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    Wyświetlanie 1-29 z 29
    Tytuł:
    Quadrupole Relaxation of $\text{}^{79}$Br Nuclei in Ferroelectric (CH$\text{}_{3}$)$\text{}_{4}$NCdBr$\text{}_{3}$ (TMCB)
    Autorzy:
    Baisa, D. F.
    Chesnokov, E. D.
    Czapla, Ż.
    Powiązania:
    https://bibliotekanauki.pl/articles/1931611.pdf
    Data publikacji:
    1994-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    Opis:
    Investigations of temperature dependence of a nuclear quadrupole spin-lattice relaxation time of $\text{}^{79}$Br nuclei in ferroelectric (CH$\text{}_{3}$)$\text{}_{4}$NCdBr$\text{}_{3}$ are presented. It is shown that in paraelectric phase in the vicinity of phase transition temperature relaxation process is determined by critical fluctuations of electric field gradient. In ferroelectric phase relaxation is related to three different mechanisms, namely: lattice vibrations, CH$\text{}_{3¯}$ group reorientations and TMA cation motions. According to the results of measurements it is concluded that the phase transition is connected with ordering of TMA cations.
    Źródło:
    Acta Physica Polonica A; 1994, 86, 3; 357-361
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Studies of Permittivity in the Triglicinium Sulphate Crystals Doped with Chromium Ions as a Function of Temperature and Electric Field
    Autorzy:
    Dziedzic, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2014251.pdf
    Data publikacji:
    2000-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    Opis:
    Permittivity in the triglicinium sulphate crystals doped with chromium ions Cr$\text{}^{3+}$ as a function of temperature and of intensity of electric field polarising the crystal was investigated. On the base of thermodynamical theory, the relationship among permittivity, temperature and electric field intensity was calculated. Coefficients of the expansion of the thermodynamic potential were determined. Experimental results were compared with those resulting from the thermodynamical theory.
    Źródło:
    Acta Physica Polonica A; 2000, 98, 4; 373-381
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Ferroelectric Phase Transition in DC Electric Field in [NH$\text{}_{2}$(CH$\text{}_{3}$)$\text{}_{2}$]$\text{}_{3}$Sb$\text{}_{2}$Cl$\text{}_{9}$ Crystals
    Autorzy:
    Dziedzic, J.
    Mróz, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2047351.pdf
    Data publikacji:
    2007-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    Opis:
    Dielectric investigations of ferro-paraelectric phase transition under influence of bias pooling DC electric field ranging from 0 to 500 kV/m were performed for [NH$\text{}_{2}$(CH$\text{}_{3}$)$\text{}_{2}$]$\text{}_{3}$Sb$\text{}_{2}$Cl$\text{}_{9}$. The linear shift of T$\text{}_{c}$ towards higher temperatures was observed. The A$\text{}_{0}$ and B coefficients from the Landau state equation are determined.
    Źródło:
    Acta Physica Polonica A; 2007, 111, 6; 873-876
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dielectric Properties of the (CH$\text{}_{3}$NH$\text{}_{3}$)$\text{}_{5}$Bi$\text{}_{2(1- x)}$Sb$\text{}_{2x}$Cl$\text{}_{11}$ Mixed Crystals
    Autorzy:
    Mróz, J.
    Dziedzic, J.
    Pykacz, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/2047087.pdf
    Data publikacji:
    2006-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    Opis:
    The (CH$\text{}_{3}$NH$\text{}_{3}$)$\text{}_{5}$Bi$\text{}_{2(1-x)}$Sb$\text{}_{2x}$Cl$\text{}_{11}$ crystals were examined from the point of view of their applicability in pyroelectric detectors. It was shown that they can be useful so far as the construction of infrared detectors is concerned due to high values of both their pyroelectric coefficient and figure of merit p/sqrtε which are both comparable with those of triglycine sulphate crystals.
    Źródło:
    Acta Physica Polonica A; 2006, 110, 4; 479-483
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nuclear Quadrupole Resonance Investigation of Phase Transition in Tetramethylammonium Cadmium Tribromide
    Autorzy:
    Baisa, D. F.
