超高真空电子束蒸镀Fe/Ru多层膜的结构和磁性

采用超高真空电子束蒸镀方法制备了Fe/Ru多层膜,Ru层厚度固定为2 nm,Fe层厚度为0.6～5 nm,研究了Fe层厚度的变化对薄膜结构及其磁性能的影响.Fe层厚度小于5 nm时,受Ru层HCP结构的影响,Fe层生长为六方晶格的亚稳相.多层膜呈现明显的平面易磁化特性,并随Fe厚度降低而减弱.Fe的平均原子磁矩和Fe层厚度的倒数存在线性关系,与死层理论预言的结果相一致.实验结果证实,亚稳相六方晶格的Fe具有铁磁性,其平均原子磁矩计算值为1.9μB,略低于BCC Fe,Fe/Ru界面层的死层厚度为0.25 nm.     

基于X射线反射研究溅射工艺对CrAlN/TiAlN周期膜界面结构的影响

为研究X射线反射技术在纳米多层膜界面微结构表征中的应用,采用反应磁控溅射技术在单晶硅基片上制备CrAlN/TiAlN纳米周期膜,利用X射线反射技术系统研究溅射工艺参数对CrAlN/TiAlN纳米周期膜界面微结构的影响规律。结果表明:增加铝靶功率可提高膜层的溅射速率和降低膜层的界面粗糙度,然而较高的铝靶功率会使膜层界面出现严重的弥散;较大和较小的负偏压都不利于形成完整的周期膜调制结构和光滑的界面;提高Ti/Cr靶电流可有效改善周期膜的调制界面结构,但太大的靶电流会导致膜层间扩散加重,形成弥散界面。N2流量与Ar流量对膜层界面粗糙度具有相反的影响作用。试验得到的优化工艺参数为:铝靶功率80W,溅射负偏压-200 V,Ti/Cr靶电流0.2A,N2流量30cm~3/min,Ar流量10cm~3/min。     

Ni /Ti 多层膜界面状态优化分析

目的减小Ni/Ti多层膜表面粗糙度,提高Ni/Ti多层膜对中子束的反射率。方法采用离子束辅助沉积设备沉积Ni/Ti周期性多层膜,通过不同抛光时间和不同离子能量轰击对多层膜界面进行清洗抛光;采用反应溅射法,在镀Ti层时使用氢气和氩气混合气为工作气体,将H原子掺入Ti层以改变晶粒结构而影响多层膜界面状态。结果随着辅助离子源功率的增加,Ni/Ti多层膜的表面粗糙度增加;在合适的离子能量下,随着抛光时间的不断增加,Ni/Ti多层膜的表面粗糙度逐渐减小。Ti层中掺H的Ni/Ti多层膜比未掺H的多层膜表面粗糙度小,界面更加清晰。结论低能量的离子轰击条件下,适当的抛光时间能对多层膜实现较好的抛光效果。Ti层中掺入H原子,抑制了Ni原子与Ti原子的扩散,减小了Ti膜层晶粒大小,从而抑制了表面粗糙度的增加。     

非理想软X射线光学多层膜的掠入射镜向反射率

对实际软X射线光学多层膜中普遍存在的主要非理想因素（层厚漂移、界面粗糙度和界面扩散）进行了定理描述,基于动力学光学理论,计算了上述非理想因素对软X射线光学多层膜的掠入射镜向反射率的影响。结果表明：层厚的随机漂移使反射率、尤其是高级反射率降低;累积层厚漂移破坏了多层膜的长程有序性,使反射峰展宽;界面扩散和界面粗糙度使反射率降低,对高级反射率的影响更甚,但二者并不破坏多层膜的长程有序性,所以反射峰的宽度不变;界面扩散和界面粗糙度对反射率影响的机制不同;在界面扩散宽度和界面粗糙度相等的情况下,界面粗糙度使反射率下降显著,用模拟退火Monte-Carlo方法对Co/C软X射线光学多层膜进行了结构评价。该方法避免复杂的求导运算,在软X射线光学多层膜的结构评价中具有较强的实用性。     

