bluuebunny/crossref_metadata_2025 huggingface dataset:
Localized Corrosion Behaviour in Dissimilar AZ31/AZ80 Friction Stir Welds
Authors: Savguira Yuri , North Thomas H. , Thorpe Steven J.
Published: May 2015

Corrosion of a dissimilar friction stir weld (FSW) made in AZ31/AZ80 magnesium alloys has been investigated using the scanning reference electrode technique (SRET), and microcapillary polarization technique. The corrosion rate of each of the base metals along with the welded specimen was estimated by mass loss testing and mixed potential theory. The stir zone material in both alloys showed a higher reduction potential than the base metal, due to the dissolution of β-Mg17Al12, and Al-Mn intermetallic particles. The dissimilar welded specimen exhibited a higher corrosion rate compared to either AZ31 or AZ80. The governing corrosion mechanism in dissimilar welds was determined to be different from FSSW joints made with a singular material. The corrosion behaviour of the dissimilar FSW joint was governed by the galvanic coupling of the two alloys, and not by the microstructural evolution that occurred during the welding process.
Polarity Reversal of Iron and Tin in Aqueous Malic Acid
Authors: Geary Steven , McMurray Hamilton Neil , de Vooys Arnoud C.A. , Williams G , Lammers K
Published: May 2015

Isolated Open Circuit Potential (OCP) measurements are performed on pure tin and iron in aqueous malic acid solutions (1 – 2x10-3mol dm-3). In de-aerated aqueous malic acid solutions ≥1.56x10-2mol dm-3 tin was found to become sacrificial with respect to iron, reversing the polarity predictions on the basis of tabulated EOCP values. In the presence of oxygen polarity reversal is not established. Additions of Sn2+ >10-4 mol dm-3 to aerated 0.1 mol dm-3 aqueous malic acid influences iron to be cathodic with respect tin. However, in the absence of oxygen tin becomes cathodic with respect to iron in 0.1 mol dm-3 malic acid solutions containing Sn2+ >10-4 mol dm-3. Voltammetric measurements indicate a self-limiting displacement mechanism of Sn2+ on the iron surface. Ex-situ XPS surface measurements confirm tin oxide coverage on iron following short immersion times in 0.1 mol dm-3 malic acid containing Sn2+ = 10-3 mol dm-3.
The Role of Tin in Suppressing Filiform Corrosion on Tin Coated and Iron-Tin Intermetallic Coated Steels
Authors: Wint Natalie , McMurray Hamilton Neil , Williams Geraint , Geary Steven , de Vooys Arnoud C.A.
Published: May 2015

This paper describes a high resolution optical and electrochemical study into how metallic tin acts to reduce the rate of filiform corrosion (FFC) initiation and propagation on tin and iron-tin intermetallic (Fe-Sn IM) coatings for packaging steels. The time-dependent extent of FFC was determined optically using time lapse photography and by repeated in-situ scanning using a scanning Kelvin probe (SKP) apparatus. FFC was not observed on tin coatings but was found to propagate at a significantly reduced rate on the Fe-Sn IM when compared to pure iron. A rotating disk electrode (RDE) technique was subsequently used. O2 reduction currents were low on both pure tin and tin coatings when compared to pure iron, intermediate values being obtained for the Fe-Sn IM. It is concluded that the rate of FFC is related to the overpotential for the oxygen reduction reaction (ORR).
Electrochemical Scanning Techniques for the Examination of Bi-Metallic Coins
Authors: Searle Justin Royston , Glover Carol Frances , Khan Khalil , Wilson Benjamin Paul , Williams Geraint , Worsley David A
Published: May 2015

Scanning Kelvin Probe (SKP) and the 3D Scanning Vibrating Electrode Technique (3D-SVET) have been used to examine a selection of bi-metallic coins. The SKP has first been used to identify the electrochemical compatibility of the two alloys and inform a prediction of the anodic and cathodic regions observed in the 3D-SVET experimentation, performed in artificial sweatsolution. This is compared to open circuit potential (OCP) measurements, also measured in artificial sweat. It was observed that the SKP in atmospheric conditions records larger potential differences between the alloys than that observed in OCP under immersion conditions, however the relative activity is consistent across all 3 techniques. The 3D-SVET clearly identifies galvanic corrosion as a result of the differences in the galvanic activity between the two alloys. The anodic activity is predominantly on the nickel brass section of the coin, while the cathodic activity remains on the cupronickel portion.
Surface Modification and Electrochemical Metallization of Advanced Polymers for Energy Application
Authors: Oriani Andrea Vittorio , Spreafico Marco Alberto , Cojocaru Paula , Triulzi Francesco , Apostolo Marco , Magagnin Luca
Published: May 2015

