Magnetostriction in electroplated CoFe alloys

The phenomenon of magnetostriction can wirelessly couple external magnetic fields to generate structural motion. This is an attractive solution for remote delivery of power to microactuators in constrained environments. This study discusses the magnetostriction of electrosynthesized CoFe thin film microactuators. Electrodeposition is commonly employed for the fabrication of metallic thin films, however the magnetostriction of such films has been rarely investigated. In particular, the magnetostrictive behavior of electroplated CoFe films is poorly understood, despite the high magnetostriction capabilities of CoFe alloys. In this work, uniformly thick and smooth Co_0.65Fe_0.35 thin films were electrochemically grown on commercially available micron-scale cantilevers. The CoFe thin films were characterized for their morphology, composition, crystal structure, and magnetic properties. The AC magnetostrictive response of the cantilevers was measured interferometrically and the actuator exhibited a maximum expected displacement of 86 nm.     

Ag2S/Ag3PO4/Ni复合薄膜的制备及其光催化性能

采用电化学方法制备Ag_2S/Ag_3PO_4/Ni复合薄膜,以扫描电子显微镜(SEM)、X射线衍射(XRD)、紫外-可见漫反射光谱(UVVis DRS)对薄膜的表面形貌、晶相结构、光谱特性及能带结构进行了表征,以罗丹明B为模拟污染物对薄膜的光催化活性和稳定性进行了测定,采用向溶液中加入活性物种捕获剂的方法对薄膜的光催化机理进行了探索。结果表明:最佳工艺制备的Ag_2S/Ag_3PO_4/Ni是由均匀的球形纳米颗粒构成的薄膜,其光催化活性明显优于纯Ag_3PO_4/Ni薄膜和纯Ag_2S/Ni薄膜,且在保持薄膜光催化活性基本不变的前提下可循环使用6次。提出了可见光下Ag_2S/Ag_3PO_4/Ni复合薄膜光催化降解罗丹明B的反应机理。     

Uniaxial magnetization performance of Co-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> nano-composite films electrochemically synthesized from acidic aqueous solution

In this study, Co-Al₂O₃ nano-composite films containing parallel-oriented cobalt nano-cylinders with length-to-diameter aspect ratios of ca. 4000 are synthesized to acquire a uniaxial magnetization property. The Co nano-cylinders were electrodeposited into anodized aluminum oxide films with numerous nano-channels under a low over-potential of less than 0.1 V using an acidic aqueous solution containing CoCl₂ at 75 °C. The long axis of Co nano-cylinders, which are electrodeposited at cathode potential of ?0.58 V vs. Ag/AgCl, coincides with the c axis of hexagonal close packed (hcp)-Co. The Co-Al₂O₃ nano-composite films show a uniaxial magnetization behavior due to the large shape anisotropy of Co nano-cylinders and the large magneto-crystalline anisotropy of the hcp-Co crystal structure. We achieved coercivity and squareness values of up to 2.4 and 1.0 kOe, respectively. This study shows an effective way to produce nano-composite films of altered coercivities.     

Ag2S/Ag3PO4/Ni复合薄膜的制备及其光催化性能

采用电化学方法制备Ag₂S/Ag₃PO₄/Ni复合薄膜,以扫描电子显微镜（SEM）、X射线衍射（XRD）、紫外-可见漫反射光谱（UV-Vis DRS）对薄膜的表面形貌、晶相结构、光谱特性及能带结构进行了表征,以罗丹明B为模拟污染物对薄膜的光催化活性和稳定性进行了测定,采用向溶液中加入活性物种捕获剂的方法对薄膜的光催化机理进行了探索。结果表明：最佳工艺制备的Ag₂S/Ag₃PO₄/Ni是由均匀的球形纳米颗粒构成的薄膜,其光催化活性明显优于纯Ag₃PO₄/Ni薄膜和纯Ag₂S/Ni薄膜,且在保持薄膜光催化活性基本不变的前提下可循环使用6次。提出了可见光下Ag₂S/Ag₃PO₄/Ni复合薄膜光催化降解罗丹明B的反应机理。     