    Chesnokov, E. D.
    Czapla, Z. V.
    Pogrebnyak, S.
    Vertegel, I. G.
    Powiązania:
    https://bibliotekanauki.pl/articles/1929552.pdf
    Data publikacji:
    1993-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    Opis:
    The critical temperature dependence of the nuclear quadrupole- resonance $\text{}^{79}$Br frequencies at the phase transition (T$\text{}_{c}$ = 163 K) was found in (CH$\text{}_{3}$)$\text{}_{4}$NCdBr$\text{}_{3}$. It was concluded that bromine nuclei take part in the phase transition not directly but via the interaction with the crystal polarization.
    Źródło:
    Acta Physica Polonica A; 1993, 84, 2; 271-274
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Studies of Elastic Waves Propagation in Triglycine Sulphate Crystals Doped with Chromium Ions
    Autorzy:
    Dziedzic, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2029264.pdf
    Data publikacji:
    2001-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    Opis:
    Velocities and scattering of transverse elastic wave propagating in the triglycine sulphate crystal doped with the Cr$\text{}^{3+}$ ions as a function of temperature and electric field which polarises the crystal were examined. Temperature dependencies of modulus of elasticity S$\text{}_{55}$ and modulus of rigidity C$\text{}_{55}$ as a function of temperature and an electric field were determined. The results were analysed and discussed.
    Źródło:
    Acta Physica Polonica A; 2001, 100, 6; 879-884
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study of Spontaneous Polarisation and Pyroelectric Modulus for the Triglycine Sulphate Crystals Doped by Chromium Ions
    Autorzy:
    Dziedzic, J.
    Stolecki, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/2014061.pdf
    Data publikacji:
    2000-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    Opis:
    The temperature dependencies of a spontaneous polarisation, P$\text{}_{s}$, and pyroelectric modulus, γ, at different electric field intensities were investigated for the triglycine sulphate crystals doped with the Cr$\text{}^{3+}$ chromium ions. On the base of thermodynamic theory the temperature dependencies of P$\text{}_{s}$ and γ at different electric field intensities were estimated. The coefficients of the expansion of the thermodynamic potential were determined. The experimental results were compared with those obtained according to the thermodynamic theory.
    Źródło:
    Acta Physica Polonica A; 2000, 98, 1-2; 55-60
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Study on Pyroelectric Properties of the TGS-TGSe Crystals with Internal Electric Field
    Autorzy:
    Dziedzic, J.
    Mróz, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2044565.pdf
    Data publikacji:
    2005-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    Opis:
    Measurements of spontaneous polarization and pyroelectric coefficient versus temperature and electric field were performed for the TGS-TGSe crystals at a definite internal electric field. The obtained results are compared with the thermodynamic theory predictions. The temperature and electric field dependencies of pyroelectric coefficient are presented together with its maximal value as a function of the electric field intensity. It was shown that the temperature, at which the pyroelectric coefficient reaches its maximal value, depends on the external electric field.
    Źródło:
    Acta Physica Polonica A; 2005, 108, 6; 971-978
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dilatomelric and Pyroelectric Study of Phase Transition in (CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$Al(SO$\text{}_{4}$)$\text{}_{2}$ · 6H$\text{}_{2}$O Ferroelectric Crystal
    Autorzy:
    Pykacz, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/1943935.pdf
    Data publikacji:
    1995-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    65.70.+y
    Opis:
    The results of linear thermal expansion and pyroelectric coefficient are given for crystal of dimethylammoniumaluminium sulphate hexahydrate. Large anomalies of these quantities has been observed around the phase transition temperature at 151 K.
    Źródło:
    Acta Physica Polonica A; 1995, 88, 6; 1097-1101
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermal Expansion of (CH$\text{}_{3}$NH$\text{}_{3}$)$\text{}_{5}$Bi$\text{}_{2}$X$\text{}_{11}$ (X=Cl, Br) Crystals in the Temperature Range from 80 to 300 K
    Autorzy:
    Jakubas, R.