Combination of polymeric and metallic layers in a single device is becoming inevitable for applications in an increasing number of fields, including alternative energy. A basic product consisting in a metal-polymer (partially fluorinated) bilayer can be simply obtained by two steps. The first step of the process consists in surface modification of the polymer by plasma treatment, whose main effect is to increase the wettability. The increase of wettability by water is crucial for the second step of the process, which consists in aqueous based electroless deposition of metals. As revealed by cross cut and bending tests, adhesion between the metallic and polymeric layer is excellent. Given the suitable transparency and weathering resistance of Halar® ECTFE, the application of this process for production of solar concentrator mirrors is being considered. Light reflection properties and UV ageing were determined for this purpose.
Fabrication and Characterization of CdS Nanoparticles Obtained via Microwave-Assisted Synthesis
Authors: Tamasauskaite-Tamasiunaite Loreta , Grinciene Giedre , Selskis Algirdas , Norkus Eugenijus
Published: May 2015

In the present study a rapid microwave heating method was used to prepare CdS nanoparticles. The morphology, structure and composition of the prepared CdS were examined by means of Field-Emission Scanning Electron Microscopy and X-ray diffraction. The optical properties of the CdS thin films deposited onto glass substrates were investigated by means of UV/Vis spectrophotometric measurements. It has been found that the size and structure of CdS particles synthesized by rapid heating irradiation depend on the alkalinity of reaction mixture and microwave power. The synthesized CdS nanoparticles have a band gap of 2.5 – 2.7 eV.
Electrochemical Deposition of Mo-Se Thin Films
Authors: Kowalik Remigiusz , Kutyła Dawid , Mech Krzysztof , Żabinski Piotr , Wróbel Mirosław , Tokarski Tomasz
Published: May 2015

The deposition of Mo-Se thin films on copper substrate by electrochemical method is reported. The electrodeposition mechanism was analyzed by cyclic voltammetry. The thin films were potentiostatically deposited from the sulfate solution at pH=6 in the wide range of potentials. The elemental analysis indicate that the formation of coatings consisting selenium and molybdenum is possible. The x-ray diffraction confirms the presence of the mixture of MoSe2 and Mo3Se4 phases in the coatings.
Electrodeposition of Nanoscale Manganese Oxide onto Nickel Foam for Energy Storage Applications
Authors: Clark Michael Patrick , Qu Wei , Ivey Douglas G
Published: May 2015

A template free anodic electrodeposition process has been developed to deposit Mn oxide and Mn oxide/ PEDOT rods onto Ni foam substrates for use as a supercapacitor. The deposit morphology has been optimized by varying deposition conditions and by characterization using SEM imaging. TEM diffraction indicates that the deposits are poorly crystalline, with a grain size less than 20 nm. XPS analysis revealed that the deposits are present as a combination of MnO2 and MnOOH. The capacitive performance of the deposits was characterized using cyclic voltammetry. The addition of PEDOT increased the capacitance of deposits from 120 (0.29 F/cm2) to 159 F/g (0.50 F/cm2) at 5 mV/s. Capacitance retention after 500 cycles was 91% and 113% for deposits with and without PEDOT, respectively.
The First Thin Film Electronic Package
Authors: Krongelb Sol , Romankiw Lubomyr
Published: May 2015

The magnetic thin-film head, announced by IBM in 1979, marked the transformation of electrochemical technology from a shop art to a precision manufacturing process with far wider applications than the thin film head. An important application of electroplating was in the fabrication of the multichip module that provided the packaging for chips in advanced computers. These modules included copper strip lines for data transmission between chips. To minimize pulse distortion, these lines had to have precisely controlled propagation characteristics, and plating through a lithographic mask was the most effective way to insure the tight control on the geometry of the lines necessary to meet this requirement. This paper highlights the evolution of packaging for computers and tells how the scientists and engineers from the IBM T.J. Watson Research Center who had created the thin film head, worked with the development and manufacturing groups at IBM’s East Fishkill plant to bring electrochemistry into the manufacture of advanced packaging modules.
Influence of Temperature on Electroless Copper Deposition from Formaldehyde-Containing Solutions Using 2-Hydroxy-1,2,3-Propanetricarboxylic Acid As Cu(II) Ligand
Authors: Kepeniene Virginija , Stagniunaite Raminta , Stalnioniene Irena , Norkus Eugenijus
Published: May 2015

