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Wyświetlanie 1-15 z 89
Tytuł:
Preparation and Some Properties of Carbon Nanotubes
Autorzy:
Byszewski, P.
Ukalski, K.
Baran, M.
Dlużewski, P.
Kozłowski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1933400.pdf
Data publikacji:
1995-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.-g
81.35.+k
Opis:
Carbon nanotubes can be grown in the DC electric arc, they grow covered by a turbostratic graphite. The mechanism of the tubes growth is discussed. The magnetic susceptibility of samples, which contained aligned nanotubes exhibits anisotropic oscillatory behavior, which is ascribed to spatial quantization of the energy levels.
Źródło:
Acta Physica Polonica A; 1995, 87, 4-5; 885-891
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geometrically Frustrated Kagome Lattice with Chemical Disorder
Autorzy:
Szymczak, R.
Baran, M.
Fink-Finowicki, J.
Krzymanska, B.
Aleshkevych, P.
Szymczak, H.
Powiązania:
https://bibliotekanauki.pl/articles/1813765.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Cr
75.20.-g
Opis:
The effect of nonmagnetic $Mg^{2+}$ and magnetic $Co^{2+}$ doping in Kagome compounds was investigated using DC magnetic susceptibility. The main effect of doping is to change the crystal field parameters. It was shown that $Co^{2+}$ doping increases considerably crystal field parameters in $Ni_3V_2O_8$ while doping with nonmagnetic $Mg^{2+}$ ions decreases considerably crystal field parameters in $Co_3V_2O_8$ crystals.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 413-416
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
MnAs Nanocrystals Embedded in GaAs
Autorzy:
Kwiatkowski, A.
Wasik, D.
Kamińska, M.
Twardowski, A.
Dłużewski, P.
Borysiuk, J.
Sadowski, J.
Powiązania:
https://bibliotekanauki.pl/articles/1811951.pdf
Data publikacji:
2008-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.-g
75.75.+a
Opis:
Magnetic properties of MnAs nanocrystals embedded in GaAs are analyzed in the frame of phenomenological model proposed by Sasaki for ferritin superparamagnets. Our calculations explain qualitatively experimental data of magnetization versus temperature, obtained according to zero-field-cooled and field-cooled protocols. They show dynamics of magnetization of MnAs nanocrystals in range of temperature from 10 K to 320 K. There is transition from state in which very slow dynamics is observed (frozen state) to state in which dynamics is fast (quasi-superparamagnetic state).
Źródło:
Acta Physica Polonica A; 2008, 114, 5; 1207-1211
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Transport and Magnetic Studies of New Mixed-Valence Compounds: K$\text{}_{3}$Cu$\text{}_{8}$Se$\text{}_{6}$, KCu$\text{}_{3}$Se$\text{}_{2}$, K$\text{}_{3}$Cu$\text{}_{8}$Te$\text{}_{6}$ and BaCuS$\text{}_{3-x}$
Autorzy:
Jacyna-Onyszkiewicz, I.
Sidowski, M.
Starodub, W.
Ratuszna, A.
Robaszkiewicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/1955832.pdf
Data publikacji:
1997-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.-g
71.30.+h
Opis:
New mixed-valent copper chalcogenides BaCuS$\text{}_{3-x}$ and K$\text{}_{3}$Cu$\text{}_{8}$X$\text{}_{6}$ with X=Se or Te and KCu$\text{}_{3}$Se$\text{}_{2}$, with chemical patterns corresponding to the recently investigated K$\text{}_{3}$Cu$\text{}_{8}$S$\text{}_{6}$ and KCu$\text{}_{3}$S$\text{}_{2}$, were synthesized. For these new samples the results of resistivity and magnetic susceptibility measurements are presented. For BaCuS$\text{}_{3-x}$, K$\text{}_{3}$Cu$\text{}_{8}$Se$\text{}_{6}$ and KCu$\text{}_{3}$Se$\text{}_{2}$ the metal-insulator transition is observed with the low temperature phase being metallic, which is untypical, whereas K$\text{}_{3}$Cu$\text{}_{8}$Te$\text{}_{6}$ is a metal in the investigated temperature range. The temperature dependence of magnetic susceptibility of the studied samples testifies to their diamagnetic or weakly paramagnetic behaviour.
