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Wyszukujesz frazę "64.60.Fr" wg kryterium: Temat


Wyświetlanie 1-9 z 9
Tytuł:
Structural Study of (NH$\text{}_{4}$)$\text{}_{4}$H$\text{}_{2}$(SeO$\text{}_{4}$)$\text{}_{3}$ in the Low-Temperature Phase
Autorzy:
Fukami, T.
Higa, N.
Chen, R. H.
Powiązania:
https://bibliotekanauki.pl/articles/2013261.pdf
Data publikacji:
2000-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.66.Fn
64.60.Fr
Opis:
The crystal structure of tetraammonium dihydrogen triselenate, (NH$\text{}_{4}$)$\text{}_{4}$H$\text{}_{2}$(SeO$\text{}_{4}$)$\text{}_{3}$, in the low-temperature phase at 141 K is studied by X-ray diffraction. The space group symmetry (triclinic P1) and the structure parameters are determined. By the shift of the Se atom from the center of the SeO$\text{}_{4}$ tetrahedron, it is suggested that the (NH$\text{}_{4}$)$\text{}_{4}$H$\text{}_{2}$ (SeO$\text{}_{4}$)$\text{}_{3}$ crystal in the low-temperature phase is ferroelectric with the electric dipole moment along the c-axis. The rotation of the SeO$\text{}_{4}$ tetrahedron suggested by electron paramagnetic resonance measurements is discussed.
Źródło:
Acta Physica Polonica A; 2000, 97, 4; 663-670
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low Field Relaxational Behavior of Taap Single Crystal (20-10$\text{}^{6}$ Hz)
Autorzy:
Fernández del Castillo, J. R.
Iglesias, T.
Przesławski, J.
Gonzalo, J. A.
Powiązania:
https://bibliotekanauki.pl/articles/1968856.pdf
Data publikacji:
1998-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.Fr
77.80.-e
Opis:
Relaxational behavior of ferroelectric telluric acid ammonium phosphate crystals were investigated in the range 20 Hz to 1 MHz by means of low field measurements of ε' and tan δ in the vicinity of ferroelectric phase transitions at a number of frequencies. Results are compared with those for triglycine selenate, a much "softer" ferroelectric material. The measuring field and frequency dependence of the effective potential barrier height for domain wall motion are compared in both crystals.
Źródło:
Acta Physica Polonica A; 1998, 93, 3; 499-503
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Crystal Structure of K$\text{}_{3}$Na(SeO$\text{}_{4}$)$\text{}_{2}$ at 340 K
Autorzy:
Fukami, T.
Chen, R. H.
Powiązania:
https://bibliotekanauki.pl/articles/1993089.pdf
Data publikacji:
1998-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.66.Fn
64.60.Fr
Opis:
The crystal structure of tripotassium sodium diselenate, K$\text{}_{3}$Na(SeO$\text{}_{4}$)$\text{}_{2}$, at 340 K is studied by single-crystal X-ray diffraction. The space group symmetry (trigonal P3̅) and structure parameters are determined. It is found that there exists the difference of the direction and the magnitude of the atomic displacement at the two phase transitions of 346 K and 334 K.
Źródło:
Acta Physica Polonica A; 1998, 94, 5-6; 795-801
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural Phase Transition and Crystal Structure for (ND$\text{}_{4}$)$\text{}_{4}$D$\text{}_{2}$(SeO$\text{}_{4}$)$\text{}_{3}$ at Low Temperature
Autorzy:
Fukami, T.
Chen, R. H.
Powiązania:
https://bibliotekanauki.pl/articles/2027434.pdf
Data publikacji:
2001-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.66.Fn
64.60.Fr
Opis:
Differential scanning calorimetry and X-ray diffraction measurements were performed on a deuterated tetraammonium dihydrogen triselenate (ND$\text{}_{4}$)$\text{}_{4}$D$\text{}_{2}$(SeO$\text{}_{4}$)$\text{}_{3}$ crystal at low temperatures. A structural phase transition is found at 182.0(3) K. The space group symmetry (triclinic P1) and the structure parameters are determined at 145 K in the low-temperature phase. The isotope effect for an asymmetric O-H-O hydrogen bond by the substitution of deuterium is discussed.
Źródło:
Acta Physica Polonica A; 2001, 100, 1; 53-65
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monte Carlo Study of a Periodically Pinned 2D Superconductor
Autorzy:
Rezlescu, N.
Anghelache, R.
Ciobotaru, I.