Electroless coating technique is one of the ways to obtain metallic coatings in which there is no usage of electric current. Trisodium salt of 2-hydroxy-1,2,3-propanetricarboxylic acid (citric acid), forming sufficiently stable complexes with copper(II) ions in alkaline solutions, was found to be a suitable ligand for copper(II) chelating in alkaline (pH > 12) electroless copper deposition solutions. The measurements were carried out in electroless copper plating solutions for 30 or 60 min. at pH 12.0 – 13.0 and 10 – 30 °C temperature. The thickness of the compact copper coatings obtained under optimal operating conditions in 1 h can reach ca. 3 μm. The copper surface determination method is based on the underpotential deposition of the thallium monolayer on the Cu electrode surface. The real surface area (in nano-scale dimensions) of the Cu electrode (SR
, cm2) was calculated using the Tl monolayer capacity Q
Tl. The surface nano-scale roughness factor R
f is calculated as a ratio of real and geometric surface areas. From Cu(II)-citrate solutions deposited copper coatings surface roughness factor (R
f) vary from ca. 2.5 up to 15.0.
Fabrication of FePt and CoPt Magnetic Nanodot Arrays by Electrodeposition Process
Authors: Homma Takayuki , Wodarz Siggi , Nishiie Daiki , Otani Tomohiro , Ge Siyuan , Zangari Giovanni
Published: May 2015

Fabrication of Co-Pt and Fe-Pt ferromagnetic nanodot arrays for the application of ultra-high density bit patterned media (BPM) by electrochemical processes was described. In order to form patterned substrates for nanodot arrays with the density higher than 1 Tbit/inch2, electron beam lithography technique was employed. Nanopatterns with 25 nm and 18 nm pitch, which correspond to 1 and 2 Tbit/inch2 were successfully formed by optimizing the condition of the lithography process, and Co-Pt and Fe-Pt with relatively high coercivity of 4.8 kOe and 10.3 kOe were formed by electrodeposition. By utilizing the nanopatterned substrates, Co-Pt and Fe-Pt nanodot arrays with 25 nm and 35 nm pitch were uniformly formed. These results demonstrate capability of the electrochemical processes for fabricating magnetic nanodot arrays with Tbit-level density.
Investigation of Electrodeposited NiFeMo for Application as Flux Concentrator in Magnetic Field Sensors
Authors: Wienecke Anja , Müller-Weihrich Konstantin , Rissing Lutz
Published: May 2015

A wide range of applications increasingly requires sensors with high performance. By use of soft magnetic materials, the sensitivity of the aforementioned systems can be improved significantly. Here, one promising material is NiFeMo. Employing electrodeposition techniques, the material can be integrated into the sensorial system. However, the process of NiFeMo electroplating is still challenging. The plating parameters like current density and frequency have a great influence on both the composition of the layer and its morphology (like grain structure, volume of pores, inclusion of impurities). This in turn influences the magnetic quality of the layer. The paper identifies some of the factors determining the layer properties.
Magnetic Beads - Basics and Applications
Authors: Ruffert Christine
Published: May 2015

Magnetic beads are small particles with a spherical shape and diameters ranging from the nano to the micro scale. Various types of such beads are commercially available. The approach of embedding ferromagnetic nanoparticles of only a few tens or hundreds of nanometers, which is on the magnetic single-domain scale in a non-magnetic matrix creates small particles with superparamagnetic properties. Superparamagnetic nanoparticles have a zero magnetization in the absence of a magnetic field, which is attributed to the ratio of the magnetic anisotropy energy and the thermal energy. The magnetic anisotropy energy depends on the orientation of the particles relative to the applied magnetic field and is proportional to the magnetic volume of the particle. The nanoparticles therefore behave as non-magnetic particles in the absence of a magnetic field. This feature entails that magnetic beads can be manipulated applying magnetic forces, but do not agglomerate in the absence of an external field, since they have no permanent magnetic moment due to the dimension of the embedded particles. The large surface-to-volume ratio of beads lends itself to a further use, i.e. for chemical bonding of target molecules. Meanwhile, magnetic beads have been established as tool for the specific attachment of biomolecules for detection and quantification. This contribution presents some basics on magnetic bead fabrication and use, which can be considered as state of the art in the area of biotechnology and biomedicine. Finally, a rather unconventional application of magnetic beads is presented comprising the magnetic manipulation of metal nanoparticles for catalyst recovery.
Biocompatibility and Biofunctionality of Magnetic Nanoparticles
Authors: Ota S , Yamada T , Takemura Yasushi
Published: May 2015