    Franqois, P.
    Lefebvre, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1930930.pdf
    Data publikacji:
    1994-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    65.70.+y
    Opis:
    Thermal expansion studies on (CH$\text{}_{3}$NH$\text{}_{3}$)$\text{}_{5}$Bi$\text{}_{2}$Cl$\text{}_{11}$ and (CH$\text{}_{3}$NH$\text{}_{3}$)$\text{}_{5}$Bi$\text{}_{2}$Br$\text{}_{11}$ in the temperature range 80-350 K are reported. The dilatometric measurements revealed a considerable similarity with respect to the anisotropy of dilatations of both isomorphous crystals. A diffused thermal anomaly was found around 170 K in (CH$\text{}_{3}$NH$\text{}_{3}$)$\text{}_{5}$Bi$\text{}_{2}$Cl$\text{}_{11}$ crystal.
    Źródło:
    Acta Physica Polonica A; 1994, 85, 3; 579-583
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dilatometric Study of the Phase Transition in (CH$\text{}_{3}$NH$\text{}_{3}$)$\text{}_{5}$Bi$\text{}_{2}$Cl$\text{}_{11}$
    Autorzy:
    Pykacz, H.
    Jakubas, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1887544.pdf
    Data publikacji:
    1991-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    65.70.+y
    Opis:
    The paper reports a dilatometric study on (CH$\text{}_{3}$NH$\text{}_{3}$)$\text{}_{5}$Bi$\text{}_{2}$Cl$\text{}_{11}$ single crystals. It is shown that elongation of the crystal is continuous but linear thermal expansion coefficients are discontinuous at phase transition temperature.
    Źródło:
    Acta Physica Polonica A; 1991, 79, 5; 695-697
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Linear Birefringence Changes in Betaine Phosphite Crystal
    Autorzy:
    Kosturek, B.
    Przesławski, J.
    Czapla, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1929341.pdf
    Data publikacji:
    1993-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    78.20.Fm
    Opis:
    Linear birefringence temperature changes are measured in the betaine phoshite crystal. The linear birefringence increments induced by antiferrodistortive, structural and ferroelectric phase transitions are analysed. Temperature derivatives of the linear birefringences are shown for comparison. Critical exponents are determined for both transitions. The antiferrodistortive phase transition is close to a tricritical one.
    Źródło:
    Acta Physica Polonica A; 1993, 83, 6; 769-775
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Monotropic Character of Polymorphism in Pentachloropyridine Crystal Studied by Calorimetric and Spectroscopic Methods
    Autorzy:
    Wójcik, G.
    Giermańsκa-Kahn, J.
    Marqueton, Y.
    Foulon, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1933583.pdf
    Data publikacji:
    1995-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    78.30.-j
    Opis:
    Pentachloropyridine crystals in two polymorphic modifications: tetragonal and monoclinic were studied by differential scanning calorimetry and polarized IR and Raman spectroscopy in 20 to 200 cm$\text{}^{-1}$ region and at different temperatures from melting point down to the liquid nitrogen temperature. The 4 K difference in melting points of both forms indicates the occurrence of monotropy. The spectra were discussed in terms of positional disorder in the studied crystals which often happen to be mixtures of the monoclinic crystal and the L- and D-forms of the tetragonal one. The monotropic transition of the metastable tetragonal crystal into the stable monoclinic one was observed in the Raman spectra and under the polarizing microscope at temperatures ranging from 170 to 185 K and as an anomaly on the differential scanning calorymetry diagram at 193 K.
    Źródło:
    Acta Physica Polonica A; 1995, 88, 2; 339-347
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optical and Dilatometric Properties of (CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$Al(SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O Crystals in Paraelectric and Ferroelectric Phases
    Autorzy:
    Podsiadła, D.
    Czapla, Z.
    Andriyevsky, B.
