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11.
Mössbauer investigations about iron atom redistribution in oxide films of zirconium alloys subjected to corrosion at 500°C in pure oxygen and water pair have been analysed. The alloys were also subjected to autoclave conditions at a pressure of 10.0 MPa and autoclave conditions at 350°C and at a pressure of 16.8 MPa, using distilled water and water with additives of lithium and fluorine. It is shown that, depending on the corrosion environment, various compounds of iron, such as α-Fe2O3, Fe3O4, and FeO, as solid solutions of iron in ZrO2 are formed in oxide films. 相似文献
12.
采用ICP-AES法对钛基复合材料中的合金元素镍、钕、铁的测定进行了研究,着重进行了基体元素及待测元素镍、钕、铁之间干扰试验及各元素在测定浓度范围内的线性相关性试验,进行了酸度试验,测定了钛基复合材料中3种元素的含量,得到了较好的精密度和准确度。方法简便、可靠,获得满意的分析结果。 相似文献
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Properties of excitons in vertically coupled GaAs/AlGaAs quantum dots were investigated using the variational method within the envelope function and effective mass approximations. It was found that when the thickness of the spacer layer becomes less than about one exciton Bohr radius, both the exciton binding energy and the fundamental optical transition energy are reduced compared to those in isolated quantum dots. This is a result of increased space extension of exciton due to the penetration of carrier wave functions into the spacer layer and corresponding reduction in confinement energy which dominates over the Coulomb interaction between the electron and the hole. 相似文献
16.
火焰原子吸收光谱法测定磁化杯中铅、镉和铁 总被引:1,自引:0,他引:1
本文研究了火焰原子吸收光谱法测定磁化杯陶瓷内胆中Ph、Cd和Fe含量的方法。样品经粉碎,用硝酸-高氯酸混合液进行消解后测定。本法灵敏度高,干扰少,简单,快速,具有良好的精密度和准确度,其相对标准偏差分别为Pb3.99%,Cd10.7%,Fe0.9%。回收率Pb100.61%,Cd101.18%,Fe102.4%。 相似文献
17.
The paper describes the possibility of designing matched interacting semiconductor quantum wells. It is shown that for a given eigenstate of a quantum well (QW), it is always possible to find another QW in such a way that the coupling leaves the original eigenstate of the host QW unperturbed irrespective of the strength of interaction. For rectangular QWs, the condition is met with whenever the second QW has appropriate width and depth so that phase travelled by an electron wave through it is an integral multiple of π. 相似文献
18.
Godfrey Gumbs 《Solid State Communications》2003,128(12):443-448
A model calculation is reported for the tunneling probability of one as well as two interacting electrons from a quantum well within a narrow channel. We discuss the cases when the two electrons are spin polarized or unpolarized by transforming the system to a noninteracting one with the use of quantal density functional theory to obtain an effective single-particle confining potential. A semiclassical approach is used to obtain the tunneling probability from this effective potential. The calculation is motivated by recent measurements of the conductance of an electron gas in a narrow channel but is not meant to explain the anomalous behavior that has been reported since, for example, we deal with a simplified two-level system. Numerical results for the tunneling probability are presented. 相似文献
19.
We investigate the electronic properties of multiwalled carbon nanotubes both before and after acid treatment with concentrated sulphuric and nitric acids. Magnetic susceptibility measurements were performed using a SQUID magnetometer and show that there is a considerable enhancement in the density of states at the Fermi level. The data shows that the diamagnetic influence from the graphitic nanotubes dominates. We experimentally observe, after acid treatment, that the diamagnetic susceptibility remains unchanged at 5 K but notably decreases at 77 K. We propose the acid treatment has increased the Van Vleck paramagnetic contribution lowering the diamagnetic response from the π-electron orbital magnetisation. The Van Vleck paramagnetic contribution is finite-temperature dependent with a diminishing contribution at higher fields. 相似文献
20.
We study the chiral behavior of the nucleon and Δ-isobar masses within a manifestly covariant chiral effective-field theory, consistent with the analyticity principle. We compute the πN and πΔ one-loop contributions to the mass and field-normalization constant, and find that they can be described in terms of universal relativistic loop functions, multiplied by appropriate spin, isospin and coupling constants. We show that these manifestly relativistic one-loop corrections, when properly renormalized, obey the chiral power-counting and vanish in the chiral limit. The results including only the πN-loop corrections compare favorably with the lattice QCD data for the pion-mass dependence of the nucleon and Δ masses, while inclusion of the πΔ loops tends to spoil this agreement. 相似文献