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Wyszukujesz frazę "P. W. K." wg kryterium: Autor


Tytuł:
Transport of Photoexcited Electron-Hole Plasma in GaN/AlGaN Quantum Well
Autorzy:
Korona, K.
Caban, P.
Strupiński, W.
Powiązania:
https://bibliotekanauki.pl/articles/1791352.pdf
Data publikacji:
2009-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ey
72.40.+w
Opis:
We report spatially resolved photocurrent measurements showing transport of excitation on long distances in plane of a 6 nm GaN/$Al_{0.1}Ga_{0.9}N$ quantum well. The strong field present in nitrides (due to large spontaneous and piezoelectric polarizations) leads to lower recombination rates of electrons and holes, so in the case of electron-hole pairs excited by light, relatively long-lived electron-hole plasma could be generated. In the case of the investigated quantum well, lifetime of few μs was expected. The thermal measurements showed that barriers were low enough, so all excited carriers could reach the electrode (thermal activation energy of 0.11 eV was found). The diffusion length for unbiased structure was about 40 μm. It was observed that the charge transport could be clearly accelerated by bias. In the biased quantum well, the transport range was of the order of 100 μm under both positive and negative bias. The reported effect of long transport range is very important for electronic devices made on the GaN/AlGaN structures.
Źródło:
Acta Physica Polonica A; 2009, 116, 5; 927-929
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Effect of Annealing Temperature on the Phase Constitution and Magnetic Properties of the Pr₈Dy₁Fe₆₀Co₇Mn₆B₁₄Zr₁Ti₃ Alloy Ribbons
Autorzy:
Przybył, A.
Pawlik, K.
Pawlik, P.
Gębara, P.
Kaszuwara, W.
Wysłocki, J.
Filipecka, K.
Powiązania:
https://bibliotekanauki.pl/articles/1402331.pdf
Data publikacji:
2015-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.20.En
91.60.Pn
Opis:
Melt-spun ribbons were produced from the Pr₈Dy₁Fe₆₀Co₇Mn₆B₁₄Zr₁Ti₃ base alloy at the surface velocity of the cooper wheel of 30 m/s. The studies showed amorphous structure of ribbons and their soft magnetic properties. X-ray diffraction was used to determine phase constitution of all obtained samples. Annealing of ribbons caused formation of nanocomposite structure, which was a result of coexistence of hard magnetic RE₂(Fe,Co)₁₄B and soft magnetic α-Fe phases. Basic magnetic properties such as: coercivity $\text{}_{J}H_{c}$, remanence $J_{r}$ and maximum energy product $(BH)_\text{max}$ were determined from the measured hysteresis loops. The microstructure of selected specimens was observed by transmission electron microscopy technique.
Źródło:
Acta Physica Polonica A; 2015, 128, 1; 94-97
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Coupling of Quantum Dots with Quantum Wells in a System Based on (Cd,Zn,Mg)Te
Autorzy:
Połczyńska, K.
Janik, E.
Kossacki, P.
Pacuski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1033157.pdf
Data publikacji:
2017-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.55.Et
78.67.Hc
73.21.La
78.67.-n
Opis:
Coupled low dimensional structures have potential applications in quantum computing and spintronics. Using molecular beam epitaxy we fabricated three kinds of systems of coupled quantum wells and quantum dots with different energy order: wells at higher energy than dots, resonant structures, and dots at higher energy than wells. By analysis of photoluminescence and reflectivity spectra, we conclude that there is a possibility of effective carrier tunneling between structures, which opens possibility of subsequent testing of spin transfer efficiency.
Źródło:
Acta Physica Polonica A; 2017, 132, 2; 369-371
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Glass forming abilities and crystallization process in amorphous Pr-Fe-Co-Zr-Nb-B alloys of various B content
Autorzy:
Pawlik, K.
Pawlik, P.
Kaszuwara, W.
Wysłocki, J.
