共查询到20条相似文献,搜索用时 15 毫秒
1.
Ti42.5Zr7.5Cu40Ni5Sn5 bulk metallic glass with a critical diameter of 4 mm was fabricated by the conventional copper mould casting method. The
supercooled liquid region ΔT
x, reduced glass transition temperature T
rg, γ parameter, and δ parameter of the alloy were measured to be 63.9 K, 0.561, 0.393, and 1.400, respectively, implying that the alloy has an
excellent glass-forming ability. The bulk metallic glass exhibits high compressive fracture strength of 2162 MPa with distinct
plastic strain of 0.9%. The fracture surface consists mainly of vein-like patterns, typical of bulk glassy alloys.
Supported by the Program for New Century Excellent Talents in University of China and the National Natural Science Foundation
of China (NSFC)(Grant No. 50771040) 相似文献
2.
For the first time, a threshold quantum secure direct communication (TQSDC) scheme is presented. Similar to the classical Shamir's secret sharing scheme, the sender makes n shares, S1, …, Sn of secret key K and each receiver keeps a share secretly. If the sender wants to send a secret message M to the receivers, he en-codes the information of K and M on a single photon sequence and sends it to one of the receivers. According to the secret shares, the t receivers sequentially per-form the corresponding unitary operations on the single photon sequence and ob-tain the secret message M. The shared shares may be reusable if it can be judged that there is no eavesdropper in line. We discuss that our protocol is feasible with current technology. 相似文献
3.
Through phase transformation kinetic analysis and experimental observation, the δ/γ transformation occurring in the non-equilibrium peritectic Fe-4.33at.%Ni alloys was systematically investigated. According to JMA solid-state transformation kinetic theory, the Time-Temperature-Transformation (TTT) curves of the δ/γ transformation in peritectic Fe-Ni alloy were calculated. On this basis, the physical correlation between the δ/γ transformation and the initial undercooling of melt (△T) was elucidated. The results indicate that the change of △T can alter not only the overall δ/γ transformation pathways but also the transformation fraction with respect to each transformation mechanism. 相似文献
4.
First-principles study of interphase Ni3Sn in Sn--Ni alloy for anode of lithium ion battery 下载免费PDF全文
This paper investigates the mechanism of Li insertion into interphase Ni3Sn in Ni-Sn alloy for the anode of lithium ion battery by means of the first-principles plane-wave pseudopotential. Compared with other phases, it is found that the Ni3Sn has larger relative expansion ratio and lower electrochemical potential, with its specific plateaus voltage around 0.3 eV when lithium atoms are filled in all octahedral interstitial sites, and the relative expansion ratio increasing dramatically when the lithiated phase transits from octahedral interstitial sites to tetrahedral interstitial sites. So this phase is a devastating phase for whole alloy electrode materials. 相似文献
5.
The coherent-entangled state |α, x; λ> with real parameters λ is proposed in the two-mode Fock space, which exhibits the properties of both the coherent and entangled states. The completeness relation of |α, x; λ> is proved by virtue of the technique of integral within an ordered product of operators. The corresponding squeezing operator is derived, with its own squeezing properties. Furthermore, generalized P-representation in the coherent-entangled state is constructed. Finally, it is revealed that superp... 相似文献
6.
SiHua Ouyang ChunChang Wang GuoZhen Liu Meng He KuiJuan Jin ZhiMin Dang HuiBin Lü 《中国科学G辑(英文版)》2008,51(3):232-236
We report here studies on the influence of oxygen pressure on the electroresistance behavior of La0.9Sr0.1MnO3 thin films fabricated by laser molecular beam epitaxy. It was found that the film deposited at lower oxygen pressure shows
larger c-axis parameter, higher resistance, and more distinct electroresistance. These results reveal that the electroresistance of
manganite thin films can be tuned by the conditions of film fabrication.
Supported by the National Natural Science Foundation of China (Grant No. 10334070) and the National Key Basic Research Program
of China (Grant No. 2004CB619004) 相似文献
7.
