Y. Wang
,
H.Z. Li
,
C.N. Yu
,
G.M. Wu
,
I. Gordon
,
P. Schattschneider
,
O. Van Der Biest
,
null
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null
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null
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null
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null
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null
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null
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null
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null
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金属学报(英文版)
Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.
关键词:
antimony
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null
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null
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null
Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films
Chromium nitride (CrN) films were deposited on Si wafers by arc ion plating (AIP) at various negative bias voltages and several groups of N-2/Ar gas flux ratios and chamber gas pressures. The authors systematically investigated the influence of negative bias voltage on the synthesis, composition, microstructure, and properties of the AIP CrN films. In this part (Part I), the investigations were mainly focused on the macroparticle distributions and film-growth characteristics. The results showed that macroparticle densities on the film surfaces decreased greatly by applying negative bias voltage, which can be affected by partial pressure of N-2 and Ar gases. From the statistical analysis of the experimental results, they proposed a new hybrid mechanism of ion bombardment and electrical repulsion. Also, the growth of the AIP CrN films was greatly altered by applying negative bias voltage. By increasing the bias voltage, the film surfaces became much smoother and the films evolved from apparent columnar microstructures to an equiaxed microstructure. The impinging high-energy Cr ions accelerated by negative bias voltages were deemed the inherent reason for the evolution of growth characteristics. (c) 2008 American Vacuum Society.
关键词:
chromium nitride films;hybrid coating system;structure zone model;si-n coatings;mechanical-properties;tin films;thin-films;pulse bias;vacuum;evaporation
Physical Review B
We have developed a quantum-mechanical approach to study the critical properties of the quantum sine-Gordon equation describing a massless scalar field in 1 + 1 space-time dimensions with interaction density proportional to cos(beta-0-phi). The main feature of the present theory is to find an appropriate starting point for perturbation expansion, which can directly treat the infrared divergences encountered in the conventional perturbation theory. Exact critical conditions for the phase transition of the model are derived; and the quantum sine-Gordon Hamiltonian is found to correspond exactly to a free-field model. Near the critical regime, a gap will open near zero momentum in the excitation spectrum, and the corresponding ground-state wave function is a pairing quasiparticle state, analogous to the BCS superconducting state. It is proved that this ground state will possess quasi-long-range and quasi-off-diagonal long-range correlations. Comparisons with the Kosterlitz-Thouless classical theory of the two-dimensional Coulomb gas are also made.
关键词:
2-dimensional coulomb gas;squeezed-state approach;yang-mills theory;superconducting films;phase-transitions;quark confinement;critical-behavior;thirring models;gauge theories;field-theory
Acta Materialia
Cyclic deformation behavior of Cu-30% Zn single crystals oriented for single slip was studied at constant plastic shear strain amplitudes (gamma(pl)) in the range of 3.8 x 10(-5)-6.4 x 10(-3) in order to understand systematically the fundamental fatigue behavior of low stacking fault energy materials. Results indicate that the cyclic hardening behavior strongly depends on the strain amplitude applied. For low strain amplitudes (gamma(pl) <3 x 10(-4)), cyclic saturation occurred after an initial cyclic hardening stage, but for high strain amplitudes (gamma(pl) greater than or equal to 6.0 x 10(-4)) saturation could not be reached until fatigue failure. The initial cyclic hardening rate (theta(0.2)) was found to decrease with increase in the applied strain amplitude. Slip bands were found to behave very similarly to Luders band appearance at the beginning as well as in the middle stage of cyclic deformation. Particularly, the similarity of the cyclic hardening behavior at low and high strain amplitudes to the work hardening response in stages I and II of tensile deformation of the same alloy has been pointed out. Cyclic stress was further decomposed into two terms, the effective stress and the internal stress, and both were found to increase continuously with cyclic deformation. It has been demonstrated that the activities of secondary slips played an important role in the continuous cyclic hardening at high gamma(pl). A comparison of the present result with previous relevant work on both wavy and planar slip materials has been attempted. The transition of wavy slip mode to planar slip mode of Cu-Al and Cu-Zn alloys has been discussed in terms of the electron-atom ratio and the critical Value of the ratio for such a transition is found to be 1.18-1.19 for both alloys. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.
关键词:
stress-strain response;dislocation-structures;alpha-brass;fatigue;alloys;cu-16;temperature;amplitude
新型炭材料
Electrochemical capacitors (ECs) store energy in eletric double-layers formed along the interface of electrode material and electrolyte, this produces an extremely large capacitance compared with the traditional capacitors. The fundamental principles of electrochemical capacitors are briefly introduced, and the key materials used like electrode materials, electrolytes, separator and current collector materials are summarized. Electrochemical capacitors with pseudocapacitance, such as metal oxides, polymers and hybrid capacitors, are also discussed. The characteristics, possible application fields, the development state, the future R&D prospects for electrochemical capacitors are highlighted.
关键词:
electrochemical capacitors;supercapacitors;storage of electric energy;principles