59Co NMR study in Co–Fe alloys/Co magnetite composites

Iron–cobalt compounds containing 20–30 at.% Fe with unusual crystallographic structure have been observed in metal-oxide composite synthesized in an aqueous media at 120–140°C. The oxide is a cobalt-containing magnetite. The metallic component is found in two crystallographic structures depending on the preparation conditions: a b.c.c. (α-Fe) structure and an α-Mn, also called Re₂₄Ti₅, structure (space group I-43m). The α-Mn-like CoFe alloy is encountered for the first time and transforms into the b.c.c. structure during annealing at temperatures as low as 160°C. In the b.c.c. structure itself, the cobalt and iron atoms present a chemical short-range order totally different from the regular B2 phase of the ordered bulk CoFe compound. This particular order is similar to the one encountered in high vacuum co-deposited thin films. For annealing temperatures larger than 400°C, the metallic component loses some Fe and transforms into nearly pure f.c.c. cobalt. This study shows that chemical as well as physical low temperature preparation techniques favor original CoFe ordered phases not achievable by conventional metallurgy.     

Phase structure and morphology of zinc-iron alloy electrodeposits

Zinc-iron alloy electrodeposits are providing higher corrosion resistance to steel components and also having better mechanical properties when compared to zinc deposits. This is due to the unique phase structure of the alloy formed. This study elucidates the phase structure of the electrodeposited alloy, based on the deposition kinetics and morphological characteristics. Deposition of iron was hindered by charge-transfer process, at low current densities. But zinc deposition was prevailed through diffusion control, only at high current densities. The probability of substitution of iron in hcp lattice along c-axis is more, than a-axis. This is because the linear density along c-axis is lower than a-axis. Intermetallic compounds of variable compositions were identified. Compounds such as FeZn₁₆, FeZn₁₃, Fe₅Zn₇₈ have dominantly “η” phase structure and FeZn₆, Fe₅Zn₂₂, Fe₂Zn₇, Fe₅Zn₂₉, Fe₃Zn₁₃ have “Γ” phase structure.     

Precipitation phenomena in FeCl3-NaH2PO2 aqueous solutions at 245°C

Precipitation phenomena in aqueous solutions containing FeCl₃ and NaH₂PO₂ in varying concentrations have been studied at 245 °C. The composition and the morphology of the resulting particles depended strongly on the concentration ratios of the reacting ions. In the presence of small amounts of NaH₂PO₂ only hematite formed of different particle shapes. An increased addition of hypophosphite ions had two effects: first, anions of phosphorus were incorporated in the solids and, second, ferric ions were reduced to ferrous ions giving a variety of products.Supported by the Electric Power Research Institute, Contract RP-966-2.On leave from Yokohama City University, Japan.     

Nanocrystalline structure and soft magnetic properties of nickel–molybdenum alloy thin films electrodeposited from acidic and alkaline aqueous solutions

Nanocrystalline nickel–molybdenum (Ni–Mo) alloy thin films were electrochemically synthesized in acidic and alkaline aqueous solutions. Transmission electron microscope bright-field images and electron diffraction patterns of the electrodeposits made it obvious that pure Ni consists of a submicron crystalline phase with the grain diameter of several hundred nanometers, while Ni–20 %Mo alloy was composed of a nanocrystalline phase with the grain diameter of a few nanometers. It was estimated that the nanocrystalline phase of electrodeposited Ni–Mo alloy thin films was introduced by the formation of supersaturated Ni–Mo solid solution phase with Mo content in the deposit more than 20 %. Submicron crystalline pure Ni thin films were hardly magnetized in perpendicular direction to the film plane while the nanocrystalline Ni–20 %Mo alloy thin films were isotropically magnetized. It was suggested that the isotropical magnetization behavior was caused by decreasing the demagnetizing field and the magneto crystalline anisotropy with a decrease in the magnetic moment and the average crystal grain size. Coercive force of a submicron crystalline pure Ni thin film electrodeposited from an acidic aqueous solution was ca. 100 Oe while that of a nanocrystalline Ni–20 %Mo alloy thin film electrodeposited from an alkaline aqueous solution was only 1～2 Oe. Soft magnetic properties of Ni–Mo alloy thin films electrodeposited from an alkaline aqueous solution were better than that from an acidic aqueous solution and it was improved with an increase in Mo content in the deposit. It was estimated that the electrodeposited Ni–Mo alloy catalysts could be easily recovered with magnetic field less than 1 kOe.     

