Biaxial nematic phase, multiphase critical point, and reentry transition in binary liquid crystal mixtures

Abstract

Articles you may be interested inTricritical behavior of the nematic to smectic-A phase transition in the binary mixture of liquid crystal A model considering both short-range and long-range interactions for liquid crystals mixtures of rod-like and plate-like molecules is presented in this paper. The model is treated in the framework of a mean ~el~, van de~ Waals-type theory. The relationship of the model to a Landau-type tr~tme~t IS dISCUSsed lD.an Appendix. It can be shown for this model that a multiphase critical po~t eXIsts between the Isotropic, rod nematic, plate nematic, and biaxial nematic phases. This ~OlDt can .be l~ted from a set of analytic equations. The fluctuations and the magnetically I~duced.bIr~frmgence ~ound this point are calculated. The model predicts the phase diagrams of blDW?'.hqUId crystal ~Ix~ures both with and without reentry transition. The reentrant phase transItIons from the bIaXIal to the uniaxial nematic phase and from the uniaxial nematic to the isotropic phase have not received prior theoretical attention but have been demonstrated in recent experiments.

Temperature-concentration behaviour of the order parameter in the nematic phases of a lyotropic liquid crystal

“…This is a confirmation of the predictive criterion of Shih and Alben [8] is not observed within the accuracy of our T and ameasurements [19]. [8][9][10], is consistent with all the phase diagrams [3,7] in which the NL and Nc phases are both present. 3.…”

“…1 of Ref. [3]), the biaxial phase appears to be an intermediate phase all along the border between the two uniaxial phases [7], as predicted by statistical models [8][9][10]. This phase diagram shows also that for a particular choice of temperature and concentration, reentrant (*) Permanent address : Centre Paul Pascal, Domaine Universitaire, 33405 Talence, France. configurations exist; i.e.…”

A generalisation of the Onsager trial-function approach: describing nematic liquid crystals with an algebraic equation of state

“…In some cases qualitative differences in the types of phase behaviour are seen when compared with the full numerical solution particularly for mixtures (see the studies on mixtures of rod and disk-like particles [137][138][139][140]). The simple model of Zwanzig [88] (in which only the three cartesian orientations of the orientational distribution function are considered) have also found popular use owing to the tractable nature of the free energy [141][142][143][144][145][146][147][148][149][150][151][152][153][154]. As a final remark on the general use of trial functions, one should mention that in addition to being a useful ingredient in providing a representation of the thermodynamic properties of the isotropic-nematic transition, the Onsager, Gaussian and related trial functions have been used to analyse and describe the degree of orientational order determined experimentally [155][156][157][158][159][160].…”

Orientational Ordering for System of Ellipsoidal Molecules Dispersed in Cubic Lattice

“…Also, in the case of a constant infinite-range isotropic interaction we have found two uniaxial phases, which are separated by a biaxial phase [4b]. Another system in which a biaxial phase could be expected is the mixture of rod-like and disc-like molecules [24,25]. In this case there is no need to go to low temperatures or high pressures, thus there is no risk of unwanted crystallization or smectic ordering as for our model described above.…”