glutamic acid ester) films display a thermotropic phase (241). Their practical appHcations have not been deterrnined. 

It should be noted that a poling process is often necessary with single-crystal ferroelectric bodies because they contain a multiplicity of randomly oriented domains. There is therefore a sequence of states of increasing orderliness polycrystalline ferroelectric ceramics, poled ferroelectric ceramics, single-crystal ferroelectrics and single-domain single crystals. 

Skupin H, Kremer F, Shilov SV, Stein P, Finkelmann H (1999) Time-resolved FTIR spectroscopy on structure and mobility of single crystal ferroelectric liquid crystalline elastomers. Macromolecules 32 3746... 

I. Dozov, I. Penchev, Ph. Martinot-Lagarde and G. Durand, On the sign of flexoelectric coefficients in nematic liquid crystals, Ferroelectrics Letters 2(4), 135-141, (1984). doi 10.1080/07315178408202434... 

Dawber, M. and Scott, J.F. (2001) Fatigue and oxygen vacancy ordering in thin-film and hulk single crystal ferroelectrics. Integr. Ferrodectr., 32, 259-266. 

Historically, theoretical approaches based on the laws of thermodynamics describe the mesoscale kinetics of ferroelectric switching by starting from seminal concepts pioneered by Landau, Devonshire, Jona, Shirane, et al. [64, 65, 66, 67, 68, 69]. Here, the state function of a single crystal ferroelectric is defined by expanding in Taylor series the Helmholtz free energy density, f = u-Ts, as a function of the independent degrees of freedom of the system ... 

Takahashi, K., Ishibashi, S., and Yamamoto, F., Direction of mesogenic side chains and its effect on the properties of polymeric ferroelectric liquid crystals, Ferroelectrics, 181, 277-285 (1996). 

Eber, N., Bata, L., Scherowsky, G., and Schliwa, A., Linear electromechanical effect in a polymeric ferroelectric liquid crystal, Ferroelectrics, 122, 139-147 (1991). Kozlovsky, M. V., Darius, M., and Haa.se, W., Frustrated pha.se behaviour of a chiral side chain polymer, European Polymer Journal, (in press). 

Moritake, H.. Fuwa, Yo., Sagioka, K., Watanabe, T.. Ozaki, M., and Yoshino, K., Light scattering in polymeric ferroelectric liquid crystal, Ferroelectrics, 181, 397-318 (1996). 

Rittenmyer K, Bhalla AS, Chang ZP, Cross LE (1983) Electrostriction and its relationship to other properties in perovskite-type crystals. Ferroelectrics 50 209... 

Li Z, Grimsditch M, Xu X, Chan SK (1993) The elastic, piezoelectric and dielectric constants of tetragonal PbTiOs single crystals. Ferroelectrics 141 313-325 MarraSP, Ramesh KT, Douglas AS (1999) The Mechanical properties of lead-titanate/polymer 0-3 composites. Compos Sci Technol 59 2163-2173 Materials Data Sheets of APC International, Tokin, Ferroperm, Morgan Matroc, Siemens Mattiat OE (1971) Ultrasonic transducer materials. Plenum Press, Tokyo McLachlan DS, Blaszkiewicz M, Newnham RE (1990) Electrical resistivity of composites. J Am Ceram Soc 73 2187-2203... 

Smectic Liquid Crystals Ferroelectric Properties and Electroclinic Effect... 

Yasuda et al. performed dielectric relaxation measurements on metastable solid MBBA, using a parallel-plate capacitor. Glass plates with strips of transparent tin-oxide-conducting coating served as electrodes. The cell was mounted in a copper beryllium pressure vessel, pressurized with liquid isopentane. A similar setup was used for the study of ferroelectric liquid crystals. Ferroelectric liquid crystals have also been studied by Chandrasekhar and co-workers who used a sapphire cell setup in a high-pressure apparatus. The sample was sandwiched... 

Figure 1. Number of known ferroelectrics. Solid line solid state ferroelectrics, where each pure compound is counted as one. Dashed line total number, including liquid crystal ferroelectrics, for which a group of homologs is counted as one. From about 1984, the proportion of liquid crystals has steadily grown which has been even more pronounced after 1990. (After Deguchi [2] as cited by Fousek [31).

It was the Harvard physicist Meyer who in 1974 first recognized that the symmetry properties of a chiral tilted smectic would allow a spontaneous polarization directed perpendicular to the tilt plane [61]. In collaboration with French chemists, he synthesized and studied the first such materials [62]. These were the first polar liquid crystals recognized and as such something strikingly new. As mentioned before, substances showing a smectic C phase had been synthesized accidentally several times before by other groups, but their very special polar character had never been surmised. Meyer called these liquid crystals ferroelectric. In his review from 1977 [43] he also discussed the possible name antiferroelectric, but came to the conclusion that ferroelectric was more appropriate. 

A. Jikli, L ELata. A. Buka, and N. fiber. Electromechanical effect in Sc liquid crystals, Ferroelectrics 69 153 (1986). 

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