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1.
Existence of [B3-O6]3− hexagonal ring growth unit in melt solution of β-BaB2O4 crystal was proved by the results of high temperature Raman measurements. A morphology evolution process of β-BaB2O4 crystal was observed by a high temperature in-situ observation device. The crystal morphology varied with the supersaturation of growth melt solution. The mechanism of β-BaB2O4 crystal morphology evolution was analyzed through the growth unit model.
Supported by the National Natural Science Foundation of China (Grant No. 60808026) and the Nanjing University of Aeronautics
and Astronautics Scientific Research Fund (Grant No. S0764-081) 相似文献
2.
Roman scattering measurement of ( 1 - x ) GeS2-x Ga2S3 system glasses was conducted in order to understand the microstructural change caused by the addition of Ga2S3 . According to the change of Raman spectra with the addition of Ga2S3, two main structural transformations were deduced : the gradual enhancement of ethane- like structural units S3 Ge- GeS3 ( 250 cm ^- 1) and S3 Ga- GaS3 (270 cm ^- 1 ) and the appearance of charge imbalanced units [ Ga2 S2 ( S1/2 )4 ]^2- and [Ga( S1/2 )4 ]^- . And this change of structural aspect seems to give as a clue to understanding the cause of the increased rare-earth solubility. 相似文献
3.
Electric contact material of Ag/SnO2 was successfully synthesized by in situ process method. The interface structure was characterized by high-resolution transmission electron microscopy (HTEM) and
simulated at atomic scale on computer. The mean-square displacements of atoms near the interface were calculated, and the
results showed that near the interface both Ag side and SnO2 were mismatched and this effect decays rapidly far from the interface. By inspecting the calculated density of states (DOS),
we found that the electric-conductivity of this composite material was decreased because of the localized 4d and 2p electrons
of Ag and O near the Fermi surface, respectively. Electron density changed acutely across the interface, so that there was
no extra compound precipitated. A micro-electric field also formed in the whole material due to the interface structure, and
this may affect the electron conduction and the related electric-conductivity of the composite. It is found that the interface
cohesive energy of Ag (111)/SnO2 (200) was −3.50 J/m2, which is higher than the experimental results.
Supported by the National Natural Science Foundation of China (Grant No. 2008CB617609), the Natural Science Foundation of
Yunnan Province (Grant No. 2006E003Z) and Science Innovation Foundation of Kunming University of Science and Technology 相似文献
4.
In this work, the relationship between electronic structure and hemocompatibility of oxygen deficient rutile TiO2−x
was studied by both theoretical calculation and experimental study. Based on the local density functional theory, first-principals
method was performed to calculate the electronic structure of rutile TiO2 with different oxygen vacancy concentration. In the range of less than 10% of (or equal) physically realistic O vacancy concentration,
the band gap of rutile TiO2 increases with increasing O vacancy concentration, leading the TiO2 changes from a p-type to an n-type semiconductor. The valance band of TiO2 is predominated by O 2p orbital, while the conduction band is occupied by Ti 3d orbital for different O vacancy concentration. The O vacancy results in the occupation of electrons at the bottom of conduction
band of TiO2, and the donor density increases with increasing O vacancy concentration. When materials come in contact with blood, the
n-type semiconductor feature of oxygen deficient TiO2−x
with the bottom of conduction band occupied by electrons would prevent charge transfer from fibrinogen into the surface of
materials, thus inhibiting the aggregation and activation of platelets, therefore improving the hemocompatibility of rutile
TiO2-x
.
Supported by the National Basic Research Program of China (Grant No. 2005CB623904), National High-Tech Research Program of
China (Grant No. 2006AA02A139) and National Natural Science Foundation of China (Grant No. 20603027) 相似文献
5.
LI Jian LIU Peng LU ShaoHua WANG Jing MAO XiangQiao WEI Huai FU YongJun ZHENG Kai NING TiGang LI TangJun & JIAN ShuiSheng 《中国科学E辑(英文版)》2009,52(5):1234-1241
A kind of erbium doped photosensitive fiber (EDPF) was proposed and fabricated, whose core was made of double layers named
photosensitive layer and erbium doped layer. The double-layer core design can overcome difficulties in fabrication of EDPF
with single core design, i.e. the conflict between the high consistency rare earth doping and high consistency germanium doping.