MingZhen Ma HaiTao Zong HaiYan Wang YanPeng Qi SunXing Liang AiJun Song WeiGuo Zhang Qiang Wang XinYu Zhang Qin Jing Gong Li RiPing Liu 《中国科学G辑(英文版)》2008,51(4):438-444
The fluidity and filling ability of glass-forming Zr-based alloy melt in copper mould were investigated both theoretically
and experimentally. The major factors which affected the flowing behavior of the metallic melt in the mold were determined,
which provides the foundation for overcoming the contradiction between the filling and formation of amorphous alloy during
the rapid cooling process of the metallic melts. The casting factors to prepare a metallic ring were discussed and selected.
As a result, a Zr-based bulk metallic glass ring was prepared successfully.
Supported by the National Natural Science Foundation of China (Grant No. 50731005), SKPBRC (Grant No. 2006CB605201/2007CB616915),
PCSIRT (Grant No. IRT0650), the Natural Science Foundation of Hebei Province of China (Grant No. E2004000209), the Scientific
Research Foundation of Education Department of Hebei Province of China (Grant No. 2004464), and the Experts and Scholars Fund
of Personnel Department of Hebei Province, China (Grant No. 2003) 相似文献
8.
A threshold proxy quantum signature scheme with threshold shared verification is proposed. An original signer could authorize
a group as its proxy signers. Then only t or more of n persons in the proxy group can generate the proxy signature on behalf of the original signer and any t − 1 or fewer ones cannot do that. When the proxy signature needs to be verified, any t or more of n persons belonging to the verification group can verify the message and any t − 1 or fewer ones cannot verify the validity of the proxy signature.
Supported by the National Basic Research Program of China (973 Program)(Grant No. 2007CB311100), the National High-Technology
Research and Development Program of China (Grant Nos. 2006AA01Z419 and 20060101Z4015), the Major Research Plan of the National
Natural Science Foundation of China (Grant No. 90604023), the Scientific Research Common Program of Beijing Municipal Commission
of Education (Grant No. KM200810005004), the Scientific Research Foundation for the Youth of Beijing University of Technology
(Grant No. 97007016200701), the Doctoral Scientific Research Activation Foundation of Beijing University of Technology (Grant
No. 52007016200702), and the National Laboratory for Modern Communications Science Foundation of China (Grant No. 9140C1101010601) 相似文献
9.
Pd80+x
Si20−x
(x = 0, 1, and 2) binary metallic glasses with the diameter ranging from 7 to 8 mm were prepared by a combination of fluxing
and water quenching or air cooling. Thermal analysis results show that with increasing Si content, the glass transition temperature
T
g, the initial crystallization temperature T
x and the onset crystallization temperature T
p of Pd-Si binary glassy alloys increase. Moreover, the supercooled liquid region reaches 61 K. It indicates that Pd-Si binary
alloys possess large glass forming ability, which can be greatly improved by fluxing treatment.
Supported by the National Basic Research Program of China (Grant No. 2007CB613905) and the National Natural Science Foundation
of China (Grant Nos. 50671050 and 50431030) 相似文献
10.
The thermodynamics structural relaxation of Fe73Cu1.5Nd3Si13.5B9 amorphous alloy from room temperature to 400°C has been investigated by measuring the structure factor with in situ X-ray diffraction. The structural information of the atomic configuration such as radial distribution function (RDF) and
neighbor atomic distance was gained by Fourier transformation. The research result shows that the amorphous structure remains
stable in the temperature range of 30 to 400°C but exhibits distinct changes in local atomic configuration with the increase
of temperature. The quantitative determination of the neighbor atomic distance suggests that the degree of short-range order
changes by the temperature altering the second nearest neighbor local atomic configuration of the amorphous when structural
relaxation occurs.
Supported by the Natural Science Foundation of Hebei Province of China (Grant No. A2007000296), the National Natural Science
Foundation of China (Grant No. 50731005), SKPBRC (Grant Nos. 2007CB616915 and 2006CB605201), and PCSIRT (Grant No. IRT0650) 相似文献
11.
