Zn0.95Co0.05O纳米线和纳米管的电泳沉积法可控合成（英文）

以阳极氧化铝为模板通过电泳沉积法制备Zn0.95Co0.05O纳米线和纳米管,并对电泳沉积法制备纳米线(管)的机理进行研究。系统的结构表征表明所得的纳米管和纳米线是由8～15nm的纤锌矿纳米晶构成的多晶结构,Co2+离子以代位掺杂形式掺入晶格,取代了晶格中的Zn2+离子。磁性表征显示制备的纳米线和纳米管具有室温铁磁性。由于Co在纳米线(管)中表面择优分布,纳米管的磁性明显高于纳米线。     

Magnetic properties improvement through off time between pulses and annealing in pulse electrodeposited CoZn nanowires

CoZn alloy nanowire arrays embedded in anodic aluminum oxide (AAO) template were fabricated by alternative current (ac) pulse electrodeposition. Various off times between pulses in an electrolyte with constant concentration of Co⁺² and Zn⁺² and acidity of 4 were employed. The effect of deposition parameters on the alloy contents, microstructures and magnetic properties of Co_xZn_1−x nanowires were studied. It is shown that, Co content increased by increasing the off time between pulses. This phenomenon enables us to fabricate Zn and Co-rich nanowires by adjusting the off time during the deposition procedure. Increasing the off time more than 200 ms increased the coercivity and squareness of CoZn nanowire arrays. A significant increase in the coercivity of CoZn nanowires was observed after annealing which was varied for the samples fabricated with different electrodeposition conditions. A coercivity of 1785 Oe was obtained for the annealed sample (a sample fabricated with 50 ms off time) from initially 240 Oe.     

Synthesis and characterization of MWCNTs/Co1−xZnxFe2O4 magnetic nanocomposites and their use in hydrogels

A novel magnetic nanocomposite of multiwalled carbon nanotubes (MWCNTs) decorated with Co_1−xZn_xFe₂O₄ nanocrystals was synthesized successfully by an effective solvothermal method. The as-prepared MWCNTs/Co_1−xZn_xFe₂O₄ magnetic nanocomposite was used for the functionalization of P/H hydrogels as a prototype of device to show the potential application of the nanocomposites. The nanocomposites were characterized by X-ray diffraction analysis, transmission electron microscopy and vibrating sample magnetometer. The results show that the saturation magnetization of the MWCNTs/Co_1−xZn_xFe₂O₄ magnetic nanocomposites increases with x when the Zn²⁺ content is less than 0.5, but decreases rapidly when the Zn²⁺ content is more than 0.5. The saturation magnetization as a function of Zn²⁺ substitution reaches a maximum value of 57.5 emu g⁻¹ for x = 0.5. The probable synthesis mechanism of these nanocomposites was described based on the experimental results.     

The local structure of Co-doped ZnO films studied by X-ray absorption spectroscopy

The Zn_0.95Co_0.05O films were deposited under different oxygen partial pressure (P_O2) by inductively coupled plasma enhanced physical vapor deposition. The effect of P_O2 on the local structure of Zn_0.95Co_0.05O films was investigated by X-ray absorption spectroscopy (XAS) at Co K-edge and L-edge. The Co L-edge XAS spectra show the spin-orbit splitting and typical shake-up satellites of the Co²⁺ ionization states. The XAS spectra at the Co K-edge indicate that Co ions substitute for Zn²⁺ sites in the tetrahedral configuration without changing the wurtzite structure. The qualitative analyses of X-ray absorption near edge structure (XANES) reveal that the main defects are oxygen vacancies when Zn_0.95Co_0.05O films were deposited under very low P_O2. The extended X-ray absorption fine structure (EXAFS) analyses provide no significant bond length deviation from the pure ZnO structure. The coordination number varies slightly with different samples. The correlation between the coordination number and the pseudo Debye–Waller factor implies that the disorder is increased in samples prepared under low P_O2.     

