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Tytuł:
Manifestation of a Coexistence of the Long-Periodic Phase with the Incommensurate Phase
Autorzy:
Sveleba, S.
Polovinko, I.
Zhmurko, V.
Pankivskyi, Y.
Powiązania:
https://bibliotekanauki.pl/articles/2011086.pdf
Data publikacji:
1999-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.-p
Opis:
Electric and optical properties of the commensurate ferroelectric long-periodic phase in [N(CH$\text{}_{3}$)$\text{}_{4}$]$\text{}_{2}$ZnCl$\text{}_{4}$ and [N(CH$\text{}_{3}$)$\text{}_{4}$]$\text{}_{2}$CoCl$\text{}_{4}$ crystals were investigated to explain mechanism of the double hysteresis loops appearance.
Źródło:
Acta Physica Polonica A; 1999, 96, 3-4; 437-444
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characteristic Features of the Modulated Phases in (MgGeF$\text{}_{6}$)·6H$\text{}_{2}$O Crystals
Autorzy:
Pankivskyi, Yu.
Sveleba, S.
Hrabanski, R.
Powiązania:
https://bibliotekanauki.pl/articles/2038375.pdf
Data publikacji:
2004-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.-p
Opis:
The temperature dependences of the optical birefringence δ(Δ n$\text{}_{c}$) in (MgGeF$\text{}_{6}$)·6H$\text{}_{2}$O crystal have been investigated. Specific properties observed in experiment such as global hysteresis, kinetic effect, thermooptic memory effect, localization of the incommensurability wave vector on the commensurate values of higher order, sensibility to the external mechanical stress confirm the existence of the incommensurate phase in current crystals.
Źródło:
Acta Physica Polonica A; 2004, 106, 4; 467-474
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigations of High Temperature Phase Transitions in (NH$\text{}_{3}$c$\text{}_{2}$H$\text{}_{5}$)$\text{}_{2}$CuCl$\text{}_{4}$ Crystals
Autorzy:
Kapustianik, V.
Korchak, Yu.
Sveleba, S.
Tchukvinskyi, R.
Girnyk, I.
Powiązania:
https://bibliotekanauki.pl/articles/1995610.pdf
Data publikacji:
1999-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.-p
Opis:
On the basis of dilatometric, optical, and dielectric investigations of (NH$\text{}_{3}$C$\text{}_{2}$H$\text{}_{5}$)$\text{}_{2}$CuCl$\text{}_{4}$ crystals the existence of phase transitions at T$\text{}_{1}$=364 and T$\text{}_{2}$=356 K was confirmed. Anomalous behaviour of the thermal expansion coefficient and optical birefringence around T$\text{}_{3}$=330 K was related to earlier unknown phase transition. Besides, it was shown that these crystals are characterised by considerable protonic conductivity, the nature of which is fairly well explained in the framework of Grotthus mechanism of proton transport.
Źródło:
Acta Physica Polonica A; 1999, 95, 3; 351-357
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Behaviour of the Optical Birefringence in Conditions of the "Viscous" Interaction
Autorzy:
Sveleba, S. A.
Zhmurko, V. S.
Pankivskyi, Yu. I.
Powiązania:
https://bibliotekanauki.pl/articles/2012956.pdf
Data publikacji:
2000-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.-p
Opis:
The temperature dependences of optical birefringence δ(Δn) for the principal cuts of [N(CH$\text{}_{3}$)$\text{}_{4}$]$\text{}_{2}$CuCl$\text{}_{4}$ crystals are measured. On the basis of the obtained experimental and theoretical data the anomalous behavior of physical parameters in conditions of the "viscous" interaction of the modulated structure with mobile defects in the incommensurate phase is explained.
Źródło:
Acta Physica Polonica A; 2000, 97, 2; 337-348
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dielectric and Dilatometric Properties of NH(CH$\text{}_{3}$)$\text{}_{3}$CuCl$\text{}_{3}$·2H$\text{}_{2}$O Low Dimensional Ferroics
Autorzy:
Korchak, Yu.