An EQCM study on the influence of saccharin on the corrosion properties of nanostructured cobalt and cobalt-iron alloy coatings

Nanostructured cobalt (Co) and cobalt-iron (CoFe) alloy coatings were electrodeposited from sulfate solutions in the presence and absence of saccharin. The effects of saccharin on the corrosion behavior of Co and CoFe alloy coatings were investigated using the electrochemical quartz crystal microbalance (EQCM) technique coupled with cyclic voltammetry (CV) measurements. Saccharin was added to the electrolyte as a grain refiner and brightener. Interestingly, opposite corrosion behaviors were found for all nanostructured coatings in 0.1 M H₂SO₄ and 0.1 M NaOH. The use of saccharin as an additive in the plating solution accelerated the anodic reaction for all deposits in acidic medium. The mass decreases while dissolution rate increased with higher saccharin concentration. Meanwhile, formation of a thick passive film on the Co electrode surface were enhanced while a hindering effect was observed for CoFe alloy coatings deposited in the presence of saccharin in alkaline solution. The anodic and cathodic curves obtained from potentiodynamic polarization experiments were also in agreement with the EQCM results.     

Ag3PO4/Ni薄膜的制备及其光催化降解罗丹明B的性能和机理

用电化学方法制备Ag₃PO₄/Ni薄膜,以扫描电子显微镜(SEM)、X射线衍射(XRD)和紫外-可见漫反射光谱(UV-Vis DRS)对薄膜的表面形貌、晶相结构、光谱特性及能带结构进行了表征,以罗丹明B为模拟污染物对薄膜的光催化活性和稳定性进行了测定,采用向溶液中加入活性物种捕获剂的方法对薄膜光催化降解机理进行了探索.结果表明:最佳工艺下制备的Ag₃PO₄/Ni薄膜具有致密的层状表面结构,是由多晶纳米颗粒构成的薄膜.薄膜具有较高的光催化活性和突出的光催化稳定性,可见光下催化作用60 min,薄膜光催化罗丹明B的降解率是多孔P25 TiO₂/ITO纳米薄膜(自制)的2.3倍;在保持薄膜光催化活性基本不变的前提下可循环使用6次.给出了可见光下薄膜光催化降解罗丹明B的反应机理.     

Ag_3PO_4/Ni薄膜的制备及其光催化降解罗丹明B的性能和机理

用电化学方法制备Ag3PO4/Ni薄膜,以扫描电子显微镜(SEM)、X射线衍射(XRD)和紫外-可见漫反射光谱(UV-Vis DRS)对薄膜的表面形貌、晶相结构、光谱特性及能带结构进行了表征,以罗丹明B为模拟污染物对薄膜的光催化活性和稳定性进行了测定,采用向溶液中加入活性物种捕获剂的方法对薄膜光催化降解机理进行了探索。结果表明:最佳工艺下制备的Ag3PO4/Ni薄膜具有致密的层状表面结构,是由多晶纳米颗粒构成的薄膜。薄膜具有较高的光催化活性和突出的光催化稳定性,可见光下催化作用60 min,薄膜光催化罗丹明B的降解率是多孔P25 Ti O2/ITO纳米薄膜(自制)的2.3倍;在保持薄膜光催化活性基本不变的前提下可循环使用6次。给出了可见光下薄膜光催化降解罗丹明B的反应机理。     

Electrochemical preparation of thin rhenium-tellurium coatings from chloride-borate electrolyte

The kinetics and mechanism of cathode electrodeposition of thin Re-Te films from a chloride-borate electrolyte containing NH₄ReO₄, TeO₂, HCl, and H₃BO₃ were studied. The region of potentials in which rhenium is electrodeposited together with tellurium was determined by cyclic voltammetry. The combined electrodeposition of rhenium and tellurium occurred with minor depolarization due to the energy liberated during the formation of the Re-Te alloy.     

Characterization of the Optical and Gas Sensitivities of a Nickel-Doped Lithium Iron Phosphate Thin Film

The influence of heat-treatment temperature on the optical properties (refractive index, transmittance, and attenuation) and gas sensitivities of nickel-doped lithium iron phosphate (LiFe_0.99Ni_0.01PO₄) thin films were discussed. LiFe_0.99Ni_0.01PO₄ was synthesized in one step using hydrothermal methods and fixed to tin-diffused glass as a sensing film by spin-coating before calcination at different temperatures. The obtained thin films were characterized by refractive index, thickness, attenuation, and porosity, as well as gas sensing performances for benzene, toluene, and xylene. The experimental results indicated that the LiFe_0.99Ni_0.01PO₄ thin films dried at 450°C displayed higher refractive indices, good transparency, and less attenuation; thus, the resulting sensor of a LiFe_0.99Ni_0.01PO₄ thin film/tin-diffused optical wave-guide exhibited a greater response to xylene in the concentration range of 0.1–1000?ppm.     

