Showing papers by "Yoshihiro Ishibashi published in 1989"
TL;DR: In this article, phase transitions of L- and D-enantiomers of 4-(1-methylheptyloxycalbonyl)phenyl 4'-octyloxybiphenyl-4-carboxylate (MHPOBC) were studied by the DSC method.
Abstract: Phase transitions of L- and D-enantiomers of 4-(1-methylheptyloxycalbonyl)phenyl 4'-octyloxybiphenyl-4-carboxylate (MHPOBC) were studied by the DSC method. Two new phases have been observed between the smectic A phase and the smectic C* phase and between the smectic C* phase and the third stable state (SY* phase) in both L- and D-MHPOBC. The new phases disappear by the introduction of more than 3% D-MHPODC into L-MHPOBC and vice versa. A phase diagram was constructed for the enantiometric mixture of L- and D-MHPOBC.
122 citations
TL;DR: In this article, the fundamental aspects of the structure, the energies of the formation and of the activation of domain walls are summarized for several one-dimensional model systems, and the effect of discreteness of atomic lattices on the activation energy of domain wall is described.
Abstract: The fundamental aspects of the structure, the energies of the formation and of the activation of domain walls are summarized for several one-dimensional model systems. The effect of discreteness of atomic lattices on the activation energy of domain wall is described. The motion of walls will be also mentioned.
51 citations
TL;DR: In this article, the effect of a new polyimide film on pretilt angle at a surface has been investigated to obtain zig-zag defect free liquid crystal cells by means of a standard rubbing technique.
Abstract: To obtain zig-zag defect-free liquid crystal cells by means of a standard rubbing technique, the effect of a new polyimide film on pretilt angle at a surface has been investigated. This new polyimide imposes the high pretilt over wide rubbing density, and good orientation of liquid crystals without zig-zag defects can be obtained for rubbing densities higher than 0.5×103. A new driving scheme to realize display devices with a high contrast ratio is proposed. This scheme is devised by utilizing anomalous switching behavior and AC-stabilized effect. The prototype of the ferroelectric liquid crystal display device shows the maximum contrast ratio of 40:1.
29 citations
TL;DR: In this paper, the effect of applying an electric field after quenching is studied and the characteristic length, defined as a mean domain width, is found to obey the power law with respect to time.
Abstract: Time evolution of domain patterns in a quenched ferroelectric triglycine sulphate (TGS) crystal is investigated in real time and in real space. The effect of applying an electric field after quenching is studied. The characteristic length, defined as a mean domain width, is found to obey the power law with respect to time. From the experimentally obtained time dependence of the area fraction of the domains with positive and negative polarization, it is found that this system behaves like one with a conserved order parameter in the studied time scale, though the order parameter in TGS is the polarization. For the system, to which the electric field is applied, it is found that the dynamical scaling law holds for the domain size distribution function.
25 citations
TL;DR: In this paper, phase transitions and switching behavior in a fluorine containing ferroelectric liquid crystal, whose optical purity was controlled by mixing (R) and (S) enantiomorphs, were studied.
Abstract: Phase transitions and switching behavior in a fluorine containing ferroelectric liquid crystal, whose optical purity was controlled by mixing (R) and (S) enantiomorphs, were studied. Only for the pure (R) or (S) enantiomorphs, the phase transition from the SmA to the third state SmCA*, occurred directly. For the mixtures of (R) and (S) enantiomorphs, the phase transition occurred from the SmA to the SmCA* via the SmC*. In these mixtures, with decreasing temperature in SmC*, internal disclination loops changed from "boat type" to "stripe type".
24 citations
TL;DR: In this article, the effect of oblique evaporation of SiO on the chevron structure and the switching behavior in a ferroelectric liquid crystal have been investigated by means of the X-ray diffraction and the stroboscopic micrographs.
Abstract: The effect of oblique evaporation of SiO on the chevron structure and the switching behavior in a ferroelectric liquid crystal have been investigated by means of the X-ray diffraction and the stroboscopic micrographs. It is found experimentally that the chevron direction and the domain structure appearing during the switching are determined by the direction of incidence of evaporated SiO. On the basis of the experimental results, it is clarified that the bow and the stern of the boat-shaped domain correspond to +2π and -2π internal disclinations, respectively. The structure of the zig-zag defect is determined.
23 citations
TL;DR: In this paper, the phase sequence of betaine phosphate was interpreted with the Landau-type thermodynamic potential, and the experimental results confirmed two low temperature transitions in the Raman spectra.
Abstract: Successive phase transitions in betaine phosphate were studied by measuring the temperature and pressure dependence of dielectric constants, and by observing the temperature dependence of the Raman spectra. The experimental results confirmed two low temperature transitions. The phase sequence is phenomenologically interpreted with the Landau-type thermodynamic potential.
15 citations
TL;DR: In this paper, the phase separation process in a binary mixture of the semi-rigid thermotropic liquid crystalline polymer and the flexible polymer was investigated by means of a polarizing microscope under crossed polarizers.
Abstract: We investigated the phase separation process in the binary mixture of the semi-rigid thermotropic liquid crystalline polymer and the flexible polymer. By raising temperature, an initially homogeneous mixture undergoes the phase separation. Utilizing the nematic property of one component, we were able to observe this segregation process by means of a polarizing microscope under crossed polarizers. We found a new mechanism to explain the coalescence of droplets in the latest stage.