Ni（OH）2 particles synthesized by high energy ball milling

1 Introduction Ni(OH)2/NiOOH has been used as positive materials in alkaline secondary batteries for more than 100 years[1- 3]. The performance improvement of Ni(OH)2/NiOOH electrode is crucial for the application of these batteries as they are all positi…     

Template-based,near-ambient synthesis of crystalline metal-oxide nanotubes,nanowires and coaxial nanotubes

In response to a growing need for metal-oxide nanotubes and nanowires for nanoelectronic applications and size-effect studies, crystalline nanotubes and nanowires in a range of metal oxides have been synthesized at near-ambient conditions and without the application of heat treatments, pressure or an external electric field. Specifically, the mechanisms of formation of crystalline TiO₂ nanotubes and nanowires from flourine-based liquid precursors inside anodic aluminum oxide templates have been elucidated. This method can be extended to synthesizing nanotubes/nanowires of other crystalline metal oxides, such as ZrO₂, SnO₂ and FeOOH. Using sequential deposition, TiO₂/ZrO₂ coaxial nanotubes have been synthesized. In principle, the methods outlined here could be used to fabricate crystalline nanotubes and nanowires of tailored dimensions in other metal oxides. The ability to synthesize, at near-ambient conditions, crystalline metal-oxide nanotubes and nanowires of tailored geometries represents a clear advantage in terms of minimal equipment requirements, low cost and possible incorporation of biomolecules and temperature-sensitive moieties.     

Ni2+和Co2+复配（MoO2-4+Zn2+）对A20碳钢的缓蚀率研究

    用静态失重法研究了在标准配制水中Ni²⁺和Co²⁺复配（MoO^2-₄+Zn²⁺）对A20碳钢的缓蚀行为.结果表明,Langelier饱和指数（LSI）、MoO^2-₄浓度、Ni²⁺和Co²⁺浓度对缓蚀率的影响程度依次为：LSI>MoO^2-₄≈Co²⁺>LSI与MoO^2-₄的交互作用;Ni²⁺对提高缓蚀率几乎无贡献.     

Fabrication of Co-doped ZnO nanorods for spintronic devices

Herein, single-crystalline Zn_1?xCo_xO (0.0≤x≤0.10) nanorods were prepared using a facile microwave irradiation method. Structural analyses by X-ray diffraction and transmission electron microscopy revealed the incorporation of Co²⁺ in the lattice position of Zn²⁺ ions into the ZnO matrix. Field emission scanning electron microscopy and TEM micrographs revealed that the length and diameter of the undoped ZnO nanorods were about ～2 μm and ～200 nm, respectively. For Co-doped ZnO, the length and diameter were found to increase with an increase of Co doping. The selected area electron diffraction pattern indicated that the Zn_1?xCo_xO (0.0≤x≤0.10) nanorods had a single phase nature with the preferential growth direction along the [0 0 1] plane. Raman scattering spectra confirmed the shift of the E ₂ ^high mode toward a lower wave number, suggested successful doping of Co ions at Zn site into the ZnO. Magnetic studies showed that Co doped ZnO nanorods exhibited room temperature ferromagnetism and the magnetization value increased with an increase in Co doping. The synthesis method presented here is a simple approach to prepare ZnO based diluted magnetic semiconductors nanostructures for practical application to spintronic devices.     

Synthesis and characterization of Eu3+ doped Gd2O3 nanotubes using multi wall carbon nanotubes as removable templates

Eu³⁺ doped Gd₂O₃ nanotubes have been synthesized using multi wall carbon nanotubes as removable templates by employing a liquid phase deposition method. The prepared Eu³⁺ doped Gd₂O₃ nanotubes were characterized by means of x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy, fourier transform infrared sepctroscopy and thermogravimetry and differential thermal analysis. XRD patterns conrm the cubic phase of Eu³⁺ doped Gd₂O₃ nanotubes. From the measured SEM images, the average diameter of the Eu³⁺: Gd₂O₃ nanotubes were estimated to be in the range of 50–70 nm. The photoluminescence analysis revealed that the Eu³⁺: Gd₂O₃ nanotubes can display a strong red emission peak at around 616 nm, due to the ⁵D₀→⁷F₂ electric dipole transition of Eu³⁺ ions. Such luminescent powders are expected to find potential applications in fluorescent lamps and display device applications.     