A sample was fabricated through the modified chemical vapor deposition method combined with solution doping technique. The
peak absorption coefficient was 48.80 dB/m at 1.53 μm, the background loss was lower than 0.1 dB/m, and the reflectivity of
the fiber Brag gratings (FBG) written directly on the sample fiber was up to 97.3% by UV-writing technology. Moreover, a C
band tunable fiber laser was fabricated using the sample fiber, in which a uniform FBG was written directly on EDPFs as a
reflector. A single wavelength lasing with a maximum wavelength tuning range of 1555.2–1558.0 nm was achieved experimentally.
Within this tuning range, the full-width at half maximum (FWHM) of the laser output was smaller than 0.015 nm and the side
mode suppression ratio (SMSR) was better than 50 dB.
Supported by the National High Technology Research and Development Program of China (863 Project) (Grant No. 2007AA01Z258),
the National Natural Science Foundation of China (Grant No. 60771008), Program for New Century Excellent Talents in University
(Grant No. NCET-06-0076), Beijing Natural Science Foundation (Grant No. 4052023), and the Beijing Jiaotong University Foundation
(Grant No. 2006XM003) 相似文献
6.
The homogeneous glass sample for the ( 1 - x ) As2S3-xCdBr2, where x=0. 015,0. 035,0.05, was prepared by the conventional melt-quenched method. Amorphoas ( 1 - x ) As2S3-xCdBr2 alloys were determined by X-ray diffraction, thermal compreheasive analysis and Raman scattering. The glass transittion temperature (TR) deereases a bit with the addition of CdBr2 . Based on the experimental data, the microstrtucture is considered to be the discrete molecule species of AsBr3 and Cd - S atomic bonds or clusters are honigeneously dispersed in a disordered polymer network formed by AsS3 pyramids interlinked by sulfur bridges. 相似文献
7.
Fang YunZhang Wu FengMin Zheng JinJu Shi FangYe Wu WenHui Sun HuaiJun Lin GenJin Man QiKui Hu JuanMei Yang XiaoHong 《中国科学E辑(英文版)》2008,51(1):46-57
The cross-section pattern of Fe-based alloy ribbon (Fe73.5Cu1Nb3Si13.5B9) annealed at different temperatures was investigated by AFM (atomic force microscope), and the effect mechanism of Nb and
Cu in Fe-based alloy ribbon annealing was analyzed with XRD diffraction crystal analysis technique and other research results.
New concepts of encapsulated grain, Nb vacancy cluster, Nb-B atom cluster and so on were proposed and used to describe the
formation mechanism of α-Fe (Si) nanocrystal. Finally, a three-phase (separation phase, encapsulated phase and nanocrystalline phase) interconnected
structure model in Fe-based nanocrystalline alloy was established.
Supported by the Natural Science Foundation of Zhejiang Province (Grant No. Y405021), Zhejiang Provincial Science and Technology
Key Project (Grant No. 2006C21109) and Key Project of Science and Technology Research of China Ministry of Education (Grant
No. 204059) 相似文献
8.
QianKu Hu QingHua Wu Guang Sun XiaoGuang Luo Bo Xu DongLi Yu JuLong He 《中国科学E辑(英文版)》2008,51(9):1464-1469
Boron-substituted carbon powder, B
x
C1−x
with x up to 0.17, has been successfully synthesized by hot filament chemical vapor deposition. The boron concentration in prepared
B
x
C1−x
samples can be controlled by varying the relative proportions of methane and diborane. X-ray diffraction, transmission electron
microscopy, and electron energy loss spectrum confirm the successful synthesis of an amorphous BC5 compound, which consists of 10–20 nm particles with disk-like morphology. Thermogravimetry measurement shows that BC5 compound starts to oxidize approximately at 620°C and has a higher oxidation resistance than carbon.
Supported by the National Natural Science Foundation of China (Grant Nos. 10474083, 50472051, 50532020, 50672081) and the
National Basic Research Program of China (Grant No. 2005CB724400) 相似文献
9.