Źródło:
Acta Physica Polonica A; 1997, 91, 2; 405-408
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Low-Temperature Structural Phase Transition in Monoclinic RbDy(WO$\text{}_{4}$)$\text{}_{2}$ Crystal
Autorzy:
Borowiec, M. T.
Dyakonov, V.
Kamenev, V.
Nabiałek, A.
Prokhorov, A.
Szymczak, H.
Załęski, M.
Powiązania:
https://bibliotekanauki.pl/articles/1968975.pdf
Data publikacji:
1998-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.30.-v
75.20.-g
Opis:
The ESR spectrum of Dy$\text{}^{3+}$ ion in the low-symmetry RbDy(WO$\text{}_{4}$)$\text{}_{2}$ crystal has been studied in the temperature region of T=4.2 ÷ 30K. The ESR linewidth was found to increase from 130 mT up to the maximum value of 190 mT at T=9K and then to decrease down to 150 mT at 4.2K. The components of the g-tensor change considerably without change of their spatial orientation in the temperature range from 12K to 7 K: g$\text{}_{z}$=2.5, g$\text{}_{x}$≈0, g$\text{}_{y}$=1.41 at T>12 K; g$\text{}_{z}$=1.53, g$\text{}_{x}$≈0, g$\text{}_{y}$=1.2 at T<7K. The observed λ-shaped behaviour of absorption linewidth and the decrease in the g-factor are assumed to be due to the low-temperature structural phase transition (T$\text{}_{SPT}$≈9 K). The width of the transition area is of about 5K. It is suggested that the symmetry of high- and low-temperature phases is identical.
Źródło:
Acta Physica Polonica A; 1998, 94, 1; 71-77
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simple Method for Calculating the Weak-Field Electron Diamagnetism in Cubic Lattices
Autorzy:
Olszewski, S.
Powiązania:
https://bibliotekanauki.pl/articles/2030424.pdf
Data publikacji:
2002-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.-g
75.20.En
76.40.+b
Opis:
The idea of electron wave packets moving along closed anisotropic Fermi surfaces placed in a constant magnetic field has been applied to the calculation of the orbital magnetic moment of an individual free electron and tightly-bound s-electron in a crystal lattice. In each case the magnetic moment is obtained as a derivative of the electron energy done with respect to the strength of the magnetic field. In the next step, calculations have been extended to electron ensembles. For a free-electron ensemble a thorough calculation of the weak-field magnetic moment gives a result similar to that obtained by a well-known method developed by Landau. On the other hand, calculations done for the s-band of the tightly-bound electrons of metallic iron give an absolute value of the magnetic moment much smaller than in the free-electron case. Simultaneously, the sign of the moment is changed indicating a lowering of the iron band electron energy with magnetization.
Źródło:
Acta Physica Polonica A; 2002, 101, 2; 249-265
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrical Transport Properties of $Yb_{8-x}Y_xV_2O_{17}$ (x=0,2,8)
Autorzy:
Sawicki, B.
Piz, M.
Filipek, E.
Groń, T.
Duda, H.
Powiązania:
https://bibliotekanauki.pl/articles/1398346.pdf
Data publikacji:
2017-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Pa
72.80.Ga
75.20.-g
Opis:
The UV-vis-NIR and electrical properties of $Yb_{8-x}Y_xV_2O_{17}$ for x=0, 2, and 8 were investigated. The band energy gap of 2.6 eV determined for $Yb_6Y_2V_2O_{17}$ (x=2) and comparable for the remaining compounds with x=0 and 8 is characteristic for insulators. Low electrical conductivity with a characteristic minimum shifting to higher temperatures from 322, via 360 to 370 K in the sequence x=0, 2 and 8, which decreases with increasing content of ytterbium was observed. Temperature dependence of thermoelectric power showed n-p transition at 410 and 467 K for x=0 and 2, respectively, and n-type conductivity for x=8, indicating mainly n-type electrical conductivity. A breakdown voltage of 26 V/mm is mainly observed for the I-V characteristics at 400 K and showing a varistor-like behavior.
Źródło:
Acta Physica Polonica A; 2017, 132, 2; 363-366
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Cr-Substitution on the Electrical Properties of $Fe_{1-x}Cr_xVSbO_6$
Autorzy:
Duda, H.
Filipek, E.
Dąbrowska, G.
Groń, T.
