Temat: 77.22.Gm - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Dynamics of the Molecules in Solid Phases of Few Chosen Schiff Bases Compounds
Autorzy:: Bąk, A.
Massalska-Arodź, M.
Tematy:: 64.70.Md
77.22.Gm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2037298.pdf Link otwiera się w nowym oknie
Opis:: The dielectric relaxation processes observed in solid phases of MBBA, OH-MBBA, and EBBA belonging to the homologous series of the Schiff bases are discussed. The data are compared with the results completed by the present authors for EBPA compound. The uniform interpretation of the temperature changes of relaxation for all mentioned compounds is proposed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Dielectric Spectroscopy Studies of 4-Cyano-3-fluorophenyl 4-Butylbenzoate Liquid Crystal at High Pressure
Autorzy:: Rozwadowski, T.
Massalska-Arodź, M.
Juszyńska, E.
Krawczyk, J.
Wojnarowska, Ż.
Paluch, M.
Tematy:: 64.70.M-
77.22.Gm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1419574.pdf Link otwiera się w nowym oknie
Opis:: For 4-cyano-3-fluorophenyl 4-butylbenzoate, nematic glassformer at ambient pressure, dielectric relaxation studies were performed under elevated pressure. In the isobaric experiment, on cooling the nematic phase two superarrhenius α-relaxations, ascribed to the reorientations of molecules around short axes and precession of long molecular axes were found and the Arrhenius β-relaxation related to intramolecular motions. Complexity of dynamics at elevated and ambient pressure is similar. Shift towards lower frequencies was found for both α-relaxations.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Measurement of Complex Permittivity of Oil-Based Ferrofluid in Magnetic Field
Autorzy:: Kúdelčík, J.
Hardoň, Š.
Varačka, L.
Tematy:: 47.65.Cb
77.22.Gm
77.22.Ch; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1030262.pdf Link otwiera się w nowym oknie
Opis:: The changes of dielectric parameters in oil-based ferrofluid have been measured in an external magnetic field. The frequency dependent real permittivity and the dissipation factor were measured within the frequency ranges from 1 mHz to 2 MHz by a capacitance method. These parameters have been studied in combined electric and magnetic field, when fields were parallel and perpendicular. The Cole-Cole model has been used to analyze measured data. When a magnetic field was applied, the interaction between the magnetic field and magnetic moments of nanoparticles led to the aggregation of magnetic nanoparticles to new structures - thick chains which had influence on the value of dielectric permittivity. At constant magnetic field the dependence of real permittivity and tanδ on angle between the electric and magnetic field (anisotropy) were measured, too. The various influences of magnetic field development on the investigated liquid are discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Magnetodielectric Properties of Transformer Oil Based Magnetic Fluids
Autorzy:: Timko, M.
Kopcansky, P.
Molcan, M.
Tomco, L.
Marton, K.
Molokac, S.
Rybar, P.
Stoian, F.
Holotescu, S.
Taculescu, A.
Tematy:: 47.65.Cb
77.22.Gm
77.22.Ch; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1428655.pdf Link otwiera się w nowym oknie
Opis:: This contribution is devoted to study of dielectric and magnetodielectric properties in transformer oil based magnetic fluid. The dielectric permittivity and their anisotropy at various mutual orientation electric (50 Hz) and magnetic field were shown at the different volume concentrations of nanoparticles at room temperature. The linear increase of dielectric constant with volume concentration was confirmed which is in good agreement with the theoretical Maxwell prediction. The dielectric anisotropy factor g(B, ω) is very close to g=1. The values of permittivity increased with the increase of volume fraction of magnetite nanoparticles. The highest value of anisotropy characterized by deviation of permittivity $Δε=ε_{∥} - ε_{⊥}$ was found for the highest volume concentration which could mean that no aggregation of magnetite nanoparticles had appeared.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Kinetic Theory of the Langevin Saturation in Dilute Solution of Dipolar Symmetric-Top Molecules in Spherical Solvents
Autorzy:: Alexiewicz, W.
Grygiel, K.
Tematy:: 05.40.Jc
77.22.-d
77.22.Gm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1812031.pdf Link otwiera się w nowym oknie
Opis:: Assuming the low molecular reorientation approximation, the formulae for the third-order electric polarization induced in liquids composed of rigid noninteracting dipolar, symmetric-top molecules in spherical solvents were derived. Our medium is acted on by a strong external dc bias electric field superimposed on a weak ac electric field, and the classical Smoluchowski-Debye equation for rotational diffusion of the symmetric-top molecules is applied. In order to highlight the influence of the anisotropy of rotational diffusion tensor components and the orientation of permanent dipole moment of the molecule on the complex linear and nonlinear electric susceptibilities, we present three-dimensional plots of the linear and nonlinear dispersion and absorption spectra, for different values of the frequency of ac electric field.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Dielectric Relaxation Phenomena in SBN Single Crystals Doped with Ce
Autorzy:: Korchak, Yu.
Kapustianyk, V.
Fedor, B.
Girnyk, I.
