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971.
Application of longitudinal generalized magneto-optical ellipsometry in magnetic ultrathin films
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The longitudinal generalized magneto-optical ellipsometry(GME) method is extended to the measurement of threelayer ultrathin magnetic films. In this work, the theory of the reflection matrix is introduced into the GME measurement to obtain the reflective matrix parameters of ultrathin multilayer magnetic films with different thicknesses. After that, a spectroscopic ellipsometry is used to determine the optical parameter and the thickness of every layer of these samples, then the magneto-optical coupling constant of the multilayer magnetic ultrathin film can be obtained. After measurements of a series of ultrathin Fe films, the results show that the magneto-optical coupling constant Q is independent of the thickness of the magnetic film. The magneto-optical Kerr rotations and ellipticity are measured to confirm the validity of this experiment. Combined with the optical constants and the Q constant, the Kerr rotations and ellipticity are calculated in theory. The results show that the theoretical curve fits very well with the experimental data. 相似文献
972.
Effects of cold rolling deformation on microstructure,hardness, and creep behavior of high nitrogen austenitic stainless steel
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Effects of cold rolling deformation on the microstructure, hardness, and creep behavior of high nitrogen austenitic stainless steel (HNASS) are investigated. Microstructure characterization shows that 70% cold rolling deformation results in significant refinement of the microstructure of this steel, with its average twin thickness reducing from 6.4 μm to 14 nm. Nanoindentation tests at different strain rates demonstrate that the hardness of the steel with nano-scale twins (nt-HNASS) is about 2 times as high as that of steel with micro-scale twins (mt-HNASS). The hardness of nt-HNASS exhibits a pronounced strain rate dependence with a strain rate sensitivity (m value) of 0.0319, which is far higher than that of mt-HNASS (m = 0.0029). nt-HNASS shows more significant load plateaus and a higher creep rate than mt-HNASS. Analysis reveals that higher hardness and larger m value of nt-HNASS arise from stronger strain hardening role, which is caused by the higher storage rate of dislocations and the interactions between dislocations and high density twins. The more significant load plateaus and higher creep rates of nt-HNASS are due to the rapid relaxation of the dislocation structures generated during loading. 相似文献
973.
974.
采用种子层辅助水热生长法制备了ZnO纳米棒有序阵列.将ZnO溶胶旋涂到玻片上,通过煅烧得到晶种,然后将载有晶种的玻片放入含有硝酸锌和六亚甲基四胺的反应釜里,经过水热反应得到垂直于玻片生长的ZnO纳米棒有序阵列.利用原子力显微镜(AFM)观测样品表面形貌并定量分析ZnO纳米棒的长度、直径和生长密度.结果表明,当旋涂转速为4 000r/min,旋涂次数为3次时所得到的ZnO晶种分布均匀,排列紧密,平均粒径为24.3nm.当反应物浓度为0.025mol/L,反应时间为3h,反应温度为90℃时,制备的ZnO纳米棒呈有序阵列,其中纳米棒的长度为164.4nm,直径为104.1nm,生长密度为64.7根/μm2. 相似文献
975.
976.
Xing-Fei Yuan Lian Zhou Yuan-Feng Duan 《International Journal of Solids and Structures》2012,49(10):1212-1226
Based on the analogy between bifurcation of equilibrium paths in structures and kinematic bifurcation of mechanisms, this paper proposes an analogous stiffness method to detect the singularity and kinematic bifurcation of mechanisms. The analogous stiffness in mechanisms is first defined as the derivative of the state variable with respect to the controlling variable. By investigating the value of analogous stiffness, the singularity can be classified into output singularity, input singularity and architectural singularity. And the kinematic characteristics of free joints at corresponding singularity configurations are expounded. The singular and kinematic bifurcation points of mechanisms can then be determined by solving analogous stiffness equations and compatibility equations simultaneously. Following that, the analytical criterion for finite motion of corresponding free joints at singularity configurations is derived from the second-order analysis of compatibility equations. The efficiency of the proposed method is finally illustrated by three typical examples. 相似文献
977.
Mechanism of micro-waviness induced KH2PO4 crystal laser damage and the corresponding vibration source
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The low laser induced damage threshold of the KH2PO4 crystal seriously restricts the output power of inertial confinement fusion. The micro-waviness on the KH2PO4 surface processed by single point diamond turning has a significant influence on the damage threshold. In this paper, the influence of micro-waviness on the damage threshold of the KH2PO4 crystal and the chief sources introducing the micro-waviness are analysed based on the combination of the Fourier modal theory and the power spectrum density method. Research results indicate that among the sub-wavinesses with different characteristic spatial frequencies there exists the most dangerous frequency which greatly reduces the damage threshold, although it may not occupy the largest proportion in the original surface. The experimental damage threshold is basically consistent with the theoretical calculation. For the processing parameters used, the leading frequency of micro-waviness which causes the damage threshold to decrease is between 350-1 μ-1 and 30-1 μ-1, especially between 90-1 μ-1 and 200-1 μ-1. Based on the classification study of the time frequencies of micro-waviness, we find that the axial vibration of the spindle is the chief source introducing the micro-waviness, nearly all the leading frequencies are related to the practical spindle frequency (about 6.68 Hz, 400 r/min) and a special middle frequency (between 1.029 Hz and 1.143 Hz). 相似文献
978.
979.
980.
Zhaoxun Lian Changcang Huang Hanhui Zhang Xihe Huang 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(1):i9-i10
The title compound, K2[VF5(H2O)], was synthesized from potassium antimony tartrate, piperazine, V2O5 and HF under hydrothermal conditions. It is isostructural with K2[FeF5(H2O)] and contains polymeric anion chains held together by strong O—H⋯F bonds. Each V atom is coordinated to five terminal F atoms and the O atom of one water molecule. Pairs of O—H⋯F bonds are formed by two cis‐related F atoms. Twofold axes run along the O—V—F axis of the V‐centred otahedra. 相似文献