单晶硅上电沉积Cu/Co纳米多层膜及其巨磁电阻效应

采用双脉冲控电位技术在单晶硅上沉积了一系列Cu/Co纳米多层膜,调制波长从200nm到5nm不等.用扫描电镜及X射线衍射对多层膜的调制结构进行了表征.采用四探针法测试多层膜的巨磁电阻（GMR）效应,研究了GMR与调制波长（λ）、铜的子层厚度（δ_Cu）的关系：λ较大时,没有观察到明显的GMR效应;λ＜30nm时,GMR效应随λ减小而增大;而λ＜8nm时,GMR值随铜层厚度的变化周期性振荡.     

薄膜厚度对NiO/NiFe/Cu/NiFe自旋阀多层膜的磁阻效应的影响

用射频磁控溅射方法制备多层膜,研究了双层膜NiO／NiFe的矫顽力Hc和交换耦合场Hex与反铁磁层NiO、铁磁层NiFe厚度的关系。结果表明：NiO厚度为70nm时,Hex最大;Hc随NiO厚度增大而增大。当NiFe厚度增加时,Hex近似线性减小;而矫顽力则随NiFe厚度增大开始有缓慢增加,然后才减小。对于NiO（70nm）／NiFe（t1nm）／Cu（2．2nm）／NiFe（t2nm）自旋阀多层膜材料,研究了NiFe膜厚度对磁阻效应的影响。结果表明：被钉扎层NiFe的厚度为3nm时,自由层NiFe的厚度为5nm时,MR值分别最大,约为1．6％。     

有机物在离子液体中无限稀释活度因子及液液界面张力的定量机构-性质关系

用PM3半经验量子化学方法计算了烷烃、烯烃和芳烃等的疏水性参数lgP、偶极矩、前线分子轨道能隙和水合能等结构描述符,与实验测定的烃类在1-丁基-3-甲基咪唑六氟磷酸盐（［C₄MIM］［PF₆］）、1-烯丙基-3-甲基咪唑四氟硼酸盐（［AMIM］［BF₄］）、1-异丁烯基-3-甲基咪唑四氟硼酸盐（［MPMIM］［BF₄］）和［MPMIM］［BF₄］-AgBF₄ 4种离子液体中的无限稀释活度因子进行定量结构-性质关系（QSPR）研究,建立的QSPR模型具有良好的关联和预测能力.同时测定了烃类等溶质与离子液体［C₄MIM］［PF₆］的液液界面张力,发现其与无限稀释活度因子有相似的变化趋势,据此采用同样的结构描述符,建立了溶质与［C₄MIM］［PF₆］界面张力的QSPR模型,模型的关联能力良好.     

新型Al2O3掺杂的SrCo0.8Fe0.2O3-δ混合导体透氧膜材料的性能

采用固相反应法制备了Al₂O₃掺杂的SrCo_0.8Fe_0.2O_3-δ(SCFA)新型钙钛矿型混合导体材料.对材料进行的结构分析表明,Al³⁺离子进入SrCo_0.8Fe_0.2O_3-δ(SCF)晶胞间隙位,降低了材料的氧非化学计量系数,并有效提高了材料的结构稳定性;对不同厚度的SCFA3［Al₂O₃掺杂量为3%（质量）］片式膜的氧渗透性能测定结果表明,SCFA3膜的氧渗透过程受到表面交换过程和体扩散过程的共同影响,其临界厚度约为131.5 μm;二氧化碳热分解(TDCD)耦合甲烷部分氧化(POM)膜反应过程（反应温度1173 K）表明,Al₂O₃掺杂的SrCo_0.8Fe_0.2O_3-δ较SrCo_0.4Fe_0.2O_3-δ (SCFZ) 具有更加优异的稳定性.     