Biocompatible magnetic nanoparticles (MNPs) have been researched for bioapplications such as imaging for diagnostics, drug delivery, hyperthermia and gene delivery. In addition, MNPs are functionalized for dispersion, biocompatibility and enhancement of therapeutic effects. In this study, polyethylenimine (PEI)-coated MNPs were prepared. The localization of PEI and PEI coated MNPs in a cell was observed with phase contrast and fluorescent microscopy and transmission electron microscopy (TEM). In addition, PEI coated MNPs were conjugated with DNA for application to magnetofection. The size distribution of preinternalized DNA/PEI/MNPs complexes after applying a dc magnetic field was measured. The size of preinternalized complexes was compared to that of internalized complexes measured by TEM. Moreover, the effect of a protein corona on cellular uptake was confirmed by size measurement and transfection experiment.
A Comparative Study of Saturation Induction with Current Density of Electrodeposited Fe-Ni-W Alloys
Authors: Mundotiya Brij Mohan , Wurz Marc Christopher , Rissing Lutz
Published: May 2015

Fe-Ni-W alloys are electroplated from an ammonical citrate bath by applying three different current density values of 28, 56, and 84 mA/cm2. The morphology and structure of Fe-Ni-W alloys are detected by Scanning Electron Microscope (SEM) and X-ray diffraction (XRD), respectively. The deposits are smooth and well adhered to the substrate at a current density of 28 mA/cm2, while at current density values of 56 mA/cm2 and 84 mA/cm2 deposits were smooth but showed cracks in the layer. All the as-plated deposits have nano crystalline structures and have two phases of WO3 and BCC structured solid solution of Ni and W in Fe. The BCC structure is the dominant microstructure at high current density. The constituents in the films are determined by Energy Dispersive X-ray spectroscopy (EDX) technique. The magnetic saturation induction of the plated deposits is studied with the help of a Vibrating Sample Magnetometer (VSM).
Photocatalysis of TiO2 – Supported Graphene Oxide and its Reduced Form towards Phenol Degradation
Authors: Al-Kandari Halema Ali , Abdullah Aboubakr Moustafa , Mohamed Ahmed meslam , Al-Kandari Shekhah Ali
Published: May 2015

Commercial nanocrystals graphite was oxidized to graphene oxide (GO) using Hummers’ method. Then, GO was directly impregnated mechanically over TiO2 (GOTi) and reduced later using a stream of hydrogen gas in a controlled reactor at 450 oC (H2RGOTi) or reduced initially by hydrazine hydrate solution (HH) in a 1000-W microwave oven then loaded later on TiO2 (HHRGOTi). Also, hydrothermal reduction was applied to obtain reduced GO/TiO2 (RGOTi). X-ray photoelectron spectroscopy (XPS), Raman spectra and X-ray diffraction patterns (XRD) confirmed the oxidation and reduction processes of graphite and GO respectively. XPS have revealed that GO surface consists mainly of hydroxyl, epoxy, carbonyl and carboxylic groups. From argon bombardment etching, it was revealed that GO is on the surface of TiO2. Catalysts were prepared and tested for photodegradation of phenol under UV illumination in presence and absence of hydrogen peroxide. In addition, the photocatalytic activity of the as-prepared catalysts was compared with commercial TiO2. It was concluded that the 0.1-RGOTi catalyst has the best performance in terms of phenol degradation under UV illumination in absences and presence of H2O2. However, its performance is better in presence of H2O2 especially at small time intervals.
Physics-Based CFD Simulation of Lithium-Ion Battery under the FUDS Driving Cycle
Authors: Li Genong , Li Shaoping
Published: May 2015

