Temat: 77.22.Ch - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Complex Dielectric Coefficient of Breast Phantom Prepared for Breast Cancer Detection
Autorzy:: Sayinti, A.
Açikalin, E.
Çoban, K.
Vertii, A.
Tematy:: 77.22.Ch; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1400036.pdf Link otwiera się w nowym oknie
Opis:: Microwave measurement techniques attract attention due to its practical solutions in breast cancer imaging. Early detection of cancer is the purpose of these imaging studies. For these imaging processes, phantoms which reflect the properties of the area to be imaged are produced. The produced homogeneous phantoms are imaged by stepper frequency of radar technology, as the narrow bands are used for heterogeneous mixtures. Phantoms are used since 70's until today. Different methods are experimented for producing phantoms of tissue, muscle, fat, skin, etc. Iron powder, polymer materials, various oils and gelatins used today are the materials used for producing the phantoms. In this study, phantom breast imaging is aimed. Phantoms breast and breast tumor samples are created. For phantoms and tumor samples, reflection and transmittion measurements are done with Network Analyzer in X-Band (8.2-12.4 GHz). Complex permittivity is calculated with Agilent 85071 Material Measurement Software-Fast Method (NIST-iterative method). It was considered breast phantom with tumor model for 3D imagine at 2-3.5 GHz frequency range.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Dielectric Properties of Triglycine Sulphate Crystals Admixtured with L-Threonine
Autorzy:: Czarnecka, A.
Stankowska, J.
Mielcarek, S.
Tematy:: 77.22.Ch; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1931325.pdf Link otwiera się w nowym oknie
Opis:: The influence of L-threonine admixture on the dielectric properties of triglycine sulphate (TGS) crystals was studied. With increasing concentration of the admixture in the solution from which the crystals were grown, their maximum permittivity and spontaneous polarization were found to decrease, their Curie point was found not much different than that for pure TGS crystals (322 K), the coercive field and bias field increased. The domain structure of the obtained crystals was also studied by the liquid crystal method.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Investigation of the Dependence of Dielectric Properties of D-Serine Admixtured TGS Crystals on the Distance from the Seed of the Crystal Growth
Autorzy:: Stankowska, J.
Czarnecka, A.
Dongo Gemi, Bangobango
Tematy:: 77.22.Ch; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1929193.pdf Link otwiera się w nowym oknie
Opis:: Dielectric properties of a D-serine admixtured triglycine sulphate (TGS) crystal were studied on samples cut out from different sites in the crystal. The value of spontaneous polarization P$\text{}_{s}$ measured on b-cuts was found to be independent of the site. Whereas the coercive field E$\text{}_{c}$ values were higher for the samples cut out closer to the seed than for those cut out at the ends of the crystal along b axis. After rejuvenation the values of the bias field E$\text{}_{b}$ increased in contrary to the effect observed in the pure TGS crystals. An exponentially decreasing dependence of the maximum permittivity ε$\text{}_{max}$ on the site of the samples (b-plates) cut out along b axis from -b to +b positions, was obtained.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Magnetic Resonance and Dielectric Studies of a Nonlinear La$\text{}_{3}$Ga$\text{}_{5.5}$Ta$\text{}_{0.5}$O$\text{}_{14}$ Single Crystal Doped with Erbium
Autorzy:: Bodziony, T.
Typek, J.
Orlowski, M.
Majszczyk, J.
Wabia, M.
Berkowski, M.
Ryba-Romanowski, W.
Guskos, N.
Likodimos, V.
Anagnostakis, E. A.
Tematy:: 76.30.Kg
77.22.Ch; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2035732.pdf Link otwiera się w nowym oknie
Opis:: Single crystal of erbium doped La$\text{}_{3}$Ga$\text{}_{5.5}$Ta$\text{}_{0.5}$O$\text{}_{14}$ grown by the Czochralski method have been investigated by electron paramagnetic resonance and dielectric spectroscopy methods. Dielectric permittivity ε measurements performed in 90-440 K temperature range have shown negligible dispersion for 1 kHz - 1 MHz frequencies and a Curie-Weiss type behaviour with C=47700 K andθ=-340 K. Electron paramagnetic resonance studies have revealed the presence of two different paramagnetic, monoclinic centres. The calculated g factor values are: g$\text{}_{1}$=1.449, g$\text{}_{2}$=11. 534, g$\text{}_{3}$=4.24 for the main M$\text{}_{1}$ centre and g$\text{}_{1}$=1.98, g$\text{}_{2}$=4.169, g$\text{}_{3}$=4.25 for the weaker M$\text{}_{2}$ centre. The temperature dependence of EPR line intensity for centre M$\text{}_{1}$ and M$\text{}_{2}$ is quite different - while lines attributed to M$\text{}_{1}$ could only be observed at low temperatures, below 20 K, lines of M$\text{}_{2}$ centre persisted up to 200 K. The M$\text{}_{1}$ centre is connected with Er$\text{}^{3+}$ ion entering substitutionally into La$\text{}^{3+}$ site, while M$\text{}_{2}$ is probably connected with 3d ions at the same site, unintentionally introduced into the material as an admixture.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

