主盐浓度和工艺条件对Sn-Ag-Cu合金镀层组成和形貌的影响

在弱酸性镀液中电沉积得到无铅Sn-Ag-Cu可焊性合金镀层。采用X射线荧光光谱仪(XRF)和扫描电子显微镜(SEM)研究了镀液中主盐浓度和电镀工艺条件对镀层的组成和形貌的影响。研究表明,Sn-Ag-Cu合金的电沉积是正则共沉积。镀液中Sn²⁺和Ag⁺浓度改变对镀层晶粒大小影响较大,Cu²⁺浓度的改变对镀层的平整度影响较大。电流密度增加、pH值下降、温度降低,都能使镀层结晶细致。     

Electrodeposition of silicon from three different ionic liquids: possible influence of the anion on the deposition process

The electrodeposition of silicon was investigated from three different ionic liquids with the cation 1-butyl-1-methylpyrrolidinium ([Py_1,4]⁺) and three different anions, namely, trifluoromethylsulfonate (TfO^?), bis(trifluoromethylsulfonyl)amide (TFSA^?) and tris(pentafluoroethyl)-trifluorophosphate (FAP^?) at room temperature and at 100 °C, respectively. The electrodeposition was performed on gold and on copper substrates. Cyclic voltammetry was used to evaluate the possible influence of anions on the deposition process. In situ STM studies were also carried out to examine the interfacial behaviour of the SiCl₄/[Py_1,4]TFSA and SiCl₄/[Py_1,4]FAP on Au(111) at room temperature. In situ STM measurements revealed that an underpotential deposition of Si in [Py_1,4]FAP occurred on Au (111) at ~ -0.5 V (vs. Fc/Fc⁺). In comparison, only adsorption of ionic liquid and gold surface reconstruction was found to occur in the potential regime between -0.3 and ?1.8 V (vs. Fc/Fc⁺), respectively, in the case of [Py_1,4]TFSA. In situ STM investigations reveal an effect of the anion on the interfacial processes. In situ I/U tunnelling spectroscopy shows that the band gap of the electrodeposits is ~1.1 eV, indicating that semiconducting silicon has been electrodeposited. Potentiostatic electrolysis was performed to deposit Si from the employed electrolytes at room temperature and at 100 °C. The deposits were characterised using scanning electron microscopy and X-ray diffraction. Thin films of Si could be obtained from the employed ionic liquids and the quality of the deposits was significantly improved at 100 °C.     

Radium isotope determination by alpha-spectrometry after electrodeposition from solution with added platinum

A method for measuring radium activity using electrodeposition onto stainless steel from solutions to which platinum ions have been added was developed. This gave high recovery with reduced electroplating times, and yielded deposits giving alpha-spectra of high resolution. Retention of the decay products in the deposit allows inference of some Ra isotopes from measurement of the activities of the high energy Po daughters. Application of the method to determination of²²⁶Ra in a marine manganese deposit is described.     

Isotopic concentration of uranium from alpha spectrum of electrodeposited source on 4H-SiC detector at 500 °C

4H-SiC alpha detectors were fabricated with a 21-μm thick depletion depth and were packaged into a stainless-steel casing with a mineral insulation cable and a standard BNC connector. The packaged detectors had a resolution of 0.624% FWHM at 5.486 MeV prior to salt immersion. The detectors were then immersed in a LiCl–KCl–UCl₃ molten salt at 500 °C, from which a thin layer of depleted uranium was electrodeposited onto the detectors. Alpha particle emission spectra were collected from the electrodeposited source. The energy resolution of the surviving detector was 2.29% FWHM at 4.198 MeV and was sufficient to separate the ²³⁴U from ²³⁸U alpha emissions (577 keV difference). The ²³⁴U/²³⁸U activity ratio and the isotopic concentrations of ²³⁴U and ²³⁸U were determined and are representative of the uranium source used in the electrodeposition.