Kapustianik, V.
Batiuk, A.
Girnyk, I.
Czapla, Z.
Dacko, S.
Powiązania:
https://bibliotekanauki.pl/articles/1872270.pdf
Data publikacji:
2004-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.-p
Opis:
On the basis of dilatometric and dielectric investigations of NH(CH$\text{}_{3}$)$\text{}_{3}$CuCl$\text{}_{3}$·2H$\text{}_{2}$O crystals the earlier unknown phase transition with considerable temperature hysteresis was found at T$\text{}_{1}^{c}$=198 K and T$\text{}_{1}^{h}$=223 K, respectively, in cooling and heating runs. Existence of the characteristic dielectric dispersion was revealed within the high-temperature phase. It corresponds to the single dielectric relaxator below 250 K as well as to co-existence of two relaxators above this temperature. The determined values of the activation energy and relaxation time are characteristic of the co-operative reorientation of the trimethylammonium cation (high-frequency relaxator) whereas the combined reorientation motions of the CuCl$\text{}_{2}$·2H$\text{}_{2}$O chains would be responsible for the low-frequency relaxation process. It was found that the above mentioned quasi-Debye type processes are involved into the mechanisms of the protonic conductivity.
Źródło:
Acta Physica Polonica A; 2004, 106, 1; 39-49
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Study of the Phase Transitions in Potassium Hydrogen Sulphate KHSO$\text{}_{4}$
Autorzy:
Tahoon, K. K.
Abosehly, A. M.
Abdel-Kader, M. M.
El-Sharkawy, A. A.
El-Mansi, F. M
Powiązania:
https://bibliotekanauki.pl/articles/1931565.pdf
Data publikacji:
1994-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
65.40.-f
64.70.-p
Opis:
We report on some thermal properties (specific heat capacity C$\text{}_{p}$, thermal conductivity λ, and thermal diffusivity σ) in addition to the differential thermal analysis thermogram and thermogravimetric analysis for potassium hydrogen sulphate (KHS), KHSO$\text{}_{4}$. The accurate measurements of the above-mentioned parameters as functions of temperature revealed that the compound undergoes two structural phase transitions around 100°C and 175°C. It seems also likely that the compound behaves as a poorly conducting material and hence the maul mechanism of the heat transfer is due to phonons. The data are correlated to the crystal structure including the two different HSO¯$\text{}_{4}$ ions.
Źródło:
Acta Physica Polonica A; 1994, 86, 3; 349-355
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
SnTe Phase Transition in Strained Superlattices PbTe/SnTe
Autorzy:
Mironov, O. A.
Makarovskii, O. N.
Nashchekina, O. N.
Shpakovskaya, L. P.
Litvinov, V. I.
Oszwałdowski, M.
Berus, T.
Powiązania:
https://bibliotekanauki.pl/articles/1933932.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.-p
73.40.-c
Opis:
An anomaly of the in-plane conductivity is observed in the superlattices PbTe/SnTe on (001)KCl in the temperature region of 60-130 K. The anomaly is caused by a structural phase transition in SnTe layer and as a result, the transition induced formation of defects. These defects are additional scattering centres which decrease the superlattice conductivity.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 853-856
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Peculiarities of Dielectric Relaxation in DMAAS Ferroelectric Crystals
Autorzy:
Kapustianik, V.
Czapla, Z.
Czukwinski, R.
Powiązania:
https://bibliotekanauki.pl/articles/2035537.pdf
Data publikacji:
2002-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.-p
77.84.-s
Opis:
This paper presents the results of investigations of the dielectric properties of NH$\text{}_{2}$(CH$\text{}_{3}$)$\text{}_{2}$Al(SO$\text{}_{4}$)$\text{}_{2}$×6H$\text{}_{2}$O crystals performed in a wide frequency range. In particular, the temperature and frequency dependences of the dielectric permittivity were measured in the region of ferroelectric phase at different rates of temperature change. The thermal dipole relaxation with a critical slowing-down at T$\text{}_{c1}$ was observed at comparatively low frequencies of measuring field. The relaxation connected with the domain freezing takes place at still lower frequencies (below 100 kHz) and was found to be strongly dependent on the rate of the temperature change. It was shown that deuteration results in a noticeable change of the parameters characterising this process including the temperature of domain wall freezing.