Powiązania:
https://bibliotekanauki.pl/articles/1054842.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.dg
61.05.cp
75.20.En
75.50.Vv
Opis:
The influence of boron contents on the glass forming abilities and magnetic properties of melt-spun ribbon samples produced from Pr₉Fe_{50+x}Co₁₃Zr₁Nb₄B_{23-x} (x=0, 2, 5, 8) alloys, were investigated. For all compositions, the rapidly solidified samples were fully amorphous, which was confirmed by X-ray diffractometry and the Mössbauer spectroscopy. Differential scanning calorimetry and differential thermal analysis studies revealed good glass forming abilities for all investigated specimens and allowed to determine thermal stability parameters of the amorphous phase. For all alloy ribbons, very large supercooled liquid region before crystallization ΔT_x reaching 100 K was measured. The Kissinger plots were constructed to determine the activation energies for crystallization. Annealing of specimens at temperatures ranging from 923 K to 1033 K for 5 min resulted in significant change of the phase constitution. The X-ray diffractometry studies have shown presence of hard magnetic Pr₂(Fe,Co)₁₄B and paramagnetic Pr_{1+x}Fe₄B₄ phases. Furthermore, with the increase of B contents in the alloy composition crystallization of α-Fe phase occurs at wider range of the annealing temperature. Anomaly of both thermal and magnetic properties was observed for the Pr₉Fe₅₂Co₁₃Zr₁Nb₄B₂₁ alloy ribbons.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 979-981
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetization Reversal Processes in the Nanocrystalline Fe-Co-Zr-Ti-Pr-B Magnets
Autorzy:
Pawlik, K.
Pawlik, P.
Wysłocki, J.
Kaszuwara, W.
Powiązania:
https://bibliotekanauki.pl/articles/1813515.pdf
Data publikacji:
2008-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ww
75.50.Kj
71.20.Eh
Opis:
Magnetization reversal processes in the magnets derived from the $Fe_{60}Co_{13}Zr_1Ti_3Pr_9B_{14}$ alloy were investigated. It was shown that the processing technique affects the magnetization reversal processes. For the nanocrystalline ribbon samples pinning of the domain walls arises at low external magnetic fields while nucleation of reversed domains occurs at higher fields. However, the nucleation fields are lower than the pinning fields for the nanocrystalline rod and tube samples produced by suction-casting technique.
Źródło:
Acta Physica Polonica A; 2008, 113, 1; 39-42
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ground State Properties of Tb$\text{}^{3+}$ Ion in TbNi$\text{}_{10}$Si$\text{}_{2}$
Autorzy:
Stefański, P.
Suski, W.
Wochowski, K.
Mydlarz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1964565.pdf
Data publikacji:
1997-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.30.Gw
75.50.Gg
Opis:
Ground state properties of Tb$\text{}^{3+}$ ion were investigated in the tetragonal ThΜn$\text{}_{12}$-type TbNi$\text{}_{10}$Si$\text{}_{2}$ compound on the basis of temperature dependence of the paramagnetic susceptibility and magnetization measurements. The rare earth temperature dependence of the susceptibility was calculated using the Van Vleck equation. The Γ$\text{}_{t5}^{(1)}$ doublet is suggested to be a ground state separated by 9 K from the first excited singlet Γ$\text{}_{t1}^{(2)}$. The magnetic moment associated with the ground state doublet agrees with saturation magnetization data at 4.2 K. The overall crystal field splitting is estimated to be 105 K.
Źródło:
Acta Physica Polonica A; 1997, 92, 2; 281-284
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A High-Energy Ball Milling as a Useful Technique for the Synthesis of $CaCu_3Ti_4O_{12}$ Electroceramics
Autorzy:
Dulian, P.
Bąk, W.
Kajtoch, Cz.
Wieczorek-Ciurowa, K.