The growth model of a spherical crystal in the undercooled melt including the surface energy, interfacial kinetics and convective
flow is established. The effect of the convective flow induced by a small far field flow on the evolution and morphological
stability of the interface of the spherical crystal is studied. The interface shape of the spherical crystal, which is affected
by the far field flow, and the dispersion relation of the growth rate of amplitude of the perturbed interface are derived.
It is shown that the convection induced by the far field flow makes the interface of the growing spherical crystal further
grow in the upstream direction of the far field flow and inhibit growth in the downstream direction; the interface of the
decaying spherical crystal further decays in the upstream direction and inhibits decay in the downstream direction. The theoretical
result suggests that both the growth of the sphere in the upstream direction and the decay of the sphere in the downstream
direction make the spherical crystal tend to evolve into an oval; the morphological stability of the interface depends on
a certain radius R
c
such that the spherical crystal is unstable when its radius is greater than R
c
and stable when its radius is less than R
c
. The surface energy and interfacial kinetics have strong stabilizing effects on the growth of the spherical crystal. In the
meantime interfacial kinetics is a table factor of the interface when the interface of the sphere is growing; it is an unstable
factor of the interface when the interface is decaying.
Supported by the National Basic Research Program of China (Grant No. 2006CB605205), the National Natural Science Foundation
of China (Grant Nos. 10672019 and 10572062), and the Science and Technology Foundation of Shanghai (Grant No. 055207081) 相似文献
10.
Electrochemical behavior of wound supercapacitors with propylene carbonate and acetonitrile based nonaqueous electrolytes 总被引:1,自引:0,他引:1
The activated carbon wound supercapacitors with TEABF4/propylene carbonate (PC) and TEABF4/acetonitrile (AN) electrolytes were prepared. The effects of the electrolyte and temperature on the capacitance behavior
were investigated by cyclic voltammetry (CV) and constant current charge-discharge. Compared with the PC-based supercapacitor,
the AN-based supercapacitor has higher capacitance and lower equivalent serial resistance (R
ES) at discharge currents ranging from 5 to 1 000 mA and 25 °C. Moreover, temperature effects are more prominent for PC-based
supercapacitor than for AN-based supercapacitor. When the measurement temperature ranges from 60 °C to −40 °C the capacitance
changes from 5.1 to 2.5 F and R
ES changes from 135 to 876 mΩ for the PC-based supercapacior, while the AN-based supercapacitor shows less change in capacitance
and R
ES. Thus AN-based supercapacitor exhibits excellent power characteristics and temperature property.
Foundation item: Project(20803095) supported by the National Natural Science Foundation of China; Project(2008AA03Z207) supported by the National
High Technology Research and Development Program of China 相似文献
11.
Based on the traditional sintering model incorporating the characteristic of microwave sintering, the ionic conductance diffusion
mechanism in microwave sintering was studied. A flat-ball model was presented to describe the kinetics process in microwave
sintering, and was applied to the sintering process of TZP and ZrO2-Al2O3 ceramics. The results indicate that the shrinkage rate of materials in microwave sintering is proportional to t
2/3 and r
−4/3, respectively, where t is the sintering time and r is the particle radius. Whereas, the shrinkage rate of materials in conventional sintering is proportional to sintering time
t
2/5. Our model suggests that microwave sintering is faster than conventional sintering, which shows a good agreement with the
experimental observation in sintering process of TZP and ZrO2-Al2O3.
Supported by the State Key Program of National Natural Science of China (Grant No. 50332010) and the National Key Technology
Research and Development Program for Resource and Environment of China (Grant Nos. 2006BAB12B03, 2006BAB12B05) 相似文献
12.
