Density, Refractive Index and Ultrasonic Velocity Studies Involving N-(p-n-Pentyloxybenzylidene)-p-n-octylaniline

The density, refractive index and ultrasonic velocity dependence on temperature for N-(p-npentyloxybenzylidene)- p-n-octylaniline, 50.8, is presented. The compound 50.8 exhibits smectic-B, smectic-A and nematic phases between the solid and isotropic liquid phases. The nematic-isotropic and smectic A-smectic B phase transformations are found to be first order. The interesting smectic A - nematic transformation is confirmed from the results to be second order, although the thermal expansion coefficient and reported enthalpy data had suggested a weak first order transition. The computed adiabatic compressibility, βad, molar sound velocity, Rn, and molar compressibility Aw are presented.

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Ultrasonic Studies in N-(p-n-butoxybenzylidene)-p-n-butylaniline

Zeitschrift für Naturforschung A ◽

10.1515/zna-1981-0913 ◽

1981 ◽

Vol 36 (9) ◽

pp. 1002-1005

Author(s):

J. V. Rao ◽

C. R. K. Murty

Keyword(s):

Sound Velocity ◽

Ultrasonic Velocity ◽

Nematic Phase ◽

Adiabatic Compressibility ◽

Sonic Velocity ◽

Isotropic Liquid ◽

Liquid Phases ◽

First Time ◽

Experimental Density

AbstractThe ultrasonic velocity in the SG(SH), SB, SA, Nc , N0 and isotropic liquid phases of N-(p-n-butoxybenzylidene)-p-n-butylaniline (BBBA) has been measured as a function of temperature. A transition in the nematic phase seems to indicate the existence of an ordinary nematic and a cybotactic nematic phase. The transition SG-SB has been found for the first time with the ultra-sonic velocity method. The adiabatic compressibility βad and the molar sound velocity Rn (Rao number) have been determined using the experimental density and ultrasonic velocity.

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Phase Transition Studies in Polymesomorphic Compounds II. Ultrasonic Velocity Studies in N(p-n-Heptyloxy Benzylidene)p-n-Butyl Aniline

Zeitschrift für Naturforschung A ◽

10.1515/zna-1982-1108 ◽

1982 ◽

Vol 37 (11) ◽

pp. 1262-1265

Author(s):

V. G. K. M. Pisipati ◽

N. V. S. Rao

Keyword(s):

Phase Transition ◽

Phase Transitions ◽

Sound Velocity ◽

Ultrasonic Velocity ◽

Adiabatic Compressibility ◽

First Order ◽

Smectic A ◽

Smectic C ◽

Good Agreement ◽

Transition Studies

The variation of ultrasonic velocity in N (p-n-heptyloxy benzylidene)p-n-butyl aniline, (HyBBA) with temperature in isotropic, nematic, smectic-A, smectic-C and smectic-G phases is measured. All the phase transitions I-N, N-SA, SA-SC and SC-SG are found to be of first order. The adiabatic compressibility βad, molar sound velocity or Rao number Rn, and molar compressibility or Wada constant AW are computed. Rn and AW of HyBBA are compared with theoretical values and found to be in good agreement with the theory.

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Synthesis, characterisation and liquid-crystalline phase transition studies on two higher homologues of 4O.m (m=14 and 16) series

MRS Proceedings ◽

10.1557/proc-709-cc5.33.1 ◽

2001 ◽

Vol 709 ◽

Cited By ~ 1

Author(s):

C. Rama Chandra Prabhu ◽

V.G.K.M. Pisipati

Keyword(s):

Phase Transition ◽

Liquid Crystalline ◽

Scanning Calorimetry ◽

First Order ◽

Smectic A ◽

Phase Transition Temperatures ◽

Crystalline Phase Transition ◽

M 14 ◽

Enthalpy Data ◽

Transition Studies

ABSTRACTThe synthesis, characterization and phase transition studies of higher homologues of N(p-nbutoxybenzylidene)p-n-alkylanilines, Viz., 4O.m series (m=14 and 16) are carried out by thermal microscopy, differential scanning calorimetry and density. The compounds exhibit a phase variant of nematic and smectic-A. Density studies reveal a first order nature of IN transitions and a weak first order NA transitions. An estimate of pressure dependence of the phase transition temperatures using the volume and enthalpy data are presented. A comparison of these results with other reported results in nO.m and other compounds are presented.

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Phase Transition Studies in PMBAB and PEBAB

Zeitschrift für Naturforschung A ◽

10.1515/zna-1984-0718 ◽

1984 ◽

Vol 39 (7) ◽

pp. 696-699 ◽

Cited By ~ 1

Author(s):

V. G. K. M. Pisipati ◽

N. V. S. Rao

Keyword(s):

Phase Transition ◽

Thermal Expansion ◽

Molar Volume ◽

Ultrasonic Velocity ◽

Adiabatic Compressibility ◽

First Order ◽

Thermal Expansion Coefficients ◽

Methylene Unit ◽

Expansion Coefficients ◽

Transition Studies

The variation of density and ultrasonic velocity with temperature in N-(p-methoxybenzylidene)- p-aminobenzonitrile (PMBAB) and N-(p-ethoxybenzylidene)-p-aminobenzonitrile (PEBAB) are presented. The density jumps and thermal expansion coefficients suggest the nematic-isotropic transition of both compounds to be of first order. The adiabatic compressibility βad, molar sound velocity Rn and molar compressibility Aw are computed. The contribution of a methylene unit to the molar volume is found to be higher than literature values. The anomalous ultrasonic velocity dip at the nematic-isotropic transition for both compounds is found to be high; the value is many times those found for other nematic-isotropic or nematicsmectic A transitions.

