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Wyszukujesz frazę "Wu, J." wg kryterium: Autor


Wyświetlanie 1-8 z 8
Tytuł:
High-Coercivity FePt Nanoparticle Assemblies Embedded in Oxide-Matrix by Atomic Layer Deposition
Autorzy:
Kong, J.
Li, A.
Gao, M.
Yan, Q.
Wu, D.
Powiązania:
https://bibliotekanauki.pl/articles/1399662.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Vv
75.75.Cd
75.50.Bb
75.50.Ss
Opis:
Self-assembled face-centered cubic FePt nanoparticles were embedded into the oxide capping layer using the atomic layer deposition technology. The effect of the oxide-matrix layer on the structure, mono-dispersibility, and magnetic properties of the FePt/oxide composite thin films was investigated. Experimental results suggest that the protection of the oxide-matrix capping layer can effectively inhibit the grain growth and particle aggregation, and preserve the ordered domains of the FePt nanoparticles during the L 1_0 ordering transition through annealing. The combination of the atomic layer deposition capping layer and self-assembled FePt nanoparticles provides a new potential approach to fabricate the ultrahigh-density magnetic recording media.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 173-176
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Advanced Characterization of Material Properties on the Nanometer Scale Using Atomic Force Microscopy
Autorzy:
Fenner, M.
Wu, S.
Yu, J.
Huber, H.
Kienberger, F.
Powiązania:
https://bibliotekanauki.pl/articles/1490089.pdf
Data publikacji:
2012-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.55.-g
07.79.-v
68.37.Ps
68.37.Uv
07.57.Pt
Opis:
We report recent advances in material characterization on the nanometer scale using scanning microwave microscopy. This combines atomic force microscopy and a vector network analyzer using microwave tip sample interaction to characterize dielectric and electronic material properties on the nanometer scale. We present the methods for calibration as well as applications. Scanning microwave microscopy features calibrated measurements of: (1) capacitance with attofarad sensitivity. For calibration a well characterized array of capacitors (0.1 fF to 10 fF) is used. The method is applied to determine the dielectric properties of thin organic films, (2) Semiconductor dopant density. Calibration is performed by imaging the cross-section of a standard sample with differently doped layers (dopant stair case) from $10^{16}$ atoms/$cm^3$ to $10^{20}$ atoms/$cm^3$.
Źródło:
Acta Physica Polonica A; 2012, 121, 2; 416-419
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Observation and Control of Interfacial Defects in ZnO/ZnSe Coaxial Nanowires
Autorzy:
Bhutto, W.
Wu, Z.
Cao, Y.
Wang, W.
Kang, J.
Powiązania:
https://bibliotekanauki.pl/articles/1361939.pdf
Data publikacji:
2014-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
62.23.Hj
61.46.Km
64.70.Nd
68.35.Ct
Opis:
ZnO/ZnSe coaxial nanowires with different ZnO core diameters were synthesized by using a two-step chemical vapor deposition. The scanning electron microscopy images demonstrated that the coaxial nanowires with small ZnO core diameter had the smoother surface than that with large ZnO core diameter. A coherent ZnSe layer with wurtzite structure was observed in the nanowire interface between the ZnO core and the ZnSe shell by high resolution transmission electron microscopy. This coherent layer is beneficial to reduce the defect density and improve the crystal quality by suppressing the phase transition. It was found that the coherent thickness was significantly related to the ZnO core diameter. For the nanowire with large ZnO core, a thin critical thickness of 2 - 3 nm was obtained. As a result, a layer of zinc blende ZnSe appeared outside the nanowire, and a lot of defects existed in the interface between the ZnSe layers with different phase structures. For the nanowire with small ZnO core, however, the critical thickness increased and a coherent coaxial structure was observed with the same lattice spacing in the ZnO core and the ZnSe shell. To obtain defect-free coaxial nanowire, an optimal structure was also proposed by theoretical calculation.
Źródło:
Acta Physica Polonica A; 2014, 125, 4; 994-996
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Annihilation Lifetime Analysis of Left- and Right-Handed Alanine Single Crystals
Autorzy:
Eren, B.
Wu, F.
Eren, E.
Jean, Y.
Van Horn, J.
Powiązania:
https://bibliotekanauki.pl/articles/1030024.pdf
Data publikacji:
2017-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
82.30.Gg
34.80.-i
87.15.B-
Opis:
Studies of the interaction of polarized light or particles (including electrons, e¯, or positrons, e⁺) with asymmetric forms of matter has been of interest to scientists since the discovery of chirality and the subsequent development of particle physics. Researchers have been interested in e⁺ interactions with chiral molecules for decades, but with mixed and indecisive results. After reviewing the field, we speculated that the e⁺ or positronium (Ps) might interact differently with chiral pairs of large single crystals, i.e., the left-handed or right-handed asymmetric forms of the crystals - and subsequently observed significant differences in "free positron" annihilation and intensities in the evaluation of left-handed or right-handed quartz single crystals. This result may be understood to be a "particle stereorecognition" phenomenon. To extend this line of inquiry we crystallized mm scale L- or D-alanine crystals and performed positron annihilation lifetime spectroscopy measurements using a ²²Na positron source. Alanine crystals were obtained via slow evaporation of water in a Dewar, or from water/acetone solvent in a temperature-controlled environment. These methods resulted in small ( ≈0.5 cm/side) or large ( ≥1.0 cm/side) crystals, respectively. While some intensity (I₂) results from left-handed and right-handed crystals varied in positron annihilation lifetime spectroscopy analysis, the errors associated with the measurements do not indicate a stereorecognition of alanine via positron interactions.