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: 6.

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: 7.

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: 8.

Tytuł:: Dielectric and AC Conductivity οf Potassium Perchlorate, $KCLO_{4}$
Autorzy:: Abdelmoneim, H.
Tematy:: 72.80.Ph
77.22.Ch
77.84.Bw; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1537744.pdf Link otwiera się w nowym oknie
Opis:: The AC conductivity σ (ω) and the complex dielectric permittivity ε*(ω) were studied as function of temperature 300 K < T < 600 K and at some selected frequencies (1-20 kHz) for polycrystalline sample of $KClO_4$. The differential thermal analysis (DTA) thermograph was also performed. The combined data support each other and indicate the existence of a structural phase transition at ≈ 575 K. Moreover, the temperature dependence of the ac conductivity behaves in accordance with Arrhenius relation, whereas the frequency dependent conductivity obeys the power law $σ(ω) = Aω^{s(T)}$. The behavior of s with temperature suggests that the hopping over the barrier model prevails. No evidence for the existence of a ferroelectric phase transition at the transition temperature.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Dielectric and Birefringent Properties of [(CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$]$\text{}_{5}$Cd$\text{}_{2}$CuCl$\text{}_{11}$ Solid Solutions in the Region of Their Phase Transitions
Autorzy:: Eliyashevskyy, Yu.
Kapustianyk, V.
Dacko, S.
Czapla, Z.
Batiuk, A.
Sveleba, S.
Tematy:: 65.40.-b
77.22.Ch; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2044636.pdf Link otwiera się w nowym oknie
Opis:: On the basis of the optical and dielectric investigations of [(CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$]$\text{}_{5}$Cd$\text{}_{2}$CuCl$\text{}_{11}$ solid solutions the existence of phase transitions at T$\text{}_{1}$=175 K and T$\text{}_{2}$=117.5 K was confirmed. Both phase transitions were found to be shifted toward lower temperatures with respect to the corresponding transitions in the "host" [(CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$]$\text{}_{5}$Cd$\text{}_{3}$Cl$\text{}_{11}$ crystals. It was found that the proton conductivity in [(CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$ ]$\text{}_{5}$Cd$\text{}_{2}$CuCl$\text{}_{11}$ crystals is realized through the Grotthus mechanism. The investigations of the birefringent properties confirmed existence of the structural changes at T$\text{}_{0}$=320 K connected with the complex co-operative effect involving weakening of the hydrogen bonds and modification of the Jahn-Teller distortion with temperature.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Electric relaxation in Nb₆VSb₃O₂₅-ceramics
Autorzy:: Groń, T.
Filipek, E.
Piz, M.
Kukuła, Z.
Pawlus, S.
Tematy:: 77.22.Ch
77.22.Gm
77.84.Bw; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1070621.pdf Link otwiera się w nowym oknie
Opis:: Broadband dielectric spectroscopy measurements of Nb₆VSb₃O₂₅ showed that in both the real (ε') and imaginary (ε'') components of permittivity there is visible relaxation process strongly obscured by dc conductivity. Application of the electric modulus representation of the data enables to study temperature evolution of this relaxation together with conductivity relaxation. It was showed that the activation energies for both processes are close. Low-frequency loss tangent increases strongly with temperature, suggesting that in the compound under study additional energy losses are associated with the conduction of electric current, as determined by the Joule-Lenz law.
Dostawca treści:: Biblioteka Nauki

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