Microstructure and ultrahigh strength of nanoscale Cu/Nb multilayers

The microstructure and mechanical properties of Cu/Nb multilayers were investigated by X-ray diffraction, transmission electron microscopy, scanning electron microscopy and nanoindentation. Ultrahigh strength of 3.27 GPa is achieved at the smallest layer thickness of 2.5 nm, which agrees well with the theoretical prediction based on the deformation mechanism of crossing of dislocations across interfaces. After that, the strength decreases with the increasing layer thickness and the transition of the deformation mechanism to confined layer slip occurs at the layer thickness of 6.5 nm. Additionally, strength of the Cu/Nb multilayers increases with increasing loading strain rate because of enhanced strain hardening.     

Oxidation behavior of aluminide coatings on carbon steel with and without electrodeposited Ni-CeO2 film by low-temperature pack cementation

A CeO₂-dispersed aluminide coating was fabricated through aluminizing the electrodeposited Ni-CeO₂ nanocomposite film on carbon steel using pack cementation method at 700 °C for 4 h. The isothermal and cyclic oxidation behavior of the CeO₂-dispersed aluminide coating at 900 °C, including the growth of oxide scale and the microstructure of the coatings, have been investigated comparing with the aluminide coating on carbon steel. The results show enhanced oxidation performance of the CeO₂-dispersed aluminide coating, which is concerned with not only CeO₂ effect on the microstructure and oxidation, but also decreased interdiffusion between the aluminide and the Ni film. The CeO₂ benefit effects and interdiffusion are discussed in detail.     

Structural and Multiferroic Properties of Bi3.4La0.6Ti3O12/CoFe2O4 Composite Thin Films

Bi_3.4La_0.6Ti₃O₁₂ and CoFe₂O₄ were synthesized by chemical solution route, and Bi_3.4La_0.6Ti₃O₁₂/CoFe₂O₄ multilayers were deposited by spin coating on Pt substrate. X-ray diffraction of multilayer structures reveals composite-like polycrystalline film. Leakage current is less than 10^?5 A at electric field < 90 KV/cm and follows the Ohmic behavior. Dielectric response shows relaxation and the loss (tan δ) is below 3% at 10⁶ Hz. Room temperature ferrroelectric polarization (P_r) = 20.2 μC/cm² and ferromagnetic memory (M_r) = 46.5 emu/cm³ has been obtained. Co-existence of FE and FM response can be attributed to stress and different permeability and permittivity involved in multilayer structures.     

Fabrication and magnetic study of Co/Pt multilayer nanowires and Co–Pt alloy nanowires electrodeposited into porous Si substrates

In this work, we grow composite structures consisting of magnetic and non-magnetic metal or alloy nanowires electrodeposited into the ion etched tracks previously created inside Si substrates. The holes are then filled by Co–Pt alloys and Co/Pt multilayers using electrodeposition technique making a large number of parallel nanowires. This process takes place in a single electrolyte containing Co⁺² and Pt⁺⁴ ions by applying a proper deposition potential using a computer control potentiostat. The magnetic properties of the sample were studied using vibrating sample magnetometer. Magnetoresistive behaviour of the nanowire samples was then studied by subjecting the samples to an external magnetic field. The results show that the Co/Pt multilayered nanowires exhibit a large magnetoresistance, while the Co–Pt alloys only show anisotropic magnetoresistance. This result could be of a great interest for the sensor fabrication community as they will provide a view on a very important direction of the development of the wide spread sensor industry, and more importantly for understanding the physical phenomena underlying the magnetic/non-magnetic nanostructures.     

