The development of a nematic two frequency addressing mixture

Abstract

An example is given for the development of a nematic two frequency addressing mixture based on the equations for the threshold voltages, the switching times, and the dielectric relaxation. New substances have been synthesized with relaxation frequencies in the kHz range and big values of the static dielectric anisotropy at room temperature. The isotropy frequency and the relation between the high and low frequency dielectric anisotropy, respectively, are adjustable by adding of substances without a relaxation mechanism in the kHz range and with a big negative static dielectric anisotropy. The produced mixture was dielectrically investigated. Calculated and experimentally found data are in a good agreement.Es wird ein Beispiel gegeben fur die Entwicklung einer nematischen Zweifrequenzadressierbaren Mischung auf der Grundlage der Gleichungen der Schwellspannungen, der Schaltzeiten und der dielektrischen Relaxation. Neue Substanzen wurden synthetisiert mit Relaxationsfrequenzen im kHz-Bereich und grolSen statrschen diefektriscfien Anisotropien bei Raunitemperatur. Die Isotropiefrequenz uncl daniit das Verhiiltnis zwischen der statischen und der hochfrequenten dielektrischen Anisotropie kann durch Zugabe von Substanzen, die grol3e negative statische dielektrische Anisotropien besitzen und keinen Relaxationsmechanismus im kHz-Bereich zeigen, eingestellt werden. Die von uns hergestelite Mischung wurde dielektrisch untersucht. Die berechneten und die experimentell ermittelten Daterk stimmen gut iiberoin

Observation of Transient Alignment-Inversion Walls in Nematics of Phenyl Benzoates in the Presence of a Magnetic Field

“…The dielectric anisotropy Δ ε of the first chemical component (1) at room temperature is −0.2, whereas the dielectric anisotropy Δ ε of the second chemical component is +0.2 . Using the formula normalΔ ε 1 , 2 = normalΔ ε 1 x 1 + normalΔ ε 2 x 2 where x 1 and x 2 designate the molar fraction of the first and second compounds, respectively, we obtained the dielectric anisotropy Δ ε for the H-1 eutectic mixture to be 0.1 in agreement with the data pointed out by Vistin’ et al…”

“…We mention that mixtures of phenyl benzoates were used for three purposes: (1) causing Freédericksz transition when the dielectric anisotropy changes its sign with growing frequency (the so-called nematic two-frequency addressing mixture), 14 (2) provoking dynamic scattering effect of the transmitted light through the liquid crystal cell, 19 and (3) formation of the Vistin'−Pikin−Bobylov flexoelectric domains (the so-called variable grating mode liquid crystal device for optical processing and computing). 20 2.2.…”

“…Let us mention that this measured value for the case of phenyl benzoates is greater compared to that obtained by Gerritsma et al for the case of MBBA. This is due to the smaller value of the anisotropy of the magnetic susceptibility of the mixture of phenyl benzoates and the bigger value of K eff : K eff = K 11 + ( 1 / 4 ) .25em ( K 33 − 2 K 22 ) …”

Dielectric dispersion in a dual-frequency nematic liquid crystal 2-chloro-4-(4-pentylbenzoyloxy)benzoate

“…4,5) An electric field controls the orientational state of LC by two processes: turn-on under an applied electric field and turn-off by removing the electric field. As the response time of turn-off is longer than that of turn-on, [6][7][8][9] the turn-off process bottlenecks any attempt to speed up the response of LC devices.…”

Wavefront control with a spatial light modulator containing dual-frequency liquid crystal

“…A unique LCSLM controller was designed to implement a dual-frequency driving scheme. Due to the highly dispersive nature of their dielectric constant, DFLC materials can be rapidly field-driven to any desired orientation state by controlling the amplitude and the frequency of the drive waveform [9][10][11][12][13]. Therefore, as compared to conventional nematic LCs, the response time of DFLC materials can be shortened by orders of magnitude.…”