Zeng Zhang Rong Zhang ZiLi Xie Bin Liu XiangQian Xiu RuoLian Jiang Ping Han ShuLin Gu Yi Shi YouDou Zheng 《中国科学G辑(英文版)》2008,51(8):1046-1052
The surface morphology, electrical properties and optical properties of Si doped n-type GaN were investigated. The intentional
SiH4 doped GaN films were grown by metal organic chemical vapor deposition with the electron concentration varying from 3×1016 cm−3 to 5.4×1018 cm−3. The surface morphology shows that the roughness and dislocation pits increase as the mass flow rate of SiH4 increases, which indicates that the quality of GaN degrades gradually. The activation energy of Si in GaN with different
n concentrations varies from 12 to 22 meV, which may originate from the interactions of donor wave functions. The carrier transport
mechanism with increasing temperature from 100 to 420 K was concluded as the complex effect of both impurity scattering and
phonon scattering. The position of the near band edge emission peak was determined by both renormalization of the band gap
and B-M effect. The intensity variations of the yellow luminescence could be explained by the change of Ga vacancy concentration
caused by Si doping.
Supported by the National Basic Research Program of China (Grant No. 2006CB6049), the National Hi-Tech Research and Development
Program of China (Grant No. 2006AA03A142), the National Natural Science Foundation of China (Grant Nos. 60721063, 60731160628
and 60676057), the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20050284004) and the Natural
Science Foundation of Jiangsu Province of China (Grant No. BK2005210) 相似文献
12.
Two multiparty simultaneous quantum identity authentication (MSQIA) protocols based on secret sharing are presented. All the
users can be authenticated by a trusted third party (TTP) simultaneously. In the first protocol, the TTP shares a random key
K with all the users using quantum secret sharing. The ith share acts as the authentication key of the ith user. When it is necessary to perform MSQIA, the TTP generates a random number R secretly and sends a sequence of single photons encoded with K and R to all the users. According to his share, each user performs the corresponding unitary operations on the single photon sequence
sequentially. At last, the TTP can judge whether the impersonator exists. The second protocol is a modified version with a
circular structure. The two protocols can be efficiently used for MSQIA in a network. They are feasible with current technology.
Supported by the National Basic Research Program of China (973 Program) (Grant No. 2007CB311100), the National High Technology
Research and Development Program of China (Grant Nos. 2006AA01Z419 and 20060101Z4015), the Major Research Plan of the National
Natural Science Foundation of China (Grant No. 90604023), the Scientific Research Common Program of Beijing Municipal Commission
of Education (Grant No. KM200810005004), the Scientific Research Foundation for the Youth of Beijing University of Technology
(Grant No. 97007016200701), the National Research Foundation for the Doctoral Program of Higher Education of China (Grant
No. 20040013007), the National Laboratory for Modern Communications Science Foundation of China (Grant No. 9140C1101010601),
and the Doctor Scientific Research Activation Foundation of Beijing University of Technology (Grant No. 52007016200702) 相似文献
13.
Large low-field-induced magnetic entropy changes, ΔS
M, are observed in La0.67Ca0.33MnO3 and La0.67Ca0.33Mn0.96Fe0.04O3 single crystals. The peaks of ΔS
M broadened asymmetrically to high temperatures under higher magnetic fields for two materials should be attributed to the
first-order magnetic phase transition at T
c. A small amount of iron doping results in an increase in the refrigerant capacity of the material though the magnetic entropy
change decreases. The discovery of excellent magnetocaloric features of these single crystals in the low magnetic field can
provide some ideas for exploring novel magnetic refrigerants operating under permanent magnet rather than superconducting
one as magnetic field source.
Supported by the State Key Project of Fundamental Research (Grant No. 2005CB724402), and the National Natural Science Foundation
of China (Grant No. 50672126)
Contributed by CHENG ZhaoHua 相似文献
14.
