化学镀制备钯复合膜成膜机制的研究

采用以肼为还原剂的化学镀液，在多孔不锈钢载体上制备钯复合膜，研究钯复合膜的形核、长大及成膜机理。结果表明，载体经敏化／活化处理后，表面获得了均匀分散的纳米晶核，化学镀时，钯沿着晶核均匀长大，逐渐成膜。为了抑制载体的氢脆，增加载体与钯膜之间的结合力，载体预镀-薄层钯膜后再对载体作封孔处理，在孔径较大的不锈钢载体上获得了无裂缝、薄而致密的复合钯膜。     

Pd微纳米粒子在石墨烯/聚酰亚胺薄膜上的电沉积及其电催化氧化甲酸（英文）

利用电化学沉积法在柔韧的石墨烯/聚酰亚胺(Gr/PI)复合膜上制备一种新的花状、微纳结构的Pd电催化剂。作为对比研究,同时在羧基化碳纳米管/聚酰亚胺(COOH-CNTs/PI)上制备Pd微纳米粒子催化剂。对合成的Pd/Gr/PI和Pd/COOH-CNTs/PI进行X射线衍射(XRD)和扫描电子显微镜(SEM)分析。XRD和SEM分析结果表明:当沉积条件相同时,相对于在COOH-CNTs/PI膜上制备的Pd微纳米粒子,在Gr/PI复合膜上电沉积得到的Pd微纳米粒子尺寸更小,分布密度更大,且分布更均匀。通过循环伏安法(CV)和计时电流法(CA)研究这两种催化剂对甲酸的电催化氧化性能。结果表明:在Gr/PI电极上沉积得到的Pd的催化效率更高、稳定性更好。这是由于在Gr/PI电极上沉积得到的Pd颗粒尺寸更小,分布密度更大,催化活性点位更多,因而对甲酸的催化氧化效果更好。     

多弧离子镀TiN/Cu纳米复合多层膜致硬机理的探讨

采用多弧离子镀技术制备单一的TiN薄膜和TiN/Cu纳米复合多层膜,研究了复合膜的硬度变化及相组成.初步探讨了TiN/Cu纳米复合多层膜的致硬机理.实验结果表明,Cu元素的掺人阻碍了TiN的生长,使复合膜硬度有了显著提高,制得硬度高达51GPa的TiN/Cu复合多层膜,其TiN以(111)和(200)两个晶面择优生长,且衍射峰强度极为接近,(200)面略高于(111)面.     

水浴法制备钯纳米颗粒及其修饰电极的电催化性能

利用Keggin结构的12-硅钨酸作为模板,采用水浴法还原硝酸钯制备了纳米钯.用透射电子显微镜(TEM)和X射线衍射(XRD)等手段对制备的钯纳米颗粒的形貌、粒径大小和结构进行了表征.利用滴涂法将Pd纳米颗粒修饰到Au电极表面,通过循环伏安法,研究了纳米Pd对肼的电催化性质.结果显示,制备的纳米钯为3～4 nm的类球形颗粒,为面心立方结构.纳米Pd修饰电极对肼具有良好的电催化氧化作用.在pH=6时,氧化峰电流(lpa)与肼的浓度呈现良好的线性关系.     

Cu/X(X=Cr,Nb)纳米多层膜力/电学性能的尺度依赖性

利用纳米压痕实验以及四探针法,系统研究了相同层厚Cu/X(X=Cr,Nb)纳米金属多层膜的力学性能(强/硬度)和电学性能(电阻率)的尺度依赖性.微观分析表明:Cu/X多层膜调制结构清晰,Cu层沿{111}面择优生长,X层沿{110}面择优生长.纳米压入结果表明,Cu/X多层膜的强度依赖于调制周期,并随调制周期的减小而增加.多层膜变形机制在临界调制周期(λ~c≈25 nm)由Cu层内单根位错滑移转变为位错切割界面.多层膜的电阻率不仅与表面/界面以及晶界散射相关,而且在小尺度下受界面条件显著影响.通过修正的FS-MS模型可以量化界面效应对多层膜电阻率的影响.Cu/X纳米多层膜可以通过调控微观结构实现强度-电导率的合理匹配.     

钯-铂双层覆膜聚酰亚胺的CECVD制备与表征

以N2、O2作载气,采用催化增强化学气相沉积(CECVO)法,于250～300℃和减压/常压下制得沉积于聚酰亚胺(PI)上的Pt,Pd/Pt和Pt/Pd金属双层薄膜.当使用Pd(hfac)2和Pt(COD)Me2为前驱体,在同一反应器内共沉积时只有Pt被沉积(钯配合物起催化剂作用),金属铂、钯顺序沉积可形成双层膜.经XPS和SEM分析了所得沉积膜的表面结构与相组成.结果表明:所有沉积层与PI衬底的粘附性能良好;沉积速率为70～80nm/h,钯、铂粒径分别为100nm和100～150nm.     