Powiązania:
https://bibliotekanauki.pl/articles/1375214.pdf
Data publikacji:
2014-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.22.Gm
81.05.-t
Opis:
This paper shows that $CaCu_3Ti_4O_{12}$ (CCTO) can be synthesized through the high-energy ball milling of CaO, CuO and $TiO_2$ powders. The dielectric characterization of CCTO obtained mechanochemically as well as, for comparison, by a high-temperature method is presented. Moreover, it is illustrated that zirconium oxide in contrast to a metallic iron generated during milling processes improves the properties of CCTO in terms of ceramic capacitors.
Źródło:
Acta Physica Polonica A; 2014, 126, 4; 931-937
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surfactant Effect on Synthesis of Nanocrystalline La$\text{}_{x}$Sr$\text{}_{1-x}$MnO$\text{}_{3}$ by Hydrothermal Method
Autorzy:
Sin, W. L.
Wong, K. H.
Li, P. Li.
Powiązania:
https://bibliotekanauki.pl/articles/2047246.pdf
Data publikacji:
2007-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
82.70.Uv
61.10.Nz
Opis:
Crystalline La$\text{}_{x}$Sr$\text{}_{1-x}$MnO$\text{}_{3}$ was prepared by a hydrothermal route in the presence of surfactant. The cationic surfactant of cetyltrimethylammonium bromide as a template is used to regulate the nucleation and crystal growth. The as-synthesized product was characterized by X-ray diffraction and transmission electron microscopy. Nanosized and uniform rod-like monocrystals of La$\text{}_{x}$Sr$\text{}_{1-x}$MnO$\text{}_{3}$ were obtained. Their magnetic properties were studied using a vibrating sample magnetometer. Our results reveal that the use of surfactant helps to lower the processing temperature and to speed up the formation and crystallization of La$\text{}_{x}$Sr$\text{}_{1-x}$MnO$\text{}_{3}$. The surfactant also provides us an additional means of controlling the nanocrystalline size and maintaining the stoichiometry of the as-prepared nanocrystallites.
Źródło:
Acta Physica Polonica A; 2007, 111, 1; 165-171
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Prototype Silicon Position-Sensitive Detector Working with Bragg-Brentano Powder Diffractometer
Autorzy:
Zięba, A.
Dąbrowski, W.
Gryboś, P.
Powroźnik, W.
Stobiecki, T.
Świentek, K.
Słowik, J.
Wiącek, P.
Powiązania:
https://bibliotekanauki.pl/articles/2030562.pdf
Data publikacji:
2002-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.85.-m
29.40.Wk
Opis:
A prototype 64-channel detector module, comprising a silicon strip detector with strip pitch of 100μm and 64-channel ASIC RX64, was tested with the X-Pert Philips MPD diffractometer. Basic parameters of the detector module, energy resolution, and detection efficiency, were evaluated as a function of the counting rate. Energy resolution of 1.1 keV FWHM for photon rate up to 1×10$\text{}^{7}$ photon/s per 1 cm of the active width of the detector was demonstrated. The prototype detector, when applied in a diffractometer utilizing Bragg-Brentano focusing principle, allows to increase the counting rate by about 2 orders of magnitude with respect to a single counter. Exemplary diffraction patterns of polycrystalline samples of Si and SiO$\text{}_{2}$ (quartz peak cluster) are presented.
Źródło:
Acta Physica Polonica A; 2002, 101, 5; 629-634
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetization Reversal Processes in Pr-Fe-B-type Nanocrystalline Magnets
Autorzy:
Pawlik, K.
Pawlik, P.
Kaszuwara, W.
Wysłocki, J.
Powiązania:
https://bibliotekanauki.pl/articles/1368000.pdf
Data publikacji:
2014-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Vv
75.60.Ej
75.50.Bb
75.50.Tt
75.50.Ww
Opis:
The magnetization reversal processes in magnets derived from rapidly solidified $Pr_{9}Fe_{52}Co_{13}Zr_{1}Nb_{4}B_{21}$ alloy samples were studied by analysis of minor hysteresis loops and recoil curves. The studies were carried out on suction-cast 1 mm diameter rod, 1 mm thick plate, 3 mm outer diameter (o.d.) tube and melt-spun ribbon samples subjected to annealing at 983 K for 5 min. The X-ray diffraction analysis has shown multiphase constitution of the samples. Structural and magnetic studies indicated that the initial state of microstructure and phase composition affects the magnetization reversal processes in annealed samples due to a variation of microstructure in samples of various shapes. Magnetic studies allowed estimation of the mean values of nucleation and pinning fields that control the magnetization reversal processes.