     

Experimental comparison of the relative yield of 3γ/2γ positron annihilation using semiconductor and scintillation detectors

The yield of three photon positron annihilation is measured using semiconductor and scintillation detectors in a comparison for applications in positron emission tomography, particularly in the exploitation of three photon positron annihilation imaging where good energy resolution and good efficiency are required. In this experimental study four detectors, High-purity Germanium (HPGe), Sodium Iodide (NaI(Tl)), Lanthanum Chloride (LaCl₃:10%Ce³⁺) and Lanthanum Bromide (LaBr₃:5%Ce³⁺) were used. The peak-to-peak method was used with a ²²Na source to determine these yields. Aluminium was employed as a reference material as its high electron density reduces positronium formation and lifetimes. Teflon was also used in order to enhance the formation of ortho-positronium, since quenching is low, leading to increased three photon positron annihilation. The relative 3γ/2γ yields obtained were (3.04±0.11)·10⁻², (2.17±0.11)·10⁻², (3.26±0.10)·10⁻² and (2.03±0.11)·10⁻² for LaBr₃:Ce, LaCl₃:Ce, NaI(Tl) and HPGe detectors, respectively. Among these detectors LaBr₃:Ce proved to be the detector of choice for three photon imaging applications as it has both good energy resolution and efficiency.     

Mössbauer and XRD investigation of electrodeposited Fe,Co and Fe-Co alloys using a gluconate plating process

Summary A fundamental requirement for electrodeposition systems of the 21st century is that the processes involved should be environmentally safe, as well as they should be suited to replace hazardous conventional processes thereby supporting global sustainability. Conventional plating baths contain hazardous components and facilitate the generation of non-desirable compounds. The subject of the present article is the electrodeposition of Fe, Co, and Fe-Co alloys from an electrolyte based on gluconate. Preliminary studies showed that good quality iron-cobalt alloy coatings could be obtained on copper substrates from an environmentally acceptable gluconate plating system. The gluconate bath is inexpensive, non-toxic and easily disposed of. We report the successful deposition of Fe, Co and Fe-Co alloys from a modified gluconate based electrolyte which has not been used previously to deposit these materials. The effect of process parameters, such as current density, pH and deposition time were investigated using the gluconate electrolyte at a temperature of 60 °C and a pH of 7. The phase composition, crystal structure and magnetic anisotropy of the obtained alloy deposits are correlated with the applied process parameters. The structural analysis of the deposits is mainly based on ⁵⁷Fe CEMS and XRD measurements. α-Fe and Co-Fe were identified as dominant phases in Fe and Co/Fe deposits, respectively. The magnetic anisotropy of the Fe-containing deposits was found to correlate with the current density applied during deposition. The time of electrodeposition, at the same time, had little if any effect on the magnetic anisotropy of the obtained deposits. The mechanism and formation of the electrodeposits are discussed on the basis of the obtained results.     

Catalytic reduction of nitrate during electrodeposition of thallium from Tl3+ solution

The voltammetric response of vitreous carbon electrodes in nitrate solution in the presence of Tl³⁺ shows the reduction of Tl³⁺ in two stages, to Tl⁺ and to metallic thallium, respectively. Nitrate ions are reduced at high rates during the second stage, concurrently with Tl deposition. The catalytic current varies with the concentration of nitrate, but is virtually independent of the Tl³⁺ concentration. No nitrate reduction occurred when Tl deposition was carried out in a single stage from Tl⁺ solution, nor during reduction of Tl³⁺ to Tl⁺. The results obtained indicate that Tl²⁺, arising from disproportionation of Tl³⁺ and Tl⁰ to yield Tl⁺, mediates the catalytic reduction of nitrate to ammonia during Tl electrodeposition from Tl³⁺ solutions.     