The physics-based electrochemical model, Newman's pseudo-2D (P2D) porous electrode model, has been widely accepted in the study of lithium-ion batteries. However, the model is built on the electrode scale. There are two challenges to apply such models in the electrochemical-thermal coupled battery simulation. The first one is how to use such electrode-scale model in the large scale simulation (battery dimension scale). The other one is how to make the physics-based model cost-efficient in a CFD simulation. In this paper, the multi-scale multi-dimensional approach (MSMD) is used to address the first technical issue and a linear approximation for source terms is used to address the second issue. As a result, Newman's P2D model can be used to simulate a lithium-ion battery's behavior under a real driving cycle.
Electrochemical Characterization of a 2-Hydroxypropyl b-Cyclodextrin Membrane with Tenoxicam
Authors: Guzmán-Hernández Dafne Sarahia , Ramirez-Silva Maria Teresa , Palomar-Pardavé Manuel , Corona-Avendaño Silvia , Romero-Romo Mario A.
Published: May 2015

The electrochemical characterization of a nonsteroidal anti-inflammatory drug named Tenoxicam was performed with a carbon paste electrode modified with 2-hydroxypropyl b-cyclodextrin. It produced a single oxidation peak for the different Tenoxicam species without reduction processes and involved an adsorption process as responsible for the formation of the single, fine oxidation peak.
Substrate Effects on the Catalytic Center of CoSe2 for Oxygen Reduction Reaction
Authors: Sreekuttan M. Unni , Mora-Hernandez Juan Manuel , Luo Yun , Alonso-Vante Nicolas
Published: May 2015

Here, we report the tuning of active reaction center of the CoSe2 nanoparticles by nitrogen doped carbon nanohorns (NCNH). CoSe2 nanoparticles supported on NCNH (CoSe2/NCNH) shows improved oxygen reduction reaction (ORR) activity compared to the same supported on carbon nanohorns and Vulcan carbon. An improved positive shift in onset potential (50 mV) and half-wave potential (150 mV) of CoSe2/NCNH compared to other catalysts indicates the intrinsic activity as well as active reaction center of CoSe2 modulated by the presence of NCNH. CoSe2/NCNH reduces molecular oxygen to hydroxide through a four-electron transfer pathway with improved electrochemical stability in alkaline condition. Air breathing direct methanol micro laminar flow fuel cells (DM-µLFFC) performance of CoSe2/NCNH as cathode catalyst shows a maximum power density and current density respectively of 10.05 mW cm-2 and 124.20 mA cm-2 with 5M methanol as fuel.
Oxide-Based Electrocatalysts toward Oxygen Reduction Reaction as Non Pt Cathodes for PEFC
Authors: Uehara Naoki , Ishihara Akimitsu , Imai Hideto , Matsumoto Masashi , Arao Masazumi , Ohgi Yoshiro , Kohno Yuji , Matsuzawa Koichi , Mitsushima Shigenori , Ota Ken-ichiro
Published: May 2015

Development of non-platinum cathode is required to commercialize polymer electrolyte fuel cells. We have investigated group 4 and 5 transition metal oxides, because they have high chemical stability under acidic atmosphere, and their costs are lower than that of platinum. In this paper, tantalum oxide-based cathodes were made from oxy-tantalum phthalocyanines by heat treatment under low oxygen partial pressure. We examined the factors which influence oxygen reduction reaction activity. According to XRD patterns, peak position and full width at half maximum of Ta2O5 0 0 1 were correlated with onset potential. In addition, it was found that amount of deposited carbon which supported electron conductivity on tantalum oxide was correlated with oxygen reduction current density.
Graphene-Polyaniline Nanofiber Composite as Electrocatalyst for Oxygen Reduction Reaction in Alkaline Media
Authors: Sankararao Mutyala , Mathiyarasu Jayaraman
Published: May 2015

Here, we report a novel, cost effective, metal free electrocatalyst for oxygen reduction reaction. Graphene nanosheet (GNS) - polyaniline (PANI) nanofiber composite was prepared by simple chemical route using pre-synthesized GNS and PANI nanofibers. The GNS-PANI nanocomposite exhibited better electrochemical performance compared to GNS alone. The structural and morphological features of this composite were examined by microscopy, spectroscopy and electro-analytical techniques. The results confirmed that PANI nanofibers are homogeneously dispersed as well as interconnected with the GNS. This characteristic feature significantly enhances the charge transfer reactions at the interface. GNS-PANI nanocomposite modified glassy carbon (GC) electrode exhibited finite onset potential for oxygen reduction reaction with a 100 mV positive shift compared to GNS modified GC electrode in alkaline electrolyte. Koutecky–Levich (K-L) plot analysis revealed that the oxygen reduction reaction proceed virtually via 4 electron pathway. Thus, the present GNS-PANI nanocomposite may be a promising cathode material for fuel cell applications.
Synergy in the Hydrazine Assisted Electro-Oxidation of Formic Acid
Authors: Machado Eduardo Giangrossi , Varela Hamilton
Published: May 2015