NiO/Co/Cu/Co/NiFe自旋阀多层膜研究

采用射频磁控溅射方法制备了一系列自旋阀多层膜。在Cu/NiFe界面处插入适当厚度的Co薄层,可增强界面处的自旋相关散射,增大自旋阀的MR值。用绝缘材料NiO作钉扎层,在大磁场中淀积了NiO/Co/Cu/Co/NiFe底自旋阀,其最大MR值达6％。     

γ-Al2O3中孔陶瓷膜的制备及表征

以粒径为0.3～0.4 μm的α-Al₂O₃为原料,通过悬浮液真空抽吸法,制备出平均孔径约为70 nm的完整无缺陷的片状α-Al₂O₃支撑体;以仲丁醇铝为前驱体,采用颗粒溶胶路线制备出稳定的Boehmite溶胶,以此溶胶采用浸浆法,在制备的α-Al₂O₃支撑体上制备出完整无缺陷的γ-Al₂O₃中孔膜,并考察了烧成温度对γ-Al₂O₃中孔膜性能的影响。结果表明,本文制备出的γ-Al₂ O₃膜的孔径约为3 nm,对PEG的截留分子量为2800～5300,纯水渗透通量为11.5～25.9 L.m^-2.h^-1［7.6×10⁵ Pa,（14±1）℃］。说明在孔径为70 nm左右的载体上直接制备孔径为3 nm的完整的中孔膜是可行的。     

Preparation and characterization of mesoporous γ-Al2O3 membranes

以粒径为0.3～0.4 μm的α-Al₂O₃为原料,通过悬浮液真空抽吸法,制备出平均孔径约为70 nm的完整无缺陷的片状α-Al₂O₃支撑体;以仲丁醇铝为前驱体,采用颗粒溶胶路线制备出稳定的Boehmite溶胶,以此溶胶采用浸浆法,在制备的α-Al₂O₃支撑体上制备出完整无缺陷的γ-Al₂O₃中孔膜,并考察了烧成温度对γ-Al₂O₃中孔膜性能的影响。结果表明,本文制备出的γ-Al₂ O₃膜的孔径约为3 nm,对PEG的截留分子量为2800～5300,纯水渗透通量为11.5～25.9 L.m^-2.h^-1［7.6×10⁵ Pa,（14±1）℃］。说明在孔径为70 nm左右的载体上直接制备孔径为3 nm的完整的中孔膜是可行的。     

酸性离子液体催化合成三醋酸甘油酯

合成了［HSO₃-pmim］Cl、［HSO₃-pmim］［H₂PO₄］、［HSO₃-pmim］［BF₄］和［HSO₃-pmim］ ［HSO₄］离子液体，用1H-NMR和FT-IR对离子液体的结构进行了确定。将几种酸功能化离子液体应用于三醋酸甘油酯的合成反应中，筛选出了一种催化效果好又可以重复使用的离子液体［HSO₃-pmim］［HSO₄］。考察了催化剂用量、原料配比和反应时间对反应的影响，得到了较佳反应条件：n(甘油)∶n（醋酸）=1∶8，催化剂用量为醇酸总质量的5.8%，反应时间6 h，反应温度(80~90) ℃。对该功能化离子液体的重复使用性进行了考察，重复使用10次后，三醋酸甘油酯的收率仍大于90%。     

SiO2负载铬基催化剂催化四氢萘合成α-四氢萘酮

以硝酸铬或重铬酸钾为Cr源,采用浸渍法制备了SiO₂负载的Cr基催化剂［Cr(Ⅲ)/SiO₂和Cr(Ⅵ)/SiO₂］,并用共浸渍法制备了K₂O改性的Cr(Ⅲ)/SiO₂催化剂［K-Cr(Ⅲ)/SiO₂］。分别以叔丁基过氧化氢和O₂作氧化剂,考察了三种催化剂催化四氢萘合成α-四氢萘酮的反应性能。结果表明,以叔丁基过氧化氢作氧化剂时,Cr(Ⅲ)/SiO₂表现出最高的反应活性和选择性,K-Cr(Ⅲ)/SiO₂与Cr(Ⅵ)/SiO₂活性相近。紫外可见漫反射光谱表征结果表明,Cr(Ⅲ)/_SiO2具有最高的低价Cr物种（Cr［L］）和高价Cr物种（Cr［H］）比例,K₂O的引入抑制了Cr［L］物种的生成。推测以叔丁基过氧化氢作氧化剂时,四氢萘氧化生成α-四氢萘醇是反应速率控制步骤,Cr［L］物种可能是催化该反应的活性中心。以O₂作氧化剂时,Cr(Ⅲ)/SiO₂与Cr(Ⅵ)/SiO₂催化剂性能相近,说明O₂在相界面传质和（或）在催化剂表面吸附可能是反应的控制步骤。     