A theoretical model of the erbium-doped waveguide ring laser is established according to the theory of erbium-doped waveguide
amplifier and the transmission matrix of waveguide directional coupler. The influence of bend radius, coupling coefficient
and doped erbium ion concentration on the characteristics of waveguide ring laser is investigated. It is shown that due to
the co-action of waveguide bend loss and other relevant loss there is an optimal bend radius which can provide simultaneously
low threshold pumping power and high laser light output power. As one part of the resonator’s loss, the laser light coupling
coefficient of directional coupler has an impact on the laser property. The analysis indicates that the laser achieves the
high output power when the coupling coefficient is about 0.2. The threshold pumping power is the minimum when the doped erbium
ion concentration is 0.85×1026 m−3. Increasing the concentration of doped erbium ions will enhance the output power of laser light as long as the concentration
doesn’t introduce remarkable up-conversion effect. The results give a good theoretical basis for the design and fabrication
of erbium-doped waveguide ring laser devices.
Supported by the National Natural Science Foundation of China (Grant No. 60807015), the Specialized Research Fund for the
Doctoral Program of Higher Education (Grant No. 200801411037), the Young Teacher Cultivation Foundation of Dalian University
of Technology (Grant No. 893210) and Doctor Start-up Foundation of Dalian University of Technology (Grant No. 893322) 相似文献
13.
Ag-TiO2 thin films were prepared on glasses.The morphology and structure of Ag-TiO2 films were investigated by XRD.SEM and FT-IR.The photocatalytic and hydrophilic properties of Ag-TiO2 thin films were also evaluated by examining photocatalytic degradation dichlorophos under sunlight illumination and the change of contact angle respectively.The research results show that the Ag-TiO2 thin film is mainly composed of 20-100nm Ag and TiO2 particles,The Ag-TiO2 thin films possess a super-hydrophilic ability and higher photocatalytic activity than that of pure TiO2 thin film. 相似文献
14.
A new cyclometalated platinum complex containing 2, 5-bis(naphthalene-1-yl)-1,3,4-oxadiazole ligand was synthesized and characterized. The UV-Vis absorptions and photoluminescent properties of the ligand and its platinum complex were investigated A characteristic metal-ligand charge transfer absorption peak at 439 nm in the UV spectrum and a strong emission peak at 625 nm in the photoluminescence spectrum were observed for this complex in dichloromethane. Cyclic voltammtry (CV) analysis shows that the EHOMO (energy level of the highest occupied molecular orbital) and ELUMO (energy level of the lowest unoccupied molecular orbital) of the platinum complex are about -5.69 and -3.25 eV, respectively, indicating that the oxadiazole-based platinum complex has a potential application in electrophosphorescent devices used as a red-emitting material. 相似文献
15.
SuPing Duan ZhenXing Liu JinBin Cao Li Lu H. Rème I. Dandouras C. M. Carr 《中国科学E辑(英文版)》2008,51(10):1721-1730
Based on measurements of FGM and HIA on board TC-1 at its apogee on September 14, 2004, we analyzed the ion high-speed flows
in the near-Earth plasma sheet observed during the substorm expansion phase. Strong tailward high-speed flows (Vx ∼ −350 km/s) were first seen at about X ∼ −13.2 RE in near-Earth magnetotail, one minute later the flows reversed from tailward to earthward. The reversal process occurred
quickly after the substorm expansion onset. The near-Earth magnetotail plasma sheet was one of key regions for substorm onset.
Our analysis showed that the ion flow reversal from tailward to earthward was likely to be in close relation with the substorm
expansion initiation and might play an important role in triggering the substorm expansion onset.
Supported by the National Natural Science Foundation of China (Grant Nos. 40620130094, 40731054, 40704027, 40390150) 相似文献
16.
YunZhang Fang JinJu Zheng FangYe Shi FengMin Wu HuaiJun Sun GenJin Lin XiaoHong Yang QiKui Man FangMin Ye 《中国科学E辑(英文版)》2008,51(9):1409-1424
The cross-section of the Fe-based alloy (Fe73.5Cu1Nb3Si13.5B9) ribbon annealed at 540°C under various tensile stress was investigated with atomic force microscope (AFM). The stress effect
mechanism in Fe-based alloy ribbon tensile stress annealed inducing transverse magnetic anisotropy field was studied using
the X-ray diffraction spectra and longitudinal drive giant magneto-impedance effect curves, and the model of direction dominant
in encapsulated grain agglomeration was established. The relationship between the direction dominant in encapsulated grain
agglomeration and magnetic anisotropy field was disclosed.
