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841.
研究了高电荷态离子129Xeq+(q=25,26,27)入射金属Mo表面产生的特征X射线谱.实验结果表明,在束流强度小于120nA条件下,高电荷态离子129Xeq+可以激发Mo的L壳层特征X射线谱.单离子X射线相对产额可达10-8量级,特征X射线的相对产额随入射离子的动能和电荷态(势能)的增加而增加.通过Mo原子的Lα1特征X射线谱,利用Heisenberg不确定关系对Mo原子的第M能级寿命进行了估算. 相似文献
842.
843.
本文采用分子动力学方法研究了在剪切载荷作用下,Cu(100)扭转晶界对Cu柱屈服强度的影响.模拟结果发现,在加载过程中,低角度扭转晶界形成的位错网发生位错形核与扩展,位错之间的塞积作用提高了Cu柱的屈服强度;对于高角度扭转晶界,晶界发生滑动降低了Cu柱的屈服强度.同时发现,随着扭转角度的增加,Cu柱的屈服强度先增大,当扭转角度大于临界角度时,Cu柱的屈服应力逐渐减小.这表明剪切载荷作用下,两种不同的机理主导Cu柱的屈服,对于小于临界角度的扭转晶界,Cu柱的屈服由晶界位错形核和扩展机理主导,对于大于临界角度
关键词:
扭转晶界
分子动力学
位错形核
晶界滑移 相似文献
844.
建立了自发噪声谱测量系统来研究稀磁半导体(Ga,Mn)As的电学噪声性质.通过测量(Ga,Mn)As材料的自发噪声谱,发现(Ga,Mn)As的自发涨落会随温度升高而逐渐增大,同时,外加磁场会降低(Ga,Mn)As的自发涨落,这来源于外加磁场导致的(Ga,Mn)As磁畴部分有序化.此外,不同频率的噪声随温度的变化规律有很大差异:当频率低于30 kHz的时候,噪声谱和温度的变化关系和热噪声很相似,但数值上明显大于热噪声的值;当频率在30 kHz左右的时候,噪声大小和温度成线性关系;当频率大于30 kHz以后,在相变点附近噪声大小和温度的关系出现了明显的转折,高频高温噪声的大小和热噪声的理论值非常接近.这些结果有助于深入理解(Ga,Mn)As磁性起源的物理机制.
关键词:
自旋电子学
稀磁半导体
自发涨落谱 相似文献
845.
Hydrothermal synthesis and dielectric properties of chrysanthemum-like ZnO particles 总被引:1,自引:0,他引:1 下载免费PDF全文
By orthogonal design theory, technological parameters of
chrysanthemum-like ZnO particles prepared in a hydrothermal process
are optimized. This paper reports a set of technological
parameters for growing chrysanthemum-like ZnO particles on a large
scale. It investigates the morphologies and crystalline structures
of the as-synthesized three-dimensional ZnO particles with a scanning
electron microscope, x-ray diffractometer and transmission electron
microscope, and the possible growth mechanism on the three-dimensional ZnO
particles. The experimental results indicate that the values of
ε', ε ' and \tan δe gradually
increase in the X band with the improvement of the developmental level
of chrysanthemum-like ZnO particles, implying that the
electromagnetic wave absorbing property depends on the morphologies
of three-dimensional ZnO particles. 相似文献
846.
Three-dimensional size and orientation of the precipitates in AZ91 magnesium alloys measured by TEM techniques 下载免费PDF全文
Knowledge of the microscopic structure, including three-dimensional
(3-D) size and orientation of the precipitates, is essential to
fully understand the mechanical properties of the magnesium
alloys and designing the alloys with better performance. Analytical
TEM with high spatial resolution offers the simultaneous
measurements of 3-D size, structure, orientation, composition of the
precipitates from one typical sample along an established
crystallographic axis. Besides popular Burgers orientation
relationship (OR), other ORs such as Pitsch--Schrader OR, Crawley
OR, Potter OR and a new OR with the form of [0001]α
1.0° from [311]γ and (11\bar 20)α
2.0° from (03\bar 3)γ between the magnesium
matrix and the precipitate γ -Mg17Al12 are
identified by TEM imaging and diffraction techniques. As a case study,
the thicknesses of the individual precipitates with Burgers OR are
further measured to be 100--200~nm through both electron energy-loss
spectroscopy and x-ray energy dispersive spectroscopy combining
differential x-ray absorption and extrapolation, which are in
agreement with the overall 3-D size statistic distribution results
obtained through analysing various samples along various directions.
Furthermore, the fabricated wedge-shape structure provides a
platform on which to study the dependence of the interfacial strain on the
variation of the thickness. 相似文献
847.
Research on the boron contamination at the p/i interface of microcrystalline silicon solar cells deposited in a single PECVD chamber 下载免费PDF全文
This paper studies boron contamination at the interface between the
p and i layers of μ c-Si:H solar cells deposited in a
single-chamber PECVD system. The boron depth profile in the i layer
was measured by Secondary Ion Mass Spectroscopy. It is found that
the mixed-phase μ c-Si:H materials with 40% crystalline
volume fraction is easy to be affected by the residual boron in the
reactor. The experimental results showed that a 500-nm thick μ
c-Si:H covering layer or a 30-seconds of hydrogen plasma treatment
can effectively reduce the boron contamination at the p/i interface.
However, from viewpoint of cost reduction, the hydrogen plasma
treatment is desirable for solar cell manufacture because the
substrate is not moved during the hydrogen plasma treatment. 相似文献
848.
Tapered dielectric structure in metal as a wavelength-selective surface plasmon polariton focuser 下载免费PDF全文
Symmetric tapered dielectric structures in metal have
demonstrated applications such as the nanofocusing of surface
plasmon polaritons, as well as the waveguiding of V-channel
polaritons. Yet the fabrication of smooth-surfaced tapered structure
remains an obstacle to most researchers. We have successfully
developed a handy method to fabricate metal-sandwiched tapered
nanostructures simply with electron beam lithography. Though these
structures are slightly different from conventional symmetric
V-shaped structures, systematic simulations show that similar
functionality of surface plasmon polariton nanofocusing can still be
achieved. When parameters are properly selected,
wavelength-selective nanofocusing of surface plasmon polaritons can
be obtained. 相似文献
849.
850.
采用量子化学计算方法和跃迁密度及电荷差分密度分析方法对含芴酮的低聚物激发态性质进行理论研究。计算得到的跃迁能和振子强度与实验数据一致。跃迁密度分析显示跃迁偶极矩的大小和方向,电荷差分密度分析揭示了分子间电荷转移的方向和结果。研究表明含芴酮的低聚物在光诱导下产生的第一激发态为分子内电荷转移激发态,而第五激发态为局域激发态。跃迁密度矩阵分析和电荷差分密度的理论分析结果易于理解含芴酮低聚物的激发态特性。 相似文献