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    Wyświetlanie 1-29 z 29
    Tytuł:
    Singular Elastic Properties of Mixtures with the Re-entrant Nematic Phase
    Autorzy:
    Czechowski, G.
    Jadżyn, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2038376.pdf
    Data publikacji:
    2004-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Md
    62.20.Dc
    61.30.-v
    Opis:
    The paper presents temperature behavior of the splay and bend elastic constants measured for n-hexyloxycyanobiphenyl and n-octyloxycyanobiphenyl mixtures - a system exhibiting the re-entrant nematic phase. It was shown that singularities in the elastic properties of the system concern not only the nematic phase (the well-known pre-smectic effects) but first of all - the smectic A phase, in which the splay and bend deformations, normally not allowed for the layered structures, can be induced.
    Źródło:
    Acta Physica Polonica A; 2004, 106, 4; 475-485
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dielectric, Viscous, and Elastic Properties of Mesogenic 4-n-Hexyloxy-4-Cyanobiphenyl
    Autorzy:
    Czechowski, G.
    Jadżyn, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2027368.pdf
    Data publikacji:
    2001-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Md
    77.84.Nh
    77.22.Gm
    66.20.+d
    Opis:
    The paper presents the results of measurements of the static and dynamic electric permittivity, the shear viscosity, and the splay and bend elastic constants for 4-n-hexyloxy-4' -cyanobiphenyl (C$\text{}_{6}$H$\text{}_{13}$O-Ph-Ph-C≡N). On the basis of the static values of the nematic principal permittivities, ε$\text{}_{ǁ}$ (T) and $\varepsilon_{\bot}(T)$, the angle between the dipole moment vector and the long axis of 4-n-hexyloxy-4'-cyanobiphenyl molecule, the apparent dipole moment and the nematic order parameter were determined. From the temperature dependences of the dielectric relaxation time (corresponding to the molecular rotation around the short axis) and the shear viscosity, the strength of the nematic potential and the effective length of 4-n-hexyloxy-4'-cyanobiphenyl molecule (in isotropic phase) were estimated. The K$\text{}_{11}$ and K$\text{}_{33}$ elastic constants were determined from the voltage dependence of the capacitance of the planar nematic cell with the method proposed by Gruler et al. and Uchida et al.
    Źródło:
    Acta Physica Polonica A; 2001, 99, 5; 579-591
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Molowa entropia orientacyjna i struktura cieczy zasocjowanych
    Molar orientation entropy and structure of the self-associated liquids
    Autorzy:
    Jadżyn, J.
    Świergiel, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/172403.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Chemiczne
    Tematy:
    dipole molekularne
    przenikalność statyczna
    entropia orientacyjna
    ciecz
    wiązania wodorowe
    przejście fazowe ciecz izotropowa-nematyk
    molecular dipoles
    static permittivity
    orientation entropy
    liquids
    hydrogen bonds
    isotropic liquids to nematic phase transition
    Opis:
    Research on the structural effects of intermolecular interactions not only brings us closer to a better understanding the macroscopic properties of liquids, but also allows one to modify these properties. Intermolecular dipolar couplings and hydrogen bonds are the most common interactions in liquids leading to formation of multimolecular entities with various structures. The natural rival of these interactions is the thermal agitation of molecules (kT), which aims to destroy the emerging structures. In this paper we present an experimental method to estimate the way of molecular self-assembly resulting from the simultaneous action of kT and intermolecular interactions. The method is based on the study of dipolar orientation effects induced by an applied electric field. As an experimental source of the information on these effects is temperature derivative of the static permittivity of tested liquid. That derivative is proportional to the liquid entropy change due to the ordering action of the electric field on the molecular dipoles. Here, we present the experimental results on temperature dependence of the static permittivity and increment of the orientation entropy of liquids where the self-association process realizes with two ways: dipolar couplings and hydrogen-bonds.
    Źródło:
    Wiadomości Chemiczne; 2017, 71, 7-8; 517-532
    0043-5104
    2300-0295
    Pojawia się w:
    Wiadomości Chemiczne
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Viscosity Behavior at the Nematic to Smectic A Phase Transition in Freely Flowing Compounds
    Autorzy:
    Jadżyn, J.