In the last few decades many discussions have been made on the mechanism of formic acid electro-oxidation, as there are three parallel pathways by which the process may proceed. In addition to this intricate mechanism, it was recently reported that in a solution containing formic acid and hydrazine, the latter may be electro-oxidized without interference of any of the intermediates of the former. In this paper we report evidences that a more-than-additive interaction between hydrazine and formic acid may occur and lead to a change in the oscillatory behavior of the system. Additionally, we also report the determination of average oxide coverage in both systems. The results herein presented suggest that hydrazine decreases the poisoning of the surface by the accumulation of subsurface oxygen. It was not possible to determine the exact mechanism of this interaction; however enough data is presented to assume that hydrazine and formic acid interact synergistically.
Mechanism of Potential Oscillation Induced by Na2SO4
and K2SO4 in H2O2-H2SO4-Pt System
Authors: Mukouyama Yoshiharu , Hasegawa Mitsuhisa , Nakanishi Shuji
Published: May 2015

A potential oscillation, named oscillations H, appears in H2O2-H2SO4-Pt System when salts such as Na2SO4 and K2SO4 are added to electrolytes, as has been reported in our previous paper (ECS Transactions 58 (2014) 99). The potential range of oscillation H overlaps with the potential region of an N-shaped negative differential resistance (N-NDR) induced by an autocatalytic effect of the formation of Pt-OH. Electrochemical impedance measurements show that oscillation H is classified into a hidden N-NDR oscillator and also that the autocatalytic effect plays an essential role in a positive feedback mechanism in oscillation H. During oscillation H, oxygen bubbles evolve from the electrode surface and the local pH at the surface is basic, which shows that H2O- produced from H2O2 is oxidized to oxygen and also that the H2O- oxidation plays an important role in a negative feedback mechanism in oscillation H.
Formation Process of Nickel Nano-Clusters for Catalytic Growth of Carbon Nanotubes for Use in Field-Effect Transistors
Authors: Keyn Martin , Schwalke Udo
Published: May 2015

Incorporation of carbon nanotubes in conventional silicon technology to exploit their outstanding electrical properties offers opportunities in nanoelectronics. We report on a fabrication technique which utilizes catalytic nickel nano-clusters and chemical vapor deposition to obtain in situ grown carbon nanotubes for field-effect devices. The crucial catalyst formation process is found to be open to influence by an oxygen plasma treatment and the annealing temperature. Here, atomic force microscopy images show the most promising results on plasma treated samples that are annealed at 920°C. Electrical measurements on fabricated devices indicate that by now devices are either well switching (on/off current ratio of 4.5 orders of magnitude) or well current carrying (80 µA).
Glyoxylic Acid as Reducing Agent for Electroless Copper Deposition on Cobalt Liner
Authors: Inoue Fumihiro , Philipsen Harold , van der Veen Marleen , Van Huylenbroeck Stefaan , Armini Silvia , Struyf Herbert , Shingubara Shoso , Tanaka Tetsu
Published: May 2015

Electroless deposition of Cu was investigated on thin Co layer for through Si via with high aspect ratio structure. The electroless deposition bath was optimized for minimizing Co corrosion during Cu nucleation by using electrochemical analysis. Glyoxylic acid, which is known as non-toxic reducing agent for electroless Cu deposition, showed anodic oxidation on Co, which did not appear for the case of formaldehyde. Furthermore, ratio of complexing agent and Cu ion also impacted Co corrosion; free complexing agent in the electroless deposition bath accelerated corrosion of Co. The optimized electroless bath which contained glyoxylic acid as reducing agent and non-free EDTA performed in 3 μm × 50 μm TSV, the electroless deposited Cu layer could serve as a seed layer for TSV filling by electrodeposition. The electroless Cu layer was continuously deposited without missing of continuity of Co layer even close to the bottom of TSV.
Case Study of Early Detection of Iron Contamination in Copper Damascene Plating Process by In-Situ Electrochemical Sensor
Authors: Jaworski Aleksander , Wikiel Hanna , Wikiel Kazimierz , Holverson Peter , Nelson Andrew
Published: May 2015