碳纳米钯的生物合成及其催化性能研究

将奥奈达希瓦氏菌(S. oneidensis MR-1)原位还原形成的零价纳米钯颗粒负载在碳纳米管(CNTs)表面,制备了Pd/CNTs纳米复合材料。用TEM、XPS等多种手段对材料进行了表征,并用对硝基苯酚(4-NP)的还原降解反应评价了Pd/CNTs的催化性能。表征结果表明,钯纳米颗粒(直径2~3 nm)较均匀地分散在CNTs表面;钯负载在CNTs上会造成其拉曼峰强的增大和特征峰的偏移,且结晶度和颗粒数目随着负载量的增加而增加。性能评价表明,Pd/CNTs对4-NP还原降解具有较高催化性能,较其催化效率较单一的CNTs降解效率提高了6.3倍;在pH = 10的条件下,5% Pd/CNTs催化18 min可将4-NP降解99.5%,经6个反应循环后对4-NP的去除率仍保持在95.2%。     

医用316L不锈钢支架表面沉积(Fe/Pd)n薄膜的研究

采用真空电弧离子镀技术,在医用316L不锈钢支架上沉积近等原子比的(Fe/Pd)n多层膜.用X射线衍射、扫描电镜、电子能谱研究(Fe/Pd)n多层膜的晶体结构、形貌和成分,分析相的转变.用CTCC-1数字磁通磁场测量仪测量样品的磁性.结果表明:医用316L不锈钢支架表面磁性膜的最佳结构为"Pd/Fe/Pd",经扩散热处理后,(Fe/Pd)n薄膜从fcc结构转变为fct结构,薄膜均匀、致密、结合强度良好,有效磁场强度可达5×10-4 T以上,有效磁性可维持6个月.     

有机膦配体对钯分子偶联催化剂活性的影响

采用3种不同的有机膦配体,设计和合成出3个有机膦钯(II)配合物,测试和表征了它们的化学结构,分别为trans-{Pd[(t-Bu)2PPh]2Cl2}、trans-[Pd(Amphos)2Cl2]、cis-[Pd(Xantphos)Cl2] ((t-Bu)2PPh=二叔丁基苯基膦、Amphos=二叔丁基-(4-二甲基氨基苯基)膦、Xantphos=4,5-双二苯基膦-9,9-二甲基氧杂蒽)。在2个Suzuki和1个Sonogashira偶联反应模型上,测定了它们的催化活性,考察了膦配体对钯分子偶联催化剂活性的影响,发现膦配体对催化活性有重要影响,且对应不同的反应模型其影响程度不同,影响机制与膦配体的配位能力和分子的空间体积有关。     

钯锰纳米多孔材料对乙醇的电催化氧化

采用熔体快淬结合去合金化法制备了钯锰纳米多孔材料(NP-PdMn)。用X射线衍射(XRD)、X射线光电子能谱分析(XPS)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对材料进行了表征,并研究了其在碱性条件下对乙醇氧化的电催化活性。表征显示,NP-Pd Mn为具有三维双连续纳米多孔结构的棒状材料;锰取代了晶格中部分钯的位置使得晶面间距变小;部分钯和锰在材料表面以氧化态存在。催化性能分析表明,与商业Pd/C相比,NP-PdMn/C催化剂具有优于商业Pd/C的催化活性和稳定性。     

Fabrication of YBCO films on Ag substrate by TFA-MOD method

Biaxial aligned YBCO films have been successfully deposited on Ag { 110 } (110) textured polycrystalline substrates by metal-organic decomposition (MOD) method using Trifluoroacetate Salt (TFA). The influence of firing temperature and Ag surface defects on phase purity and texture, surface morphology of YBCO films was studied. Holding temperature at 900℃ for 30 rain benefits to improve orientation and connectivity of YBCO films. The surface of YBCO films deposited on unpolished Ag substrate has many holes and stripes, which are parallel to the rolling stripe on Ag substrates. To eliminate the rolling stripe on the Ag surface, Ag substrates were polished prior to films deposition. The film grown on polished Ag substrates has a smooth surface and good connectivity of grains without parallel stripes. The YBCO films have an onset of transition around 90K and critical current densities of 15000 A/cm^2.     

Tarnishing resistance of silver–palladium thin films

Ag–Pd decorative coatings are supposed to provide better tarnishing resistance as compared to pure Ag, while keeping good optical (brightness) and mechanical properties (ductility). Palladium has a similar optical appearance as silver, and forms a thin protective oxide surface layer. Thus, a small incorporation of Pd in Ag could improve its tarnishing resistance.

