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141.
基于第一性原理密度泛函理论(DFT)方法研究了Cu12Fe团簇的结构稳定性、热力学稳定性和反应活性.计算得出正二十面体Fe原子核心团簇Ih-core比正二十面体Fe原子壳层团簇Ih-shell的热力学稳定性更强.通过分析吸附能讨论了CO和H2在Ih-core团簇上的吸附构型.计算结果表明,Ih-core团簇以顶角Corner位吸附CO时吸附能最大,吸附模型最稳定,H2吸附过程中发生了解离,两个氢原子均形成表面Facet位吸附构型.最后,通过分析前线轨道得到吸附过程的轨道信息. 相似文献
142.
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
143.
本文利用X射线粉末衍射和位敏探测技术,研究了R2Fe4/3W2/3O7(R=Er、Yb、Dy)化合物经高温高压处理后的变化情况。在3.7 GPa,1 200 ℃条件下,六方相R2Fe4/3W2/3O7化合物按两种方式分解,而直接由R2O3,Fe2O3和WO3原料出发,经上述同样的高温高压条件合成所得的产物与六方相高温高压分解产物相同,均为R2WO6、RFeO3、WO3和Fe2O3的多相聚合物。同时给出了R2Fe4/3W2/3O7六方相高温高压下的稳定区范围。 相似文献
144.
145.
Jianpeng Li Dingshu Xiao Peichu Wang Hongyan Chen Minghua Deng Degang Zhu Jie Yu 《Particle & Particle Systems Characterization》2023,40(1):2200141
Transition metal compounds anchored on N-doped carbon (NC) show intrinsic activity and stability for oxygen reduction reaction (ORR). However, the interaction between the transition metal compounds and NC still needs to be strengthened for electron transfer at the compounds/carbon interface. Herein, Fe/Fe3C hybrid nanoparticles encapsulated into N-doped carbon (Fe@NC) are used as high-performance ORR catalysts. Benefiting from the strong interaction at Fe/Fe3C nanoparticles/NC interface, the electrons can transfer from Fe/Fe3C hybrid nanoparticles to NC, redistributing the electron density of active sites and promoting the ORR process. The as-synthesized Fe@NC exhibits outstanding ORR catalytic activity with an onset potential of 1.01 V and a half-wave potential of 0.92 V in alkaline media. It also shows prominent cycling stability and tolerance to methanol crossover, superior to Pt/C catalyst. The theoretical analysis reveals that the Fe nanoparticles have regulated the electron distributions at the heterojunction interface. The Gibbs free energy diagrams for ORR illustrate that the rate-determining step is the conversion of OH* to OH−. In situ Raman spectra give evidence of O-containing intermediates to prove the ORR process. 相似文献
146.
对以本征Si及重掺杂p型和n型Si作为中间层的Fe/Si多层膜的层间耦合进行研究,并通过退火,增大Fe,Si之间的扩散,分析界面扩散对层间耦合的影响. 实验结果表明,层状结构良好的制备态的多层膜,Fe,Si之间也存在一定程度的扩散,它是影响层间耦合的 主要因素,远远超过了半导体意义上的重掺杂,使不同种类的Si作为中间层的层间耦合基本 一致.进一步还发现,在一定范围内增大Fe,Si之间的扩散,即使多层膜的层状结构已经有了相当的退化,Fe/Si多层膜的反铁磁耦合强度基本保持不变.
关键词:
Fe/Si多层膜
层间耦合
界面扩散 相似文献
147.
The deformation surrounding Vickers indentations on InGaAsP/InP epilayers have been studied in detail. The surface topography was characterized by using atomic force microscopy (AFM). The material pile-up and sink-in regions around the indentation impression was observed for the quaternary InGaAsP/InP epilayers. The sectional analysis mode of the AFM shows the depth profile at the indented region. Microindentation studies were carried out for different atomic fraction of the quaternary InGaAsP/InP compound semiconductor alloys. The microhardness values of InGaAsP/InP epilayers were found to be in the range of 5.08 and 5.73 GPa. These results show that the hardness value of the quaternary alloy drastically increases as the composition of As was increased by 0.01 atomic fraction and when the phosphorous concentration decreases from 0.4 to 0.38. The reason may be that the increase in As concentration hardens the lattice when phosphorous concentration was less and hardness decreases when phosphorous was increased. 相似文献
148.
Fu Ri Ling Zhi Hong He Jian Quan Yao Baio Wang Shao Ji Jiang 《Optics & Laser Technology》2008,40(7):941-945
A series of near-stoichiometric Zn:Fe:LiNbO3 crystals were grown by the high-temperature top-seed solution growth (HTTSSG) method from stoichiometric melts doped with 6 mol% K2O. Infrared (IR) transmission spectra were measured and discussed in terms of the defect structure of the near-stoichiometric Zn:Fe:LiNbO3 crystals. The results of the transmitted beam pattern distortion method show that the optical damage resistance of the near-stoichiometric Zn:Fe:LiNbO3 crystals increases rapidly when the ZnO concentration exceeds a threshold value. The threshold value concentration of ZnO of the near-stoichiometric Zn:Fe:LiNbO3 crystals is much lower than that of the congruent LiNbO3 crystals. The dependence of the optical damage resistance on the defect structure of the near-stoichiometric Zn:Fe:LiNbO3 crystals are discussed, and the holographic recording properties of the near-stoichiometric Zn:Fe:LiNbO3 crystals are investigated. 相似文献
149.
P. T. Jochym K. Parlinski A. M. Oleś 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(2):173-179
The magnetization distribution, its energetic characterization by the
interlayer coupling constants and lattice dynamics of (001)-oriented
Fe/Pt multilayers are investigated using density functional theory
combined with the direct method to determine phonon frequencies.
It is found that ferromagnetic order between consecutive Fe layers is
favoured, with the enhanced magnetic moments at the
interface. The bilinear and biquadratic coupling coefficients between Fe
layers are shown to saturate fast with increasing thickness of
nonmagnetic Pt layers which separate them. The phonon calculations
demonstrate a rather strong dependence of partial iron phonon
densities of states on the actual position of Fe monolayer
in the multilayer structure. 相似文献
150.
The present work analyses, in detail, the optimization of a sonochemical process with respect to concentration of precursor and power supplied in a system. This is due to that even a small change in power dramatically changes the high-energy conditions created with the bubble collapse. A model reaction that has been considered for this purpose involves the decomposition of Fe(CO)5 in decalin solvent as this reaction is strongly influenced by the cavitation conditions. Sonochemical treatment of this carbonyl results in the formation of amorphous Fe2O3, which on heat treatment gives nanocrystalline Fe2O3. It has been observed that concentration and power density parameters play an important role to obtain higher decomposition of Fe(CO)5 and hence higher yield of the amorphous Fe2O3 product. Also, using the experimentally observed results, a correlation (polynomial) has been developed. 相似文献