Synthesis, structure and optical properties of CoAl2O4 spinel nanocrystals

CoAl₂O₄ nanocrystals were synthesized by sol-gel method using citric acid as a chelating agent at low temperature. The as-synthesized samples were characterized by thermal analysis, X-ray powder diffraction, infrared spectroscopy and transmission electron microscopy. The results show that CoAl₂O₄ spinel is the only crystalline phase with a size of 10-30 nm in the temperature range 500-1000 °C. The temperature dependence of the distribution of Al³⁺ and Co²⁺ ions in the octahedral and tetrahedral sites in nanocrystals was investigated by X-ray photoelectron spectroscopy (XPS). It is observed that the inversion parameter decreases with increasing annealing temperature. Analysis of the absorption properties indicates that Co²⁺ ions are located in the tetrahedral sites as well as in the octahedral sites in the CoAl₂O₄ nanocrystals. The origin of the green color (300-500 nm absorption band) should be due to the octahedrally coordinated Co²⁺ ions.     

Inhibitory effects of manganeous,cadmium and zinc ions on hydrogen evolution reaction and corrosion of iron in sulphuric acid solutions

The presence of metal ions (Cd²⁺, Mn²⁺, Zn²⁺), more electronegative than the cathodic potential for the hydrogen evolution reaction on iron in a 0.25M H₂SO₄ solution, inhibits the hydrogen evolution reaction and corrosion of iron. This effect has been explained as the under-potential deposition of the adatoms of these metals on iron.     

花球状Mg(OH)2的制备及其对重金属离子的快速高效去除(英文)

由MgSO₄废液制备球形花状Mg(OH)₂,并评估其对重金属离子的吸附性能。合适的制备条件为Mg²⁺浓度2 mol/L、Mg²⁺/NH₄OH摩尔比1:0.5、温度120℃和时间1h。由超薄片组成的球形花状Mg(OH)2对重金属离子具有良好的吸附能力,6min即可达到吸附平衡。20℃时Mg(OH)₂对Ni²⁺、Cu²⁺、Zn²⁺、Pb²⁺、Fe³⁺和Co²⁺的最大吸附量分别为58.55、85.84、44.94、485.44、625.00和27.86 mg/g。吸附过程符合Langmuir模型,为单分子层吸附。吸附动力学符合准二级动力学模型,化学吸附是其作用机制。球形花状Mg(OH)₂是合格的重金属离子吸附材料。     

Distinctions between the Activating Effects of Sulfuric and Phosphoric Acids on the Process of Zinc Chromating

Activating effect of anions of sulfuric and phosphoric acids (both in the range from 0.025 to 0.200 mol/l) on the process of zinc chromating in acid (pH 1.1) 0.2 M CrO₃ solution is studied by analytical methods. A general balance of oxidized zinc (Zn²⁺) and reduced chromium (Cr³⁺) and their distribution between the solution and chromate film for different solution compositions, as well as the elemental composition throughout the film's depth, are determined. It is found that the zinc oxidation and Cr⁶⁺ reduction reactions do not proceed in the absence of SO^2– ₄ ions (that is, when only PO^3– ₄ ions are present), so that the chromate film cannot form. However, the PO^3– ₄ ions combined with SO^2– ₄ ions increase the Zn²⁺ and Cr³⁺ ions concentration in the solution significantly, while their concentrations in the film correspondingly decrease. SO^2– ₄ ions activate the zinc surface because they form soluble complex compounds with Zn²⁺ and Cr³⁺ ions and increase the part of the surface, on which the cathodic reduction of Cr⁶⁺ to Cr³⁺ occurs. The activating action of phosphoric acid is caused by the increase in the total (analytical) concentration of H⁺ ion in the solution; hence, the deposition of the Cr³⁺ and Zn²⁺ hydroxide compounds onto zinc is retarded, due to the increased near-surface concentration of H⁺ ion.     