    Myshchyshyn, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/2011078.pdf
    Data publikacji:
    1999-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    78.20.Fm
    Opis:
    Experimental investigation of the thermal linear expansion l(T) and temperature dependencies of the interference optical path difference D(T) were carried out for (CH$\text{}_{3}$)$\text{}_{2}$ NH$\text{}_{2}$Al(SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O crystal, in the range of 120-310 K for three crystal physical directions. Decrease in electrostriction coefficients g of crystal was observed on approaching the phase transition point T$\text{}_{c}$ ≈ 150 K in ferroelectric phase. Relative temperature changes of the lengthening δl/l and refractive index δn/(n-1) are of the same order of magnitude. Peculiarities of temperature dependence of dilatometric and optical parameters of (CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$Al(SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O testify for qualitative reconstruction of chemical bonds in the crystal when temperature changes in the same phase.
    Źródło:
    Acta Physica Polonica A; 1999, 96, 3-4; 409-416
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optical Investigations of Phase Transitions in (NH$\text{}_{4}$)$\text{}_{2}$SbF$\text{}_{5}$ Crystal
    Autorzy:
    Andriyevsky, B.
    Czapla, Z.
    Stadnyk, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/1932114.pdf
    Data publikacji:
    1995-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    78.20.Fm
    Opis:
    Results of optical thickness and refractive indices measurements for (NH$\text{}_{4}$)$\text{}_{2}$SbF$\text{}_{5}$ crystal in the temperature range 100-310 K are presented. The measurements were done with interference method using He-Ne laser (λ = 632.8 nm). At T$\text{}_{c1}$ = 292 K and T$\text{}_{C2}$ = 168 K two continuous phase transitions with critical indices β$\text{}_{1}$ = 0.38 and β$\text{}_{2}$ ≤ 0.57 were observed. Additional anomaly of temperature changes of interference order with maximum at T$\text{}_{c3}$ ≈ 132 K were found. This anomaly resembles a diffused transition. Temperature-averaged values of derivatives of refractive indices dn$\text{}_{g}$ /dT = -3.3 × 10$\text{}^{-5}$ K and dn$\text{}_{m}$/dT = -2.9 × 10$\text{}^{-5}$ K$\text{}^{-1}$ evidenced a decrease in optical anisotropy (birefringence) along the b-axis on heating run.
    Źródło:
    Acta Physica Polonica A; 1995, 87, 3; 611-617
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Specific Heat of (NH$\text{}_{2}$(CH$\text{}_{3}$)$\text{}_{2}$)$\text{}_{3}$Bi$\text{}_{2}$I$\text{}_{9}$
    Autorzy:
    Plackowski, T.
    Włosewicz, D.
    Tomaszewski, P. E.
    Baran, J.
    Marchewka, M. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1932127.pdf
    Data publikacji:
    1995-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    65.40.-f
    Opis:
    The specific heat of title compound was measured by adiabatic calorimeter in the temperature range 80-315 K. The phase transitions at about 304, 285 and 235 K were confirmed. A new structural phase transition at about 125 K was observed as well as new anomaly on differential scanning calorimetry (DSC) curve at about 318 K. The peculiar multiple character of C, anomalies may be explained in terms of phase transitions or intermediate phases induced by impurities. The specific heat data are in agreement with the independent DSC measurements and with preliminary X-ray studies.
    Źródło:
    Acta Physica Polonica A; 1995, 87, 3; 635-641
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optical and Dilatometric Manifestations of Phase Transitions in K$\text{}_{2}$SeO$\text{}_{4}$ Crystal
    Autorzy:
    Andriyevsky, B.
    Myshchyshyn, O.
    Powiązania:
    https://bibliotekanauki.pl/articles/1967887.pdf
    Data publikacji:
    1997-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    78.20.Fm
    64.70.Kb
    Opis:
    Temperature dependencies of the characteristic optical paths difference D(Τ) of K2SeO4 crystal in the range of 80-295 K were measured using the Jamen type interferometer. Significant anomalies of D(Τ) dependencies in the vicinity of incommensurate-paraelectric phase transition (T$\text{}_{i}$ = 130 K) are observed. On the basis of D(Τ) temperature dependencies measured experimentally and linear expansion l(Τ) known, the temperature derivative of the refractive indices dn/dT are found to be negative in the ranges above and below the temperature T$\text{}_{i}$=130 K.