    Czechowski, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/2037296.pdf
    Data publikacji:
    2004-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Md
    83.80.Xz
    66.20.+d
    Opis:
    The paper shows that the shear viscosity at the nematic to smectic A phase transition in freely flowing n-hexyloxycy$ $anobiphenyl + n-octyloxycyanobiphenyl mixtures (a system exhibiting the reentrant nematic phase) corresponds to the Mięsowicz η$\text{}_{3}$ viscosity coefficient and its temperature behavior is analogous (but strongly enhanced) to that observed for the η$\text{}_{2}$ viscosity coefficient at the isotropic to nematic phase transition.
    Źródło:
    Acta Physica Polonica A; 2004, 105, 5; 459-465
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optical Order Parameter of Dichroic Azo-Dyes in Liquid Crystalline Side-Chain Polysiloxanes
    Autorzy:
    Chrzumnicka, E.
    Bauman, D.
    Jadżyn, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2035645.pdf
    Data publikacji:
    2002-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.41.+e
    61.30.Gd
    64.70.Md
    Opis:
    Polarized light absorption spectra of seven dichroic azo-dyes dissolved in mesogenic side-chain polysiloxanes were recorded as a function of temperature. On the basis of the spectra the optical order parameter of the dyes was determined. The influence of the dye on the phase transition temperatures of polysiloxanes was examined. The results obtained for polysiloxanes were compared with the data for low molecular weight liquid crystal.
    Źródło:
    Acta Physica Polonica A; 2002, 102, 6; 767-780
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Viscous Behavior of Binary Mixtures of Mesogenic Solvent/Non-Mesogenic Solute
    Autorzy:
    Jadżyn, J.
    Czechowski, G.
    Laskowski, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/2046831.pdf
    Data publikacji:
    2006-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Md
    66.20.+d
    83.80.Xz
    83.85.Jn
    Opis:
    The paper presents results of the shear viscosity measurements performed on diluted binary mixtures of mesogenic solvent n-hexylcyanobiphenyl (C$\text{}_{6}$H$\text{}_{13}$PhPhC≡N,6CB) and two non-mesogenic admixtures: (i) n-heptylcyanophenyl (C$\text{}_{7}$H$\text{}_{15}$PhC≡N,7CP), composed of the molecules of the same polarity as the solvent molecules but of a slightly shorter length, and (ii) 4-n-propylcyclohexyl-4'-n-pentylphenyl (C$\text{}_{3}$H$\text{}_{7}$CyHxPhC$\text{}_{5}$H$\text{}_{11}$,3CyP5), composed of the non-polar molecules but of a length very close to that of the mesomorphic solvent molecules. The experiment showed that the concentrational depression of the clearing temperature and the temperature extent of the isotropic + nematic (I + N) two-phase region in the mixtures are significantly smaller, i.e. the nematic phase is more thermodynamically stable, when the admixture molecular length is compatible to that of the mesogenic solvent, regardless of the polarity of the admixture molecules. The activation energy for freely flowing mixtures in the isotropic, nematic, and two-phase I + N regions was determined and discussed.
    Źródło:
    Acta Physica Polonica A; 2006, 109, 6; 723-730
    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:
    Temperature Dependence of the Viscosity of Isotropic Liquids
    Autorzy:
    Jadżyn, J.
    Czechowski, G.
    Lech, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/2030494.pdf
    Data publikacji:
    2002-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    66.20.+d
    83.85.Jn
    Opis:
    Temperature dependence of the shear viscosity measured for isotropic liquids belonging to the three homologous series: 4-(trans-4'-n-alkylcyclohexyl) isothiocyanatobenzenes (C$\text{}_{n}$ H$\text{}_{2n+1}$ CyHx Ph NCS; nCHBT, n=0÷12), n-alkylcyanobiphenyls (C$\text{}_{n}$H$\text{}_{2n+1}$ Ph Ph CN; nCB, n=2÷12) and 1,n-alkanediols (HO(CH$\text{}_{2}$)$\text{}_{n}$OH; 1,nAD, n=2÷10) were analysed with the use of Arrhenius equation and its two modifications: Vogel-Fulcher and proposed in this paper. The extrapolation of the isothermal viscosity of 1,n-alkanediols (n=2÷10) to n=1 leads to an interesting conclusion concerning the expected viscosity of methanediol, HOCH$\text{}_{2}$OH, the compound strongly unstable in a pure state.