Mo／SiO2软X射线多层膜反射镜的界面分析

用Ｘ射线衍射的动力学理论对磁控溅射法制备的Ｍｏ／ＳｉＯ２多层膜低角Ｘ射线衍射谱进行拟合，定量分析了膜层的周期结构和界面粗糙度。同时，用Ａｕｇｅｒ电子能谱证实了多层膜成分的周期性以及比较明晰的层界面，随样品厚度的增加，界面粗糙度增加。     

AlN/Si3N4纳米多层膜的显微结构及力学性能

采用射频磁控溅射方法制备了AlN、Si3N4单层薄膜和调制比为1的不同调制周期的AlN/Si3N4纳米多层膜。薄膜采用X射线衍射仪、X射线反射仪、高分辨率透射电子显微镜、原子力显微镜和纳米压痕仪进行表征。结果表明：AlN是多晶,Si3N4呈非晶,多层膜的界面非常尖锐;单层膜及多层膜均呈岛状生长,多层膜的表面粗糙度介于两单层膜之间,并且随着调制周期的增加,粗糙度下降;多层膜在所研究的层厚范围内,硬度值比根据混合法则计算得到的值高3.5GPa左右,没有出现超硬效应。     

Ru掺杂BaFe2As2体系Ba(Fe1-xRux)2As2的面内电输运性质演化研究

纵向磁阻能够反映铁砷化合物中载流子和自旋自由度间相互作用,为利用其对等价掺杂铁砷化合物的输运性质和自旋磁涨落进行研究,采用高温助熔剂法制备了高质量的Ba(Fe1-xRux)2As2单晶样品,测量了其中超导样品的ab面面内纵向磁阻。发现外场H作用下电阻值降低且磁阻大小随H2线性增大,分析表明负的纵向磁阻源于磁场对体系自旋涨落的压制效应;随着Ru掺杂量x增加,纵向磁阻系数曲线逐步下移,说明欠掺杂样品中自旋涨落较为剧烈,曲线下移反映了掺杂对体系内反铁磁自旋涨落的压制过程;应用二维反铁磁金属巡游电子模型对纵向磁阻的定性分析发现:随Ru掺杂量增加,模式耦合系数在最佳掺杂量子临界点处形式发生改变,说明伴随体系长程反铁磁序完全被压制,最佳掺杂和过掺杂样品内载流子与自旋涨落的作用方式产生了变化。     

界面精细结构与界面反应产物结构

界面的原子结构特征对材料的性能有很重要的影响.本文介绍用选区电子衍射及高分辨电子显微术研究半导体超晶格、金属多层膜、陶瓷和复合材料相界面的精细结构及界面反应产物结构的结果.对两相之间的取向关系,界面的台阶、小面和粗糙度,界面的原子键合,界面的共格性,错配位错的性质及界面附近弹性应变松弛度,界面附近缺陷结构,电子束辐照或制备工艺条件引起的界面固态化学反应动力学和反应机制以及界面反应产物结构进行了分析和讨论。     

测定膜基界面结合能的努氏印痕能量法

研究了涂层与基体界面结合能的测定方法，用理论和实验技术分析了努氏界面印痕法加载过程中，膜基试样吸收外加能量而转化为塑性变形能的行为、以及表面形状改变能和涂层界面断裂表面能，建立了努氏界面印痕能量法。对铁基Ni/Fe、镍基Cu/Ni低压等离子喷涂涂层进行界面结合强度的研究和分析得到涂层界面的断裂表面能。铁基纯镍Ni/Fe涂层界面的断裂表面能比镍基铜Cu/Ni涂层的高。界面微观分析表明：镍基铜Cu/Ni涂层材料疏松，膜基界面存在较多裂纹，涂层和基体中观察不到元素扩散层。Ni/Fe涂层界面结合致密，约有2μm的元素扩散层，微观分析现象与界面结合能的测定结果吻合。     