    Źródło:
    Acta Physica Polonica A; 1997, 92, 3; 557-562
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Structural and Electrical Conductivity Studies of Doped ZnS
    Autorzy:
    Sharma, S. V.
    Chand, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1920763.pdf
    Data publikacji:
    1992-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    64.80.Gd
    66.90.+r
    Opis:
    The effect of cobalt impurities on transport and structural properties of doped ZnS has been studied through electrical resistivity, X-ray diffraction and scanning electron microscopy. Correlating the results obtained, it has been shown that the Co concentrations considerably influence the transport properties as well as the structural features, in particular the β → α phase transformation of ZnS.
    Źródło:
    Acta Physica Polonica A; 1992, 81, 6; 653-658
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Phase Transitions in (CH$\text{}_{3}$)$\text{}_{2}$ CHNH$\text{}_{3}$CdCl$\text{}_{3}$ Crystal
    Autorzy:
    Krzewska, U.
    Jakubas, R.
    Dacko, S.
    Czapla, Z.
    Waśkowska, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/1920518.pdf
    Data publikacji:
    1992-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    05.70.Fh
    77.20.+y
    Opis:
    The crystal of (CH$\text{}_{3}$)$\text{}_{2}$CHNH$\text{}_{3}$CdCl$\text{}_{3}$ was grown and its physical properties were investigated. On the ground of DSC, dylatometric and dielectric investigations the phase transition at 390 K on heating process was revealed. On cooling two phase transitions at 382 K and 352 K were found. Polarized microscope observations show appearance of ferroelastic domain structure and cracks at 390 K on heating. On cooling the observed domain structure vanishes at 352 K.
    Źródło:
    Acta Physica Polonica A; 1992, 81, 3; 379-384
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Relaxation of Free Volume in Polycarbonate and Polystyrene Studied by Positron Annihilation Lifetime Spectroscopy
    Autorzy:
    Cangialosi, D.
    Wübbenhorst, M.
    Schut, H.
    Picken, S. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2042204.pdf
    Data publikacji:
    2005-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    78.70.Bj
    82.35.Lr
    64.70.Kb
    Opis:
    We present the time evolution of polycarbonate and polystyrene free volume probed by positron annihilation lifetime spectroscopy, which occurs after thermal rejuvenation above the glass transition temperature (T$\text{}_{g}$) and after plastic deformation via cold rolling. The ortho-positronium (τ$\text{}_{o-Ps}$) lifetime and its intensity (I$\text{}_{o-Ps}$) are used to characterise, respectively, size and concentration of the free volume holes. Our results suggest that the effect of plastic deformation on the polymer microstructure is far different from that of a thermally rejuvenated sample contrarily to common beliefs. In particular, plastic deformation results in an increase inτ$\text{}_{o-Ps}$ and a decrease in I$\text{}_{o-Ps}$, whereas rejuvenation above T$\text{}_{g}$ results in an increase in I$\text{}_{o-Ps}$ whileτ$\text{}_{o-Ps}$ remains unchanged. In addition, physical aging below T$\text{}_{g}$ after plastic deformation manifests as a reduction of τ$\text{}_{o-Ps}$, whereas a decrease in I$\text{}_{o-Ps}$ is observed after thermal rejuvenation. These results corroborate the idea of an amorphous-amorphous transition induced by plastic deformation.
    Źródło:
    Acta Physica Polonica A; 2005, 107, 4; 690-696
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Optical and Ultrasonic Investigations of Phase Transitions in Ferroelectric RbHSeO$\text{}_{4}$ Single Crystal
    Autorzy:
    Sveleba, S. A.
    Bublik, M. I.
    Polovinko, I. I.
    Kityk, A. V.
    Sopronuk, V. P.