Thin Ag–Pd films were deposited by magnetron co-sputtering from Pd and Ag targets. The Ar gas pressure, target power and substrate temperature were varied to modify the chemical composition of the films and optimise their properties.

The optical properties of the films were evaluated by spectroscopic ellipsometry and colorimetry. Increasing Ar gas pressure and substrate temperature results in a drastic decrease of the specular reflectivity of the films. At constant deposition conditions the reflectivity of the Ag–Pd films decreases with increasing Pd content.

The film hardness, evaluated by nanoindentation, increases with Pd content.

The tarnishing resistance of the films was evaluated by sulphidation tests. The colour change of the films due to the sulphidation was measured by colorimetry. The nature of chemical bonds of the tarnished products was evidenced by XPS. The results suggest an improvement of tarnishing resistance of the Ag–Pd films with increasing Pd content.     

扩散热处理对316L不锈钢表面钯／铁薄膜形貌和相组成的影响

采用真空电弧离子镀工艺，在316L不锈钢表面沉积钯，铁（Pd／Fe）合金薄膜并进行真空扩散热处理，观察扩散热处理工艺对Pd／Fe薄膜的形貌和相组成的影响。结果表明：采用真空电弧离子镀工艺，可在316L不锈钢表面沉积均匀的Pd／Fe膜；扩散热处理工艺对Pd／Fe膜的形貌和相组成有显著影响。经900℃保温1h处理后，Pd膜与Fe膜间互扩散形成一定量的Pd-Fe合金相；随着热处理温度升高，Pd,Fe膜层向316L基体扩散的距离增大，同时基体中的Cr，Ni向外扩散的量也增多。     

Effects of Ag nanoshape and AgGa phase in Ag-Si nanostructure using 2-step etching process

The etching scale was controled by the layball process and a focus ion beam (FIB) was used to investige the dry-wet etching (DWE) mechanism. Increasing the beam current of dry-etching raised the height of nano prominent structures, but deteriorated the interface of Ag/Si film, and even damaged the Ag film because of Ga⁺ bombardment. Regardless of the Ag nanoshape deposition, the residual Ag films were doped with Ga⁺ and were sensitive to DWE. After wet-etching, the nano hollow formed and the Ag films sunk. However, AgGa sidewall films formed by the concentration gradient and the oxidative potential and this increased the volume of microporous phases, resulting in a reduction in the depth. Also, 15-30 nm Ag nano-particles were able to enhance the DWE mechanism in the Ag/Si nanostructures.     

Silver nanoparticle catalyst for electroless Ni deposition and the promotion of its adsorption onto PET substrate

Silver nanoparticle catalyst was prepared to replace Pd catalyst for electroless Ni plating. The adsorption of Ag nanoparticle onto the poly(ethylene terephthalate) (PET) was promoted by conditioning the substrate with 3-aminopropyltrimethoxysilane and 3-mercaptopropyl- triethoxysilane. Electroless Ni deposition was started at the PET substrates catalyzed with Ag nanoparticle linking to the substrate via Ag-S bond. The composition and topography of nickel plating PET films were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis, respectively. Peel adhesion strength, more than 50 N/cm, was achieved for planting nickel layer to the Ag activated PET substrate; however, a relative low value as 10.2 N/cm was obtained for the sample with Pd catalyst by the same measurement. Silver catalyst together with silane modification has the significant merits for electroless deposition of Ni on PET film.     

Influence of misfit and interfacial binding energy on the shape of the oxide precipitates in metals: ; Interfaces between Mn3O4 precipitates and Pd studied with HRTEM

Transmission electron microcopy (TEM) revealed Mn₃O₄ precipitates with two types of dominant shape in Pd–3 at.% Mn that was internally oxidized in air at 1000°C. One type is octahedrally shaped and bounded by {111} planes of the Mn₃O₄. These observations were compared with earlier observations in the Ag/Mn₃O₄ system and the octahedrons show a relatively larger truncation by (002) in Pd than in Ag. Further, the second type of precipitate shape, comprising about 1/3 of all of the precipitates in Pd, was not observed in Ag. It corresponds to a plate-like structure, showing an orientation relationship where the tetragonal axes of Mn₃O₄ are parallel to the cube axes of Pd, with the c-axis of Mn₃O₄ as habit plane normal. High-resolution TEM observations revealed the presence of a square misfit dislocation network with line direction 〈110〉 and Burgers vector 1/2〈110〉 at these interfaces with (002)Mn₃O₄6{200}Pd. The general conclusions of the present analysis are: (1) the anisotropy in interface energy for oxide precipitates in a metal matrix is substantial due to the ionic nature of the oxide, giving well-defined shapes associated with the Wulff construction; (2) the influence of misfit energy on the precipitate shape as bounded by semi-coherent interfaces is important only if sufficient anisotropy in mismatch is present and if the matrix is sufficiently stiff; and (3) the stronger coupling strength due to electronic binding effects across the interface in Pd compared with Ag is responsible for formation of the dislocation network structures at larger misfit.     