Powiązania:
https://bibliotekanauki.pl/articles/1955503.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.Fr
75.10.Hk
74.25.Bt
Opis:
We show that a natural assumption on the moving mechanism of vortices in a periodically pinned, two-dimensional superconductor in the mixed state is the basis for a n-clock-like model. The pinning points are considered to be centered in each unit cell of the superconducting lattice. This property enables one to use a discrete version of the XY model used in the simulations focusing on the melting of the Abrikosov lattice of vortices in a system of Josephson arrays. A Monte Carlo study performed on the corresponding Hamiltonian in a field given by a filling factor of f=1/2 exhibits two phase transitions, at the temperatures T$\text{}_{c1}$≈0.325 and T$\text{}_{m}$≈0.65. The numerical estimation of the Challa parameters for both transitions indicates their continuous nature. The physical meaning of the lower transition is the expulsion of the magnetic field from the superconducting system, i.e. the Meissner effect. The physical equivalent of the upper transition is the melting of the pinned vortex lattice.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 337-340
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulations of the 3D Ising Model at Criticality
Autorzy:
Blöte, H. W. J.
Kamieniarz, G.
Powiązania:
https://bibliotekanauki.pl/articles/1930588.pdf
Data publikacji:
1994-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
64.60.-i
64.60.Fr
75.40.Mg
64.60.Ak
Opis:
We present some new finite-size results for the Binder cumulant that we obtained by means of a transfer-matrix perturbation expansion and by the cluster Monte Carlo methods - the Swendsen-Wang and Wolff algorithms and the largest-cluster method. A finite-size scaling analysis taking into account a correction to scaling locates the critical coupling at Kc = 0.221649(4).
Źródło:
Acta Physica Polonica A; 1994, 85, 2; 395-398
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Critical Behaviour of Some 2D Lattice Models
Autorzy:
Kamieniarz, G.
Blöte, H. W.J.
Dekeyser, R.
Powiązania:
https://bibliotekanauki.pl/articles/1930586.pdf
Data publikacji:
1994-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.50.+q
64.60.-i
64.60.Cn
64.60.Ak
64.60.Fr
75.40.Mg
Opis:
The density series of the non-interacting hard-square lattice gas model are reanalyzed by the ratio, Dlog Padé and differential approximant methods. The problem of poor consistency between series and other results is resolved. Transfer matrix calculations are performed, implementing both finite-size scaling and conformal invariance. Very accurate estimates of the critical exponents y$\text{}_{t}$, and y$\text{}_{h}$ are obtained in agreement with Ising universality. Furthermore, an improvement of the value of the critical density ρ$\text{}_{c}$ is found. In addition, the universal critical-point ratios of the square of the second and the fourth moment of the magnetization for ferromagnetic Ising models on the square and on the triangular lattice with periodic boundary conditions are reported.
Źródło:
Acta Physica Polonica A; 1994, 85, 2; 389-393
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thickness Dependence of Effective Critical Exponents in Three-Dimensional Ising Plates
Autorzy:
Marqués, M. I.
Gonzalo, J. A.
Powiązania:
https://bibliotekanauki.pl/articles/2014019.pdf
Data publikacji:
2000-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.10.Hk
64.60.Fr
75.70.-i
02.50.Ng
Opis:
Phase transitions in Ising plates of equal area and different thicknesses have been studied by the Monte Carlo approach. The evolution of the critical temperature and of the effective critical exponents with the thickness of the lattice has been numerically determined. The thickness dependence of the maximum value of the effective critical exponents is well described by an exponential decay towards the respective three-dimensional value.
Źródło:
Acta Physica Polonica A; 2000, 97, 6; 1033-1037
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effective Field Methods for Magnetic Systems
Autorzy:
Kamieniarz, G.
Dekeyser, R.
Musiał, G.
Powiązania:
https://bibliotekanauki.pl/articles/1930600.pdf
Data publikacji:
1994-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.60.Cn
64.60.Fr
05.50.+q
75.10.Dg
75.10.Hk
75.10.Jm
75.40.Cx
75.40.Mg
Opis:
The self-consistency conditions inherent in the mean-field approximation are extended to take into account some pair correlations. Ii is shown that this extension is systematically improvable and applicable to the spin systems with short-range interactions in the entire temperature region. With two correlations included and the renormalization-group ideas implemented, the critical properties of the Ising model are satisfactorily revealed. Moreover, the improved estimates of the thermodynamical quantities for the quantum linear XY model from the finite-size calculations are found down to very low temperatures.
Źródło:
Acta Physica Polonica A; 1994, 85, 2; 413-417
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-9 z 9

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