    Czapla, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1920942.pdf
    Data publikacji:
    1992-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    77.20.+y
    05.70.Fh
    Opis:
    Birefringence and ultrasonic measurements were done for ferroelectric RbHSeO4 crystal. Influences of both stresses (σ$\text{}_{i}$) and pressure on the properties and phase transition were studied as well. The observed dependence of δ(Δn$\text{}_{b}$) = f(σ$\text{}_{5}$) shows hysteresis loop characteristic of ferroelectric phase whereas the dependence of δ(Δn$\text{}_{c}$) = f(σ$\text{}_{6}$) shows hysteresis loop characteristic of ferroelastic phase. Birefringence measurements prove the phase transition to ferroelectric phase at 373 K. Additionally, the phase transition was found at 398 K. The new phase may be regarded as an incommensurate one. On the grounds of the stresses influence the phase diagram is constructed in coordinates T, σ$\text{}_{5}$. The linear decrease in T$\text{}_{c}$ with increase in pressure is observed in ultrasonic studies and it is similar to the results obtained in DSC measurements.
    Źródło:
    Acta Physica Polonica A; 1992, 82, 3; 481-486
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Rhombohedral Distortion in Fe$\text{}_{3-y}$Zn$\text{}_{y}$O$\text{}_{4}$ at Verwey Transition
    Autorzy:
    Kozłowski, A.
    Kąkol, Z.
    Zalecki, R.
    Knight, K.
    Honig, J. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1955841.pdf
    Data publikacji:
    1997-02
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.50.Gg
    64.70.Kb
    61.12.-q
    Opis:
    The time-of-flight neutron diffraction data were collected for two Fe$\text{}_{3-y}$Zn$\text{}_{y}$O$\text{}_{4}$ powder samples showing different order of the Verwey transition: y=0.0072 - first order, y=0.0249 - second order. Measurements were performed on spallation neutron source in ISIS Rutherford Appleton Laboratory. At low temperatures (below Verwey transition temperature T$\text{}_{V}$) clear splitting of certain reflections characteristic of rhombohedral distortion was observed for both samples. We found that this distortion is much bigger for the sample exhibiting first-order than for the sample showing second-order transition.
    Źródło:
    Acta Physica Polonica A; 1997, 91, 2; 443-446
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dielectric Study of Pure Polymer and Mixed Monomer-Polymer Single Crystals of pTS Diacetylene: a Comparison with Neutron Scattering Results
    Autorzy:
    Longevile, S.
    Even, J.
    Bertault, M.
    Kołodziej, H. A.
    Sworakowski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1933586.pdf
    Data publikacji:
    1995-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    61.12.-q
    77.84.Jd
    Opis:
    Temperature and frequency dependences of the electric permittivity in mixed monomer-polymer single crystals of the diacetylene pTS (2,4-hexadiynylene bis(p-toluenesulphonate)) are reported. The dependences were determined in the temperature range 100-250 K, and in the frequency range 100 Hz - 1 MHz. Two types of single crystals were studied: nearly-fully polymerized ones, and those containing ca. 20% of polymer in the monomer matrix. The dynamics is characterized by a high-frequency response (v ≫ 3 GHz) which corresponds to the soft mode analysed previously by the Raman and neutron inelastic scatterings. At low frequencies (v ≤ 1 kHz), another component is observed, its dielectric intensity peaking around the transition temperature in the fully polymerized crystals. The results are consistent with the results obtained from NMR and neutron scattering experiments.
    Źródło:
    Acta Physica Polonica A; 1995, 88, 2; 359-367
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    EPR Study of the Phase Transition in Dimethylammonium Gallium Sulfate Hexahydrate
    Autorzy:
    Hrabański, R.
    Janiec-Mateja, M.