Mydlarz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1399099.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Pa
72.80.Ga
75.20.-g
Opis:
$Fe_{1-x}Cr_xVSbO_6$ solid solution is semiconductor with the activation energy decreasing both in the intrinsic and extrinsic conductivity temperature regions as the Cr-content increases. The n-type conduction is observed for Fe-richer samples while a change of the Seebeck coefficient (from n to p) - for Cr-richer ones. Magnetic isotherms for all samples of solid solution under study are characteristic of the universal Brillouin function, indicating paramagnetic response. These effects are discussed within the framework of the appearance of the mixed valence of both Fe and Cr ions.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 833-835
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Cr-Substitution on the Electrical Properties of $Fe_{1-x}Cr_{x}SnSbO_6$
Autorzy:
Groń, T.
Dąbrowska, G.
Filipek, E.
Duda, H.
Sawicki, B.
Powiązania:
https://bibliotekanauki.pl/articles/1398554.pdf
Data publikacji:
2016-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Pa
72.80.Ga
75.20.-g
Opis:
$Fe_{1-x}Cr_xSnSbO_6$ solid solution shows semiconducting behaviour with the activation energy decreasing from $E_{A}$=0.64 eV for x=0.0 to $E_{A}$=0.32 eV for x=1.0 in the intrinsic conductivity temperature region as well as the n-type conduction at room temperature. The I-V characteristics and the conductance G at 300 and 400 K showed symmetrical and nonlinear behavior in the voltage range (-100, 100 V) suggesting the electron emission over the potential barrier especially for the boundary compounds FeSnSbO₆ and CrSnSbO₆. These effects are discussed in the context of the energy gap $E_{g}$>1.6 eV many times greater than the thermal energy kT.
Źródło:
Acta Physica Polonica A; 2016, 129, 1a; A-153-A-156
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electrical Properties of Sr₂InV₃O₁₁
Autorzy:
Groń, T.
Filipek, E.
Pacześna, A.
Urbanowicz, P.
Sawicki, B.
Duda, H.
Powiązania:
https://bibliotekanauki.pl/articles/1398582.pdf
Data publikacji:
2016-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.20.Pa
72.80.Ga
75.20.-g
Opis:
The electrical conductivity σ (T) and thermoelectric power S(T) measurements of Sr₂InV₃O₁₁ showed the insulating state and the change of sign of thermopower from p to n at $T_{n-p}$=400 K. The I-V characteristics provided the evidence of symmetrical and non-linear behaviour typical of strong emission of charge carriers induced by temperature and voltage. Relative dielectric permittivity $ε_{r}$ as well as loss tangent (tan δ) strongly depend both on the temperature in the range of 295-400 K and the frequency in the range of 5×10² to 1×10⁶ Hz, showing the broad maximum at 320 K. These effects are considered as a relaxation process like in the Maxwell-Wagner or Jonscher model as well as the conduction of electric current, as determined by the Joule-Lenz law.
Źródło:
Acta Physica Polonica A; 2016, 130, 5; 1239-1241
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diluted Magnetic Semimetals - Beyond Heisenberg Coupling
Autorzy:
Wilamowski, Z.
Story, T.
Jantsch, W.
Powiązania:
https://bibliotekanauki.pl/articles/1931949.pdf
Data publikacji:
1995-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.-g
75.30.Hx
76.20.+q
Opis:
We analyse effects which cannot be explained assuming the isotropic Heisenberg form of sp-d or of the indirect d-sp-d (RKKY) coupling. Resonance line broadening, a line shift and an enhancement of the magnetic anisotropy in diluted magnetic semimetals are discussed.
Źródło:
Acta Physica Polonica A; 1995, 87, 1; 189-192
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Paramagnetism of Cu_3RE_2W_4O_{18} Semiconductors (RE = Gd, Dy-Er)
Autorzy:
Groń, T.
Tomaszewicz, E.
Duda, H.
Mazur, S.