    Źródło:
    Acta Physica Polonica A; 2002, 101, 4; 495-503
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Singular Pretransitional Behavior of the Electric Field-Dependent Part of the Thermodynamic Quantities of Strongly Polar Mesogenic Liquids in the Isotropic Phase
    Autorzy:
    Jadżyn, J.
    Déjardin, J.-L.
    Czechowski, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/2047352.pdf
    Data publikacji:
    2007-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Md
    65.40.Gr
    77.22.Ch
    Opis:
    A new interpretation of the pretransitional temperature behavior of the static dielectric permittivity and its derivative in terms of the basic thermodynamic quantities: the internal energy, the entropy, and the Helmholtz free energy is presented. It was shown that in the case of strongly polar mesogenic compounds (as the homologous series of alkylcyanobiphenyls) the electric field-induced increments of both the internal energy and the entropy exhibit a critical-like temperature dependence in the vicinity of transition from the isotropic liquid to the nematic phase. As a most important pretransitional effect, it is shown that at a temperature of about 10 degrees before the phase transition, an electric field applied to the isotropic liquids induces an increase in the entropy (Δ S>0) instead of its decrease, as observed far from the phase transition or for the non-mesogenic dipolar liquids.
    Źródło:
    Acta Physica Polonica A; 2007, 111, 6; 877-884
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Prenematic Self-Assembling of Mesogenic Molecules in Isotropic Liquid and Orientational Order in Nematic Phase
    Autorzy:
    Wolarz, E.
    Bauman, D.
    Jadżyn, J.
    Dąbrowski, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1493609.pdf
    Data publikacji:
    2011-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    42.70.Df
    61.30.Gd
    77.22.Ch
    Opis:
    Dielectric relaxation study of nematogenic 4-n-alkyl-4'-cyanobiphenyls (nCB, n = 5, 6), 4-(trans-4'-n-alkylcyclohexyl)isothiocyanatobenzenes (nCHBT, n = 6, 8), 4-cyanophenyl-4'-n-alkylbenzoates (nCPB, n = 6, 8), 4-cyano-3-fluorophenyl-4'-n-octyloxybenzoate (8OCFPB), and 4-cyanophenyl-4'-n-octyloxy-3'-fluorobenzoate (8OCPFB) was performed in the frequency range from 50 kHz to 100 MHz in the nematic and isotropic phases. The static permittivity and the relaxation process related to the rotation of molecules around their short axis was analyzed. For some of these liquid crystals anomalous temperature dependence of static permittivity in the pretransitional region of the isotropic phase was observed. Based on the Meier-Saupe-Martin model of molecular diffusion in nematics, the orientational order parameter 〈$P_2$〉 was determined from dielectric relaxation times and retardation factor. The values of 〈$P_2$〉 calculated from the dielectric relaxation data were compared with the results obtained from measurements of polarized electronic absorption. Correlations between the magnitude of the dielectric pretransitional effect and the orientational order in the nematic phase were discussed.
    Źródło:
    Acta Physica Polonica A; 2011, 120, 3; 447-454
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dielectric Relaxation of 4-Cyanophenyl 4-n-Decyloxybenzoate in the Isotropic, Nematic, and Smectic A Phases
    Autorzy:
    Ginovska, M.
    Czechowski, G.
    Andonovski, A.
    Jadżyn, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2014555.pdf
    Data publikacji:
    2000-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Md
    77.84.Nh
    77.22.Gm
    Opis:
    The paper presents the results of the dielectric relaxation study performed for the isotropic, nematic, and smectic A phases of 4-cyanophenyl 4'-n-decyloxybenzoate (C$\text{}_{10}$H$\text{}_{21}$O-Ph-COO-Ph-C≡ N, CP10DB) in the frequency range from 100 kHz to 100 MHz. In the nematic and smectic A phases the permittivity was measured with the probing electric field E parallel to the macroscopic molecular orientation (the director n). The recorded dielectric spectra correspond to the rotation of CP10DB molecules around the short axis and can be quite well described in the framework of the Debye model. It was found that the values of the activation energy for the molecular reorientations in the isotropic and smectic A phases of CP10DB are quite close to each other, whereas in the nematic phase the energy is remarkably higher.