Źródło:
Acta Physica Polonica A; 2002, 102, 3; 365-372
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Temperature Dependence of Domain Structure in Cobalt
Autorzy:
Szmaja, W.
Polański, K.
Dolecki, K.
Powiązania:
https://bibliotekanauki.pl/articles/1964829.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.60.-d
64.70.-p
Opis:
The type-I magnetic contrast in a scanning electron microscope is used to study the domain behaviour on the basal planes of cobalt monocrystals of different thicknesses during a heating cycle. Digital image processing is applied to the original scanning electron microscope images for their restoration, enhancement and analysis. The main reasons for the application of digital image processing are: low level of type-I magnetic contrast, particularly used at the higher temperatures, and the complex character of the magnetic domain structure. The changes in both domain structures and type-I magnetic contrast are due to the strong temperature dependence of magnetocrystalline anisotropy energy for the hcp phase of cobalt, which implies the rotation of magnetic easy axis from the c-axis to the basal plane. The temperature of the magnetic phase transition between an open-flux and a closed-flux domain configuration was found to be dependent on the specimen thickness. The changes in domain structure during the heating cycle were reversible under the condition that the specimen was not carried through the hcp-to-fcc phase transition. Otherwise, they were partially or completely irreversible and were caused by crystal imperfections originating from the transition. The paper shows the great advantage of using digital image processing system for data restoration, enhancement and analysis.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 469-472
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of the Introduction of Copper into Amorphous $As_2Se_3$ Matrix on Its Thermal and Structural Characteristics
Autorzy:
Štrbac, G.
Lukić-Petrović, S.
Štrbac, D.
Čajko, K.
Turyanytsa, I.
Powiązania:
https://bibliotekanauki.pl/articles/1399717.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.kj
64.70.P-
65.60.+a
Opis:
This paper describes the results of the determination of some thermal and structural parameters of glasses from the $Cu_{x}(As_2Se_3)_{100-x}$ system for x=0, 1, 5, 10 and 15 at.%. Based on the differential scanning calorimetry curves taken at different heating rates, glass transition temperature $T_{g}$, onset temperature of crystallization $T_{onset}$, and melting temperature $T_{m}$ of crystalline units formed are determined. The values of activation energy $E_{g}$ of glass transition process are calculated. These characteristic temperatures served as the basis for the calculation of the parameters of thermal stability of the glasses towards crystallization.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 256-258
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kinetic Analysis of Thermal Processes in Ag-As-S-Se System Based on DSC Measurements
Autorzy:
Čajko, K.
Lukić-Petrović, S.
Štrbac, G.
Ivetić, T.
Powiązania:
https://bibliotekanauki.pl/articles/1398711.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
65.60.+a
64.70.kj
64.70.P-
64.70.kg
Opis:
Thermal properties of glasses from the system $Ag_x(As_{40}S_{30}Se_{30})_{100-x}$ for x=0, 0.5, 1, 3, and 5 at.% were investigated by differential scanning calorimetry. The DSC curves were obtained under non-isothermal conditions which allowed determination of the glass transition temperature $T_{g}$ (onset temperature), crystallization temperature $T_{p}$ (corresponding to the crystallization peak maximum), melting temperature $T_{m}$, crystallization enthalpy $H_{c}$, and melting enthalpy $H_{m}$. The DSC curves obtained at the same heating rate were analyzed in order to study the variation of glass transition temperature with Ag concentration. Observed $T_{g}$ shift toward higher values, with increase in the heating rate, is in agreement with the Lasocka equation. Samples with 3 at.% and 5 at.% Ag were further thermally treated at different heating rates with the aim of analyzing kinetic processes of crystallization. The Moynihan and Kissinger models were used to calculate the activation energy of glass transition and activation energy of crystallization. For the samples that showed the crystallization processes an assessment of the thermal stability was done based on different criteria.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 509-513
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical properties of soda-lime-silica glasses with variable peanut shell contents
Autorzy:
Aktas, B.