Synergistic corrosion inhibition study of Armco iron in sodium chloride by piperidin-1-yl-phosphonic acid-Zn system

Electrochemical techniques, weight loss method and surface analysis were used to study the synergistic inhibition offered by Zn²⁺ and piperidin-1-yl-phosphonic acid (PPA) to the corrosion of Armco iron in 3% chloride solution. It is observed that the combination between PPA and Zn²⁺ shows excellent inhibition efficiency. The potentiodynamic polarization curves reveal that 5 × 10⁻³ mol l⁻¹ of PPA has only 76.7% inhibition efficiency whereas the mixture containing 5 × 10⁻³ mol l⁻¹ PPA -20%Zn²⁺ has 90.2% inhibition efficiency. This suggests that a synergistic effect exists between Zn²⁺ and PPA. The Fourier transform infrared (FTIR) spectrum of the film formed on iron indicates phosphonates zinc salt formation. A suitable mechanism of corrosion inhibition is proposed based on the results obtained. The surface film analysis showed that in the absence of Zn²⁺, the protective film consists of Fe²⁺-PPA complex formed on the anodic sites of the metal surface, whereas in the presence of Zn²⁺, the protective film consists of Fe²⁺-PPA complex and Zn(OH)₂.     

Investigation on the synthesis and quantum confinement effects of pure and Mn added Zn(1−x)CdxS nanocrystals

Zn_(1−x)Cd_xS and Zn_(1−x)Cd_xS:Mn²⁺ semiconductor quantum dots (2-4 nm) have been prepared by a novel solvothermal route assisted microwave heating method. The growth parameters governing the smaller size and higher yield have been optimized. The synthesized QDs exhibit a significant blue shift as compared to their corresponding bulk counterpart in the UV-vis optical absorption spectrum. The dielectric constant value varies from 2.79 to 6.17 (at 40 °C, 1 kHz) depending upon the composition of the alloy; lower value corresponds to Zn_0.75Cd_0.25S:Mn²⁺ and the higher value corresponds to Zn_0.25Cd_0.75S:Mn²⁺. The crystallite size to exciton bohr radius ratio being <1 indicates a strong quantum confinement effect in both CdS and ZnS QDs. The quantum confinement effect exists in the sequence of ZnS:Mn²⁺ < Zn_(1−x)Cd_xS:Mn²⁺ (x < 0.5) < ZnS < Zn_(1−x)Cd_xS < CdS < CdS:Mn²⁺.     

Studies on the magnetic, magnetostrictive and electrical properties of sol-gel synthesized Zn doped nickel ferrite

Zinc doped nickel ferrite i.e., Ni_1−xZn_xFe₂O₄ (0 ≤ x ≤ 0.6) have been prepared by using sol-gel method. X-ray diffraction of these samples shows the presence of single-phase cubic spinel structure. The room temperature magnetic measurements showed that saturation magnetization (M_s) increases with the substitution of Zn²⁺ ions up to x = 0.4 and thereafter it begins to decrease, whereas magnetostriction (λ) value decreases with the addition of Zn²⁺ in the Ni-Zn ferrite. Dielectric permittivity (?′), dielectric loss tangent (tan δ) and AC conductivity (σ_AC) for all the prepared samples have been studied as a function of frequency and composition in the range from 0.05 Hz to 10 MHz at room temperature. It has been observed that initially ?′, tan δ and σ_AC decreases with the substitution of Zn²⁺ up to x = 0.4 and then increases with the further addition of Zn²⁺ ions. Variation in the slope parameter s with zinc contents indicates the presence of different type of conduction mechanism in different compositions. The dielectric loss curves exhibit relaxation peaks which shift with the addition of Zn contents. The results have been explained on the basis of space charge polarization according to Maxwell-Wagner's two-layer model and the hopping of charges between Fe²⁺ and Fe³⁺ as well as between Ni³⁺ and Ni²⁺ ions at the octahedral sites.     