INFLUENCE OF THE NONMAGNETIC METAL SPACER ON THE MAGNETIC PROPERTIES AND MICROSTRUCTURE OF THE MULTILAYER FILMS

Ta / NiFe/Bi （ Ag, Cu ）/FeMn/Ta and Ta / NiFe1/FeMn / Bi （ Ag, Cu ）/NiFen/Ta films were prepared by magnetic sputtering. The texture and the dependences of the exchange-coupling field on the thickness of Bi, Ag, and Cu in Ta/NiFe/Bi（Ag, Cu） /FeMn/Ta and Ta/NiFe/FeMn/Bi（Ag, Cu）/NiFe/Ta films were studied. XPS results indicate that the Bi atoms migrated into the FeMn layer during the deposition process and a FeMnBi alloy was probably formed or the Bi atoms existed as an impurity in the FeMn layer in Ta/NiFe/Bi（Ag, Cu ）/FeMn/Ta. Otherwise, in Ta/NiFe/FeMn/Bi （Ag, Cu）/NiFe/Ta films, Bi, Ag, and Cu atoms do not remain entirely at the interface of the FeMn/ NiFeⅡfilm, but at least partly segregate to the surface of the NiFe film.     

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利用扫描电镜、X射线衍射和电子背散射衍射研究了CVD自支撑金刚石薄膜的表面形貌组织、织构和晶界分布。研究表明:金刚石薄膜制备气氛纯度较低,造成薄膜中存在较多孪晶。沉积气体中甲烷浓度升高,孪晶发生频率增加,孪晶对织构组分的影响程度增加。高频率孪晶使薄膜中{100}织构转变为{122}织构,但没有观察到明显的{511}和{411}孪晶织构,说明孪晶取向的变化具有一定的选择性。     

Effect of Ag nanoparticle size on the plasmonic photocatalytic properties of TiO2 thin films

Photocatalytic TiO₂ films combined with Ag nanoparticles (NPs) embedded-SiO₂ films were fabricated by means of a RF magnetron sputtering and subsequent rapid thermal annealing (RTA). X-ray diffraction results show that the TiO₂ films have anatase phase when annealed at 500 °C. The Ag NPs were formed by deposition and subsequent annealing at 600 °C. Scanning electron microscopy (SEM) results show that the density of the NPs decreases with increasing Ag film thickness. For example, the average NP diameter varies from ~ 19.3 to ~ 55.9 nm as the film thickness increases from 2 to 12 nm. Transmittance measurements show that as the Ag NP size decreases, the plasmonic peaks shift towards the shorter-wavelength region and become narrower. It is further shown that under UV-illumination (352 nm), all the TiO₂ films with the Ag NPs show higher methylene blue decomposition rates compared to the TiO₂ only films and the TiO₂ films with Ag NP (a 7 nm-thick Ag film) show the best decomposition rate among the samples possibly due to the combined effects of optimized localized field amplification and radiative efficiency.     

The Structure and Texture Development of Ni Alloy Electrodeposits—III Nickel-Zinc Electrodeposits

Electrodeposited nickel-zinc alloys have been studied using ‘direct’ methods e.g. x-ray diffraction and transmission electron microscopy on coatings having different thicknesses, deposited on mild steel and copper substrates at current densities of 10 and 60 mA cm². In all cases the coatings evolved with a complex bcc gamma phase. The work has confirmed and extended the ideas of Finch et al.^{1 3} and Pangarov^4-6 to alloy deposition. It has been shown that a better understanding, particularly of the initial deposition stages, can be obtained by considering both strain and surface energy effects. In all cases the film formed at the coating/substrate interface develops with a {110} texture on both mild steel and copper substrates at current densities of 10 and 60 mA cm². From surface energy considerations a {110} texture would be expected as in bcc metals this orientation has the lowest surface energy. XRD measurements by glancing angle indicate that in the initial stage of deposition, the zinc and nickel atoms deposit in the recesses in the {110) plane of the mild steel as the initially formed deposit had a d-spacing similar to that of the mild steel. Similar effects were also indicated for the nickel-zinc film deposited on copper substrates indicating that ‘templating’ occurs during deposition on both mild steel and copper substrates. A semi-quantitative model based on surface energy and strain energy considerations has been used to explain the texture development. Furthermore, the structures of deposits studied in the present work tended to be fine grained in the initial stages but developed coarser columnar due to selected grain growth with favoured grains becoming broader during the intermediate and final of growth. However, unlike previous work on bcc nickel-zinc alloys⁷ which developed a {111} texture in thicker films the {110} texture remained dominant in the majority of the films examined and the final texture in 20 μm bulk films was a {110}.