CdS/α-Fe2O3 hierarchical nanostructures, where the CdS nanorods grow irregularly on the side surface of α-Fe2O3 nanorods, were synthesized via a three-step process. The diameters and lengths of CdS nanorods can be tuned by changing the
ethylenediamine (EDA) and Cd ion concentrations. The magnetic investigations by superconducting quantum interference device
indicate that the hierarchical nanostructures have an Morin transition at lower temperature (230 K) than that of the single
bulk α-Fe2O3 materials (263 K). Importantly, the hierarchical nanostructures exhibit weakly ferromagnetic characteristics at 300 K. A
sharp peak assigned to the surface trap induced emission are observed in room temperature PL spectra. Combining with the optoelectronic
properties of CdS, the CdS/α-Fe2O3 hierarchical nanostructures may be used as multi-functional materials for optoelectronic and magnetic devices.
Supported by the National Natural Science Foundation of China (Grant Nos. 50772025 and 50872159), the Ministry of Science
and Technology of China (Grant No. 2008DFR20420), the China Postdoctoral Science Foundation (Grant Nos. 20060400042 and 200801044),
the Natural Science Foundation of Heilongjiang Province, China (Grant No. F200828), the Specialized Research Fund for the
Doctoral Program of Higher Education of China (Grant No. 20070217002), and the Innovation Foundation of Harbin City (Grant
No. RC2006QN017016) 相似文献
15.
The band structures of BSb and B
x
Ga1−x
Sb alloys are studied using first-principles calculations in the generalized gradient approximation. By SQS-8 supercells to
model a random alloy, the direct transition energy-gap (Γ
15v−Γ
1c) bowing of 3.0 eV is obtained for B
x
Ga1−x
Sb alloys in x = 0–50%, in x = 0–11% the energy-gap is the band-gap and increases by 7 meV/%B with boron composition increasing; by SQS-16 supercells
the bowing parameter is about 1.9 eV in x = 0–12.5%. The formation enthalpies of mixing, ΔH, are calculated for B
x
Ga1−x
As and B
x
Ga1−x
Sb alloys. A comparison of enthalpies indicates that B
x
Ga1−x
Sb films with boron composition of 7% may be possible.
Supported by the National Natural Science Foundation of China (Grant No. 10774031) and the Guangdong Provincial Natural Science
Foundation (Grant No. 07001790) 相似文献
16.
Multiferroic NiFe2O4 (NFO)-BaTiO3 (BTO) bilayered thin films are epitaxially grown on (001) Nb-doped SrTiO3 (STO) substrates by pulsed-laser deposition (PLD). Different growth sequences of NFO and BTO on the substrate yield two kinds of epitaxial heterostructures with (001)-orientation, i.e. (001)-NFO/(001)-BTO/substrate and (001)- BTO/(001)-NFO/substrate. Microstructure studies from x-ray diffraction (XRD) and electron microscopies show differences between these two heterostructures, which result in different multiferroic behaviours. The heterostructured composite films exhibit good coexistence of both ferroelectric and ferromagnetic properties, in particular, obvious magnetoelectric (ME) effect on coupling response. 相似文献
17.
On SrTiO3 single crystal substrate, by using the pulsed electron deposition technique, the high-quality electron doped Nd1.85Ce0.15CuO4−δ
superconducting film was successfully fabricated. After careful study on the R-T curves of the obtained samples deposited with different substrate temperatures, thicknesses, annealing methods and pulse
frequencies, the effects of them on the superconductivity of the films were found, and the reasons were also analyzed. Additionally,
by using the same model of the pulsed laser deposition technique, the relation between the target-to-substrate distance and
the deposition pressure was drawn out as a quantitative one.
Supported by the Key Project of Zhejiang Provincial Natural Science Foundation (Grant No. Z605131), the ‘100 Talents Project’
of Chinese Academy of Sciences, the Creative Research Group of National Natural Science Foundation of China (Grant No. 60321001)
and the National Natural Science Foundation of China (Grant No. 60571029) 相似文献
18.