    Czapla, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/2043560.pdf
    Data publikacji:
    2005-08
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    76.30.Fc
    77.80.-e
    Opis:
    X-band electron paramagnetic resonance investigations of single crystals of Cr$\text{}^{3+}$-doped dimethylammonium gallium sulphate hexahydrate are presented from room temperature down to 110 K. The crystal undergoes a order-disorder phase transition to ferroelectric phase at 134 K and additionally a first-order transition into a low temperature non-ferroelectric phase at T$\text{}_{c2}$=116 K. The spin-Hamiltonian parameters were determined for paraelectric and ferroelectric phases. The spin-Hamiltonian parameters in the paraelectric phase are: g=1.982±0.002, b$\text{}_{2}^{0}$=(890±10)×10$\text{}^{-4}$ cm$\text{}^{-1}$, b=(386±15)×10$\text{}^{-4}$ cm$\text{}^{-1}$. Remarkable EPR line width changes confirm the order-disorder character of the ferroelectric phase transition. Additionally observed triplet lines demonstrate freezing-out of dimethylammonium reorientations which can be considered as a prime reason for this transition similarly as observed in dimethylammonium aluminium sulfate hexahydrate.
    Źródło:
    Acta Physica Polonica A; 2005, 108, 2; 283-290
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    X-ray Study of Ferroelectric Phase Transition in (NH(CH$\text{}_{3}$)$\text{}_{3}$)$\text{}_{3}$Sb$\text{}_{2}$Cl$\text{}_{9}$
    Autorzy:
    Tomaszewski, P. E.
    Powiązania:
    https://bibliotekanauki.pl/articles/1932124.pdf
    Data publikacji:
    1995-03
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    61.50.Ks
    77.80.Bh
    65.70.+y
    Opis:
    The lattice parameters of a title crystal, TMACA, were measured from a room temperature to 405 K by the X-ray single-crystal Bond method. The high-temperature paraelectric phase should have the monoclinic symmetry (space group P2/c). Some peculiarities on dielectric behaviour of the crystal were explained. The hypotheses on incommensurability of the paraelectric phase as well as on the parent normal (trigonal) phase were presented.
    Źródło:
    Acta Physica Polonica A; 1995, 87, 3; 631-634
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Connection between Reorientational Motions of NH$\text{}_{3}$ Groups and Phase Transitions in [Ni(NH$\text{}_{3}$)$\text{}_{6}$](NO$\text{}_{3}$)$\text{}_{2}$ and [Mg(NH$\text{}_{3}$)$\text{}_{6}$](NO$\text{}_{3}$)$\text{}_{2}$ Compounds
    Autorzy:
    Migdał-Mikuli, A.
    Mikuli, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/1933652.pdf
    Data publikacji:
    1995-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    28.20.Cz
    61.50.Ks
    35.20.Yh
    Opis:
    Quasielastic neutron scattering data for [Νi(ΝH$\text{}_{3}$)$\text{}_{6}$](ΝO$\text{}_{3}$)$\text{}_{2}$ and [Mg(ΝH$\text{}_{3}$)$\text{}_{6}$](NO$\text{}_{3}$)$\text{}_{2}$ were subjected to a new analysis. On the basis of the excess of intensity of elastic component observed in these spectra in comparison to the intensity of this component resulting from the applied reorientational model this analysis determined temperature dependence of the new "R" parameter. This parameter gives us information concerning the number of these NH$\text{}_{3}$ groups which in the [Me(NΗ$\text{}_{3}$)$\text{}_{6}$]$\text{}^{2+}$ cation reorientate with the correlation time of order of 10$\text{}^{-12}$ s. It has been ascertained that in phases I and II of both substances under study all NH$\text{}_{3}$ groups reorientate fast (R = 6ΝH$\text{}_{3}$ groups), whereas in phases III and IV only part of these groups reorientate fast (R = 3ΝΗ$\text{}_{3}$ groups - in the case of [Νi(ΝΗ$\text{}_{3}$)$\text{}_{6}$](ΝO$\text{}_{3}$)$\text{}_{2}$ and R = 2ΝΗ$\text{}_{3}$ groups - in the case of [Mg(ΝΗ$\text{}_{3}$)$\text{}_{6}$](NO$\text{}_{3}$)$\text{}_{2}$). Moreover, the temperature dependence of reorientational correlation time τ for these fast reorienting ΝH$\text{}_{3}$ groups were also determined. The remaining NH$\text{}_{3}$ groups reorientate on a much slower time scale. Both temperature dependencies: R vs. Τ and τ vs. Τ register a deep thermal hysteresis of the phase transition: phase II - phase III (Τ$\text{}_{C2}^{h}$ - T$\text{}_{C2}^{c}$ ≈ 95 K and ≈ 35 K respectively for [Ni(ΝΗ$\text{}_{3}$)$\text{}_{6}$](ΝO$\text{}_{3}$)$\text{}_{2}$ and [Mg(ΝΗ$\text{}_{3}$)$\text{}_{6}$](NO$\text{}_{3}$)$\text{}_{2}$).