A case of detection of iron contamination of the plating solution used in semiconductor manufacturing by a system for plating bath process control utilizing a novel approach that combines advanced electroanalytical methods with various statistical data analysis techniques based on chemometric factor analysis is described. Retrospective research aiming to determine the iron contamination level is presented. The electroanalytical techniques employed, including DC- and AC-voltammetry, are designed to provide a response strongly affected by the presence of specific contaminants while being practically insensitive to the varying concentrations of deliberately added bath constituents. The shape differences between deformed and training set voltammograms are quantified using various outlier-detection chemometric techniques. The specificity of the response to the presence of a likely contaminant combined with multi-parameter quantification of its presence enables not only early-fault detection but also its diagnosis, therefore automating the troubleshooting process.
Electrodeposition and Characterisation of Novel Ni-NbOx Composite Coatings as a Diffusion Barrier for Liquid Solder Interconnects - Part II: Diffusion Barrier Performance
Authors: Wang Jing , Wilcox Geoffrey D , Mortimer Roger J , Liu Changqing , Ashworth Mark A
Published: May 2015

The control of interfacial microstructural stability is of utmost importance to the reliability of liquid solder interconnects in high temperature electronic assemblies. This is primarily due to excessive intermetallic compounds (IMCs) that can form and continuously grow during high temperature operation, which renders conventional barrier metallisations inadequate. With the intention of reducing such excessive IMC growth, electrically conducting, NbOx containing Ni coatings were developed using electrodeposition and were assessed as solder diffusion barrier layers in terms of their electrical conductivity and barrier property. The present work adopts a novel electrochemical route to produce Ni-NbOx composite coatings of good uniformity, compactness and purity, from non-aqueous glycol-based electrolytes consisting of NiCl2 and NbCl5 as metal precursors. The effects of cathodic current density and NaBH4 concentrations on the surface morphology, composition and thickness of the coatings were examined. Increased NaBH4 concentrations were found to elevate the maximum deposit thickness (above 10 µm), although these led to a reduction in the co-deposited Nb content. The composite coatings generally exhibited good electrical conductivity. The reaction between a liquid 52In-48Sn solder and Ni-NbOx, with Nb contents up to 6 at.%, was studied at 200ºC. The results indicate that, Ni-NbOx with sufficient layer thickness and higher Nb content, offered longer service lifetime. Nb enrichment was generally observed at or close to the reaction front after high temperature storage which suggests evident effectiveness of the enhanced diffusion barrier characteristics. A mechanism for the role of Nb as a barrier performance enhancer was postulated.
On the Fabrication of Backside Illuminated Image Sensors: Bonding Oxide, Edge Trimming and CMP Rework Routes
Authors: Cavaco Celso , Peng Lan , Sebaai Farid , Verbinnen Greet , Visker Jakob , Olmen Jan , Tezcan Deniz Sabuncuoglu , Osman Haris
Published: May 2015

A comprehensive insight to a part of the fabrication process of backside illuminated (BSI) image sensor devices is here discussed. While showing the available process window, special emphasis is given to the key integration developments. The three main areas discussed in this work are bonding using different oxide layers, wafer edge trimming, and CMP rework routes. These processes are relatively new to imager fabrication and hence require mastering each step to achieve the yield requirements of an imager product.
Precursor Concentration and Substrate Effects on High Rate Dip-Coated Vanadium Oxide Thin Films
Authors: Glynn Colm , Aureau Damien , O'Hanlon Sally , Daly Luke , Geaney Hugh , Collins Gillian , Etcheberry Arnaud , O'Dwyer Colm
Published: May 2015

Uniform thin films of vanadium pentoxide were dip-coated from a high-concentration vanadium oxytriisopropoxide precursor which is shown to be resistant to the dewetting processes which can form surface pinhole defects. Through appropriate withdrawal speed choice, the thin films have a smooth uniform surface morphology with a low rms roughness of <1 nm in both their amorphous and crystallized states. The structure of the thin films follows that of bulk vanadium pentoxide but in a nanostructured form. The deposition methods shown can be applied to prepare thin films upon a variety of different substrates and other alkoxide based metal oxide materials.
A Scanning Kelvin Probe Investigation of the Interaction of PEDOT:PSS Films with Metal Surfaces and Potential Corrosion Protection Properties
Authors: Glover Carol Frances , Watson Trystan , Bryant Daniel , Williams Geraint
Published: May 2015

