电沉积Ni80Fe20/Cu纳米多层膜及其巨磁电阻效应

采用单槽控电位双脉冲技术在n-Si（111）晶面上制备了［Ni₈₀Fe₂₀/Cu］_n多层膜,用SEM观测了多层膜的断面形貌,利用X射线衍射（XRD）表征了多层膜的超晶格结构。采用四探针法研究了多层膜的巨磁电阻（GMR）性能,结果表明,多层膜的GMR值随着Cu层厚度的变化发生周期性振荡,随着NiFe层厚度的增加先增大后减小;当样品结构为［NiFe（1.6 nm）/Cu（2.6 nm）］₈₀时,GMR值可达6.4%;多层膜的最低饱和磁场仅为750Oe。磁滞回线测试结果表明,反铁磁耦合多层膜具有较小的矩形比,更适宜作为磁头材料。     

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％。     

单槽脉冲电沉积制备铜/镍纳米多层膜及其性能

用单槽脉冲电沉积法在含CuSO4、NiSO4和Na3C6H5O7的镀液中制备了不同调制波长的Cu/Ni纳米多层膜,对其进行了截面形貌观察及显微硬度测量.结果表明,制备的多层膜平整,层间界清晰.其显微硬度在调制波长为100 nm时出现峰值.当调制波长大于100 nm时,多层膜显微硬度的变化符合Hall-Petch关系;当调制波长小于100 nm时,显微硬度开始下降.X射线衍射表明,膜层中存在压应力,Ni层形成了强(100)织构.     

大自旋极化率半金属Fe_3O_4薄膜制备及其磁性能

采用磁控溅射法先在Si(100)基片上沉积适当厚度的Fe薄膜作为底层,通过对Fe底层厚度及氧气流量的控制,使底层Fe形成化学计量的无缓冲层的Fe3O4多晶薄膜。通过X射线衍射和磁强计分析了样品的结构和磁性能。结果表明:当初始氧气流量为1.5mL/s时,在15nm的Fe薄膜底层上可成功制备高晶粒织构的化学计量的Fe3O4薄膜。将Fe3O4薄膜应用到巨磁电阻(giant magnetoresistance,GMR)多层膜中,由于多层膜材料间电阻率的失配,利用Fe3O4半金属薄膜并不能获得预见的大GMR效应。     

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%。     

高反射率Ag-Cu纳米膜玻璃的制备与表征

采用磁控溅射法在玻璃基片上制备纳米Ag薄膜,并在其上镀一层Cu膜作为附着层,利用U-4100分光光度计测量纳米膜玻璃对可见光(380～780nm)和太阳光(340～1 800nm)的反射率;用Auger电子能谱仪测量膜的成分;聚焦离子束和超级扫描电子显微镜测量双层膜中单层膜的厚度.结果表明:膜厚小于110m的银膜,反射率随膜厚增加而变大,当膜厚大于110nm时,其反射率趋于一定值,附着层Cu膜对膜玻璃反射率影响不大.另外,在膜厚一定的情况下,随着玻璃厚度的增加,膜玻璃反射率逐渐减小.膜玻璃对可见光的反射率可以达到97.85%,太阳光的反射率可以达到96.74%.采用聚焦离子束和超级扫描电子显微镜相结合的方法测量多层膜中单层膜的厚度,得到了较好的结果.     

有机发光器件的光电性能研究

采用真空蒸发镀膜的方法制备了ITO/TPD（30nm）/Alq3（40nm）/LiF/Al结构的有机发光器件,讨论了Alq3的沉积速率和缓冲层LiF的厚度对器件光电性能的影响。结果表明：Alq3膜的沉积速率为0.2nm/s时所形成的器件光电性能最好,启亮电压为10V,最大发光效率为2.58cd/A;不同厚度LiF层的注入,使器件的光电性能有了不同程度的改善,LiF层厚度为2nm时效果最佳,启亮电压降至7V,亮度提高了1345cd/m2,最大发光效率达4.4cd/A。     