Źródło:
Acta Physica Polonica A; 2014, 126, 1; 186-187
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
X-Ray Diffraction Investigations of NdGaO$\text{}_{3}$ Single Crystal
Autorzy:
Mazur, K.
Sass, J.
Giersz, W.
Reiche, P.
Schell, N.
Powiązania:
https://bibliotekanauki.pl/articles/1964526.pdf
Data publikacji:
1997-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.10.Fq
61.50.Ks
68.35.Bs
Opis:
Neodymium gallium perovskite single crystals grown with the Czochralski method were examined with several complementary X-ray methods. By means of X-ray diffraction topography and reciprocal space diagram the structural perfection and crystal homogeneity of the studied wafers were determined. Additionally, the results of the X-ray reflectometry investigations of the surface perfection after the mechanochemical treatment are presented.
Źródło:
Acta Physica Polonica A; 1997, 92, 1; 226-230
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
ESR and Electron Spin Echo Studies of Spin-Lattice Relaxation of Hydrazinium Radical in Li(N$\text{}_{2}$H$\text{}_{5}$)O$\text{}_{4}$ Single Crystal
Autorzy:
Morawski, P.
Hoffmann, S. K.
Hilczer, W.
Goslar, J.
Powiązania:
https://bibliotekanauki.pl/articles/1964224.pdf
Data publikacji:
1997-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.80.Ed
76.30.Rn
Opis:
A hydrazinium ṄH-NH$\text{}_{3}^{+}$ radical was identified by ESR in γ-irradiated Li(N$\text{}_{2}$H$\text{}_{5}$)SO$\text{}_{4}$ single crystal. Unpaired electron is strongly localized on the nitrogen atom as compared to hydrazinium radicals in other crystals. Angular variations of the multicomponent ESR spectra and computer calculations gave the isotropic hyperfine coupling parameters (in mT): a$\text{}_{N1}$ = 1.93, a$\text{}_{N2}$ = 0.80, a$\text{}_{H1}$ = 2.50, a$\text{}_{H1'}$ = 0.48 (NH$\text{}_{3}$), and a$\text{}_{H2}$ = 1.40 (adjacent molecule). The radiation defects containing unpaired electrons do not influence much the protonic conductivity along the hydrazine molecule chains in the crystal. It confirms a tunelling mechanism of the conductivity activated by NH$\text{}_{2}$-group rotation. Spin-lattice relaxation time T$\text{}_{1}$ varies strongly with temperature in the range from 100 ms (10 K) to 90 μs (170 K) and is governed by spectral diffusion (1/T$\text{}_{1}$ ∝ T$\text{}^{2}$) and a Murphy-type mechanism (1/T$\text{}_{1}$ ∝ cosech(Δ/T)) with Δ = 150 cm$\text{}^{-1}$. A distribution of the spin-relaxation times was observed with temperature independent dispersion parameter β = 0.76.
Źródło:
Acta Physica Polonica A; 1997, 91, 6; 1121-1129
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Anharmonic Optical Phonon Effects in ZnO Nanocrystals
Autorzy:
Khusnutdinov, S. V.
Dynowska, E.
Zaleszczyk, W.
Makhniy, V. P.
Wysmołek, A.
Korona, K. P.