硅橡胶复合膜用于含酚水溶液渗透萃取传质过程

以苯酚为模型污染物,以氢氧化钠溶液为萃取液,利用平板复合膜［聚二甲基硅氧烷（PDMS）/聚偏氟乙烯（PVDF）］构造渗透萃取体系,系统地研究了该体系渗透萃取含酚水溶液的传质过程与特性。探讨了料液与萃取液的浓度及流量、运行温度等操作条件及活性层厚度对渗透萃取传质性能的影响。结果表明,pH>13时,总传质系数K_ov不随萃取液流量及浓度变化而变化;苯酚的液膜传质系数kf与膜面流动Reynolds数Re^0.46呈正比,传质通量与温度符合Arrhenius方程。在苯酚初始浓度5.0～15.0 g•L^-1范围内,K_ov为定值。活性皮层厚度为4、6、8 μm的膜扩散传质系数分别为15.0×10^-7、9.9×10^-7及7.5×10^-7m•s^-1（323.2 K）,较均质膜提高了2～4倍。苯酚在复合膜中的传质仍属膜阻控制的传质。     

添加剂对Cu/Co多层膜电结晶成核机理及磁性的影响

在硼酸镀液中以单晶S i(111)为基底用双槽法制备Cu/Co多层膜,在镀液中分别加入了镀铜添加剂2000#和镀钴添加剂5#。探讨了镀层电结晶成核机理,在基础镀液中铜电结晶为三维连续成核过程,钴电结晶在较低电位下为三维连续成核,在较高电位下为三维瞬时成核过程。加入添加剂后,铜、钴电结晶均为三维瞬时成核过程。测试了Cu/Co多层膜的磁性能;添加剂能提高多层膜的磁性能,无添加剂的Cu/Co多层膜的巨磁阻(GMR)值约为5%,而在加入了添加剂后,其GMR值高达52%。     

Preparation and Characterisation of Electrodeposited Ni—Cu/Cu Multilayers

Ni–Cu/Cu multilayers have been, grown from a single electrolyte under potentiostatic conditions at different electrolyte pH values. The current-time transients recorded during deposition indicated different growth modes of the Ni–Cu layers. Structural characterisation by X-ray diffraction revealed that the multilayers have the same crystal structure and texture as their (1 0 0) textured polycrystalline Cu substrate. Scanning electron microscopy showed that the films grown at low pH (2.2) have smoother surfaces than those grown at high pH (3.0). Energy dispersive X-ray analysis revealed that the magnetic layers of the multilayers electrodeposited at high pH contain much more Cu compared to those deposited at low pH. Anisotropic magnetoresistance was found for nominal Cu layer thicknesses below 0.6 nm, and giant magnetoresistance (GMR) above 0.6 nm. The shape of the magnetoresistance curves for GMR multilayers indicated the predominance of a superparamagnetic contribution, possibly due to the discontinuous nature of the magnetic layer. For multilayers with the same bilayer and total thicknesses, the GMR magnitude decreased as the electrolyte pH increased. Besides possible structural differences, this may have come from a strong increase in the Cu content of the magnetic layers since this causes a nearly complete loss of ferromagnetism at room temperature.     

Effect of sub-layer thickness on magnetic and giant magnetoresistance properties of Ni-Fe/Cu/Co/Cu multilayered nanowire arrays

Ni–Fe/Cu/Co/Cu multilayered nanowire arrays were electrodeposited into anodic aluminum oxide template by using dual-bath method at room temperature. Scanning electron microscopy and transmission electron micros-copy were used to characterize the morphology and structure of the multilayered nanowire arrays. Vibrating sample magnetometer and physical property measurement system were used to measure their magnetic and giant magnetoresistance (GMR) properties. The effect of sub-layer thickness on the magnetic and GMR proper-ties was investigated. The results indicate that magnetic properties of electrodeposited nanowires are not affect-ed obviously by Cu layer thickness, while magnetic layers (Ni–Fe and Co layers) have significant influence. In addition, GMR ratio presents an oscillatory behavior as Cu layer thickness changes. The magnetic and GMR properties of the multilayered nanowire arrays are optimum at room temperature for the material structure of Ni–Fe (25 nm)/Cu (15 nm)/Co (25 nm)/Cu (15 nm) with 30 deposition cycles.     

