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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
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:
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:
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:
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:
Radiation Stability of the BSA Modified Biocompatible Magnetic Fluid
Autorzy:
Tomašovičová, N.
Haysak, I.
Kováč, J.
Kubovčíková, M.
Závišová, V.
Timko, M.
Okunev, A.
Zorkovská, A.
Kopčanský, P.
Powiązania:
https://bibliotekanauki.pl/articles/1368667.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Mm
61.30.Gd
64.70.Md
Opis:
The aim of the presented work was to investigate the stability of biocompatible magnetic fluid, i.e. water-based magnetic fluid containing magnetite nanoparticles stabilized by surfactant sodium oleate and modified by bovine serum albumin (BSA) after electron irradiation. Samples with the same concentration of $Fe_{3}O_{4}$ but different mass ratio BSA/$Fe_{3}O_{4}$ (w/w=0.25, 1.0 and 2.5) were studied. The electron irradiation caused about 10% reduction of the saturation magnetization in the samples with w/w BSA/$Fe_{3}O_{4}$ ratio of 0.25 and less than 5% in the samples with w/w BSA/$Fe_{3}O_{4}$ ratio of 1 and 2.5.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 262-263
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural Changes in Liquid Crystals Doped with Rod-Like Magnetic Particles Studied by Surface Acoustic Waves
Autorzy:
Bury, P.
Veveričík, M.
Kúdelčík, J.
Kopčanský, P.
Timko, M.
Závišová, V.
Powiązania:
https://bibliotekanauki.pl/articles/1032787.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.Gd
75.50.Mm
43.35.Bf
Opis:
The effect of rod-like magnetic particles on liquid crystal (6CHBT) structural changes in electric and weak magnetic fields were studied by means of the attenuation of surface acoustic wave of frequency 30 MHz propagating along ferronematic liquid crystals. Three low volume concentrations (Φ=1×10¯⁵, 1×10¯⁴ and 1×10¯³) of rod-like magnetic particles were added to liquid crystal during its isotropic phase. Several measurements including the investigation of the effects of electrical and magnetic fields applied both separately and in conjunction as well as the influence of temperature on the surface acoustic wave attenuation were performed. The distinctive surface acoustic wave attenuation responses induced by both electric and magnetic fields in studied ferronematic liquid crystals have been observed suggesting both structural changes and the orientational coupling between magnetic moments of magnetic particles and the director of the liquid crystal. Obtained results confirmed the significant influence of the presence of magnetic particles on the structural properties and resulting behavior of 6CHBT liquid crystal.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 913-915
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:
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
    Wyświetlanie 1-10 z 10

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