In most situations, the signer is generally a single person. However, when the message is written on behalf of an organization,
a valid message may require the approval or consent of several persons. Threshold signature is a solution to this problem.
Generally speaking, as an authority which can be trusted by all members does not exist, a threshold signature scheme without
a trusted party appears more attractive. Following some ideas of the classical Shamir’s threshold signature scheme, a quantum
threshold group signature one is proposed. In the proposed scheme, only t or more of n persons in the group can generate the group signature and any t − 1 or fewer ones cannot do that. In the verification phase, any t or more of n signature receivers can verify the message and any t − 1 or fewer receivers cannot verify the validity of the signature.
Supported by the National Basic Research Program of China (973 Program)(Grant No. 2007CB311100), the National High-Technology
Research and Development Program of China (Grant Nos. 2006AA01Z419 and 2006AA01Z440), the Major Research Plan of the National
Natural Science Foundation of China (Grant No. 90604023), the Scientific Research Common Program of Beijing Municipal Commission
of Education (Grant No. KM200810005004), the Scientific Research Foundation for the Youth of Beijing University of Technology
(Grant No. 97007016200701), the Doctoral Scientific Research Activation Foundation of Beijing University of Technology (Grant
No. 52007016200702), the ISN Open Foundation, and the National Laboratory for Modern Communications Science Foundation of
China (Grant No. 9140C1101010601) 相似文献
19.
Wang LiRong Ma Jie Ji WeiBang Wang GuiPing Xiao LianTuan Jia SuoTang 《中国科学G辑(英文版)》2008,51(2):147-156
In this paper, an ultra-high resolution photoassociation spectroscopy study on photoassociation of cesium atoms is reported.
The cold cesium gas in the magneto-optical trap is illuminated by a photoassociation laser with red-tuning as large as 40
cm−1 below the 6S
1/2 + 6P
3/2 dissociation limit, and the photoassociation to the excited state ultracold molecule is detected. High signal-to-noise ratio
is obtained by using the lock-in detection of the fluorescence from the modulated cold Cs atoms. The 0
g
−
, 1g and 0
u
+
long-range states which correspond to 6S
1/2 + 6P
3/2 dissociation limit are present in the photoassociation spectrum. The effective coefficients of leading long-range interactions
and the corresponding vibrational quantum number are obtained using LeRoy-Bernstein Law. It is found that photoassociation
process creates rotating molecules and the high J value is a hint that higher partial waves participate in the PA process in the presence of trapping laser.
Supported by 973 Program of China (Grant. No. 2006CB921603), the National Natural Science Foundation of China (Grant Nos.
10574084, 60678003, and 60778008), the Special Foundation for State Major Basic Research Program of China (Grant No. 2005CCA06300),
and the Youth Science Foundation of Shanxi Province of China (Grant No. 20041013) 相似文献
20.
Fe-based bulk metallic glasses (BMGs) normally exhibit super high strength but significant brittleness at ambient temperature.
Therefore, it is difficult to investigate the plastic deformation behavior and mechanism in these alloys through conventional
tensile and compressive tests due to lack of distinct macroscopic plastic strain. In this work, the deformation behavior of
Fe52Cr15Mo9Er3C15B6 BMG was investigated through instrumented nanoindentation and uniaxial compressive tests. The results show that serrated
flow, the typical plastic deformation feature of BMGs, could not be found in as-cast and partially crystallized samples during
nanoindentation. In addition, the deformation behavior and mechanical properties of the alloy are insensitive to the applied
loading rate. The mechanism for the appearance of the peculiar deformation behavior in the Fe-based BMG is discussed in terms
of the temporal and spatial characteristics of shear banding during nanoindentation.
Supported by the National Natural Science Foundation of China (Grant Nos 50571109, 10572142 and 56771102) and the National
Basic Research Program of China (973 Program)(Grant No 2007CB613900) 相似文献