插头镀金线镀层厚度计算模型研究

电镀镍金镀层厚度是PCB产品可靠性的关键指标,文章从插头镀金线实际生产需求出发,运用法拉第定律和多元函数进行数学推导,得出一个普遍适用于插头镀金线镀层厚度理论计算模型。在理论计算模型的基础上进行多次试验分别得出电镀镍和电镀金的电流效率,并对实际镀层厚度计算模型的有效性进行重复试验验证。试验结果表明,我们可以得出一个合理的镀层厚度计算模型以指导插头镀金线实际生产。     

多层LEMs性能与结构参数的关系

建立一多层LEMs柔顺机构的一般伪刚体模型.基于LET铰链等效弹簧刚度模型,推导出LEMs输入载荷和输出角位移的一般理论计算公式.分析了影响机构角位移输出的主要结构参数,以及相同载荷下这些参数对角位移输出的影响趋势.根据分析结果,对机构实例的结构尺寸参数设计了一组初始值.通过实例的理论计算与有限元仿真,分析得到机构的LET外铰链扭转片段长度和宽度尺寸变化对角位移和误差的不同影响效果.     

Perpendicular magnetic anisotropy of Co_(85)Cr_(50)/Pt multilayers

The CoCr/Pt bilayers and (CoCr/Pt)20 multilayers with Pt underlayer were prepared by DC magnetron sputtering. The effects of prepared condition on perpendicular magnetic anisotropy were investigated. The results show that the thickness of Pt under-layer has a great effect on the microstructure and perpendicular magnetic anisotropy of CoCr/Pt bilayers and (CoCr/Pt)20 multilayers. When the thickness of Pt underlayer increases, Pt(111) and CoCr(002) peaks of both CoCr/Pt bilayers and (CoCr/Pt)20 multilayers increase and the bilayer periodicity of the multilayers is improved. The effective magnetic anisotropy of (CoCr/Pt)20 multilayers with Pt underlayer was much larger than that of CoCr/Pt bilayers. The (CoCr/Pt)20 multilayers has a stronger perpendicular magnetic anisotropy than that of CoCr/Pt bilayers. This is ascribed to the interface magnetic anisotropy of the multilayers.     

电磁波在磁性分层薄膜中的传播非互易反射

本文采用传输矩阵研究了电磁波在磁性多层膜和超晶格中的透射和反射,获得了层状磁性介质的透射和反射系数,包括:(1)半无限磁性表面,(2)磁性多层膜,(3)半无限磁性超晶格。数值计算结果表明,磁性分层系统中电磁表面模可以通过电磁波斜入射在膜面上而激发出来,表现为S-极化反射曲线的尖谷,因此,本文指出电磁波传播的色散曲线可以用一种类似衰减全反射(ATR)的技术来测量。     

LEED and Optical Spectroscopy Study of an Organic Epitaxial Multilayer Film

Epitaxial multilayers of 2,9‐di(2‐hydroxyethyl)‐anthra[2,1,9‐def:6,5,10‐d′e′f′]diisoquinoline‐1,3,8,10‐tetrone (DMe‐PTCDI) were prepared on epitaxially grown phthalocyanine copper(II ) complex (CuPc) multilayers on Ag(110) by molecular beam epitaxy. This work presents LEED and photoluminescence investigations of a highly ordered organic heterosystem. Four different mono‐ and multilayer structures are presented. LEED images taken during preparation of the monolayer structures show a dose‐dependent structural phase transition. Photoluminescence measurements on the heterosystem show a temperature‐dependent transition in the fluorescence spectrum, resulting in a significant intensity increase. The results are compared to a previous study of DMe‐PTCDI on Ag(110).     

On the island nucleation process in LPOMVPE In0.2Ga0.8As/GaAs multilayers grown on GaAs and AlAs buffers

A comparative study of the nucleation of In enriched islands in In_0.2Ga_0.8As/GaAs multilayers grown on top of GaAs or AlAs buffers deposited on GaAs substrates with various miscut parameters was performed by using X-ray diffraction, transmission electron microscopy (TEM) and atomic force microscopy (AFM) techniques. Experimental results showed that the evolution of the self-assembly strongly depends on the miscut parameters and the morphology of the buffer/multilayer interface. For the samples with the same nominal strain misfit between the bilayers the nucleation is enhanced for the larger initial miscut on the substrate and the degree of the lateral ordering across the interface is promoted by the morphology of the underlying AlAs buffer layer.