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991.
Silicon nanowires grown from Au-coated Si substrate 总被引:1,自引:0,他引:1
Xing Y.J. Yu D.P. Xi Z.H. Xue Z.Q. 《Applied Physics A: Materials Science & Processing》2003,76(4):551-553
Amorphous Si nanowires were grown on an Au-coated Si substrate by heat treatment at 1000 °C under an H2 atmosphere. The nanowires have a length of several tens of a micron and a diameter of 10–20 nm. The growth mechanism of the
nanowires was investigated and explained with a solid–liquid–solid model.
Received: 11 July 2002 / Accepted: 7 July 2002 / Published online: 4 December 2002
RID="*"
ID="*"Corresponding author. Fax: +86/10-62751615, E-mail: yudp@pku.edu.cn 相似文献
992.
P.A.?Hu Y.Q.?LiuEmail author X.B.?Wang 《Applied Physics A: Materials Science & Processing》2003,77(6):743-745
Highly aligned amorphous SiOx nanowires with lengths of up to several hundred microns were synthesized by using a millimeter-sized droplet of elemental gallium as a catalyst. Gallium displays highly catalytic activity for the growth of SiOx nanowires. Some novel patterns of aligned SiOx nanowires, including honeycomb-like and spindle-like structures, were observed. These SiOx nanowires are expected to be used in nanooptics and reinforcing composites. PACS 61.46.+w; 81.07.Vb; 81.16.Be 相似文献
993.
The backscattered fluorescence of nitrogen from filaments generated by intense ultra-fast Ti:sapphire laser pulses propagating
in air is studied. The backscattered fluorescence from N2 molecules and ions show an exponential increase with increasing filament length, indicating amplified spontaneous emission.
Received: 11 October 2002 / Revised version: 3 December 2002 / Published online: 26 February 2003
RID="*"
ID="*"Corresponding author. Fax: +1-418/6562-623, E-mail: qluo@phy.ulaval.ca 相似文献
994.
Q. Hu H. Araki H. Suzuki N. Ishikawa W. Yang T. Noda 《Applied Physics A: Materials Science & Processing》2003,76(4):561-563
A few of the interesting structures made by the assemblage of Si-Ge nanowires fabricated by the floating-zone melting-vapor
method have been observed. They reveal shapes that are similar to coral, jellyfish and sea anemones. The pre-sintered substrate
bar has some large crystalline particles (1–15 μm), which produce sites that are energetically predisposed to nucleation.
The peculiar structures created by the assemblage of Si-Ge nanowires form on favored nucleation sites that consist of numerous
bundles of nanowires with diameters of 20–50 nm. The periodic variation in the diameter of the bundles of nanowires is a common
feature of these structures. In addition, a growth mechanism assisted by the coexistence of Ge and Si-Ge oxides is suggested.
The growth process of these assemblages opens up new possibilities for the study of the growth mechanism of Si-Ge nanowires.
Received: 25 July 2002 / Accepted: 9 September 2002 / Published online: 17 December 2002
RID="*"
ID="*"Corresponding author. Fax: 81-298/59-2736, E-mail: HU.Quanli@nims.go.jp 相似文献
995.
H.L. Bai Z.J. He W.B. Mi P. Wu Z.Q. Li E.Y. Jiang 《Applied Physics A: Materials Science & Processing》2003,77(3-4):533-541
Amorphous CoMoN/CN compound soft-X-ray multilayers were fabricated by dual-facing-target sputtering. Their structural thermal stability has been investigated by monitoring the structural evolutions of CN and CoMoN sublayers at annealing temperatures up to 800 °C using complementary measurement techniques, and measuring the coefficient of interfacial diffusion at annealing temperatures below 300 °C. The period expansion at annealing temperatures below 600 °C, which is usually observed in annealed metal/carbon soft-X-ray multilayers, is only 5%. The enhanced sp2 to sp3 bond ratio caused by the incorporation annealing effect of nitrogen [1] is thought to be responsible for the improved thermal stability of CN sublayers. Mo addition greatly suppresses the structural thermal evolution of CoMoN sublayers. XPS and TEM analyses indicate that the strong chemical bonding between N and Co atoms and Mo nitride aggregation in the grain boundary of cobalt are the main mechanisms for the high thermal stability of CoMoN sublayers. The layered structure of the CoMoN/CN multilayers still exists at the annealing temperature of 800 °C, while Co/C and CoN/CN multilayers have already been destroyed at this temperature. Compared with Co/C and CoN/CN multilayers, the smaller negative interdiffusivity measured by X-ray diffraction reveals the stable interfaces of CoMoN/CN multilayers. These results illustrate that refractory metal incorporation and strong chemical bond establishment are quite effective in obtaining thermally highly stable compound soft-X-ray optical multilayers . PACS 68.65+g; 68.55.Ln; 68.35.Fx; 68.60.Dv 相似文献
996.
