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Wyszukujesz frazę "61.30.Gd" wg kryterium: Temat


Tytuł:
An optical study to estimate orientational order parameter on some benzylideneaminophenylbenzoate liquid crystals
Autorzy:
Subhan, C.
Jeevan Kumar, R.
Panduranga, P.
Jayashreeand, B.
Fakruddin, K.
Powiązania:
https://bibliotekanauki.pl/articles/1070607.pdf
Data publikacji:
2016-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.79.Kr
78.15.+e
61.30.Gd
Opis:
The birefringence technique has been used for the evaluation of order parameter in the nematic phase along with the density measurements, which are needed for the calculation of molecular polarizabilities of the compounds. Birefringence and density studies have been carried out on the three liquid crystalline compounds viz.(1) (E)-4-((4-hexyloxy)benzylidene)amino)phenyl 4-butoxybenzoate(2) (E)-4-((4-hexyloxy)benzylidene)amino)phenyl 4-(decycloxy)benzoate and(3) (E)-4-((4-hexyloxy)benzylidene)amino)phenyl 4-(tridecycloxy)benzoate.Using birefringence and density data the molecular polarizabilities are evaluated by two different internal field models due to Vuks and Neugebauer. The mean molecular polarizability of the compounds is also evaluated by employing modified Lippincott δ-function model. The results reveal that both the theoretical and experimental values obtained are very near to each other.
Źródło:
Acta Physica Polonica A; 2016, 129, 3; 284-288
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative Study of Orientational Order of Some Liquid Crystals from Various Homologous Series
Autorzy:
Bielejewska, N.
Chrzumnicka, E.
Mykowska, E.
Przybylski, R.
Szybowicz, M.
Władysiak, K.
Bauman, D.
Powiązania:
https://bibliotekanauki.pl/articles/2047169.pdf
Data publikacji:
2006-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.Gd
33.20.Fb
33.20.Kf
33.50.Dq
Opis:
The long-range orientational order of liquid crystals from homologous series of 4-n-alkyl-4'-cyanobiphenyl, 4-n-alkoxy-4'-cyanobiphenyl, trans-4-n-alkyl(4'-cyano-phenyl)-hexane, and 4-(trans-4'-n -alkylcyclohexyl)-isothiocyanato-benzene was studied by means of classical methods of optical spectroscopy: absorption of the polarized light, fluorescence depolarization, and Raman scattering depolarization. The absorption, emission, and Raman scattering spectra of linearly polarized light were recorded as a function of temperature in the whole range of the mesophase. On the basis of these spectra the order parameters ⟨P$\text{}_{2}$⟩ and ⟨P$\text{}_{4}$⟩ as well as the orientational distribution function were determined. The results obtained for members of various series with the same number of carbon atom in the alkyl chain were compared. It was found that the orientational order of liquid crystal molecules depends on the structure of the rigid core, on the kind of the terminal group as well as on the alkyl chain length. The odd-even effect for the order parameters, explained as the alteration of interaction between alkyl chains, was observed.
Źródło:
Acta Physica Polonica A; 2006, 110, 6; 777-793
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Correlation Length in PBnA Liquid Crystal Family
Autorzy:
El Guermai, K.
Ayadi, M.
El Boussiri, K.
Powiązania:
https://bibliotekanauki.pl/articles/1992845.pdf
Data publikacji:
1998-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.-v
61.10.-i
64.70.Md
61.30.Gd
Opis:
We present a study of the range molecular interactions inside layers in smectic phases A and I of PBnA (phenyl-4 benzylidene 4'-alkylaniline) liquid crystals family. The purpose of this work is to determine the correlation length of the molecules' gravity centers in existing domain of smectic phases and at the transition between them. We used X-rays in-plane peaks of the pattern diffraction of aligned sample by a magnetic field.
Źródło:
Acta Physica Polonica A; 1998, 94, 5-6; 779-784
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dielectric and Optical Studies of Homologous Series of Bicyclo[2,2,2]octane Derivatives with -NCS Terminal Group
Autorzy:
Herba, H.
Żywucki, B.
Czechowski, G.
Bauman, D.