反应磁控溅射氧化钨电致变色薄膜厚度对结构、性能的影响

采用脉冲直流反应磁控溅射镀膜方法在FTO透明导电玻璃上制备厚度分别为50nm、100nm、150nm、200nm、250nm和300nm的氧化钨薄膜;采用XRD( X射线衍射) 和AFM（原子力显微镜）分析薄膜着色前后晶体结构和表面形貌的变化;采用电化学工作站和可见-近红外分光光度计对薄膜的循环伏安特性和光学性能进行测试。研究获得：不同厚度氧化钨薄膜均为结晶态,具有单斜晶系结构;随着薄膜厚度增加,薄膜结晶程度逐渐增加;薄膜着色/褪色循环中,不同厚度氧化钨薄膜均发生单斜晶系WO2.92与立方晶系WO3的可逆转变,产生晶格应变,并且随厚度增加,薄膜晶格应变先减小后增大,薄膜厚度为250nm时变色前后晶格应变最小,厚度进一步增加至300nm薄膜着色产生应变明显增大。在相同驱动电压下,随薄膜厚度增加,光学调制幅度（550nm）、着色效率先增大后减小,厚度为250nm时获得最大调制幅度76.01%,和着色效率21.04cm2/C;当厚度进一步增加至300nm时,薄膜褪色态透过率降低到49.30%后无法继续褪色,着色效率也开始下降。使用XPS进一步分析了薄膜着、褪色状态下W元素的化学态,发现300nm薄膜褪色后一部分W5+无法转变成W6+,导致薄膜仍为蓝色。     

AZO基双层/多层薄膜的制备及性能

采用磁控溅射法在普通钠钙浮法玻璃表面先获得厚度为50 nm的AZO(掺铝氧化锌)底层,然后制备出不同Ag层厚度(4、6、8或10 nm)的Ag/AZO双层膜以及不同AZO顶层厚度(10、30、50或70 nm)的AZO/Ag/AZO多层膜,考察了它们的表面形貌、晶体结构、方块电阻、透光率和品质因子.结果表明,Ag层厚度为6 nm时,Ag/AZO双层膜表面Ag粒子分布均匀,致密度较好,晶粒尺寸最大,综合性能最佳.在此双层膜的基础上沉积50 nm厚的AZO顶层可以较好地覆盖Ag层,提高薄膜的致密度,令晶粒尺寸明显增大,得到综合性能最佳的AZO/Ag/AZO多层膜.     

夹心结构FeNi/Cu／FeNi多层膜巨磁阻抗效应的研究

采用MEMS技术在玻璃基片上制备了夹心结构FeNi/Cu/FeNi多层膜,在100KHz-40MHz范围内研究了FeNi/Cu/FeNi多层膜中的巨磁阻抗效应特性。当磁场Hext施加在薄膜的长方向时,巨磁阻抗效应随磁场的增加而增加,在某一磁场下达到最大值,然后随磁场的增加而下降到负的巨磁阻抗效应。在频率为5MHz时,巨磁阻抗效应在磁场Hext=800A/m时达到最大值25．2％;在磁场Hext=9600A／m时,巨磁阻抗效应为-7．3％。巨磁阻抗效应的最大值及负的巨磁阻抗效应与多层膜中磁各向异性轴的取向及发散有关。另外,当磁场施加在薄膜的短方向时,薄膜表现出负的巨磁阻抗效应,在频率5MHz、磁场Hext=9600A/m时,巨磁阻抗效应可达-19．3％。     

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.     

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.     

陶瓷膜通道相互作用的实验分析及CFD优化

提出陶瓷膜过滤时,通道之间存在3种效应关系（壁厚效应、干扰效应、遮挡效应）,并用实验进行了验证。对于多通道陶瓷膜构型的设计,要考虑3种效应。膜孔径小于200 nm的陶瓷膜,可以增大其通道的排布密度,通过提高装填密度可以提高单位体积的处理量;膜孔径大于500 nm的陶瓷膜,中间的通道对通量几乎没有贡献,提高装填密度意义不大。固定膜元件的外径,选取通道直径a_c和壁厚a_w,并设定两参数的比值为α,采用计算流体力学（CFD）软件进行模拟计算,获得了通量与处理量随孔径与α值的变化关系。     

Structural characterization of diamond-like carbon films for ultracold neutron applications