Q. Ren D. Xu Y.T. Chow Z.H. Lü C.B. Ma G.H. Zhang H.P. Chan P.L. Chu 《Applied Physics A: Materials Science & Processing》2003,76(2):183-186
Composite thin films of PbTiO3 nanocrystals and high-transparency PEKc polymer for applications in electro-optical devices were prepared using the spin
coating technique. The size of the PbTiO3 nanocrystals was estimated to be 30–40 nm using a transmission electron microscope. The transmission technique, a simple
method for measuring the electro-optic coefficients of poled composite polymer films was developed. The electro-optic coefficient
γ33 of poled PbTiO3/PEKc composite polymer films was measured to be 18.34 pm V-1 at 633 nm under room temperature. The index at 633 nm and the dielectric constant at 100 kHz under room temperature were
determined to be 1.65248 and 7.32, respectively. The figure of merit F2=n7γ2/ε was estimated to be 1546, showing very good electro-optical properties.
Received: 5 February 2002 / Accepted: 12 March 2002 / Published online: 19 July 2002
RID="*"
ID="*"Corresponding author. Fax: +852/2788-7791, E-mail: eeytc@cityu.edu.hk 相似文献
997.
H.R. Zeng G.R. Li Q.R. Yin Z.K. Xu 《Applied Physics A: Materials Science & Processing》2003,76(3):401-404
Pb(Zr,Ti)O3 (PZT) ferroelectric thin film was prepared by the sol-gel technique and crystallized with a (111) preferred orientation.
The domain structure and polarization reversal behavior were investigated by using scanning force microscopy (SFM) piezoresponse
mode at the nanometer scale. A step structure of approximately 30 nm in width was directly observed, which was formed during
the polarization reversal process. The presence of the step structure reveals that the forward domain-growth mechanism is
the dominant domain-switching process in our PZT thin films.
Received: 6 August 2002 / Accepted: 9 August 2002 / Published online: 28 October 2002
RID="*"
ID="*"Corresponding author. Fax: +86-21/5241-3122, E-mail: huarongzeng@163.net 相似文献
998.
Sato M Hubbard BE English LQ Sievers AJ Ilic B Czaplewski DA Craighead HG 《Chaos (Woodbury, N.Y.)》2003,13(2):702-715
Intrinsic localized modes (ILMs) have been observed in micromechanical cantilever arrays, and their creation, locking, interaction, and relaxation dynamics in the presence of a driver have been studied. The micromechanical array is fabricated in a 300 nm thick silicon-nitride film on a silicon substrate, and consists of up to 248 cantilevers of two alternating lengths. To observe the ILMs in this experimental system a line-shaped laser beam is focused on the 1D cantilever array, and the reflected beam is captured with a fast charge coupled device camera. The array is driven near its highest frequency mode with a piezoelectric transducer. Numerical simulations of the nonlinear Klein-Gordon lattice have been carried out to assist with the detailed interpretation of the experimental results. These include pinning and locking of the ILMs when the driver is on, collisions between ILMs, low frequency excitation modes of the locked ILMs and their relaxation behavior after the driver is turned off. 相似文献
999.
ITQ-21 has been synthesized from F- free gels; aluminum can be incorporated and this does not affect the rate of nucleation. The introduction of stoichiometric amounts of NH4F with respect to the number of double four rings (D4R) present in the structure leads to an increase in the nucleation and crystallization rate with a quantitative incorporation of fluoride ions into the solid. 相似文献
1000.
Jose Manuel?Hermida-RamónEmail author Gunnar?Karlstr?m Bengt?Nelander 《Theoretical chemistry accounts》2003,110(3):190-195
The relation between the so called basis set superposition error and intramolecular vibrational frequencies calculated at the Hartree Fock SCF level of approximation was investigated. A linear conformation of HF dimer was chosen as test system for the investigation. It was found that the direct basis set superposition error for the studied system is rather small. It was further found that the shifts are mainly determined by the geometry parameters of the system.
AcknowledgementsJ. M. H.-R. wishes to thank the Ministerio de Educación, Cultura y Deporte for the award of a research grant. 相似文献