基体材料表面粗糙度对Ti/TiN/Zr/ZrN多层膜性能的影响（英文）

采用真空阴极电弧沉积技术,在4组表面粗糙度不同的Cr17Ni2钢基体上制备Ti/Ti N/Zr/Zr N多层膜。采用扫描电镜、X射线衍射仪、显微硬度计、结合力划痕仪、砂粒冲刷试验仪和盐雾试验机分析测试多层膜的截面形貌、膜层厚度、相组成、硬度、膜/基结合力、抗砂粒冲刷性能和耐腐蚀性能等。结果表明:所制备的多层膜厚度为11.37μm,维氏硬度为29.36 GPa;多层膜能显著地提高Cr17Ni2钢基体的抗砂粒冲刷和耐盐雾腐蚀能力;基体材料表面粗糙度对膜层性能的影响很大,基体表面粗糙度越小,其膜/基结合力、抗砂粒冲刷性能和耐盐雾腐蚀性能越佳;为了获得具有良好综合性能的膜层,待表面处理的基体表面粗糙度必须控制在Ra0.40μm。     

MAGNETIC PERFORMANCE TRANSITION IN Fe/Tb MULTILAYERS INDUCED BY INTERFACE ROUGHNESS

1. IntroductionIn the past decade, metastable phaJses have been fOund in various multilayers when thedeposited nonequilibrium phases have same crystal structure as the substrate. On suitablesubstrate and under moderate environments it is possible to induce growth of metastablephases. An example is the epitaxial growtli of fcc Fe on fcc Cu substrate where bothelements have close atomic .i...Il'2]. Since the substrate has same crystal structure asthe nonequilibrium phase, the lower interface e…     

Structural transition and magnetic properties of evaporated Fe/Gd multilayers

Fe/Gd multilayers were prepared by alternate vapor deposition of pure Fe and Gd at a rate of 0.01-0.03 nm/s in an ultra-high-vacuum electron-gun evaporation system.The effects of the constituent metal layer thickness on the microstructures and magnetic properties of the films were investigated by low angle X-ray diffraction,transmission electron microscopy,and vibrating sample magnetometer.The experimental results show that a transition from the polycrystalline to amorphous state in the Fe layers occurs with the decrease of Fe layer thickness in the Fe/Gd multilayers.The saturation magnetization of the muitilayers reduces significantly with decreasing Fe layer thickness and increasing Gd layer thickness.A superparamagnetic behavior at room temperature is observed for the [Fe(0.6 nm)/Gd(4.0 nm)]15 multilayer due to the formation of discontinuous Fe layers.     

Microstructure and mechanical properties of TiN/AlN multilayers deposited by filtered vacuum arc deposition

Nanometer TiN/AlN multilayers were prepared on silicon substrate by filtered vacuum arc deposition.The structures of the nanometer TiN/AlN multilayer were studied by using X-ray diffraction. The 12 nm TiN/AlN multiplayer is composed of cubic TiN structure and hexagonal wurzite AlN structure, but the 2 nm period multilayer is composed of face centered cubic structure TiN and AlN with strong (200) texture. The surface roughness, hardness and elastic modulus of multilayer are dependent on the period of multilayer. The hardness of the TiN/AlN multilayers is higher than that suggested by a simple rule of mixture. The peaking hardness of nanometer TiN/AlN multilayers at period of 2 nm is about 42 GPa, much higher than that of 12 nm. The wear resistance of the nanometer TiN/AlN multilayers was also studied.     

MAGNETORESISTANCE EFFECT OBSERVED IN Fe／Mo MULTILAYERS PREPARED BY ELECTRON BEAM EVAPORATION

The Fe/Mo multilayers were prepared by electron beam evaporation, the micro structure and magnetic properties of the multilayers were studied by X-ray diffraction, vibrating-sample magnetometer (VSM) et al. The experimental results revealed that the Fe/Mo multilayers in our experimental conditions behaved magnetoresistance effect with a sharp peak on magnetoresistance (MR) ratio curve, and magnetoresistance is easily saturated at low applied magnetic fields. For [Fe(1.5nm)/Mo(1.0nm)]4,2 multilayers, MR ratio could arrive to 0.1%. The antiferromagnetic interlayer coupling could be observed in some films at room temperature. The strength of the antiferromagnetic interlayer coupling J in the films is low because of the low saturation field Hs. The relationship between magnetic properties and micro structure was also discussed in this paper.     