    Źródło:
    Acta Physica Polonica A; 2000, 98, 6; 715-720
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dynamics of Nematogenic Molecules with Transverse Component of Dipole Moment
    Autorzy:
    Douali, R.
    Czechowski, G.
    Legrand, Ch.
    Jadżyn, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2037273.pdf
    Data publikacji:
    2004-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Md
    77.84.Nh
    77.22.Gm
    Opis:
    The paper presents the results of studies of the dielectric relaxation of nematic 4'-butyloxy-3-fluoro- 4-isothiocyanatotolane, performed for different values of the angle between the probing electric field E and the macroscopic orientation of the sample (the director n) forced by the magnetic field B. Due to a relatively large transverse component of the dipole moment of 4'-butyloxy- 3-fluoro-4-isothiocyanatotolane, the studies allowed one to interpret consistently the dielectric relaxation spectra connected with the molecular rotation around the long axis.
    Źródło:
    Acta Physica Polonica A; 2004, 105, 4; 365-371
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dielectric Relaxation in Hydrogen Bonded Urea-Based Supramolecular Polymer N,N-di(2,2-dipentylheptyl)urea
    Autorzy:
    Jadżyn, J.
    Bouteiller, L.
    Déjardin, J.-L.
    Czechowski, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/2047092.pdf
    Data publikacji:
    2006-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.82.Pv
    77.22.Gm
    81.16.Fg
    82.30.Rs
    Opis:
    Results of the dielectric relaxation studies, performed for supramolecular polymer formed by N,N'-di(2,2-dipentylheptyl)urea dissolved in carbon tetrachloride, are presented. The measurements were done for N,N'-di(2,2-dipentylheptyl)urea concentration up to about 7% (in mole fraction) in the frequency region from 100 kHz to 100 MHz and at the temperatures from 5ºC to 50ºC. The analysis of the experimental data were performed with the Havriliak-Negami equation. In the studied range of N,N'-di(2,2-dipentylheptyl)urea concentration and temperature, the obtained values of exponentsα andβ of the Havriliak-Negami equation are equal to 0.9±0.1 and 0.7±0.1, respectively, showing an anomaly in the dielectric relaxation behavior close to the Davidson-Cole type. Two examples of the modeling of dielectric properties of the supramolecular polymer solutions were presented.
    Źródło:
    Acta Physica Polonica A; 2006, 110, 4; 495-504
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modeling of the Viscosity Behavior in the Interface Area of Two Miscible Liquids
    Autorzy:
    Szwajczak, E.
    Stragaczyński, R.
    Herba, H.
    Świergiel, J.
    Jadżyn, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1808026.pdf
    Data publikacji:
    2009-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    65.20.-w
    66.20.Ej
    83.85.Vb
    Opis:
    The paper presents the results of the share viscosity (η) investigations performed for binary mixtures composed of the liquids of extremely different viscosities: a high-viscous α-tocopherol acetate (η ≈ 10 Pa s) is mixed with 4-n-propylcyclohexyl-4'-n-pentylphenyl (η ≈ 10 mPa s) and mesitilene (η ≈ 1 mPa s), the two low-viscous solvents composed of the non-polar molecules of an essentially different shape. It was found that the viscosities of the mixtures, disregarding the molecular shape of the non-polar admixture, exhibit a strong nonlinear dependence on tocopherol mole fraction and, at a given temperature, the dependence can be described with an exponential function. For a constant tocopherol concentration in the mixtures, the viscosity temperature dependences are well described with the Vogel-Fulcher-Tammann relation. The results can be considered as a model of the viscosity behavior related to the laminar flow of miscible liquids of a different viscosity being in contact to each other.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 5; 905-908
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Molecular Dynamics of 4-(trans-4-n-Heptylcyclohexyl)- Isothiocyanatobenzene Studied with Dielectric Relaxation Spectroscopy
    Autorzy:
    Bauman, D.
    Czechowski, G.
    Jadżyn, J.
    Legrand, C.
    Douali, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/2014055.pdf
    Data publikacji:
    2000-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Md
    77.84.Nh
    77.22.Gm
    Opis:
    Dielectric relaxation study was carried out for the nematic and isotropic phases of 4-(trans-4'-n- heptylcyclohexyl)isothiocyanatobenzene in the frequency range from 100 kHz to 1 GHz. In the nematic phase two relaxation processes were recorded for the electric permittivity component measured parallel to the molecular orientation (director n) and three relaxation processes - for the perpendicular permittivity component. The strength of the nematic potential and the nematic order parameter were estimated.