Supported by the Natural Science Foundation of Zhejiang Province (Grant No. Y405021), Key Project of Science and Technology
of Zhejiang Province (Grant No. 2006C21109) and Key Project of Science and Technology Research of China Ministry of Education
(Grant No. 204059) 相似文献
17.
Based on the empirical electron theory of solids and molecules (EET), the statistical values of valence electron structure
parameters Sn
A and SE
A which can characterize the properties of alloy phases are calculated, and influences of alloying elements (e.g., V, Nb, Mo,
Hf, Zr, Fe, Mn, Co, Cr, Si, and so on) on the phase transition temperature and eutectoid reaction of titanium alloy are discussed
with the statistical values of valence electron structure parameters. The research results agree well with real situations.
Supported by the National Natural Science Foundation of China (Grant No. 50471022, 50741004) and National Key Basic Research
Program of China (“973”) (Grant No. 2007CB613807) 相似文献
18.
Cu2ZnSnS4 (CZTS) thin films were successfully fabricated on glass substrates by sulfurizing Cu-Sn-Zn multilayer precursors, which were
deposited by ion beam sputtering and RF magnetron sputtering, respectively. The structural, electrical and optical properties
of the prepared films under various processing conditions were investigated in detail. Results showed that the as-deposited
CZTS thin films with the precursors by both ion beam sputtering and RF magnetron sputtering have a composition near stoichiometric.
The crystallization of the samples, however, has a strong dependence on the atomic percent of constituents of the prepared
CZTS films. A single phase stannite-type structure CZTS with a large absorption coefficient of 104/cm in the visible range could be obtained after sulfurization at 520°C for 2 h. The samples relative to the RF magnetron
sputtering showed a low resistivity of 0.073 Ωcm and band gap energy of about 1.53 eV. The samples relative to the ion beam
sputtering exhibited a resistivity of 0.36 Ωcm and the band gap energy is about 1.51 eV.
Supported by the National Natural Science Foundation of China (Grant No. 10574106), the Planned Science and Technology Project
of Guangdong Province (Grant No.2003C05005) and the Natural Science Fund of Zhanjiang Normal University (Grant No.200801) 相似文献
19.
The high-dense nanocrystalline BaTiO3 (BT) ceramics with grain size smaller than 100 nm have been successfully prepared by the two step sintering and the spark
plasma sintering (SPS) process. The successive transitions in nanograin BT ceramics from rhombohedral to orthorhombic, tetragonal
and cubic transitions, similar to those in coarse BT ceramics, were revealed by in-situ temperature dependent Raman spectrum.
The multiphase coexistence and the diffused phase transition character were demonstrated in the 8 nm nanocrystalline BT ceramics.
Supported by the National Basic Research Program of China (“973” Project) (Grant No. 2002CB613301) and the National Natural
Science Foundation of China (Grant No. 50872093) 相似文献
20.
Konjac glucomannan beads have been investigated as metal biosorbent for Pb(II) from aqueous solu-tions. The effect of contact time, solution pH, initial metal concentration, and desorption were studied in batch experiments at 20℃±2℃. Maximum mental sorption was found to occur at initial pH 4.0―5.5. Kinetic studies revealed that the initial uptake was rapid and equilibrium was established in 3 h and that the data followed the prseudo-second order reaction. The equilibrium sorption data at initial pH 4.0 were described by the Langmuir and Freundlich isotherm models; however, Langmuir isotherm model has been found to provide the best correlation. The highest value of Langmuir maximum uptake (qmax) was found to be 105.71 mg·g-1. Similar Freundlich empirical constant (KF) was obtained to be 1.98 for lead. Adsorption-complexation may be involved in the sorption process of lead. Desorption experi- ments showed evidence that after two contacts neither HCl nor EDTA solutions were able to desorb lead from the konjac glucomannan beads, but the desorbtion efficacy of HCl solution was higher than EDTA solution. The results obtained show that konjac glucomannan beads may be used for the treat-ment of wastewater contaminated with lead. 相似文献