Anisotropic heat transport in the octylcyanobiphenyl (8CB) liquid crystal

Marinelli, M.; Mercuri, F.; Foglietta, S.; Zammit, U.; Scudieri, F.

doi:10.1103/physreve.54.1604

Cited by 58 publications

(51 citation statements)

References 16 publications

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“…The results from this study which were obtained for randomly oriented molecules show also consistency with other results in the literature [14][15][16][17][18][19][20][21]. This study can be analyzed in detail and can be improved for molecular orientation of nematic liquid crystals at certain directions.…”

Section: Resultssupporting

confidence: 90%

Numerical Determination of Thermal-Diffusivity Coefficients of Some Nematic Liquid Crystals in Situ

Yılmaz

Yildirim

2009

Int J Thermophys

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In this study, a new experimental study has been implemented to determine the thermal-diffusivity parameters of industrial nematic liquid crystals, 4-pentyl-4 -cyanobiphenyl (5CB) and 4 -octyl-4-cyanobiphenyl (8CB), both numerically by using the finite difference method (FDM) for forward solutions and experimentally by measuring the temperature variation with time and position. The most important parts of this experimental study are the heating system and the liquid crystal cell, which were constructed in-house to determine the temperatures of the materials in situ. Four different positions for local measurements have been studied, and the optimum graph of this variation has been determined. The experimental and theoretical results of this study are consistent with previous measurements performed by means of a conventional thermal technique.

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Section: Resultssupporting

confidence: 90%

Numerical Determination of Thermal-Diffusivity Coefficients of Some Nematic Liquid Crystals in Situ

Yılmaz

Yildirim

2009

Int J Thermophys

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“…25,26 The sample was prepared by smearing out a small drop of the liquid over the pyroelectric transducer. By heating above the clearing temperature, a flat liquid layer was obtained.…”

Section: Resultsmentioning

confidence: 99%

Absolute values of specific heat capacity and thermal conductivity of liquids from different modes of operation of a simple photopyroelectric setup

Caerels

Glorieux

Thoen

1998

Review of Scientific Instruments

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Photothermal techniques offer a nice tool for the determination of changes in thermal parameters of different types of samples. Using a very thin pyroelectric transducer, a very simple and versatile ac calorimeter can be built. The described inverse pyroelectric technique allows high-resolution ac-calorimetric measurements of the temperature dependence of the specific heat capacity. Since measuring frequencies up to a few hertz can be used, which are higher than in most alternative ac-calorimetric setups, noise can be reduced and measuring times shortened. With a small modification of the measurement cell, the determination of absolute specific heat capacity and thermal conductivity values of liquid samples was achieved. Comparison of the frequency response of the system with and without a solid thermal load in the neighborhood of the sample yields data with an accuracy of about 5% and 10% for specific heat capacity and thermal conductivity, respectively. If necessary, absolute values of specific heat capacity and thermal conductivity can also be obtained by making contact between a (solid) thermal load and the liquid. A pure ac-calorimetric operation is then no longer possible, thus restricting this mode of operation to homogeneous or to properly aligned anisotropic liquids.

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“…The homeotropic single-domain sample in the smecticA phase shows values of the thermal diffusivity that are considerably larger than those found in situations where the molecules are, on average, randomly oriented like in the isotropic phase [9,14,15]. On the contrary, the thermal diffusivity values in the focal conic textured sample is lower than that in the isotropic phase.…”

Section: Resultsmentioning

confidence: 63%

“…On the contrary, the thermal diffusivity values in the focal conic textured sample is lower than that in the isotropic phase. It is well-known that in single-domain samples (homeotropic/planar), the thermal transport parameters are significantly different (respectively larger/smaller) than those in the isotropic phase [9,14,15]. It is therefore expected that, in mesophases of multi-domain samples, like the one corresponding to the focal conic texture, the values of the thermal transport properties should correspond to an average of the values for the homeotropic and for the planar single-domain samples.…”

Section: Resultsmentioning

confidence: 99%

“…This is related to the fact that the thermal transport parameters are largest when measured with the heat flow direction parallel to the molecular long axis [9]. All these observations can be performed simultaneously in a photopyroelectric (PPE) calorimetric set-up [9][10][11][12], where the LC samples were contained in quartz cells of calibrated thickness ranging between 10 and 100 µm. The cell side in contact with the LC was coated with a 300-nm-thick optically opaque Ti layer.…”

Section: Methodsmentioning

confidence: 99%

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Strain induced homeotropic alignment in the smecticA phase of liquid crystals

et al. 2013

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We present a method to align liquid crystal (LC) samples in their SmecticA phase, useful to obtain permanent\ud homeotropic single domains even in compounds where the nematic phase is absent. It is based on the application\ud of a strain field, within the sample volume, which tends to align the molecules all towards a common direction.\ud The study was carried out in samples of 4-decyl-4-cyanobiphenyl (10CB), 4-octyl-4-cyanobiphenyl (8CB)\ud and n-hexyl-4-n-pentyloxy biphenyl-4-carboxylate (65OBC) LCs, and the alignment efficiency was monitored by\ud polarisation microscopy observations and by thermal diffusivity measurements

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Anisotropic heat transport in the octylcyanobiphenyl (8CB) liquid crystal

Cited by 58 publications

References 16 publications

Numerical Determination of Thermal-Diffusivity Coefficients of Some Nematic Liquid Crystals in Situ

Numerical Determination of Thermal-Diffusivity Coefficients of Some Nematic Liquid Crystals in Situ

Absolute values of specific heat capacity and thermal conductivity of liquids from different modes of operation of a simple photopyroelectric setup

Strain induced homeotropic alignment in the smecticA phase of liquid crystals

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