Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 29

Number of results on page
first rewind previous Page / 2 next fast forward last

Search results

Search:
in the keywords:  64.70.Kb
help Sort By:

help Limit search:
first rewind previous Page / 2 next fast forward last
1
Publication available in full text mode
Content available

Ferroelectric Phase Transition in DC Electric Field in [NH_2(CH_3)_2]_3Sb_2Cl_9 Crystals

100%
Dziedzic J., Mróz J.
Acta Physica Polonica A
|
2007
|
vol. 111
|
issue 6
873-876
EN
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_2(CH_3)_2]_3Sb_2Cl_9. The linear shift of T_c towards higher temperatures was observed. The A_0 and B coefficients from the Landau state equation are determined.
2
Publication available in full text mode
Content available

Study on Pyroelectric Properties of the TGS-TGSe Crystals with Internal Electric Field

100%
Dziedzic J., Mróz J.
Acta Physica Polonica A
|
2005
|
vol. 108
|
issue 6
971-978
EN
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.
3
Publication available in full text mode
Content available

Studies of Elastic Waves Propagation in Triglycine Sulphate Crystals Doped with Chromium Ions

100%
Dziedzic J.
Acta Physica Polonica A
|
2001
|
vol. 100
|
issue 6
879-884
EN
Velocities and scattering of transverse elastic wave propagating in the triglycine sulphate crystal doped with the Cr^{3+} ions as a function of temperature and electric field which polarises the crystal were examined. Temperature dependencies of modulus of elasticity S_{55} and modulus of rigidity C_{55} as a function of temperature and an electric field were determined. The results were analysed and discussed.
4
Publication available in full text mode
Content available

Dielectric Properties of the (CH_3NH_3)_5Bi_{2(1- x)}Sb_{2x}Cl_{11} Mixed Crystals

100%
Mróz J., Dziedzic J., Pykacz H.
Acta Physica Polonica A
|
2006
|
vol. 110
|
issue 4
479-483
EN
The (CH_3NH_3)_5Bi_{2(1-x)}Sb_{2x}Cl_{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.
5
Content available remote

Quadrupole Relaxation of ^{79}Br Nuclei in Ferroelectric (CH_{3})_{4}NCdBr_{3} (TMCB)

100%
Baisa D. F., Chesnokov E. D., Czapla Z.
Acta Physica Polonica A
|
1994
|
vol. 86
|
issue 3
357-361
EN
Investigations of temperature dependence of a nuclear quadrupole spin-lattice relaxation time of ^{79}Br nuclei in ferroelectric (CH_{3})_{4}NCdBr_{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_{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.
6
Content available remote

Study of Spontaneous Polarisation and Pyroelectric Modulus for the Triglycine Sulphate Crystals Doped by Chromium Ions

100%
Dziedzic J., Stolecki B.
Acta Physica Polonica A
|
2000
|
vol. 98
|
issue 1-2
55-60
EN
The temperature dependencies of a spontaneous polarisation, P_{s}, and pyroelectric modulus, γ, at different electric field intensities were investigated for the triglycine sulphate crystals doped with the Cr^{3+} chromium ions. On the base of thermodynamic theory the temperature dependencies of P_{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.
7
Content available remote

Nuclear Quadrupole Resonance Investigation of Phase Transition in Tetramethylammonium Cadmium Tribromide

100%
Baisa D., Chesnokov E., Czapla Z., Pogrebnyak S., Vertegel I.
Acta Physica Polonica A
|
1993
|
vol. 84
|
issue 2
271-274
EN
The critical temperature dependence of the nuclear quadrupole- resonance ^{79}Br frequencies at the phase transition (T_{c} = 163 K) was found in (CH_{3})_{4}NCdBr_{3}. It was concluded that bromine nuclei take part in the phase transition not directly but via the interaction with the crystal polarization.
8
Content available remote

Studies of Permittivity in the Triglicinium Sulphate Crystals Doped with Chromium Ions as a Function of Temperature and Electric Field

100%
Dziedzic J.
Acta Physica Polonica A
|
2000
|
vol. 98
|
issue 4
373-381
EN
Permittivity in the triglicinium sulphate crystals doped with chromium ions Cr^{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.
9
Content available remote

Optical Investigations of Phase Transitions in (NH_{4})_{2}SbF_{5} Crystal

63%
Andriyevsky B., Czapla Z., Stadnyk V.
Acta Physica Polonica A
|
1995
|
vol. 87
|
issue 3
611-617
EN
Results of optical thickness and refractive indices measurements for (NH_{4})_{2}SbF_{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_{c1} = 292 K and T_{C2} = 168 K two continuous phase transitions with critical indices β_{1} = 0.38 and β_{2} ≤ 0.57 were observed. Ad­ditional anomaly of temperature changes of interference order with maximum at T_{c3} ≈ 132 K were found. This anomaly resembles a diffused transition. Temperature-averaged values of derivatives of refractive indices dn_{g} /dT = -3.3 × 10^{-5} K and dn_{m}/dT = -2.9 × 10^{-5} K^{-1} evidenced a decrease in optical anisotropy (birefringence) along the b-axis on heating run.
10
Content available remote

Dilatometric Study of the Phase Transition in (CH_{3}NH_{3})_{5}Bi_{2}Cl_{11}

63%
Pykacz H., Jakubas R.
Acta Physica Polonica A
|
1991
|
vol. 79
|
issue 5
695-697
EN
The paper reports a dilatometric study on (CH_{3}NH_{3})_{5}Bi_{2}Cl_{11} single crystals. It is shown that elongation of the crystal is continuous but linear thermal expansion coefficients are discontinuous at phase transition temperature.
11
Content available remote

