000041806 001__ 41806 000041806 005__ 20210121114516.0 000041806 0247_ $$2doi$$a10.1103/PhysRevE.92.062505 000041806 0248_ $$2sideral$$a93240 000041806 037__ $$aART-2015-93240 000041806 041__ $$aeng 000041806 100__ $$aRobles-Hernández, B. 000041806 245__ $$aTwist, tilt, and orientational order at the nematic to twist-bend nematic phase transition of 1¿, 9¿-bis(4-cyanobiphenyl-4'-yl) nonane: A dielectric, H 2 NMR, and calorimetric study 000041806 260__ $$c2015 000041806 5060_ $$aAccess copy available to the general public$$fUnrestricted 000041806 5203_ $$aThe nature of the nematic-nematic phase transition in the liquid crystal dimer 1¿, 9¿-bis(4-cyanobiphenyl-4'-yl) nonane (CB9CB) has been investigated using techniques of calorimetry, dynamic dielectric response measurements, and H2 NMR spectroscopy. The experimental results for CB9CB show that, like the shorter homologue CB7CB, the studied material exhibits a normal nematic phase, which on cooling undergoes a transition to the twist-bend nematic phase (NTB), a uniaxial nematic phase, promoted by the average bent molecular shape, in which the director tilts and precesses describing a conical helix. Modulated differential scanning calorimetry has been used to analyze the nature of the NTB-N phase transition, which is found to be weakly first order, but close to tricritical. Additionally broadband dielectric spectroscopy and H2 magnetic resonance studies have revealed information on the structural characteristics of the recently discovered twist-bend nematic phase. Analysis of the dynamic dielectric response in both nematic phases has provided an estimate of the conical angle of the heliconical structure for the NTB phase. Capacitance measurements of the electric-field realignment of the director in initially planar aligned cells have yielded values for the splay and bend elastic constants in the high temperature nematic phase. The bend elastic constant is small and decreases with decreasing temperature as the twist-bend phase is approached. This behavior is expected theoretically and has been observed in materials that form the twist-bend nematic phase. H2 NMR measurements characterize the chiral helical twist identified in the twist-bend nematic phase and also allow the determination of the temperature dependence of the conical angle and the orientational order parameter with respect to the director. 000041806 536__ $$9info:eu-repo/grantAgreement/ES/MINECO/MAT2012-35358-C03-02$$9info:eu-repo/grantAgreement/ES/MINECO/MAT2012-35358-C03-03 000041806 540__ $$9info:eu-repo/semantics/openAccess$$aby-nc-nd$$uhttp://creativecommons.org/licenses/by-nc-nd/3.0/es/ 000041806 590__ $$a2.252$$b2015 000041806 591__ $$aPHYSICS, MATHEMATICAL$$b6 / 53 = 0.113$$c2015$$dQ1$$eT1 000041806 591__ $$aPHYSICS, FLUIDS & PLASMAS$$b10 / 30 = 0.333$$c2015$$dQ2$$eT2 000041806 592__ $$a1.183$$b2015 000041806 593__ $$aCondensed Matter Physics$$c2015$$dQ1 000041806 593__ $$aStatistical and Nonlinear Physics$$c2015$$dQ1 000041806 593__ $$aStatistics and Probability$$c2015$$dQ2 000041806 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion 000041806 700__ $$aSebastián, N. 000041806 700__ $$aFuente, De La 000041806 700__ $$aLópez, D.O. 000041806 700__ $$aDiez-Berart, S. 000041806 700__ $$aSalud, J. 000041806 700__ $$0(orcid)0000-0003-4416-1036$$aRos, M.B.$$uUniversidad de Zaragoza 000041806 700__ $$aDunmur, D.A. 000041806 700__ $$aLuckhurst, G.R. 000041806 700__ $$aTimimi, B.A. 000041806 7102_ $$12013$$2765$$aUniversidad de Zaragoza$$bDpto. Química Orgánica$$cÁrea Química Orgánica 000041806 773__ $$g92, 6 (2015), 062505[16 pp]$$pPhys. rev., E$$tPhysical Review E$$x2470-0045 000041806 8564_ $$s3027811$$uhttps://zaguan.unizar.es/record/41806/files/texto_completo.pdf$$yVersión publicada 000041806 8564_ $$s131730$$uhttps://zaguan.unizar.es/record/41806/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada 000041806 909CO $$ooai:zaguan.unizar.es:41806$$particulos$$pdriver 000041806 951__ $$a2021-01-21-10:59:41 000041806 980__ $$aARTICLE