Wąsik, A.
Jadżyn, J.
Powiązania:
https://bibliotekanauki.pl/articles/1933452.pdf
Data publikacji:
1995-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.Gd
77.22.Ch
78.20.Fm
Opis:
The static dielectric constants and the optical birefringence for four members of the homologous series of bicyclo[2,2,2]octane derivatives with -NCS terminal group (pentyl to octyl) have been measured as a function of temperature. From the dielectric anisotropy, the optical birefringence as well as the polarized absorption spectra of the dichroic dye dissolved in the liquid crystalline host the order parameter has been determined. The results obtained by using various experimental methods have been compared with those calculated from the Maier-Saupe mean field theory. It has been found that the order parameter for the successive homologues shows alternation similar to that exhibited for the nematic-isotropic transition temperature.
Źródło:
Acta Physica Polonica A; 1995, 87, 6; 985-994
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dielectric Properties of Lyotropic Magnetic Liquid Crystal
Autorzy:
Kopčanský, P.
Tomčo, L.
Jadzyn, J.
Swiergiel, J.
Majorošová, J.
Kubovčíková, M.
Timko, M.
Rajňák, M.
Šipošová, K.
Gažová, Z.
Bednariková, Z.
Hu, Chin-Kun
Hayryan, S.
Studenyak, I.
Kovalchuk, T.
Kovalchuk, O.
Powiązania:
https://bibliotekanauki.pl/articles/1387983.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.Gd
61.30.St
75.50.Mm
Opis:
An important feature of lyotropic liquid crystals is the self-assembly of the amphiphilic molecules as supermolecular structures. We have studied the formation of nematic liquid crystal phase in solutions containing lysozyme amyloid fibrils and magnetic nanoparticles using oscilloscopic method. Interaction of fibrils with magnetic nanoparticles under the external magnetic field resulted in fibril re-arrangement. The analysis of the obtained results suggests that the decrease in conductivity of solutions in presence of magnetic field is due to decrease of the ion mobility caused by re-arrangement of structures in the solution. The obtained results allow determination of the optimum ratio of the components which can lead to preparation of solutions with a more ordered structure in presence of magnetic field.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 632-634
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Diffusion on (ZrO$\text{}_{2}$)$\text{}_{0.8}$(Y$\text{}_{2}$O$\text{}_{3}$)$\text{}_{0.2}$ Ceramic
Autorzy:
Sharma, S. V.
Chand, P.
Powiązania:
https://bibliotekanauki.pl/articles/1933619.pdf
Data publikacji:
1995-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.16.-d
64.80.Gd
66.30.-h
76.30.Fc
81.20.Lb
Opis:
Effect of iodine and lithium diffusion on undoped and doped (with transition metal ions: Ti, V, Ni, Fe, Cu, Co and Mn) samples of polycrystalline (ΖrO$\text{}_{2}$)$\text{}_{0.8}$(Y$\text{}_{2}$O$\text{}_{3}$)$\text{}_{0.2}$ ceramic has been investigated using X-ray diffraction, scanning electron microscopy and electron paramagnetic resonance.
Źródło:
Acta Physica Polonica A; 1995, 88, 3; 503-509
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of Order on Spectral Properties of Discotic Liquid Crystal Heptyloxydibenzopyrene
Autorzy:
Uznański, P.
Powiązania:
https://bibliotekanauki.pl/articles/1993253.pdf
Data publikacji:
1998-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.Gd
Opis:
The spectral properties of discotic heptyloxydibenzopyrene were studied by UV-VIS absorption, fluorescence, and infrared spectroscopy as a function of temperature in two different types of spectroscopic cells. The molecule was found to be a sensitive spectroscopic probe of molecular orientation on a surface. Capillary-filled cells caused the liquid crystal to assume a parallel orientation with respect to the surface, whereas spin-coating caused the orientation of columns to be statistically more nonuniform. It was shown from the spectroscopic studies that the molecular orientation changed on going from crystal to liquid crystalline state and a conclusion was drawn that bulk molecular alignment of columnar phase was defined by an interface imposed by an external surface.