Specific Heat of (NH_{2}(CH_{3})_{2})_{3}Bi_{2}I_{9}

63%
Plackowski T., Włosewicz D., Tomaszewski P., Baran J., Marchewka M.
Acta Physica Polonica A
|
1995
|
vol. 87
|
issue 3
635-641
EN
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.
12
Content available remote

Optical and Dilatometric Properties of (CH_{3})_{2}NH_{2}Al(SO_{4})_{2}·6H_{2}O Crystals in Paraelectric and Ferroelectric Phases

63%
Podsiadła D., Czapla Z., Andriyevsky B., Myshchyshyn O.
Acta Physica Polonica A
|
1999
|
vol. 96
|
issue 3-4
409-416
EN
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_{3})_{2} NH_{2}Al(SO_{4})_{2}·6H_{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_{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_{3})_{2}NH_{2}Al(SO_{4})_{2}·6H_{2}O testify for qualitative reconstruction of chemical bonds in the crystal when temperature changes in the same phase.
13
Content available remote

Dilatomelric and Pyroelectric Study of Phase Transition in (CH_{3})_{2}NH_{2}Al(SO_{4})_{2} · 6H_{2}O Ferroelectric Crystal

63%
Pykacz H.
Acta Physica Polonica A
|
1995
|
vol. 88
|
issue 6
1097-1101
EN
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.
14
Content available remote

Monotropic Character of Polymorphism in Pentachloropyridine Crystal Studied by Calorimetric and Spectroscopic Methods

63%
Wójcik G., Giermańsκa-Kahn J., Marqueton Y., Foulon M.
Acta Physica Polonica A
|
1995
|
vol. 88
|
issue 2
339-347
EN
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^{-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.
15
Content available remote

Linear Birefringence Changes in Betaine Phosphite Crystal

63%
Kosturek B., Przesławski J., Czapla Z.
Acta Physica Polonica A
|
1993
|
vol. 83
|
issue 6
769-775
EN
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.
16
Content available remote

Optical and Dilatometric Manifestations of Phase Transitions in K_{2}SeO_{4} Crystal

63%
Andriyevsky B., Myshchyshyn O.
Acta Physica Polonica A
|
1997
|
vol. 92
|
issue 3
557-562
EN
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_{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_{i}=130 K.
17
Content available remote

Thermal Expansion of (CH_{3}NH_{3})_{5}Bi_{2}X_{11} (X=Cl, Br) Crystals in the Temperature Range from 80 to 300 K

63%
Jakubas R., Franqois P., Lefebvre J.
Acta Physica Polonica A
|
1994
|
vol. 85
|
issue 3
579-583
EN
Thermal expansion studies on (CH_{3}NH_{3})_{5}Bi_{2}Cl_{11} and (CH_{3}NH_{3})_{5}Bi_{2}Br_{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_{3}NH_{3})_{5}Bi_{2}Cl_{11} crystal.
18
Publication available in full text mode
Content available

Relaxation of Free Volume in Polycarbonate and Polystyrene Studied by Positron Annihilation Lifetime Spectroscopy

51%
Cangialosi D., Wübbenhorst M., Schut H., Picken S.
Acta Physica Polonica A
|
2005
|
vol. 107
|
issue 4
690-696
EN
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_g) and after plastic deformation via cold rolling. The ortho-positronium (τ_{o-Ps}) lifetime and its intensity (I_{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_{o-Ps} and a decrease in I_{o-Ps}, whereas rejuvenation above T_g results in an increase in I_{o-Ps} whileτ_{o-Ps} remains unchanged. In addition, physical aging below T_g after plastic deformation manifests as a reduction of τ_{o-Ps}, whereas a decrease in I_{o-Ps} is observed after thermal rejuvenation. These results corroborate the idea of an amorphous-amorphous transition induced by plastic deformation.
19
Content available remote

Connection between Reorientational Motions of NH_{3} Groups and Phase Transitions in [Ni(NH_{3})_{6}](NO_{3})_{2} and [Mg(NH_{3})_{6}](NO_{3})_{2} Compounds

51%
Migdał-Mikuli A., Mikuli E.
Acta Physica Polonica A
|
1995
|
vol. 88
|
issue 3
527-532
EN
Quasielastic neutron scattering data for [Νi(ΝH_{3})_{6}](ΝO_{3})_{2} and [Mg(ΝH_{3})_{6}](NO_{3})_{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_{3} groups which in the [Me(NΗ_{3})_{6}]^{2+} cation reorientate with the correlation time of order of 10^{-12} s. It has been ascertained that in phases I and II of both substances under study all NH_{3} groups reorientate fast (R = 6ΝH_{3} groups), whereas in phases III and IV only part of these groups reorientate fast (R = 3ΝΗ_{3} groups - in the case of [Νi(ΝΗ_{3})_{6}](ΝO_{3})_{2} and R = 2ΝΗ_{3} groups - in the case of [Mg(ΝΗ_{3})_{6}](NO_{3})_{2}). Moreover, the temperature dependence of reorientational correlation time τ for these fast reorienting ΝH_{3} groups were also determined. The remaining NH_{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^{h}_{C2} - T^{c}_{C2} ≈ 95 K and ≈ 35 K respectively for [Ni(ΝΗ_{3})_{6}](ΝO_{3})_{2} and [Mg(ΝΗ_{3})_{6}](NO_{3})_{2}).
20
Content available remote

Structural and Electrical Conductivity Studies of Doped ZnS

51%
Sharma S., Chand P.
Acta Physica Polonica A
|
1992
|
vol. 81
|
issue 6
653-658
EN
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.
first rewind previous Page / 2 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.