Alpha spectrometry and secondary ion mass spectrometry of electrodeposited uranium films

Electrodeposited natural uranium films prepared by electrodeposition from solution of uranyl nitrate UO₂(NO₃)₂·6H₂O on stainless steel discs in electrodeposition cell. Solutions of NaHSO₄, and Na₂SO₄ and electric current from 0.50 up to 0.75 A were used in this study. Recalculated weights and surface’s weights of ²³⁸U from the alpha activities and secondary ion mass spectrometry (SIMS) intensities resulted in a linear regression. A dependency between of ²³⁸U surface’s weights recalculated from alpha activities and signal intensity of ²³⁸U in SIMS was investigated in order to determine a potential of SIMS in quantitative analysis of surface samples containing uranium. In the SIMS spectra of electrodeposited uranium films we found that upper layer consist not only from isotopes of uranium (ions ²³⁴U⁺, ²³⁵U⁺, and ²³⁸U⁺). In the positive polarity SIMS spectra, various molecules ions of uranium were suggested as UH⁺, UH₂ ⁺, UO⁺, UOH⁺, UO₂ ⁺, UO₂H⁺, UO₂H₂ ⁺, as well as possibly ions UNO⁺ and UNOH⁺.     

Electrodeposition and Magnetic Characterization of Iron and Iron–Silicon Alloys from the Ionic Liquid 1‐Butyl‐1‐methylpyrrolidinium Trifluoromethylsulfonate

The electrodeposition of soft magnetic iron and iron–silicon alloys for magnetic measurements is presented. The preparation of these materials in 1‐butyl‐1‐methylpyrrolidinium trifluoromethylsulfonate, [Py_1,4]TfO, at 100 °C with FeCl₂ and FeCl₂+SiCl₄ was studied by using cyclic voltammetry. Constant‐potential electrolysis was carried out to deposit either Fe or FeSi, and deposits of approximately 10 μm thicknesses were obtained. By using scanning electron microscopy and X‐ray diffraction, the microstructure and crystallinity of the deposits were investigated. Grain sizes in the nanometer regime (50–80 nm) were found and the presence of iron–silicon alloys was verified. Frequency‐dependent magnetic polarizations, coercive forces, and power losses of some deposits were determined by using a digital hysteresis recorder. Corresponding to the small grain sizes, the coercive forces are around 950–1150 A m^?1 and the power losses were at 6000 J m^?3, which is much higher than in commercial Fe(3.2 wt %)Si electrical steel. Below a polarization of 1.8 T, the power losses are mainly caused by domain wall movements and, above 1.8 T, by rotation of magnetic moments as well as domain wall annihilation and recreation.     

Catalytic formation of hydrogen in electrolysis of chromium(II) chloride

It was determined that in the electrolysis of chromium(II) chloride the electrodeposits containing chromium and chromium(II) oxide which are formed on the cathode surface accelerate catalytically the reaction Cr²⁺+H⁺ Cr³⁺+1/2 H₂. As a result of superposition of the chemical reaction on the electrochemical process the absolute hydrogen yield in the electrolysis reaches 3500–4500%.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 23, No. 1, pp. 111–113, January–February, 1987.     

A high resolution 4π alpha spectrometer with silicon surface barrier detectors

An alpha counting system has been designed which gives counting geometry of nearly 4π with resolution capabilities of 25 keV or better. The alpha source is electro-deposited onto a thin gold foil which is sandwiched between two silicon surface barrier detectors. Alpha pulses from the two detectors are amplified, normalized and summed as a single pulse height spectrum. The techniques for the electrodeposition of the alpha activity onto the thin gold foil are described.     

Valence electronic states of NH2+ and PH2+ dications

The ab initio second-order effective valence-shell Hamiltonian that is based on the multireference many-body perturbation theory has been applied to determine adiabatic potential energy curves for the valence states of NH²⁺ and PH²⁺ dications. For PH²⁺, three low-lying quasi-bound states (X¹∑⁺, a³ Π, A¹Π) are found and their spectroscopic constants are characterized. In NH²⁺, no quasi-bound states are found. The potential energy curves for NH²⁺ are compared with those for PH²⁺ to understand the difference between these two valence isoelectronic cations. © 1993 John Wiley & Sons, Inc.     