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Phase Transitions by Dilatometry, Part I: Synthesis, Characterisation and Isotropic to Smectic-A and Smectic-A to Smectic-B Transitions in Two Liquid Crystalline Higher Homologues of N-(p-n-nonyloxybenzylidene) p-n-alkylanilines

Zeitschrift für Naturforschung A ◽

10.1515/zna-2004-0902 ◽

2004 ◽

Vol 59 (9) ◽

pp. 537-542 ◽

Cited By ~ 1

Author(s):

C. Rama Chandra Prabhu ◽

S. Lakshminarayana ◽

V. G. K. M. Pisipatia

Keyword(s):

Phase Transition ◽

Differential Scanning Calorimetry ◽

Transition Temperature ◽

Liquid Crystalline ◽

Scanning Calorimetry ◽

First Order ◽

Smectic A ◽

M 12 ◽

Phase Variants ◽

Enthalpy Data

Two higher homologues of N(p-n-nonyloxybenzylidene)p-n-alkylanilines, viz. the 9O.m series with m = 12 and 16, are synthesised and characterised by thermal microscopy, differential scanning calorimetry and density studies. The compounds exhibit the phase variants smectic-A, smectic-B and smectic-G. Density studies reveal the first order nature of the isotropic to smectic-A and smectic-A to smectic-B transitions. An estimate of the pressure dependence of the phase transition temperature, using volume and enthalpy data, is presented. A comparison of these results with those reported on nO.m and other liquid crystalline compounds is presented.

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First-order transition between nematic phases in lyotropic liquid crystals

Liquid Crystals ◽

10.1080/02678299008033845 ◽

1990 ◽

Vol 7 (6) ◽

pp. 877-881 ◽

Cited By ~ 16

Author(s):

L. Q. Amaral

Keyword(s):

Liquid Crystals ◽

Order Transition ◽

Lyotropic Liquid Crystals ◽

First Order ◽

First Order Transition ◽

Nematic Phases

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Periodic structures on liquid-phase smectic A, nematic and isotropic free surfaces

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.9.34 ◽

2018 ◽

Vol 9 ◽

pp. 342-352

Author(s):

Anna N Bagdinova ◽

Evgeny I Demikhov ◽

Nataliya G Borisenko ◽

Sergei M Tolokonnikov ◽

Gennadii V Mishakov ◽

...

Keyword(s):

Periodic Structures ◽

Near Field ◽

Optical Microscope ◽

Isotropic Liquid ◽

Free Surfaces ◽

Smectic A ◽

Atomic Force ◽

Liquid Phases ◽

Stripe Structure ◽

Structure Analyzer

The free boundary of smectic A (SmA), nematic and isotropic liquid phases were studied using a polarized optical microscope, an interferometric surface structure analyzer (ISSA), an atomic force microscope (AFM) and a scanning near-field optical microscope (SNOM). Images of the SmA phase free surface obtained by the polarized microscope and ISSA are in good correlation and show a well-known focal domain structure. The new periodic stripe structure was observed by scanning near-field optical microscopy on the surface of the smectic A, nematic and isotropic phases. The properties of this periodic structure are similar to the charged liquid helium surface and can be explained by nonlinear electrostatic instabilities previously described.

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Static dielectric pretransitional effects in thermotropic liquid crystals

Opto-Electronics Review ◽

10.2478/s11772-008-0043-y ◽

2008 ◽

Vol 16 (4) ◽

Cited By ~ 4

Author(s):

J. Jadżyn ◽

G. Czechowski

Keyword(s):

Liquid Crystalline ◽

Helmholtz Free Energy ◽

Electronic Devices ◽

Thermodynamic Quantities ◽

Static Permittivity ◽

Temperature Behaviour ◽

Isotropic Liquid ◽

First Order ◽

Thermotropic Liquid Crystals ◽

First Order Transition

AbstractThe paper presents a review of recent results on static dielectric behaviour in vicinity of weakly first order transition from isotropic liquid to a liquid crystalline nematic phase of compounds used in opto-electronic devices. Temperature behaviour of static permittivity and its derivative are interpreted in terms of a basic thermodynamic quantities increment (internal energy, entropy and Helmholtz free energy) induced by a probing electric field.

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Specific Volume and Ultrasonic Velocity Studies of the Liquid Crystal N-(p-n-hexyloxybenzylidene)-p-n-butylaniline (Hx BBA)

Zeitschrift für Naturforschung A ◽

10.1515/zna-1983-0709 ◽

1983 ◽

Vol 38 (7) ◽

pp. 762-764 ◽

Cited By ~ 10

Author(s):

L. V. Choudary ◽

J. V. Rao ◽

P. N. Murty ◽

C. R. K. Murty

Keyword(s):

Thermal Expansion ◽

Liquid Crystal ◽

Ultrasonic Velocity ◽

Specific Volume ◽

Velocity Variation ◽

Velocity Measurements ◽

First Order ◽

Smectic A ◽

Thermal Expansion Coefficients ◽

Expansion Coefficients

Abstract Specific volume and ultrasonic velocity measurements have been carried out on the liquid crystal N-(p-n-hexyloxybenzylidene)-p-n-butylaniline in the isotropic, nematic, smectic A, smectic B and smectic G phases. The variation of the specific volume with temperature shows that the corresponding transitions are of first order. Thermal expansion coefficients have been calculated for all the mesophases. The ultrasonic velocity variation with temperature confirms the transitions.

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