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991.
L. Znaidi G.J.A.A. Soler Illia R. Le Guennic C. Sanchez A. Kanaev 《Journal of Sol-Gel Science and Technology》2003,26(1-3):817-821
Microcrystalline ZnO films presenting well-defined and tunable orientation were obtained by spin coating of alcoholic sols by two different approaches, based on controlled hydrolysis-condensation of Zn-ethanolamine complexes. As-deposited films are formed by amorphous zinc oxide-acetate submicronic particles, which are transformed into oriented ZnO after thermal treatment. The orientation of ZnO depends on the synthesis method, and the solvent. While in ethanol and [Zn] = 0.05 mol·L–1, films consist of rectangular platelets oriented with the (100) planes parallel to the substrate (a//n), the orientation of the particles changes to (c//n) for systems in 2-methoxyethanol (2-ME) and [Zn] = 0.75 mol·L–1. A study of chemical factors that influence the orientation (precursor, solvent, MEA/Zn ratio, concentration, coating parameters, heat treatment) is presented. 相似文献
992.
Weidong Huang Xuhong Wang Li Wang Mei Sheng Liqiang Xu Frank Stubhan Le Luo 《Journal of Electronic Materials》2004,33(2):101-105
The moisture diffusion in globtop material for a chip-on-board (COB) package coated with SiNx and silicone, respectively, or coated with SiNx plus silicone were measured by embedding a humidity sensor in the globtop and recording the capacitive change in three different
temperature/humidity environments. The experimental results were simulated by Fick’s diffusion law with finite-element method
modeling. The moisture diffusion coefficients and activation energies were calculated to quantitatively compare the moisture-resistance
effects of different coatings. For example, at 85°C/85% RH, the moisture diffusion coefficients for the uncoated reference,
SiNx-coated, silicone-coated, and silicone/SiNx double-layered coated samples are 1E-5, 0.8E-5, 0.7E-5, and 0.2E-5 mm2/s, respectively. The experimental and simulation results show that double-layered coating with silicone/SiNx has excellent moisture-resistance properties because it not only smoothes the steps on a printed circuit board (PCB) but
also keeps the good moisture resistance of the inorganic films. 相似文献
993.
Martinez A. Provost J.-G. Dagens B. Sallet V. Jahan D. Merghem K. Ferlazzo L. Landreau J. Le Gouezigou O. Harmand J.-C. Ramdane A. 《Electronics letters》2004,40(7):425-427
High frequency characterisation of three-quantum well GaInNAs/GaAs lasers operating at 1.35 /spl mu/m is reported. A relaxation frequency as high as 7.4 GHz and a 9.7 GHz small-signal bandwidth are demonstrated, indicating the potential for high bit rate (10 Gbit/s) direct modulation of these dilute nitrides on GaAs devices. 相似文献
994.
A. M. Yacomotti F. Raineri G. Vecchi I. Sagnes M. Strassner L. Le Gratiet R. Raj A. Levenson 《Applied physics. B, Lasers and optics》2005,81(2-3):333-336
We report the fast switching capabilities of a two-dimensional Al0.3Ga0.7As photonic crystal slab around 1.5 μm. The slab is supported by an AlOx low-index thick layer that plays the role of an efficient heat sink. By pumping at 0.8 μm in the absorption of the Al0.3Ga0.7As quantum wells, the optical response is modified in the transparency region: a 200% change in the reflectivity is obtained with a total response time of 8ps. 相似文献
995.
996.
Alouini M. Brunel M. Bretenaker F. Vallet M. Le Floch A. 《Photonics Technology Letters, IEEE》1998,10(11):1554-1556
Dual tunable wavelength operation of Er,Yb:phosphate glass laser is reported. The spatial separation of the laser eigenstates and the use of two properly designed intracavity etalons permit one to tune the two wavelengths independently from 1540.5 to 1562.7 nm. The generated beat note, monitored using a Michelson interferometer, is experimentally shown to be adjustable from dc to 2.7 THz. The linewidth of this beat note is found to be less than 10 kHz. Several applications are discussed 相似文献
997.
We study the solutions of an equation of the form Lu=f, where L is a pseudo-differential operator defined for functions on the unit sphere embedded in a Euclidean space, f is a given function, and u is the desired solution. We give conditions under which the solution exists, and deduce local smoothness properties of u given corresponding local smoothness properties of f, measured by local Besov spaces. We study the global and local approximation properties of the spectral solutions, describe
a method to obtain approximate solutions using values of f at points on the sphere and polynomial operators, and describe the global and local rates of approximation provided by our
polynomial operators.
The research of this author was supported, in part, by grant DMS-0204704 from the National Science Foundation and grant W911NF-04-1-0339
from the U.S. Army Research Office 相似文献
998.
在制药厂车间中,空调系统是非常重要的一环,除完成对车间内温湿度的精确控制之外,还有一个重要的作用,就是控制车间与室外空气的压差,使车间内保持微正压状态,维持车间的洁净度达到GMP要求。 相似文献
999.
In this paper we describe the alloying process of ultra-thin Al layers (below 8 × 1015 Al/cm2) deposited on Ni(1 1 1). For this purpose Auger electron spectroscopy, low energy electron diffraction, and ion beam analysis-channelling measurements have been performed in situ in an ultra-high vacuum chamber. Al deposits formed at low temperature (about 130 K) are strained defective crystalline layers retaining the substrate orientation. Alloying takes place, with very progressive Ni enrichment, in a very broad temperature range between 250 K and 570 K. This feature shows that diffusion of the alloy species is more and more difficult when the Ni concentration increases. At 570 K a crystallographically and chemically ordered Ni3Al phase is formed, and its order continuously improves upon annealing, up to 750 K. We have shown by ion beam methods that this alloy is three-dimensional, extending up to 16 (1 1 1) planes for the thickest deposits. The Ni3Al phase can also be obtained directly by Al deposition at 750 K, but its crystalline quality is lower and the layer is probably formed of grains elongated along 〈1 1 −2〉 directions. The Al content of the thin Ni3Al layers formed mostly dissolves in the bulk above 800 K. However a small amount of Al remains segregated at the Ni crystal surface. 相似文献
1000.
Experiments on hydrodynamic and heat transfer behavior of the flow in a twisted curved channel were conducted in a water tunnel and also in two heat exchanger coils tested in a heat exchanger test facility. The flow regime, designated “chaotic advection,” is a subclass of laminar flow with high mixing properties. Preliminary results show that heat transfer is enhanced due to the chaotic trajectories generated in the flow. 相似文献