Albaskara, M.
Yalcin, S.
Dogru, K.
Powiązania:
https://bibliotekanauki.pl/articles/1057876.pdf
Data publikacji:
2017-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Kf
81.70.-q
64.70.P
Opis:
In this study, the mechanical properties of soda-lime-silica glasses were investigated by using micro-Vickers indentation tests, while varying the amount of peanut shell powder added to the glass. Peanut shell powder was obtained by grinding peanut shells. It was added as a dopant to glass at 0.5-5 wt.%, with the final glass samples being produced by melting. Peanut shell addition had led to a decreased density of the soda-lime-silica glasses, and X-ray diffraction data of the peanut shell-doped soda-lime-silica glasses indicated the presence of two crystalline phases, namely, anorthite (Na_{0.45}(Ca_{0.55}Al_{1.55}Si_{2.45}O₈) and magnesium aluminum silicate (MgAl₂Si₃O_{10})₆. The Young's modulus values of the soda-lime-silica glasses increased along with the amount of peanut shell powder added. Peanut shell addition to the soda-lime-silica glasses has also caused increased hardness. Fracture toughness values of these glass samples were in the range of 0.91-1.04 MPa m^{1/2}. Thus, the mechanical properties (e.g. E and K_{C}) of soda-lime-silica glasses could be enhanced through peanut shell addition.
Źródło:
Acta Physica Polonica A; 2017, 131, 3; 511-513
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Size Evolution of the Light Induced Sodium Clusters
Autorzy:
Hnat, B.
Jakubczyk, D.
Kolwas, K.
Kolwas, M.
Powiązania:
https://bibliotekanauki.pl/articles/1920745.pdf
Data publikacji:
1992-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
36.40.+d
31.70.Hq
64.70.-p
Opis:
We report the observation of the size evolution of the laser light formed clusters. A cell containing sodium vapor and the buffer gas (He) under high pressure was used in the experiment. Changes of the radius and of the density of transient clusters were observed via the time evolution of the intensity of right-angle scattered light. The rate of the cluster radius growth was found to vary from 0.012 to 0.1 μm/s.
Źródło:
Acta Physica Polonica A; 1992, 81, 6; 629-637
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evolution of Laser Light Induced Sodium Clusters
Autorzy:
Kolwas, M.
Kolwas, K.
Jakubczyk, D.
Powiązania:
https://bibliotekanauki.pl/articles/1931531.pdf
Data publikacji:
1994-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.-p
31.70.Hq
36.40.+d
Opis:
We investigated the growing sodium clusters, induced by the laser light resonant with a sodium dimer transition. We observed the intensity of light scattered by clusters. The clusters were produced in the stainless steel cell containing sodium vapor and helium. We obtained data on cluster mean size and dynamics from fitting the theoretical formulas to the experimental data. The model of clusters' evolution basing on the thermodynamics of the vapor-liquid transition was applied.
Źródło:
Acta Physica Polonica A; 1994, 86, 1; 257-266
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monte Carlo Simulations of the Ashkin-Teller Model
Autorzy:
Dębski, L.
Powiązania:
https://bibliotekanauki.pl/articles/2013697.pdf
Data publikacji:
2000-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Hk
75.40.Mg
64.70.-p
Opis:
Monte Carlo simulations are used to analyse the behaviour of the extended Ashkin-Teller model in two (2D) and three (3D) dimensions from the ratio of the square of the second moment of the order parameter to its fourth moment. The critical surface in three dimensional parameter space is calculated in regions where the Ising transitions are expected both for the ferro-and antiferromagnetic regions.
Źródło:
Acta Physica Polonica A; 2000, 97, 5; 859-862
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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