Zinc-cobalt alloy: electrodeposition and characterization

Zinc-cobalt alloy electrodeposits offer enhanced corrosion protection to steel, compared to zinc deposits. A near neutral zinc-cobalt alloy sulfate bath was developed. In the absence of β-naphthol and sodium lauryl sulfate (SLS), only a light grey and non-uniform deposit was obtained. Addition of boric acid yielded a grey and uniform deposit. To obtain the grey uniform alloy deposit, the optimum bath composition was: 0.5 M ZnSO₄, 0.5 M CoSO₄, 40 g/L H₃BO₃, 0.865 g/L SLS and 0.345 g/L β-naphthol. The current efficiency for alloy deposition was 50% in the current density range 0.5–2.5 A/dm². X-ray fluorescence studies on the alloy deposit formed on steel revealed 58–75% zinc on the surface. Anodic stripping voltammetric studies were carried out on zinc-cobalt alloy films formed on glassy carbon to identify the phases formed in the alloy. Zn-Co alloy film dissolution peaks suggested the existence of β, β₁ and γ phases of the alloy. Electronic Publication     

The internal energy of product ions formed in mass spectral reactions

Major factors which determine the distribution of internal energy of a primary product ion A⁺, P(E)_A+, at formation are delineated in terms of the quasi-equilibrium theory and a variety of experimental evidence is offered to support these conclusions. These major factors include: the P(E) of the molecular ion, the rate constants as a function of energy, κ(E), for M⁺·→A⁺ + N⁰ and for competing reactions of M⁺·, and the partitioning of excess internal energy between A⁺ and N⁰. The ‘fluctuation effect’ on this partitioning makes P(E)_A+ relatively insensitive to many structural and energy changes.     

Study of transport processes in plants by radioabsorption and microradiographic methods

The passive transport processes in plants of²²Na⁺,¹³⁷Cs⁺,⁴⁵Ca²⁺,⁶⁵Zn²⁺,⁵⁹Fe³⁺ and³²PO ₄ ³⁻ ions and the plant-protecting agent “Saphidon (¹⁴C)” were studied by a radioabsorption method. The parameters of the passive transport processes of²¹²Pb²⁺, borate and tetraborate ions in plants were measured by quantitative microradiographic methods, using photoemulsion and solid state nuclear track detectors. Ion diffusion concentration profiles within the plants were determined at various diffusion times and temperatures. The equation of linear diffusion combined with convection was used to determine the diffusion coefficients characteristic of the transport processes.     

金属离子(Na~+、K~+、Ca~(2+)、Mg~(2+)、Zn~(2+))与鸟嘌呤异构体配合物的稳定性

在B3LYP/6-311++G**水平上用极化连续介质模型(PCM)系统研究了金属离子(M+/2+=Na+,K+,Ca2+,Mg2+,Zn2+)和十三种鸟嘌呤异构体形成的配合物GnxM+/2+(n为鸟嘌呤异构体的编号,x表示M+/2+与鸟嘌呤异构体的结合位点)在气(g)液(a)两相中的稳定性顺序.着重探讨了液相中配合物的稳定性差异,并且从溶质-溶剂效应、结合能、形变能及异构体的相对能量等几个方面分析了造成稳定顺序发生变化的原因.报道了溶液中这五种金属离子与鸟嘌呤异构体结合形成的六种基态配合物:aG1N2,N3Na+,aG1N2,N3K+,aG1O6,N7Ca2+,aG1N2,N3Mg2+(aG1O6,N7Mg2+),aG2N3,N9Zn2+.可以看出,除了在Zn2+配合物中鸟嘌呤异构体为G2外,构成其余四种金属离子配合物的鸟嘌呤异构体都是G1,但结合位点不同.同时对气相中各类配合物稳定性也进行了系统的排序,并报道了几种较稳定的配合物,如:gG3N1,O6K+,gG5N1,O6K+,gG3N1,O6Ca2+/Mg2+,gG4O6,N7Ca2+/Mg2+.     