14 citations
TL;DR: In this article, the temporal evolution of the domain structure in TGS (Triglycine sulphate) quenched from the paraelectric phase to the ferroelectric phase has been investigated by means of the liquid crystal method.
Abstract: The temporal evolution of the domain structure in TGS (Triglycine sulphate) quenched from the paraelectric phase to the ferroelectric phase has been investigated by means of the liquid crystal method. The sequential photographs obtained were analyzed by the image processing technique. From the spatial correlation functions of the patterns, the correlation is found to depend on the direction, but the dynamical scaling law holds irrespective of the direction. It is clarified by detailed observation of the pattern that the system behaves like the one with a conserved order parameter, though the order parameter in this system is the polarization.
11 citations
TL;DR: In this paper, the successive phase transitions in hexagonal BaTiO 3 are discussed on the basis of the Landau-type free energy function, putting the emphasis on the transition between the intermediate phase II and the lowest temperature phase III.
Abstract: The successive phase transitions in hexagonal BaTiO 3 is discussed on the basis of the Landau-type free energy function, putting the emphasis on the transition between the intermediate phase II and the lowest temperature phase III. It is pointed out that to induce the phase III with the space group P2 1 the twelveth order term in the order parameters, transforming under the symmetry operations as the bases of the two-dimensional E 2 u representation of the 6/mmm group, is required.
10 citations
TL;DR: The structural phase transitions in zirconia ZrO 2 are interpreted phenomenologically, based upon the Landau-type thermodynamic potential derived on the consideration of the change of translational as well as rotational symmetry of the unit cell as discussed by the authors.
Abstract: The structural phase transitions in zirconia ZrO 2 are interpreted phenomenologically, based upon the Landau-type thermodynamic potential derived on the consideration of the change of translational as well as rotational symmetry of the unit cell. The difference between Chan's model and ours is mentioned.
TL;DR: A process of eigenvalue analysis based on the theory of Hilbert and Schmidt was developed and applied to solve the integral equation relating the observed spectrum and the intensity distribution observed by the spectroscopic instrument.
Abstract: In all spectroscopic methods, there exists an integral equation relating the observed spectrum and the intensity distribution observed by the spectroscopic instrument. An improved spectrum can be reconstructed by solving this integral equation. A process of eigenvalue analysis based on the theory of Hilbert and Schmidt was developed and applied to solve the equation. Formulation of this method and some computer simulations are presented on the results from a Fabry-Perot interferometer, a diffraction grating, and a two-beam interferometer. We also apply this method to spectroscopic techniques and considerations of resolution.
TL;DR: In this paper, a model for the reentrant phase transition, including an incommensurate phase as the sandwiched phase, is substantiated for the phase transition sequence in the perovskite-type layer compound bis-n-propylammonium tetrachloromanganate (C 3 H 7 NH 3 ) 2 MnCl 4 (PAMC) by detailed considerations of the symmetry aspect of the phase transitions concerned, a thermodynamic potential functional is obtained to reproduce the phase sequence.
Abstract: The model for the reentrant phase transition, including an incommensurate phase as the sandwiched phase, is substantiated for the phase transition sequence in the perovskite-type layer compound bis-n-propylammonium tetrachloromanganate (C 3 H 7 NH 3 ) 2 MnCl 4 (PAMC) By detailed considerations of the symmetry aspect of the phase transitions concerned, a thermodynamic potential functional is obtained to reproduce the phase sequence, where the pseudo-Lifshitz invariant plays an important role
TL;DR: In this paper, the structural phase transition of Pb3(VO4)2 has been investigated using the Raman spectra of the crystal at 357 K and exhibits a hysteresis of 10 K.
TL;DR: In this article, dielectric constants have been measured for ( −)-4-(2′-methylbutyl) benzoate ester of 4-n-octyloxy benzoic acid (HS927SO).
Abstract: Dielectric constants have been measured for (–)-4-(2′-methylbutyl) benzoate ester of 4-n-octyloxy benzoic acid (HS927SO). ESR spectra of two doxyl spin probes (Metyl-12-doxyl-stearate and CSL) dissolved in smectic A and C* phases of HS927SO and DOBAMBC were observed, and long-range collective distortions in molecules of liquid crystal have been found both in HS927SO and DOBAMBC of smectic A phases.
TL;DR: In this article, the phase transitions in CH 3 NH 3 HgCl 3 are discussed in terms of the Landau-type thermodynamic potential, starting from a hypothesized prototypic phase of high symmetry.
Abstract: The phase transitions in CH 3 NH 3 HgCl 3 are discussed in terms of the Landau-type thermodynamic potential, starting from a hypothesized prototypic phase of high symmetry It has turned out that the reverse of relative stability of the monoclinic and the trigonal phases actually observed can be well interpreted
TL;DR: In this paper, the authors measured the intensity of the transmitted light through the tungstic acid during the gelation process and estimated volume evolution of the scatterer with the results of the present observation and the radius dependence of the scattered light.
Abstract: Intensity of the transmitted light through the tungstic acid has been measured during the gelation process. The transmitted intensity decreased drastically (by a factor of 1/20) as time passed. The logarithm of turbidity of the tungstic acid shows linear dependence on log t in the first stage of the gelation, and then the rate of the change slows down. This behavior can be explained by the change of the light scattering mechanism found in the previous study. We have estimated volume evolution of the scatterer with the results of the present observation and the radius dependence of intensity of the scattered light.