Powiązania:
https://bibliotekanauki.pl/articles/1399149.pdf
Data publikacji:
2013-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Pp
75.20.-g
75.30.Cr
Opis:
$Cu_3RE_2W_4O_{18}$ tungstates (RE = Gd, Dy-Er) are paramagnets in the temperature range 4.2-300 K visible also in the absence of the energy losses in the curve of the imaginary part of magnetic susceptibility, χ". The negative values of the paramagnetic Curie-Weiss temperature, θ, may suggest the weak antiferromagnetic coupling below 4.2 K. The temperature independent component of magnetic susceptibility has a positive value indicating a domination of the Van Vleck contribution. Calculations of the effective number of the Bohr magnetons revealed that the orbital contribution to the magnetic moment comes mainly from the $RE^{3+}$ ions.
Źródło:
Acta Physica Polonica A; 2013, 124, 5; 885-887
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phononic Band Gap Width Control through Structural and Material Parameters in Two-Dimensional Phononic Crystals
Autorzy:
Śliwa, I.
Krawczyk, M.
Powiązania:
https://bibliotekanauki.pl/articles/2044562.pdf
Data publikacji:
2005-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.20.+g
43.35.+d
43.40.+s
Opis:
The phononic band structures of two-dimensional solid phononic crystals with different lattice and scatterer symmetry are studied numerically, with three types of lattice (square, triangular, and rectangular) and four different scatterer shapes (circle, hexagon, square, and rectangle) considered. XY and Z vibration modes are investigated separately. Two types of phononic crystal are considered: one composed of high-density rods embedded in a low-density matrix, the other of low-density rods in a high-density matrix. In the former case, lattice type and polarization being fixed, the broadest gaps are obtained when the symmetry of the rods corresponds to that of the lattice (the shape of a rod is identical with that of the first Brillouin zone); the largest gap width values are observed in triangular lattice-based crystals (compared to those based on the square and rectangular lattices), the shape of the corresponding first Brillouin zone being closest to a circle. These rules do not apply to structures in which the density of the rod material is lower than that of the matrix. In this case, when the symmetry of the rods corresponds to that of the lattice, gaps either fail to appear at all, or are much narrower than in other configurations. The effect of other material parameter values (such as the longitudinal and transversal velocity values) on the relation between the energy gap width and the scatterer symmetry is found to be much lesser.
Źródło:
Acta Physica Polonica A; 2005, 108, 6; 943-957
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetism in $NdMnO_{3+δ}$ Studied by the Single Crystal Neutron Diffraction
Autorzy:
Mihalik, M.
Maťaš, S.
Vavra, M.
Powiązania:
https://bibliotekanauki.pl/articles/1368766.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.-g
75.30.-m
75.50.Gg
Opis:
We present the single crystal neutron diffraction experiment performed on the $NdMnO_{3+δ}$ compound. The aim of the experiment was to study/revisit the magnetic structure of the compound. We have confirmed the ordering of Mn sublattice below $T_{N}$=85.5 K and confirmed that the Nd sublattice orders below $T_{1}$ ≈ 20 K with Nd moments aligned parallel to the b-axis.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 284-285
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nuclear Data Evaluation for ²¹⁷Th
Autorzy:
Nafee, S.
Al-Ramady, A.
Shaheen, S.
Powiązania:
https://bibliotekanauki.pl/articles/1398746.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
21.10.-k
23.20.-g
23.35.+g
29.30.-h
Opis:
Thorium-217 was produced by the reaction ¹⁷⁰Er (⁵⁰Ti, xn) ^{220-x}Th. The nuclei were studied by Evaporation Residues gamma-alpha-gamma coincidence measurements (ER-γ-α-γ). The evaluated decay data for the ²¹⁷Th nuclide resulted from the above interaction is presented in this report. Three delayed γ-transitions (309, 673 and 1269 keV) have been measured from the ER-γ(-γ)-α correlations and γ-γ coincidences. They were assigned to ²¹⁷Th, based on the level systematics of the N=127 isotones. The evaluated half-lives T_{1/2} for these levels were assigned to be 64-₂₂⁺⁶⁴, 69-₁₇⁺³² and 66-₁₅⁺²⁷ μs, respectively. In addition, an isomeric state (2252+x) keV is presented in the ²¹⁷Th decay scheme between the 2252 (21/2+) and 2362 (25/2+) keV. Q (α) has been updated based on the recent published work of the Atomic Mass Evaluation AME2012 as well. Moreover, the total conversion electrons as well as the K-Shell to L-Shell, L-Shell to M-Shell and L-Shell to N-Shell conversion electron ratios have been calculated using BrIcc code v2.3.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 669-672
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 89

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