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81.
In this work we report, for the first time, an experimental observation of a superheating phenomenon in metal thin films. By means of cold rolling, Pb thin films of about 20 nm thick were sandwiched by Al layers, and between them semicoherent epitaxial Pb/Al interfaces were formed. In situ x-ray diffraction analysis indicated that the confined Pb thin films could be superheated for at least 6 degrees C. Thermodynamic analysis indicated that such a substantial superheating in the confined two-dimensional thin films may originate from suppression of growth of the molten droplets by the epitaxial Al/Pb/Al confinement, instead of suppression of melt nucleation for the confined particle superheating. 相似文献
82.
从准三能级Yb离子的能级结构出发,建立了Yb离子的抽运和激光速率方程,结合解析和数值方法,研究了Yb激光介质的抽运动力学过程,包括抽运激发效率、最低抽运强度、激光能量提取效率等关键参数.比较了三类典型的Yb激光介质性能:Yb:S-FAP,Yb:YAG以及Yb:FP-glass.以放大自发辐射(ASE)为设计判据,重点研究了脉冲储能型Yb激光器的设计准则,包括增益介质的厚度与掺杂浓度.最后利用此模型给出了基于Yb:S-FAP以及Yb:YAG的100J级二极管抽运固体激光器(DPSSL)的总体设计参数.将对基于Yb激光介质的脉冲储能型DPSSL的设计提供有益的参考.
关键词:
Yb离子
速率方程
抽运动力学
二极管抽运固体激光器 相似文献
83.
84.
Dunxi Yu Minghou Xu Hong Yao Jiancai Sui Xiaowei Liu Yun Yu Qian Cao 《Proceedings of the Combustion Institute》2007,31(2):1921-1928
The chemical composition of particles generated during pulverized coal combustion is the consequence of their formation processes. This work aims to use the size resolved elemental composition of coal-derived particles to identify their formation modes. A size-classified bituminous coal is burnt in a laboratory drop tube furnace at 1150, 1250, and 1350 °C, respectively. The elemental composition of the size-segregated particles from coal combustion is analyzed and the total mass fraction size distributions of Si and Al are obtained. Three particle formation modes are observed in these distribution profiles. The coarse mode has the highest value of the total mass fraction of Si and Al while the ultrafine mode has the lowest one. The total mass fraction of Si and Al in these two modes is nearly independent of particle size. It is believed that the coarse mode is formed by the mineral coalescence mechanism and the ultrafine mode by the vaporization–condensation mechanism. The difference in the total mass fraction of Si and Al between the central mode and the other two indicates that the central mode is formed by different mechanisms. Based on the observation that the total mass fraction of Si and Al in this mode increases with increasing particle size, heterogeneous condensation of vaporized species on existing fine residual ash particles is proposed to account for the formation of these particles. The study of the elemental composition of the three modes represented in five categories verifies the proposed formation mechanisms for them to some extent. 相似文献
85.
It is crucial to deal with the grid non‐orthogonality effectively in solving the flow in complex geometries, especially at high Reynolds numbers. In this study, the newly proposed Coupled and Linked Equations Algorithm Revised‐ER (CLEARER) algorithm is adopted to solve this problem successfully. In CLEARER algorithm the second relaxation factor is introduced in constructing the contravariant interface velocities, by setting it to a low value. CLEARER algorithm can overcome the severe grid non‐orthogonality and non‐linearity of equations effectively. After the numerical results with CLEARER are validated with the benchmark solutions, this algorithm is used to solve the lid‐driven flow in inclined cavity with inclination angles varying from 10 to 170°, and Reynolds numbers varying from 5000 to 15 000. The streamlines and the centerline velocity distributions are provided in detail for all cases, which may offer some guidance for the study in this area. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
86.
IntroductionThechemistryoforganoaluminum,organogalliumandorganoindiumcomplexeshasattractedmuchat'tentionduenotonlytotheirinterestingstructuralandchemicalpropertiesbutalsotheirapplicationinsemiconductormaterialsl-5.InthecourseofourstudiesonexploringvolatileMOCVDprecursorsthathavethepropertiesoflowertoxicityandhigherstability,wehaverecentlyreportedonthesynthesisandcharacterizationofintermolecularadducts'-',novelbondingmodecomplexes",',andthecomplexesinwhichN/Omixed-donorcrownethersasligands'l'… 相似文献
87.
88.
A variational approach is employed for obtaining zero-free solutions of a nonlinear eigenvalue problem that appears in several recent studies. Our proofs are elementary but our results are sharp and yield corrections to several existing assertions in the literature. 相似文献
89.
Yang Xiang Bo Zhou Xianjie Wang Yu Sui Zhe Lü 《Journal of magnetism and magnetic materials》2009,321(9):1188-1191
Mn4+-rich perovskite manganites (nominal composition: Pr0.1Ca0.9MnO3) were synthesized by using a citric acid method and sintered at different temperatures (800, 900, 1000, and 1300 °C) to adjust the concentration of charge carrier. All the samples are found to be in the cluster glass state at low temperature, as indicated by dc and ac magnetization. With the increase of sintering temperature, the ferromagnetic component in samples increases at first, and attains a maximum at 1000 °C, then decreases again at 1300 °C, which could be well interpreted by the change of charge carrier concentration induced by nonstoichiometry, consistent with the trend on the phase diagram. However, nonstoichiometry breaks long-range Mn-O-Mn interaction, resulting in the variance from the phase diagram. 相似文献
90.
Zhiguo Liu Dawei Dong Milan Liu Yu Sui Wenhui Su Zhengnan Qian Zhe Li 《Hyperfine Interactions》2005,163(1-4):13-27
The quadrupole splitting distributions (QSDs) from the Mössbauer spectra of triphylite, ferrisicklerite and purpurite at 298 K and 80 K were obtained by the use of the Voigt-based quadrupole splitting distribution (QSD) method for the first time. QSDs of Fe2+ and Fe3+ are attributed to Fe2+ and Fe3+ at the corresponding octahedrally coordinated sites in the crystal structures of the three phosphate minerals. The influence on the distortion of the M2 site by different next-nearest neighbor (NNN) configurations was discussed based on the Jahn–Teller effect in purpurite, and the authors propose two M2 subsites with different distortions in purpurite. Two QSDs of Fe3+ in the Mössbauer spectra of purpurite are tentatively assigned to Fe3+ at the two M2 subsites, and next-nearest neighbor (NNN) effects were used to interpret the Mössbauer spectra of purpurite. 相似文献