Dielectric anisotropy in PCPB/MBBA mixtures showing the dual frequency characteristic

Takikawa, Yuichi; Kaneko, Kosuke; Odani, Shunsuke; Ikemura, Takeshi; Iwata, Makoto

doi:10.7567/1347-4065/ab4ece

Cited by 5 publications

(5 citation statements)

References 29 publications

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“…The dielectric anisotropy, e D , for the PCPB/MBBA mixture obtained in our previous study (Fig. 2) 15) changes sign in this temperature range, implying that the sample exhibits DFLC characteristics. The crossover frequency increases with the temperature.…”

Section: Methodssupporting

confidence: 51%

Freedericksz transition in a dual-frequency nematic liquid crystal

Takikawa

Kaneko

Odani

et al. 2020

Jpn. J. Appl. Phys.

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The Freedericksz transition was investigated in a dual-frequency liquid crystal consisting of a mixture of 2-chloro-4-(4-pentylbenzoyloxy)benzoate and N-(4-methoxybenzylidene)-4-butylaniline, in which dielectric anisotropy strongly depends on the frequency of the applied ac electric field. Because the threshold voltage for the transition from an undistorted state of orientation to a distorted one is a function of the dielectric anisotropy and of the Frank elastic constants, the threshold voltage was expected to depend on the frequency. The threshold voltage increased steeply as the frequency approached the crossover frequency at which the dielectric anisotropy vanished and the threshold voltage eventually diverged. Furthermore, we examined the Freedericksz transition under ac voltages of two different frequencies.

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Section: Methodssupporting

confidence: 51%

Freedericksz transition in a dual-frequency nematic liquid crystal

Takikawa

Kaneko

Odani

et al. 2020

Jpn. J. Appl. Phys.

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“…Such properties are beneficial for applications and more convenient for fundamental studies than features of MBBA. In recent decades, MBBA has been particularly interesting for fundamental research as a classic example of a rod-like LC molecule with the transverse dipole moment [3,6,7,[35][36][37][38][39][40][41][42]52].…”

Section: Methodsmentioning

confidence: 99%

“…The mentioned mechanism should be absent for rod-like molecules with the transverse (perpendicular) dipole moment with respect to the long molecular axis. The classic example is MBBA (4-methoxybenzylidene-4 ′ -butylaniline), for which linear changes of dielectric constant are observed in the isotropic liquid on approaching the I-N transition [3,6,[35][36][37][38][39][40][41][42].…”

Section: Introductionmentioning

confidence: 99%

The Dominance of Pretransitional Effects in Liquid Crystal-Based Nanocolloids: Nematogenic 4-methoxybenzylidene-4′–butylaniline with Transverse Permanent Dipole Moment and BaTiO3 Nanoparticles

Drozd-Rzoska,

Łoś,

Rzoska

2024

Nanomaterials

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The report presents static, low-frequency, and dynamic dielectric properties in the isotropic liquid, nematic, and solid phases of MBBA and related nanocolloids with paraelectric BaTiO3 nanoparticles (spherical, d = 50 nm). MBBA (4-methoxybenzylidene-4′–butylaniline) is a liquid crystalline compound with a permanent dipole moment transverse to the long molecular axis. The distortions-sensitive analysis of the dielectric constant revealed its hidden pretransitional anomaly, strongly influenced by the addition of nanoparticles. The evolution of the dielectric constant in the nematic phase shows the split into two regions, with the crossover coinciding with the standard melting temperature. The ‘universal’ exponential-type behavior of the low-frequency contribution to the real part of the dielectric permittivity is found. The critical-like pretransitional behavior in the solid phase is also evidenced. This is explained by linking the Lipovsky model to the Mossotti catastrophe concept under quasi-negative pressure conditions. The explicit preference for the ‘critical-like’ evolution of the apparent activation enthalpy is worth stressing for dynamics. Finally, the long-range, ‘critical-like’ behavior of the dissipation factor (D = tgδ), covering the isotropic liquid and nematic phases, is shown.

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“…It is well knowledge that nematic LCs are commonly utilized in screen technologies due to the fact that an electric field may simply control their molecule orientation. In addition, increasing the electric field, particularly when applied to devices containing nematic liquid crystals, decreases the response time of molecules [1]. Due to these benefits, they are used in compact displays such as smartphones, calculators, and digital cameras, midsize displays like computers, and large displays like projectors and televisions [2].…”

Section: Introductionmentioning

confidence: 99%

Investigation of Dielectric Properties of Mbba-5cb Nematic Liquid Crystal Structures

Önsal

2022

Mugla Journal of Science and Technology

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The dielectric anisotropy (〖∆ε〗^') is the response of the LC molecules to an applied electric field. In this study, the dielectric properties of 4-pentyl-4'-cyanobiphenyl (5CB) and N-(4-methoxybenzylidene)-4-butylaniline (MBBA) nematic liquid crystals with positive and negative dielectric anisotropy were investigated in detail. In addition, a structure with zero dielectric anisotropy was obtained by mixing MBBA and 5CB liquid crystals in certain rate (1:0.02). The behavior of the samples under 0V and 20V voltages was investigated in detail. Dielectric measurements were made with dielectric spectroscopy technique, which is a powerful method to investigate the molecular interaction mechanisms of liquid crystal materials, at a frequency of 1 kHz-10 MHz and a voltage of 0-20 V at room temperature. Some important parameters such as dielectric anisotropy (∆ε^'), relaxation frequency (f_R), relaxation time (τ) were determined for the samples. When electric field is applied to nematic liquid crystals, it is seen that, depending on the voltage, the relaxation frequency decreases, and the relaxation time increases.

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Dielectric anisotropy in PCPB/MBBA mixtures showing the dual frequency characteristic

Cited by 5 publications

References 29 publications

Freedericksz transition in a dual-frequency nematic liquid crystal

Freedericksz transition in a dual-frequency nematic liquid crystal

The Dominance of Pretransitional Effects in Liquid Crystal-Based Nanocolloids: Nematogenic 4-methoxybenzylidene-4′–butylaniline with Transverse Permanent Dipole Moment and BaTiO3 Nanoparticles

Investigation of Dielectric Properties of Mbba-5cb Nematic Liquid Crystal Structures

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