Chiral differentiation of the noscapine and hydrastine stereoisomers by electrospray ionization tandem mass spectrometry

Energy‐dependent collision‐induced dissociation (CID) of the dimers [2 M + Cat]⁺ of the noscapine and hydrastine stereoisomers was studied where Cat stands for Li⁺, Na⁺, K⁺ and Cs⁺ ions. These dimers were generated ‘in situ’ from the electrosprayed solution. The survival yield (SY) method was used for distinguishing the noscapine and hydrastine dimers. Significant differences were found between the characteristic collision energies (CE₅₀, i.e. the collision energy necessary to obtain 50% fragmentation) of the homo‐ (R,R; S,S) and heterochiral (R,S; S,R) stereoisomers. To distinguish the enantiomer pairs L‐, D‐tyrosine ([M + Tyr + Cat]⁺) and L‐, D‐lysine ([M + Lys + Cat]⁺) were used as chiral selectors. Furthermore, these heterodimers [M + amino acid + Cat]⁺ were also applied to determine the stereoisomeric composition. It was found that the characteristic collision energy (CE₅₀) of the noscapine and hydrastine homodimers ([2 M + Cat]⁺) was inversely proportional to the ionic radius of the cations. Furthermore, the structures of the dimers [2 M + Cat]⁺ were studied by high level quantum chemical calculations. Copyright © 2015 John Wiley & Sons, Ltd.     

Up-conversion yield in glass ceramics containing silver

Small silver particles are known to increase the fluorescence yield in rare-earth-doped glasses. These particles can be grown easily in glass ceramics of general composition (PbF₂, GeO₂, YbF₃, ErF₃). We have studied the effect of the addition of silver on the up-conversion yield due to sequential energy transfer between Yb³⁺ and Er³⁺ ions. The origin and the information that can be obtained from this effect are discussed.     

RIMS analysis of ion induced fragmentation of molecules sputtered from an enriched U3O8 matrix

Resonance ionization mass spectrometry was used to measure the composition of the sputtered flux from 15 keV Ga⁺, Au⁺, Au₂ ⁺ and Au₃ ⁺ primary ions impacting a ²³⁵U enriched U₃O₈ standard. We demonstrate that molecular fragmentation decreases as the primary ion mass and nuclearity increases. Stopping and range of ions in matter calculations show that cluster ions (Au₂ ⁺ and Au₃ ⁺) deposit more of their energy via direct knock-ons with near-surface target atoms, whereas monatomic ions (Ga⁺ and Au⁺) penetrate much deeper into the target sub-surface region. We correlate these results to the experimental observations by showing that increased cluster ion sputter yields partition the projectile energy over a larger number of sputtered molecules. Therefore, while cluster ions deposit more total energy into the near surface region of the target compared to monatomic ions, the energy per molecule decreases with projectile mass and nuclearity. Less energy per molecule decreases the number of U–O bond breaks and, consequently, leads to a decrease in molecular fragmentation. Additionally, the extent of molecular fragmentation as a function of ion dose was evaluated. We show that molecular fragmentation increases with increased ion dose; primarily as a result of sub-surface chemical damage accumulation. The relative intensity of this effect appears to be projectile independent.     

Evaluating the potential alpha energy of radon progeny

Potential alpha energy concentration of radon progeny can be measured using the alpha-spectroscopy with the silicon semiconductors detectors and the gross-counting attached with the ZnS detectors. The decay method was applied where the alpha particles emitted from the ²¹⁸Po to ²¹⁴Po were detected. In the case of the decay products, the amount and aerodynamic behavior of radioactivity are important, and also need to be measured. During the experiment, the radon gas was supplied and evaluated from the experimental room with constant concentration. Then the air sample was used as the known volume and the grab sampling technique was developed for estimating the concentration of radon decay products. However the proper calculation was applied for estimating the potential alpha energy of radon progeny through of ²¹⁸Po, ²¹⁴Pb and ²¹⁴Bi.