Źródło:
Acta Physica Polonica A; 2017, 132, 5; 1456-1460
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Signature of Hot Phonons in Reliability of Nitride Transistors and Signal Delay
Autorzy:
Matulionis, A.
Liberis, J.
Matulionienė, I.
Šermukšnis, E.
Leach, J.
Wu, M.
Ni, X.
Morkoç, H.
Powiązania:
https://bibliotekanauki.pl/articles/1506173.pdf
Data publikacji:
2011-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.70.+m
73.50.Fq
73.61.Ey
Opis:
Lifetime of non-equilibrium (hot) phonons in biased GaN heterostructures with two-dimensional electron gas channels was estimated from hot-electron fluctuations. Dependence of the lifetime on the electron density is not monotonous - the resonance-type fastest decay serves as a signature of hot phonons. The signature is resolved in nitride heterostructure field effect transistors when the gate voltage is used to change the channel electron density. The transistor cut-off frequency decreases on both sides of the resonance in agreement with the enhanced electron scattering caused by longer hot-phonon lifetimes. The signature is also noted in device reliability experiment: the enhanced temperature of hot phonons, possibly, triggers formation of new defects and accelerates device degradation.
Źródło:
Acta Physica Polonica A; 2011, 119, 2; 225-227
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Design and the First Test Results of a Fast LTD Stage
Autorzy:
Chen, L.
Zhou, L.
Zou, W.
Ren, J.
Li, Y.
Wu, S.
Xie, W.
Feng, S.
Deng, J.
Powiązania:
https://bibliotekanauki.pl/articles/1807988.pdf
Data publikacji:
2009-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
84.70.+p
52.75.Kq
84.60.Ve
Opis:
Linear transformer driver stages are designed to be used as a primary energy storage in high power pulsed generators. In this report, the design and test results of the linear transformer driver stage prototype that delivers ≈100 kA fast pulse with 133 ns FWHM into a ≈0.87 Ω resistive load are described. This stage consists of 20 (100 kV, 20 nF) storage capacitors that are arranged in 10 identical bricks located evenly around the axis of the stage. Each brick contains two capacitors, a multi-gap switch, and the output connector that transfers the energy to the resistive load. The outer diameter of the stage is ≈1.5 m, at a length of ≈20 cm. The stage is developed to demonstrate the possibility of the fast linear transformer driver technology to create high power pulsed generators.
Źródło:
Acta Physica Polonica A; 2009, 115, 6; 1186-1188
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of a 20 kJ Sparker for High Resolution Ocean Seismic Survey
Autorzy:
Sun, Y.
Gao, Y.
Yan, P.
Wang, J.
Yuan, W.
Wu, H.
Wang, Y.
Wan, P.
Zhao, G.
Powiązania:
https://bibliotekanauki.pl/articles/1807914.pdf
Data publikacji:
2009-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
52.80.Wq
43.30.+m
Opis:
An ocean sparker with a stored energy of 20 kJ was developed for high resolution ocean seismic survey. The sparker is mainly composed of a high voltage high frequency charging supply, energy storage capacitors, a discharging switch and discharging electrodes. The H-bridge inverter and series resonant mode were adopted in the charging supply, and a dry high voltage transformer was used to improve the safety and maintenance, the average charging rate exceeded 4 kJ/s. An optical fiber connected between the high voltage system and the control system was used to isolate high voltage and transmit the high voltage signal. The high voltage electrodes of the discharging electrodes consisted of several hundreds of electrodes. The experimental results show that the sparker can be operated at repetition rates of 12 shots/min, and can meet the expected design requirements. Further field tests will be done in the near future.
Źródło:
Acta Physica Polonica A; 2009, 115, 6; 1059-1061
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rheological and Thermal Transport Characteristics of a Transformer Oil Based Ferrofluid
Autorzy:
Paulovičová, K.
Tóthová, J.
Rajňák, M.
Wu, Z.
Sundén, B.
Wadsö, L.
Tobiáš, T.
Kopčanský, P.
Timko, M.
Lisý, V.
Powiązania:
https://bibliotekanauki.pl/articles/1030831.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
47.65.Cb
83.80.Gv
66.20.Ej
44.35.+c
Opis:
Ferrofluids based on insulating liquids are intensively studied as a potential substitute of liquid dielectric in high voltage technologies. In this work we focus on the experimental investigation of flow and thermal transport characteristics of a ferrofluid based on transformer oil (Mogul) and iron oxide nanoparticles. The magneto-rheological behavior of the ferrofluid was studied by a rotational rheometer in the shear rate range from 1 to 1000 s¯¹ and magnetic field up to 1 T. By means of a thermal constants analyzer and a transient plane source method we obtained the thermal conductivity, specific heat and thermal diffusivity values for the studied oil and the ferrofluid. It is shown that the Newtonian character of the ferrofluid changes to a non-Newtonian with application of the magnetic field. The notable magneto-viscous effect has been observed especially at low shear rates. We found that the doping of the transformer oil by 3 wt% of the nanoparticles results in a thermal conductivity enhancement by about 3.2%.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 564-566
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-8 z 8

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