    Źródło:
    Acta Physica Polonica A; 1995, 88, 3; 527-532
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Radiation Effects in DMAAS:Cr Ferroelectric Crystal
    Autorzy:
    Kapustianik, V.
    Czapla, Z.
    Eliyachevskyy, Yu.
    Korchak, Yu.
    Kulyk, B.
    Rudyk, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/2037039.pdf
    Data publikacji:
    2003-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    78.40.Ha
    64.70.Kb
    77.84.-s
    78.30.Hv
    Opis:
    This paper presents the results of investigations of the radiation effects in NH$\text{}_{2}$(CH$\text{}_{3}$)$\text{}_{2}$Al(SO$\text{}_{4}$)$\text{}_{2}$×6H$\text{}_{2}$O crystals doped with chromium. On the basis of absorption spectroscopy and resonance Raman scattering study it has been shown that comparatively low doses of radiation first of all causes recharging of Cr$\text{}^{3+}$ on Cr$\text{}^{4+}$ ions. Besides, the processes of dehydrogenation and the changes in arrangement of the hydrogen bond network were observed. These changes are followed by distortion of the complexes bonded by such a type of bonds.
    Źródło:
    Acta Physica Polonica A; 2003, 104, 6; 571-580
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Magnetite Fe$\text{}_{3}$O$\text{}_{4}$: the Correlated Electron-Phonon System
    Autorzy:
    Kozłowski, A.
    Kąkol, Z.
    Tarnawski, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/2047312.pdf
    Data publikacji:
    2007-04
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    64.70.Kb
    75.40.-s
    63.20.Kr
    71.30.+h
    75.30.Cr
    Opis:
    In the paper the influence of magnetic as well as electron-lattice interactions on the Verwey transition in magnetite related compounds is discussed based on the authors' experimental activity and available literature. While magnetism was proved to only reflect the transition, the results of nuclear inelastic scattering show that lattice dynamics actively participates in it. The studies of diffuse neutron scattering and heat capacity suggest also that the low temperature lattice properties of slightly doped magnetite are distinct from those with higher dopant concentration. Finally, recent theoretical results strongly suggest that the Verwey transition in magnetite cannot be understood and described without strong involvement of electron-lattice interactions.
    Źródło:
    Acta Physica Polonica A; 2007, 111, 4; 537-547
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Microstructure Development in Multilayer $TiB_x // TiSi_y C_z$ Coatings during Post-Deposition Heat Treatment
    Autorzy:
    Twardowska, A.
    Rajchel, B.
    Morgiel, J.
    Mędala-Wójcik, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/1398372.pdf
    Data publikacji:
    2016-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    81.15.Cd
    81.20.-n
    42.62.-b
    61.43.Dq
    68.37.-d
    68.37.Lp
    68.65.Ac
    64.70.Kb
    Opis:
    Multilayer amorphous $TiB_{x} // TiSi_{y}C_{z}$ coatings were formed by duplex treatment: dual beam ion beam assisted deposition and pulsed laser deposition. Post-deposition heating was applied to activate crystallization in the coating. In situ transmission electron microscopy heating experiments were conducted in the temperature range 20-600°C. Crystallization of TiB₂ phase in $TiB_{x}$ layers begun at 450°C, while $TiSi_{y}C_{z}$ layers retained nearly amorphous up to 600°C.
    Źródło:
    Acta Physica Polonica A; 2016, 130, 4; 1124-1126
    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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