MoO42-与 Zn2+对镁合金在 NaCl 溶液中的协同缓蚀作用

采用动电位极化曲线法,结合腐蚀后的表面微观形貌及EDS能谱分析,研究了MoO42-与Zn2+对AZ31镁合金在3.5%NaCl溶液中的协同缓蚀性能。结果表明:0.005 mol/L Zn2+与0.05 mol/L钼酸钠联合作用,可有效抑制镁合金在NaCl溶液中的腐蚀,Zn2+促进MoO42-在合金表面的吸附,缓蚀效果优于单一的钼酸盐缓蚀剂。缓蚀机制是:钼酸盐与Zn2+协同作用,使镁合金表面形成更为致密的钝化膜,从而抑制镁合金的腐蚀。     

PMMA/Zn2SiO4:Eu3+(Mn2+) Composites: Preparation, Optical, and Thermal Properties

Luminescent composites of poly(methylmethacrylate) (PMMA) and nanophosphors (Zn₂SiO₄:Mn²⁺, Zn₂SiO₄:Eu³⁺) were prepared by dispersion casting method. It was found that nanoparticles embedded in PMMA matrix preserve their typical phosphorescence emission. The influence of Zn₂SiO₄ nanofillers on thermal properties of PMMA was also investigated. A shift towards higher glass transition temperatures and slight improvements in thermal stability of the nanocomposites compared to pure PMMA were observed and are discussed herein.     

Electrochemical deposition of aluminum on W electrode from AlCl_3-NaCl melts

Electrochemical deposition of aluminum on W electrode from AlCl3-NaCl melts was studied by cyclic voltammetry and chronopotentiometry. The results show that Al ( Ⅲ) is reduced in two consecutive steps, i.e., 4Al2Cl7-+3e-→Al+7AlCl4- and then AlCl4-+3e-→Al+4Cl-. The electrochemical reaction of 4Al2Cl7-+3e-→Al+7AlCl4- is reversible. Certain nucleation overpotential is required during the deposition of aluminum on W electrode. Chronopotentiometry analysis also shows that Al (Ⅲ ) is reduced in two consecutive steps under certain current density, which is in reasonable agreement with cyclic voltammograms. By using constant current deposition, the electrodeposits on Al substrate obtained at between 50 and 100 mA/cm2 are quite dense and well adherent to the Al substrate. The electrochemical deposition of aluminum on Cu substrate in AlCl3-NaCl melts indicates that the intermetallic compounds are formed. The intermetallic compounds are AlCu and Al2Cu.     

Synergistic corrosion inhibition by the sodium dodecylsulphate-Zn system

The inhibition efficiency (IE) of sodium dodecylsulphate (SDS) in controlling corrosion of carbon steel immersed in the environment containing 60 ppm of Cl⁻, in the absence and presence of Zn²⁺ has been evaluated by weight-loss method. It is observed that SDS and Zn²⁺ individually are not good inhibitors. But their combination shows excellent IE. For example, 100 ppm of SDS has only 10% inhibition efficiency whereas 75 ppm of Zn²⁺ has 45% IE. Interestingly their combination shows 93% IE. This suggests that a synergistic effect exits between Zn²⁺ and SDS. The influence of pH on the IE of the SDS-Zn²⁺ system has been evaluated. The protective film has been analysed by Fourier transform infrared (FTIR) and fluorescence spectra. A suitable mechanism of corrosion inhibition is proposed based on the results obtained from weight-loss method, and FTIR and fluorescence spectra. It is found that in the absence of Zn²⁺, the protective film consists of Fe²⁺-SDS complex formed on the anodic sites of the metal surface. In the presence of Zn²⁺, the protective film consists of Fe²⁺-SDS complex and Zn(OH)₂. The protective film is found to be UV-fluorescent.