Źródło:
Acta Physica Polonica A; 1998, 94, 5-6; 825-834
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhancement of Nematic Order of Liquid Crystals in Thin Cells
Autorzy:
Aswini, P.
Govind, A.
Powiązania:
https://bibliotekanauki.pl/articles/1489838.pdf
Data publikacji:
2012-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.Gd
61.30.-v
64.70.mf
Opis:
Experimental observations show that the nematic order parameter is significantly enhanced as the thickness of the cell is reduced. Calculations of earlier theories do not agree well with the experimental data. We propose a simple extension of Maier-Saupe theory to account for the enhancement. A molecule near the surface is assumed to feel the mean field potential (the Maier-Saupe type) and also the surface induced potential. This is included in the Maier-Saupe theory. Our calculations are in better agreement with the experimental data.
Źródło:
Acta Physica Polonica A; 2012, 121, 3; 625-627
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Guest Effect on Nematic-Isotropic Phase Transition Temperature of Liquid Crystal 6CHBT
Autorzy:
Bauman, D.
Solczyński, J.
Chrzumnicka, E.
Powiązania:
https://bibliotekanauki.pl/articles/1968468.pdf
Data publikacji:
1997-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.Gd
64.70.Md
Opis:
The polarized absorption spectra of seven dichroic azo dyes dissolved in the nematogenic liquid crystal host 6CHBT have been recorded as a function of temperature. On the basis of these spectra, the guest order parameter has been determined. Moreover, the influence of the dye addition on the behaviour of the guest-host mixture in the vicinity of the nematic- isotropic phase transition has been examined. The experimental results have been compared in some details with the calculations done on the basis of the mean field theory for binary mixtures.
Źródło:
Acta Physica Polonica A; 1997, 92, 6; 1151-1161
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Guest Influence on the Dipolar Association of the Nematic Liquid Crystal Host
Autorzy:
Bauman, D.
Fan, Zhong-Xiao
Haase, W.
Powiązania:
https://bibliotekanauki.pl/articles/1891637.pdf
Data publikacji:
1991-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.Gd
61.10.
64.70.Ew
Opis:
X-ray diffraction method has been used to study the molecular organization in 4-n-pentyl-4'-cyano-p-terphenyl doped with guest dye molecules. It has been found that the dye with strong polar end group affects significantly the monomer to dimer ratio in the nematic phase of the liquid crystal studied.
Źródło:
Acta Physica Polonica A; 1991, 80, 4; 545-552
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Guest-Host Interactions in Nematic p-Cyano-p-Alkylphenylcyclohexanes
Autorzy:
Bauman, D.
Moryson, H.
Jadżyn, J.
Powiązania:
https://bibliotekanauki.pl/articles/1930624.pdf
Data publikacji:
1994-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.Gd
64.70.Md
Opis:
Studies of the temperature dependence of the guest order parameter for binary mixtures of the dichroic azo dye in the homologous series of the p-cyano-p'-alkylphenylcyclohexane were performed. Odd-even effect for the order parameter value was observed. A correlation between the shift in the nematic-isotropic transition temperature after dye addition and the orientation of the guest molecules in the nematic host was discussed.
Źródło:
Acta Physica Polonica A; 1994, 85, 3; 553-562
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
How to Enhance Sensitivity of Liquid Crystals to External Magnetic Field?
Autorzy:
Kopčanský, P.
Tomašovičová, N.
Gdovinová, V.
Timko, M.
Éber, N.
Tóth-Katona, T.
Jadzyn, J.
Honkonen, J.
Chaud, X.
Powiązania:
https://bibliotekanauki.pl/articles/1383988.pdf
Data publikacji:
2015-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Mm
61.30.Gd
61.30.Hn
Opis:
Liquid crystals, due to their large dielectric anisotropy, respond very sensitively to application of an external electric field, whereas they are only weakly sensitive to the magnetic field. A possible way of improving that sensitivity is doping liquid crystals with magnetic nanoparticles. As a result, stable colloidal suspensions of liquid crystals with relatively low concentrations of magnetic nanoparticles (called ferronematics, ferrocholesterics, ferrosmectics, etc.) can be produced. We illustrate some examples of the influence of the magnetic field, as well as of a superposition of magnetic and electric fields on the structural transitions (e.g. on the Fréedericksz transition) in ferronematics based on the calamitic liquid crystal 4-(trans-4'-n-hexylcyclohexyl)-isothiocyanatobenzene (6CHBT). It is shown that the samples respond to the applied magnetic field of low strength. The effects of the magnetic particles and magnetic field on the nematic to isotropic phase transition temperature are discussed as well.