    Źródło:
    Acta Physica Polonica A; 2000, 98, 1-2; 71-81
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study of Magnetic Fredericksz Transition in Ferronematics
    Autorzy:
    Kopčanský, P.
    Koneracká, M.
    Jadżyn, J.
    Czechowski, G.
    Żywucki, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/1964799.pdf
    Data publikacji:
    1997-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Md
    61.30.Gd
    Opis:
    The magnetic Fredericksz transition in ferronematics (thermotropic nematic liquid crystals 7CB and MBBA combined with fine magnetic particles of a size 10 nm) as a function of concentration of magnetic particles was studied by using simple dielectric measurements. The increase of the threshold magnetic field is observed in 7CB based ferronematic while the decrease of threshold field in MBBA based ferronematic is observed when the concentration of magnetic particles is increased. Experimental results are discussed in the framework of Brochard, de Gennes and Burylov, Raikher theories.
    Źródło:
    Acta Physica Polonica A; 1997, 92, 2; 437-440
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Gelation Process of Toluene-Based bis-Urea in Cyclohexane Studied with Magnetic Resonance Imaging
    Autorzy:
    Tritt-Goc, J.
    Boguszyńska, J.
    Szwaj, M.
    Boutellier, L.
    Jadżyn, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2043392.pdf
    Data publikacji:
    2005-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    82.70.Gg
    76.60.Pc
    82.56.Lz
    82.56.Na
    Opis:
    Magnetic resonance imaging was used for studies of the gelation and swelling processes of toluene-based bis-urea prepared in a form of cylindrical tablet and immersed in cyclohexane. The processes were investigated with the use of Bruker AVANCE (300 MHz) spectrometer equipped with a micro imaging probe head. The images were taken for cyclohexane protons within the bis-urea gel formed around the sample dry core at different intervals of the immersion. The mobility of the solvent molecules was estimated from the spatially resolved distribution of the spin-spin relaxation time T$\text{}_{2}$ and the spin densitiesρ, calculated on the basis of the images obtained. It was shown that the time-evolution of the thickness of the gel layer can be well described by the power equation with an exponent equal to 0.47 (±0.04), indicating the Fickian nature of the diffusion of cyclohexane molecules.
    Źródło:
    Acta Physica Polonica A; 2005, 108, 1; 81-87
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Anomalous Dielectric Relaxation in Binary Mixtures of Mesogenic Solvent/Non-Mesogenic Solute
    Autorzy:
    Jadżyn, J.
    Bauman, D.
    Déjardin, J. -L.
    Ginovska, M.
    Czechowski, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/2043683.pdf
    Data publikacji:
    2005-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.30.Eb
    64.70.Md
    87.15.Nn
    68.35.Rh
    83.10.Mj
    Opis:
    Dielectric relaxation studies for mixtures of strongly polar and mesogenic n-heptylcyanobiphenyl with non-polar and non-mesogenic carbon tetrachloride (CCl$\text{}_{4}$) were performed. The absorption band broadening due to fractional diffusion was observed. A correlation between the non-mesogenic admixture concentration and the anomalous diffusion exponent was found.
    Źródło:
    Acta Physica Polonica A; 2005, 108, 3; 479-489
    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:
    The Influence of Magnetic Particles on the Nematic Droplets Formation in Liquid Crystal
    Autorzy:
    Majorošová, J.
    Gdovinová, V.
    Tomašovičová, N.
    Juríková, A.
    Závišová, V.
    Jadzyn, J.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1032205.pdf
    Data publikacji:
    2017-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Mm
    61.30.Gd
    67.30.Hm
    Opis:
    In this work the thermotropic nematic liquid crystal 4-trans-4'-n-hexyl-cyclohexyl-isothiocyanato-benzene (6CHBT) was dissolved in phenyl-isothiocyanate and doped with spherical magnetic particles with volume concentration ϕ₁=10¯⁴ and ϕ₂=10¯³. The influence of the volume concentration on the phase transitions from isotropic to nematic phase was studied by three experimental methods: optical microscopy, differential scanning calorimetry, and dielectric measurements. The obtained results confirmed the coexistence of isotropic and nematic phase, i.e. nematic or ferronematic droplets in isotropic phase in a wide temperature range between nematic and isotropic phase.
