Binary mixtures of nCB and nOCB liquid crystals. Two experimental evidences for a smectic A–nematic tricritical point

Miscibility studies of two twist-bend nematic liquid crystal dimers with different average molecular curvatures. A comparison between experimental data and predictions of a Landau mean-field theory for the NTB–N phase transition

“…2 shows how the nematic range increases from pure CB7CB dimer when the concentration of CB7CB in the binary mixtures decreases, showing a behaviour analogous to binary mixtures exhibiting the smectic A (SmA) to nematic phase transition. 39 For this phase transition, the SmA-N latent heat (or the entropy change) is reduced as the nematic range is increased and this experimental observation was explained firstly by Kobayashi 43 and McMillan 44 and shortly after by de Gennes, 45 who developed a phenomenological theory for the SmA-N transition based on a Landau mean-field approach. Recently, Mukherjee 46 has developed an improved theoretical analysis within the Landau phenomenological theory about the influence of the chain flexibility on the SmA-N phase transition.…”

“…This is an important difference with those binary phase diagrams exhibiting the SmA-N phase transition where the transitional entropy decreases as the nematic range increases but the heat capacity peak associated with the SmA-N phase transition is not suppressed even when the transitional entropy is very small or zero. 39,[47][48][49] Fig . 4 shows the K 3 and K 1 elastic constants for pure FFO9OCB and CB7CB and three selected binary mixtures as a function of the shifted temperature, T À T N TB -N , in the N-phase.…”

Twist, tilt, and orientational order at the nematic to twist-bend nematic phase transition of 1″,9″-bis(4-cyanobiphenyl-4′-yl) nonane: A dielectric,H2NMR, and calorimetric study

“…The MDSC technique is also suitable 184 for quantitative measurements of latent heats for first-order 185 transitions, even if they are weak. A more detailed description 186 of the MDSC technique can be found elsewhere [29]. …”

Tricritical behavior of the nematic to smectic-A phase transition in the binary mixture of liquid crystal

“…Thus, for T NA /T IN ≈ 0.99 a TCP is suggested. The tricritical behavior of the N-SmA phase transition has been observed by changing the alkyl end chains, 2 varying the concentration in binary mixtures, [5][6][7][8][23][24][25][26] increasing the pressure, 9 and increasing the electric field. 19 As for a) Author to whom correspondence should be addressed.…”