The effect of multilayer structure on magnetic properties of FePt thin films

The Fe/Pt multilayer films with different structures were deposited by RF magnetron sputtering on glass substrates, and the L1₀-FePt films were obtained after theas-deposited samples were subjected to vacuum annealing at various temperatures. Results show that the Fe/Pt multilayer structure can effectively reduce the ordering temperature of FePt film, and the in-plane coercivity of [Fe (5.2 nm)/Pt (5.2 nm)]₇ multilayers can reach 161.2 kA/m after annealed at 350 ℃ for 30 min. When Fe and Pt layer thickness is equal, the coercivity of the film is the largest. On the other hand, the different Fe-Pt crystalline phases such as Fe₃Pt and FePt₃ phases are formed after annealing when the thickness ratio of Fe/Pt deviates from 1 after annealing. When Fe and Pt have the same thickness, the thinner single layer gets the lower ordering temperature and the larger coercivity.     

Thermal stability of microstructure and mechanical properties of Ni/Ru multilayers

The microstructure, hardness and thermal stability of Ni/Ru multilayers prepared by evaporation deposition were investigated by X-ray diffraction, transmission electron microscopy, vacuum annealing and nanoindenation. The hardness values of as deposited multilayers increase, while their elastic modulus values decrease, with decreasing periodicity. After annealing at low temperature (below 450 °C), the decrease in hardness of multilayers with larger periodicity is more remarkable than that of multilayers with smaller periodicity due to coarsening of the in-plane grain size. The higher temperature (600 °C) annealing results in the breakdown of the periodical structure and a significant drop in hardness for multilayers with smaller periodicity. The results were discussed according to Orowan-type single dislocation bowing mechanism.     

调制结构对TiN/TaN多层膜的生长行为及力学性能的影响

利用反应磁控溅射方法,制备了调制周期相同而调制比不同的TiN／TaN多层膜．利用XRD,HRTEM和纳米压痕仪分别对多层膜的结构、微观状态和力学性能进行了系统研究．结果表明：调制结构不仅改变多层膜的生长速率,而且能导致多层膜择优生长取向的变化;界面应力的存在使得薄膜生长速率随沉积层厚度的增加而下降;在TiN／TaN多层膜中存在着各自独立外延生长的[111]和[100]两种取向的调制结构,且具有不同的调制周期;调制周期为6nm左右的TiN／TaN多层膜的硬度与弹性模量分别提高约50％与30％;在调制比为3：1时,硬度最大值为34．2GPa,弹性模量为344．9GPa;根据结构和力学性能的分析结果,讨论了TiN／TaN多层膜的硬化机制．     

Microstructure and nanoindentation hardness of Ag/Fe multilayers

Ag/Fe multilayers with well compositional modulation periodicity of 4-60 nm were prepared at room temperature by evaporation deposition using an ultra high vacuum (UHV) chamber. Their microstructure and hardness were investigated using XRD, TEM and nanoindentation. The fcc/bcc type multilayers show a textured polycrystalline growth with Ag (111) and Fe (110) in Ag layers and Fe layers, respectively. The hardness increases with decreasing periodicity and approaches the maximum of 6.36 GPa at the periodicity ...     

气相沉积铁钇多层膜的磁学性能

研究了气相沉积技术制备的Fe/Y多层膜的磁学性能,试验结果表明,当多层膜中铁层厚度减少到1．4nm时,薄膜由铁磁性转变为超顺磁性;多层膜的饱和磁化强度随铁层厚度的减少和钇层厚度的增加而显著降低。