    Źródło:
    Acta Physica Polonica A; 2017, 131, 4; 955-957
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Structural Phase Transitions in 6CB-Based Ferronematics
    Autorzy:
    Tomašovičová, N.
    Koneracká, M.
    Kopčanský, P.
    Timko, M.
    Závišová, V.
    Tomčo, L.
    Jadżyn, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1810567.pdf
    Data publikacji:
    2009-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Mm
    61.30.Gd
    61.30.Hn
    Opis:
    The structural transitions in ferronematics based on the thermotropic nematic liquid crystal 4-cyano-4'-hexylbiphenyl were studied. The ferronematic samples were prepared by doping with magnetic suspension consisting of $Fe_3O_4$ particles (10 nm in diameter) coated with oleic acid as a surfactant with different volume concentrations of magnetic particles (from $10^{-5}$ to $10^{-3}$). Freedericksz transitions were studied in combined electric and magnetic fields. The experimental results indicated soft anchoring with perpendicular initial orientation between the magnetic moment of the magnetic particles and director.
    Źródło:
    Acta Physica Polonica A; 2009, 115, 1; 336-338
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic Field Induced Structural Transitions in 6CHBT-Based Ferronematics
    Autorzy:
    Tomašovičová, N.
    Timko, M.
    Koneracká, M.
    Závišová, V.
    Jadżyn, J.
    Beaugnon, E.
    Chaud, X.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1428990.pdf
    Data publikacji:
    2012-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Mm
    61.30.Gd
    61.30.Hn
    Opis:
    Ferronematics are stable colloidal suspensions of magnetic particles in nematic liquid crystals. The presence of the magnetic particles enhances the magnetic susceptibility of ferronematics, in comparison with pure liquid crystals. In this work the thermotropic liquid crystal 4-(trans-4'-n-hexylcyclohexyl)-isothiocyanato-benzene (6CHBT) and 6CHBT dissolved in phenyl isothiocyanate were doped with spherical magnetic nanoparticles with aim to increase the sensitivity of the liquid crystal on an external magnetic field. The volume concentration of the magnetic particles was 5 × $10^{-4}$. The phase transition temperature from isotropic to nematic phase in the external magnetic field up to 12 T was monitored by precise capacitance measurements in the capacitance cells filled with nematic sample as well as with the prepared ferronematic sample. There was no observable shift in the transition temperature in the case of pure 6CHBT, 6CHBT doped with spherical particles and 6CHBT dissolved in phenyl isothiocyanate while in the case of 6CHBT dissolved in phenyl isothiocyanate doped with spherical magnetic particles the shift in the temperature about 9C of the phase transition from isotropic to droplet state at the external magnetic field 12 T was observed.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 5-6; 1276-1278
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetic-Field Induced Isotropic-Nematic Phase Transition in PDLC Doped with Magnetic Nanoparticles
    Autorzy:
    Mitróová, Z.
    Tomašovičová, N.
    Timko, M.
    Koneracká, M.
    Tomčo, L.
    Jadżyn, J.
    Palewski,, T.
    Kopčanský, P.
    Kovalchuk, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/1429068.pdf
    Data publikacji:
    2012-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.30.Gd
    75.30.Hx
    75.75.Fk
    77.84.Nh
    Opis:
    The paper presents a study of the polymer dispersed liquid crystals that consist of liquid crystal 4-trans-4'-n-hexyl-cyclohexyl-isothiocyanatobenzene (6CHBT) microdroplets dispersed in polyvinyl alcohol and doped with various kinds of magnetic particles. As magnetic nanoparticles there were used single walled carbon nanotubes and magnetite labeled single walled carbon nanotubes. The volume concentration of the particles was 2 × $10^{-3}$. Magnetic properties were investigated by a SQUID magnetometer. The higher saturation magnetization has been achieved in sample polymer dispersed liquid crystal doped with magnetite labeled single walled carbon nanotubes. The phase transition temperature from isotropic to nematic phase at the external magnetic field 0 T and 12 T was monitored by precise capacitance measurements in the capacitance cell filled with prepared sample. The significant shift of the phase transition temperature (0.2°C) at the external magnetic field 12 T has been observed in sample polymer dispersed liquid crystal doped with magnetite labeled single walled carbon nanotubes.