Źródło:
Acta Physica Polonica A; 2015, 127, 2; 157-162
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Nonstoichiometry on Magnetocaloric Effect in $(La_{0.7}Ca_{0.3})_{1 - x}Mn_{1+x}O_3$
Autorzy:
Sazanovich, A.
Pietosa, J.
Pashchenko, A.
Zubov, E.
Dyakonov, V.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/1419814.pdf
Data publikacji:
2012-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Sg
61.50.Nw
65.40.gd
Opis:
Magnetocaloric effect in $(La_{0.7}Ca_{0.3})_{1 - x}Mn_{1 + x}O_3$ manganites with x = 0, 0.1, 0.2 has been investigated. It is found a strong influence of nonstoichiometry caused by excessive manganese on the magnetic entropy change. The magnetocaloric effect was evaluated from the isothermal curves of spontaneous magnetization versus the applied magnetic field by using the well-known thermodynamical Maxwell relation. The maximum entropy value, $| \Delta S_{M}^\text{max} |,$ near the ferromagnetic-paramagnetic phase transition is shown to increase with the manganese content. The $La_{0.56}Ca_{0.24}Mn_{1.2}O_3$ manganite exhibits the largest $| \Delta S_{M}^\text{max} |$ value equal to $3.09 J kg^{-1} K^{-1}$ at 15 kOe near $T_{C}$ = 267 K. The magnetocaloric effect values obtained allow to propose that the studied manganites are promising materials for future cooling application.
Źródło:
Acta Physica Polonica A; 2012, 122, 1; 162-166
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations of Director Field Arrangement Induced in Tunable Liquid Crystalline Waveguide
Autorzy:
Walczak, A.
Powiązania:
https://bibliotekanauki.pl/articles/1993128.pdf
Data publikacji:
1998-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.Gd
Opis:
Measurements of the refractive index profile have been made to provide data for obtaining local optical axis arrangement in the waveguide cross-section. Liquid crystalline planar waveguide tuned with the electric field has been used. A new approach is proposed to accomplish refractive index profile measurements in a direct way. The modal line method is presented as a tool that allows one to do it and to improve the attenuated total reflection disadvantages as well. The obtained results maintain applicability of the modal line method for a direct refractive index profile measurement. To verify the method, nematic 6CHBT (4-trans-4-n-hexyl-cyclohexyl- isothiocyanatobenzene) described earlier in the literature has been examined. A nematic mixture W602 contained 6CHBT as a main component has been examined too.
Źródło:
Acta Physica Polonica A; 1998, 94, 5-6; 813-823
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low Magnetic Field Response in Ferronematics
Autorzy:
Gdovinová, V.
Tomašovičová, N.
Závišová, V.
Éber, N.
Tóth-Katona, T.
Royer, F.
Jamon, D.
Jadzyn, J.
Kopčanský, P.
Powiązania:
https://bibliotekanauki.pl/articles/1031035.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Mm
61.30.Gd
61.30.Hn
Opis:
In this work the 4-n-hexyl-4'-cyanobiphenyl liquid crystal was doped with differently shaped magnetite nanoparticles. The structural changes were observed by capacitance measurements. Influence of the shape of magnetic particles on magnetic Fréedericksz transition depends on the type of anchoring, which is characterized by the density of the anchoring energy and by the initial orientation between the liquid crystal molecules and the magnetic moment of the magnetic particles. It was observed that in the case of doping with spherical particles, the critical magnetic field is shifted to higher values with increase of volume concentration of the magnetic nanoparticles but decreases with increase of biasing voltage. In the case of doping with rod-like particles, the critical magnetic field is almost independent of the volume concentration of the magnetic nanoparticles.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 934-936
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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