Eliyashevskyi, Yu.
Tematy:: 77.22.-d
77.22.Ch
77.22.Gm
77.80.Jk; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1505140.pdf Link otwiera się w nowym oknie
Opis:: The dielectric study of $Sr_{0.73}Ba_{0.27}Nb_2O_6:Ce$ (SBN) crystals along [010] crystallographic axis was performed in the temperature region of 310-360 K and frequency range from 25 Hz up to 1 MHz. The thermal dipole relaxation of quasi-Debye-type for this orientation of sample was observed in both investigated structural phases. The phase transition was most clearly seen from the temperature dependence of the relaxation time at $T_{c}$ = 320 K. The relaxation processes were related to the collective oscillations of the Nb-O bonds in the two different type corner-sharing $NbO_6$ octahedra aligned along c-axis.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Terahertz Spectroscopy of Ordered $PbSc_{1//2}Nb_{1//2}O_3$ Ceramics
Autorzy:: Macutkevič, J.
Adomavičius, R.
Krotkus, A.
Valušis, G.
Grigalaitis, R.
Banys, J.
Bormanis, K.
Sternberg, A.
Tematy:: 77.22.Gm
77.80.-e
77.80.Bh; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1813210.pdf Link otwiera się w nowym oknie
Opis:: The ordered $PbSc_{1//2}Nb_{1//2}O_3$ ceramics were studied by THz transmission spectroscopy in the temperature range of 80-300 K. Below ferroelectric phase transition temperature the strength of central mode gradually decreases and gives evidence for a mixed displacive and order-disorder character of the transitions. Ferroelectric phase transition is connected with an abrupt freezing and rise of polar nanoregions into ferroelectric domains.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: The Positive Temperature Coefficient of Resistivity Effect in the $Pb(Fe_{1//2}Nb_{1//2})O_{3}$ Ceramics Admixed with Lithium
Autorzy:: Bochenek, D.
Tematy:: 77.80.-e
77.80.Bh
77.22.Gm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1795785.pdf Link otwiera się w nowym oknie
Opis:: In the paper technological conditions were looked for to obtain the $Pb(Fe_{1//2}Nb_{1//2})O_{3} (PFN) ceramics and the PFN ceramics with the lithium admixture with the highest electric conduction and conditions appropriate for the PTC-R effect formation. Measurements of dc electrical resistivity, dielectric permittivity and dielectric loss were made as functions of temperature from room temperature to 190°C, at 1 kHz. The best set of values of dielectric loss and dielectric constant, from the ferroelectricity point of view, were obtained when the precursor with orthorhombic structure was employed. By creating appropriate technological conditions in the PFN ceramics the PTC-R effect can occur above the Curie temperature. Their electric properties are determined by presence of a basic phase of the potential barrier on the grain boundaries.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Anomalous Dielectric Spectra of Ferro- and Ferrielectric Liquid Crystalline Phase in MHPNBC
Autorzy:: Dubois, F.
Douali, R.
Wawrzyniak, A.
Legrand, Ch.
Ropa, P.
Wróbel, S.
Dąbrowski, R.
Tematy:: 77.22.Gm
77.84.Nh
64.70.M; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1399013.pdf Link otwiera się w nowym oknie
Opis:: MHPOBC analogue with long achiral alkyl chain has been investigated by dielectric spectroscopy studies in the wide temperature range. Low frequency dielectric spectroscopy revealed the existence of normal ferroelectric phase (in a narrow gap), two ferri- and three antiferroelectric phases in addition to paraelectric phase and alpha sub-phase. The compound studied shows exceptionally strong dependence of the dielectric permittivities on measuring electric field in the temperature range of ferro- and ferrielectric phases.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Dielectric Properties of Liquid Crystalline Isothiocyanato-tolane Derivatives with Fluorine Atom at Various Lateral Positions
Autorzy:: Czub, J.
Urban, S.
Dąbrowski, R.
Gestblom, B.
Tematy:: 64.70.Md
77.22.Gm
77.84.Nh; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2043376.pdf Link otwiera się w nowym oknie
Opis:: Dielectric studies were performed for several isothiocyanato-tolane compounds having the F atom attached to the benzene rings at different lateral positions and the alkoxy or alkyl chain at the p-position. They form the nematic phase in broad temperature intervals. The static as well as dynamic properties of the compounds in the nematic and isotropic phases were studied. Tensor permittivity components: ε$\text{}_{ǁ}$, ε$\text{}_{⊥}$, Δε, as functions of temperature were measured. The complex dielectric permittivity, ε$\text{}^{*}$(f)=ε'(f)-iε''(f), was measured in the frequency range of 1 kHz - 3 GHz from which the relaxation times τ$\text{}_{ǁ}$ and τ$\text{}_{⊥}$ were calculated. The order parameter S(T) was determined from the dielectric data. It was found that the close vicinity of the F atom and the alkoxy group results in blocking of the internal rotation of the wing around the O-phenyl bond.
Dostawca treści:: Biblioteka Nauki

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