Powiązania:
https://bibliotekanauki.pl/articles/2048106.pdf
Data publikacji:
2011-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ga
74.25.nd
63.20.kg
Opis:
Zinc oxide (ZnO) is a very promising material for optoelectrical devices operating at the short-wavelength end of the visible spectral range and at the near UV. The Raman scattering studies of ZnO heterolayers formed by isothermal annealing show sharp phonon lines. In addition to the A$\text{}_{1}$(TO), E$\text{}_{1}$(TO), E$\text{}_{2}^{H}$, and E$\text{}_{1}$(LO) one-phonon lines, we observed two-phonon lines identified as: E$\text{}_{2}^{H}$ - E$\text{}_{2}^{L}$, E$\text{}_{2}^{H}$ + E$\text{}_{2}^{L}$, and 2LO at 332, 541, and 1160 cm$\text{}^{-1}$, respectively (at room temperature). The identification of the E$\text{}_{2}^{H}$ - E$\text{}_{2}^{L}$ peak was confirmed by its thermal dependence. Temperature dependent measurements in the range 6-300 K show that the phonon frequencies decrease with temperature. The E$\text{}_{2}^{H}$ peak is at energy 54.44 meV (439.1 cm$\text{}^{-1}$), at 4 K and due to phonon-phonon anharmonic interaction, its energy decreases to 54.33 meV (438.2 cm$\text{}^{-1}$) at room temperature. The Grüneisen parameter found for this oscillation mode was γ$\text{}_{E}$ 2H = 1.1 at about 300 K. The intensity of the E$\text{}_{2}^{H}$ - E$\text{}_{2}^{L}$ peak increases strongly with temperature and this dependence can be described by the Bose-Einstein statistics with activation energy of 13.8 meV (nearly equal to the energy of the E$\text{}_{2}^{L}$ phonon).
Źródło:
Acta Physica Polonica A; 2011, 119, 5; 678-680
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Annealing in Multicomponent bcc Alloys
Autorzy:
Szymański, K.
Perzyńska, K.
Satuła, D.
Dobrzyński, L.
Zaleski, P.
Waliszewski, J.
Rećko, K.
Biernacka, M.
Olszewski, W.
Powiązania:
https://bibliotekanauki.pl/articles/1506614.pdf
Data publikacji:
2011-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
71.20.Be
76.80.+y
61.05.Qr
61.50.Ks
81.30.Hd
Opis:
Multicomponent single phase alloys were synthesized according to the idea of iron-average atom system. X-ray diffraction shows formation of bcc phase and traces of unidentified phase. Mössbauer spectra indicate presence of two components with different hyperfine magnetic field distributions. The high field component corresponds to the majority ferromagnetic phase. Few per cent of iron builds low field component. The dominant effect of annealing consists in an increase of the low field component.
Źródło:
Acta Physica Polonica A; 2011, 119, 1; 62-64
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative Morphological Analysis of Graphene on Copper Substrate obtained by CVD from a Liquid Precursor
Autorzy:
Weiss, M.
Walkowiak, M.
Wasiński, K.
Półrolniczak, P.
Kokocińska, B.
Strupiński, W.
Powiązania:
https://bibliotekanauki.pl/articles/1032380.pdf
Data publikacji:
2017-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.65.Pq
81.05.ue
Opis:
Graphene film has been produced on untreated Cu substrate by a chemical vapor deposition technique in ambient pressure with liquid ethanol serving as the carbon precursor. The obtained material has been subjected to morphological study, directly on Cu substrate, by means of optical microscopy, scanning electron microscopy, atomic force microscopy, and a detailed Raman analysis. As a benchmark material, graphene obtained on Cu by a conventional CVD from gaseous methane was used. This simple experimental setup has proved to enable obtaining large area graphene samples with nearly 100% substrate coverage and large domains of one carbon layer. As compared to graphene from gaseous precursor, the presented approach resulted in visibly more defects and impurities. These imperfections are due to more complex precursor molecular structure and lack of Cu pretreatment with hydrogen, the later cause being easy to eliminate in course of further optimization of the method. The described approach can be regarded as a viable, low-cost, and experimentally simple alternative for the existing techniques of producing large area graphene. By providing direct comparison with the conventional method, the paper's intention is to provide deeper insight and to fill gap in the understanding of mechanisms involved in graphene formation on copper.
Źródło:
Acta Physica Polonica A; 2017, 131, 6; 1497-1506
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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