AuPd和AgPd枝晶纳米催化剂催化甲酸分解制氢

由枝晶构成的AuPd和AgPd三维多孔泡沫薄膜在室温下分解甲酸制氢具有高催化活性。该高催化活性是由于纳米枝晶中存在大量的活性位点,如台阶、角、扭结、边缘以及合金间的电子效应。多孔泡沫膜除了具有较高的活性外,还具有其他优良的性能：在不需要有机添加剂的情况下,利用氢气泡模板法在Ti基板上可在5 min内快速沉积多孔泡沫催化剂,无需后处理便可用于催化甲酸分解制氢;通过将电沉积泡沫膜浸入或者拉出HCOOH+HCOONa溶液,可控制氢气的产生或停止;该泡沫催化剂通过去离子水清洗或者在H₂SO₄溶液中进行循环伏安扫描、干燥后就可活化重新使用。     

激光刻蚀模板中电沉积特殊结构CIGS薄膜

本文利用激光刻蚀模板,在水溶液中电沉积制备金属铜薄膜,讨论了温度、电流、硫酸铜浓度对薄膜形貌的影响. 采用SEM对制备的铜薄膜进行表征,结果表明在沉积温度为30 ℃,沉积电流为4 A·dm^-2(表观工作电流密度),硫酸铜浓度在20 ~ 50 g·L^-1的水溶液中电沉积可以得到中空馒头状和开口碗状结构的铜薄膜. 利用激光刻蚀模板,在离子液体1-丁基-3-甲基咪唑三氟甲磺酸盐([BMI][TfO]) - 30 Vol%丙醇混合电解质中电沉积CIGS薄膜,研究了沉积电势、沉积时间对薄膜形貌的影响. SEM观察发现,在沉积电势为-1.8 V,沉积时间为1.5 h条件下电沉积可以得到近似柱状的簇状花束样的CIGS薄膜, 电沉积铜后再进一步电沉积CIGS,得到了均匀有序的鼓包柱状结构的Cu/CIGS复合薄膜. 用恒电势方波法对制备的薄膜真实表面积进行测试,计算结果表明,与无模板电沉积制备的CIGS薄膜相比,激光刻蚀模板法制备的Cu/CIGS复合薄膜的表面积提高了约8倍.     

Porous cobalt hydroxide film electrodeposited on nickel foam with excellent electrochemical capacitive behavior

A new porous cobalt hydroxide film has been successfully electrodeposited on nickel foam from 0.1?M cobalt nitrate electrolyte at ?1.0?V vs. SCE without adding any surfactant. The microstructure and surface morphology of prepared cobalt hydroxide films were physically characterized by X-ray diffraction analysis and scanning electron microscopy. The results indicate that an interlaced network structure was obtained. The effects of electrodeposition time, deposition potential, and different substrates on the specific capacitance and microstructure of prepared porous ??-Co(OH)₂ thin film were systematically studied. The results indicate that the film deposited on nickel foam at ?1.0?V has excellent electrochemical properties. A maximum specific capacitance of 1473?F?g^?1 could be achieved at a current density of 2?A?g^?1.     