    Źródło:
    Acta Physica Polonica A; 2012, 121, 5-6; 1299-1301
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sensitivity of 6CHBT Liquid Crystal Doped with Ferroelectric or Magnetic Particles to Electric and Magnetic Fields
    Autorzy:
    Majorošová, J.
    Tomašovičová, N.
    Timko, M.
    Koneracká, M.
    Studenyak, I.
    Kovalchuk, O.
    Kovalchuk, S.
    Jadżyn, J.
    Kopčanský, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1368661.pdf
    Data publikacji:
    2014-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Mm
    61.30.Gd
    64.70.Md
    Opis:
    Introduction of ferroelectric or magnetic nanoparticles into nematic liquid crystal is a promising method for the improvement of the electro-optic or magneto-optic properties of different nematic liquid crystals by non-chemical way. This work is devoted to the study of composite systems of liquid crystal with spherical ferroelectric or magnetic particles with the aim to study their sensitivity to electric and magnetic fields. The nematic 4-(trans-4'-n-hexylcyclohexyl)-isothiocyanatobenzene (6CHBT) liquid crystal was doped with SbSI ferroelectric particles or with $Fe_{3}O_{4}$ magnetic particles. The structural transitions in ferronematic samples were indicated by capacitance measurements in a capacitor made of ITO-coated glass electrodes in combined electric and magnetic fields. The obtained results showed the increase of the shift in critical voltage with increasing magnetic field in both kinds of samples.
    Źródło:
    Acta Physica Polonica A; 2014, 126, 1; 260-261
    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:
    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
    Tytuł:
    The Anchoring Energy of Liquid Crystal Molecules to Magnetic Particles in HAB-Based Ferronematics
    Autorzy:
    Tomašovičová, N.
    Koneracká, M.
    Kopčanský, P.
    Timko, M.
    Závišová, V.
    Vajda, A.
    Fodor-Csorba, K.
    Éber, N.
    Tóth-Katona, T.
    Jadzyn, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1813941.pdf
    Data publikacji:
    2008-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Mm
    61.30.Gd
    61.30.Hn
    Opis:
    In this work we describe the magnetic Freedericksz transition in HAB-based (4, 4'-di-n-heptylazoxybenzene) ferronematics. The ferronematic samples were prepared with two different volume concentrations of magnetic particles $φ_1 = 2×10^{-5}$ and $φ_2 = 2×10^{-4}$. The liquid crystal HAB is nematic at the temperatures from ≈53°C to 70°C and smectic A at the temperatures under 53°C. The anisotropy of dielectric permitivity of HAB liquid crystal is positive in nematic phase and negative in smectic A phase. The magnetic Fredericksz transition was studied in nematic phase at temperature 60°C.
    Źródło:
    Acta Physica Polonica A; 2008, 113, 1; 591-594
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Structural Phase Transition in Liquid Crystal Doped with Gold Nanoparticles
    Autorzy:
    Kopčanský, P.
    Tomašovičová, N.
    Koneracká, M.
    Timko, M.
    Mitróová, Z.
    Závišová, V.
    Éber, N.
    Fodor-Csorba, K.
    Tóth-Katona, T.
    Vajda, A.
    Jadzyn, J.
    Beaugnon, E.
    Chaud, X.
    Powiązania:
    https://bibliotekanauki.pl/articles/1535052.pdf
    Data publikacji:
    2010-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Mm
    61.30.Gd
    61.30.Hn
    Opis:
    The influence of the inclusion of the dodecanethiol functionalized gold particles (with diameter 3-5 nm) on the structural transitions was investigated. The studied samples were based on the nematic liquid crystal 4-(trans-4'-n-hexylcyclohexyl)-isothiocyanatobenzene (6CHBT). The volume concentration of the gold particles was $ϕ_1 = 2 × 10^{-4}$ and $ϕ_2 = 10^{-3}$. The obtained results showed that the inclusion of the gold particles in the 6CHBT liquid crystal increases the sensitivity of such system on the external magnetic field.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 5; 988-989
    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
      Wyświetlanie 1-29 z 29

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