NiO/NiFe/Cu/NiFe自旋阀中巨磁电阻效应的各向异性

用射频磁控溅射的方法制备自旋阀NiO／NiFe／Cu／NiFe,通过改变外磁场、电流以及钉扎层易轴间的相对取向,研究自旋阀中的磁电阻与三者相对取向间的关系。结果表明,在自旋阀中磁电阻效应具有各向异性的特点。各向异性的起因在于磁性材料的磁各向异性和磁性材料中电子散射的各向异性。     

Characterisation of CoNi(Cu)/Cu multilayers deposited from a citrate electrolyte in a flow channel cell

CoNi(Cu)/Cu multilayers consisting of 50 and 200 bi-layers were deposited from a citrate electrolyte in a flow channel cell by a dual pulse plating technique. The dissolution of the ferromagnetic components during pulse plating was studied using an oscilloscope and cyclic voltammetry. It was found that the dissolution was suppressed due to the passivation of the ferromagnetic layers before the deposition of an atomic layer of nonmagnetic component on them. The passivation was a function of the nickel ion concentration in the electrolyte. X-ray studies showed that the deposit had a preferred crystal orientation of [1 1 1] and suggested the formation of a super-lattice. Atomic force microscopy studies showed a four-fold increase of the roughness of the ferromagnetic surface with increasing layer thickness from 6 to 10 nm, whereas the roughness of the nonmagnetic surface only changed slightly with increasing layer thickness. The multilayers exhibit giant magnetoresistance.     

Electrochemical behaviour and physical properties of Cu/Co multilayers

Cobalt/copper multilayer formation was analysed over different substrates in order to control the bilayer thickness and quality of coatings. Using a sulphate-citrate bath, at pH 4.7, electrodeposition conditions were optimised to prepare good alternate Cu/Co layers with high efficiency, by minimising the oxidation of cobalt layers during copper deposition. For multilayers with cobalt and copper layers of several nanometers, direct observation by scanning electron microscopy (SEM) or tapping mode-atomic force microscopy (TMAFM) gives layer thickness in agreement with the value calculated from deposition charges. Therefore, this calculation has been used to estimate the thickness of the thinner layers for which direct observation was difficult or impossible. A relation between the response of different characterisation methods was found. When the thickness of each layer in Cu/Co multilayers is >1.8-2 nm, potentiodynamic stripping experiments show separate peaks related to cobalt and copper oxidation. In these conditions, magnetoresistance of the coating is low. For thinner layers, the stripping response shows overlapping peaks or even a single oxidation peak. In these conditions the magnetoresistance begin to increase.     

Electrodeposition of Co-Ni-Cu/Cu multilayers: 1. Composition, structure and magnetotransport properties

Co-Ni-Cu/Cu multilayers have been deposited from a sulfate/sulfamate bath by controlling the current and the potential for the deposition of the magnetic and the copper layer, respectively. The magnetic layer thickness was varied between 1.2 nm and 12 nm, while the Cu layer thickness was in the range of 1.1-2.3 nm. Alloys with direct current have also been produced for comparison. All multilayer deposits exhibited a face centered cubic structure, while a small amount of hexagonal close packed phase was also present in the d.c. deposited alloys. The composition analysis showed that the codeposition of Co and Ni can be classified as anomalous codeposition for both d.c. and compositionally modulated deposits, regardless of the simultaneous deposition of Cu. The composition of the magnetic layer was affected by its layer thickness. This finding led to the conclusion that there must be a composition gradient in the magnetic layer in the growth direction. The magnetoresistance of the multilayers increased with increasing copper layer thickness, while the superparamagnetic contribution in the magnetoresistance increased with decreasing deposition current density of the magnetic layers.     

纳米金属多层膜的巨磁电阻效应

磁电阻效应是指材料的电阻随外加磁场变化而变化的现象。介绍了金属多层膜的制备及磁性检测方法。阐述了金属多层膜结构对巨磁电阻的影响．综述了金属多层膜巨磁电阻效应的研究现状、理论解释，并展望了其研究方向，