可见光高催化活性GO/Ag3PO4/Ni复合薄膜的制备和性能

以磷酸铵和氧化石墨烯悬浊液的混合液为电解液,采用电化学共沉积法制备了Ag3PO4基GO/Ag3PO4/Ni复合薄膜。运用扫描电子显微镜(SEM)、能量色散谱(EDS)、X射线衍射(XRD)、拉曼光谱(Raman)和紫外可见漫反射光谱(UV-Vis DRS)等对其形貌、物相和光谱特性进行分析。最佳工艺制备的GO/Ag3PO4/Ni复合薄膜呈现出GO包覆在直径为100 nm左右的Ag3PO4纳米球外的表面形貌。GO片与Ag3PO4纳米球之间存在强电荷相互作用。与单独的Ag3PO4纳米球相比,GO片的附着导致带隙缩小,可见光区的吸收率增强。可见光下考察了复合薄膜降解罗丹明B的光催化活性和稳定性,并利用荧光光谱和捕获剂法对薄膜的光催化机理进行了探索。结果表明,GO片的加入不仅显著提高了Ag3PO4的光催化活性,而且提高了Ag3PO4的结构稳定性。光催化降解罗丹明B 60 min时,GO/Ag3PO4/Ni复合薄膜的降解率是Ag3PO4/Ni薄膜的1.32倍。在保持薄膜光催化活性基本不变的前提下可循环使用7次。GO优异的电荷传导性能,以及Ag3PO4纳米球与GO片之间的正协同效应是提高复合薄膜光催化性能的主要原因。     

Modelling the formation and growth of anodic passive films on metals in concentrated acid solutions

Two model approaches to the formation of passive films as adsorbed layers during the active anodic dissolution of a metal in acid and their subsequent growth are presented. The first depicts passivation as proceeding in parallel to active dissolution. Adsorption of water on active surface sites leads to passivation, whereas adsorption of acid leads to active dissolution of the metal. The model is consistent with the impedance response during passivation of Fe and an Fe-20%Mo alloy in concentrated H₃PO₄. The second model is an updated version of the so-called surface charge approach to the mechanism of conduction of anodic passive films. It is based on the assumptions that oxygen vacancies are the main ionic charge carriers and the field strength in the barrier layer is constant. A negative surface charge built up at the film/solution interface via accumulation of metal vacancies accelerates oxygen vacancy transport, thus explaining the pseudoinductive behaviour of the metal/film/electrolyte system under small amplitude a.c. perturbation. The model describes the growth of thin anodic films on Fe, Mo and an Fe-20%Mo alloy in concentrated H₃PO₄. Received: 24 January 1997 / Accepted: 18 April 1997     

Surface characteristics of anodic oxide films fabricated in acid and neutral electrolytes on Ti–10V–2Fe–3Al alloy

Anodic oxide films were fabricated on Ti–10V–2Fe–3Al alloy in acid (H₂SO₄/H₃PO₄) and neutral environmental friendly (C₄H₄O₆Na₂) electrolytes. The morphology, roughness, crystalline structure of the anodic oxide film were characterized by using scanning electron microscopy, atomic force microscopy, Raman spectroscopy and electrochemical impedance spectroscopy (EIS). The results showed that the oxide film fabricated in H₂SO₄/H₃PO₄ electrolyte had a porous structure and the thickness of the film was 3.5 µm. The oxide film fabricated in C₄H₄O₆Na₂ electrolyte presented a nonporous structure that sustained the evident microstructure of the substrate, and the thickness of the film was 6.0 µm. The surface average roughness values of the two types of films were 245 nm and 166 nm, respectively. The phase of the anodic oxide films consisted mainly of anatase and rutile. EIS results showed that the film fabricated in C₄H₄O₆Na₂ electrolyte had higher impedance of the outer layer, while the film fabricated in H₂SO₄/H₃PO₄ electrolyte had higher impedance of the inner layer. Moreover, we attempt to explain the differences in the anodizing kinetics, structure and electrochemical impedance of anodic oxide films by the different films growth processes in the two types of electrolytes. Copyright © 2012 John Wiley & Sons, Ltd.     

纯相Li2MnO3薄膜的制备及作为锂离子电池正极材料的电化学行为

采用固相烧结法制备了纯相Li₂MnO₃正极材料及靶材,采用脉冲激光沉积（PLD）法在氧气气氛、不同温度下沉积了Li₂MnO₃薄膜. 通过X射线衍射（XRD）和拉曼（Raman）光谱表征了薄膜的晶体结构,采用扫描电镜（SEM）观察薄膜形貌及厚度,利用电化学手段测试了Li₂MnO₃薄膜作为锂离子电池正极材料性能. 结果表明,PLD 方法制备的纯相Li₂MnO₃薄膜随着沉积温度升高薄膜结晶性变好. 25 ℃沉积的薄膜难以可逆充放电,400 ℃沉积的薄膜具有较高的电化学活性和循环稳定性. 相对于粉末材料,400与600 ℃制备的Li₂MnO₃薄膜电极平均放电电位随着循环次数的衰减速率明显低于相应的粉体材料.