We have produced hydrogen-free diamond-like carbon (DLC) films by vacuum arc deposition for use as wall coating material in ultracold neutron (UCN) applications. The sp³ fraction, the main quality factor for DLC used in UCN applications, was varied from 0.4 to 0.9, the coating thickness between 10 nm and 120 nm. The samples were characterized by using X-ray Absorption Near-Edge Spectroscopy (XANES), X-ray induced Photoelectron Spectroscopy (XPS), Laser induced surface Acoustic Waves (LAwave), cold neutron reflectometry and Raman spectroscopy at visible excitation wavelength. We observe reasonable agreement between the different results for film thicknesses below 20 nm. For larger thickness, we find that the surface-sensitive methods XPS and XANES yield smaller sp³ fractions (by up to 20%) than the bulk-sensitive LAwave, being consistent with the assumption of a lower-density surface layer on a nominal-density bulk layer.     

Electrochemical Surface Modification of Aluminium Sheets for Application to Nano-electronic Devices: Anodization Aluminium and Electrodeposition of Cobalt-Copper

A nano-porous anodized aluminium oxide layer was synthesized on the surface of bulk aluminium at a wide range of anodization voltages. The barrier layer at the pore bottom of anodized aluminium oxide layer was chemically etched to make good electrical contact for nanowires electrodeposited in the pores thus formed on metallic aluminium substrates. Cathodic polarization was examined at a wide range of cathode potentials to investigate the electrodeposition behaviour of Cu and Co into the pores. Co₈₁Cu₁₉/Cu multilayered nanowires were fabricated using a pulse-plating technique into the templates. Co-alloy layer and Cu layer thicknesses were adjusted to 10 nm, by controlling the deposition times. The temperature dependence of the resistance of Co₈₁Cu₁₉/Cu multilayered nanowires grown on the template presented clean metallic characteristics and a giant magnetoresistance (GMR) of 23% was reached at 4 K.     

硅烷偶联剂对聚甲基丙烯酸甲酯/二氧化硅纳米复合材料结构与性能的影响

采用乙烯基三乙氧基硅烷(WD-20)作为偶联剂,通过溶胶-凝胶法合成了聚甲基丙烯酸甲酯(PMMA)/二氧化硅(SiO₂)纳米复合材料,采用紫外-可见光谱、红外光谱、扫描电子显微镜和热机械分析等研究了材料的结构和性能.结果表明,WD-20的加入对纳米复合材料透明性、耐热性能和微观形态结构有较大影响,随着WD-20用量的增加,纳米复合材料透明性增加,SiO₂分散相尺寸变小,玻璃化转变温度增加.当WD-20与四乙基原硅酸盐（TEOS）之比为0.2时,所制备的纳米复合材料的溶胶分数为6%、玻璃化转变温度为250 ℃以上、可见光透过率在80％以上、SiO₂分散相尺寸小于100 nm.     

Fabrication & characterization of macroporous CdSe nanostructure via colloidal crystal templating with electrodeposition method

Large area ordered arrays of macroporous Cadmium Selenide (CdSe) nanostructure, which possesses high refractive index and negligible absorption in the visible spectrum critical for the realization of photonic band gaps, was prepared via colloidal templating by galvanostatic electrodeposition. This work investigates the effect of electrodeposition parameters on the macroporous CdSe nanostructure. Field Emission Scanning Electron Microscope (FESEM) images showed two and three dimensional porous structures, consisting of interconnected close-packed arrays of pores. For CdSe thin film of thickness less than 1/3 of the diameter of a polystyrene sphere, it showed a monolayer of circular pores. As for film thickness close to the diameter of the sphere, the pores adopted irregular rounded triangular shapes. When the film thickness was more than one layer of the colloidal polystyrene template, the pores were spherical and had the same diameter as the polystyrene spheres. X-ray Diffraction (XRD) showed that the CdSe films prepared had a cubic structure with nanometer grain size, which was smaller than the diameter of the template spheres as well as the diameter of the interconnected channels. A range of 45–70 nm thick CdSe films with > 90% optical transmittance showed that there was negligible absorption at wavelength of 750 nm. In addition, the CdSe thin film exhibited a band gap energy of 2.07 eV, blue-shifted from the characteristic 1.7 eV of CdSe. This blue-shift characteristic of the deposited CdSe film further indicated that it was nanocrystalline which is potentially useful in photonic applications.