The study of conducting polymers (CPs) is of high current interest due to their incorporation in a range of applications, including optical and electronic devices. Poly(3,4-Ethylenedioxythiophene)-Poly(Styrene Sulphonate) (PEDOT:PSS) is considered one of the most electrochemically and thermally stable CPs currently available. In many applications there is a requirement for electrical contact to be made between an organic PEDOT:PSS layer and a metallic substrate. Therefore, an understanding of the interaction between the CP and various metals, in order to gauge the long term stability of the metal-CP interface, is of high importance. An in-situ scanning Kelvin probe (SKP) has been employed to measure the Volta potential differences of various PEDOT:PSS coated metal surfaces to identify instances where a reaction may be taking place at the interface. A redox potential of ca. -0.15 V vs. SHE has been shown where PEDOT:PSS is present in both oxidized and reduced form on the metal surfaces.
One Step Synthesis of Pure Cubic and Monoclinic HfO2 Nanoparticles: Effects of Temperature and Ambient on the Photoluminescent Properties
Authors: Rauwel Protima , Galeckas Augustinas , Rauwel Erwan
Published: May 2015

We report on the one-pot synthesis and characterization of pure cubic and monoclinic phase HfO2 nanoparticles. An average particles size of 2.6 nm was estimated from transmission electron microscopy studies. The equivalent synthesis conditions of the two polymorphs provided means for direct comparison of their optical absorption and emission properties, which are found to exhibit different behaviors as functions of temperature and ambient. The origin of the strong visible luminescence observed from both cubic and monoclinic HfO2 is discussed in terms of surface-defects and nanosize of the particles. The comparative analysis of the PL responses of the two polymorphs suggests that emission at 3.1eV originates from the oxygen vacancy related defects.
Preparation of Carbonaceous Fiber Sheets Derived from Bamboo and Application to Gas Diffusion Layer of Proton Exchange Membrane Fuel Cells
Authors: Matsumura Takuya , Kinumoto Taro , Matsuoka Miki , Tsumura Tomoki , Toyoda Masahiro
Published: May 2015

Carbonaceous sheets were obtained from phyllostachys (bamboo), and their potential for use as the gas diffusion layers (GDLs) of proton exchange membrane fuel cells (PEMFCs) was investigated. Fibers, which were mainly composed of cellulose, were obtained from phyllostachys via roll-pressing and chemical treatment in an autoclave with 0.1 mol dm-3 NaOH solution, followed by defibration by an electric blender. The fibers were molded into a sheet by a papermaking procedure. The fibrous morphology remained even after carbonization under an Ar atmosphere at 1000 - 3000oC. The electric conductivity increased as the carbonization temperature was raised up to 2500oC. A single PEMFC operation test was carried out by using the carbonaceous fiber sheet as the GDL. The maximum power was 140 mW cm-2, whereas it was 170 mW cm-2 for a conventional GDL composed of carbon fibers.
Preparation of LaMnO3-CNF and Its Activity for Oxygen Electrode Reaction in 0.1 mol dm-3 KOH Solution
Authors: Ono Kohei , Kinumoto Taro , Tsumura Tomoki , Toyoda Masahiro
Published: May 2015

A composite catalyst (LaMnO3-CNF), containing LaMnO3 and carbon nanofiber (CNF), was prepared by a co-precipitation method for use as a cathode catalyst in metal hydride (MH)/air battery. The catalytic activities for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) were investigated in aqueous KOH. The onset potential for the ORR of CNF and the composite catalyst was estimated to be 0.84 V and 0.91 V vs. a reversible hydrogen electrode (RHE), respectively. To estimate the onset potential for the OER, in-situ OER measurements were carried out using a dissolved oxygen sensor during chronoamperometry at the charging potential of a MH/air battery. The onset potential was found to be 1.65 V for CNF and 1.60 V for the composite catalyst.
Self-Propelled Motion of Oil Droplets on Au Electrode during Sn Electrodeposition
Authors: Mukouyama Yoshiharu , Shiono Tetsuaki
Published: May 2015

It has been reported that self-propelled motion of oil droplets on Au electrode occurs during Sn electrodeposition and also that the velocity of the motion increases with a negative shift in the electrode potential (Chemphyschem, 9, 2302 (2008)). We, then, have studied the origin of the imbalance between interfacial tension acting on opposite sides of the droplet causing the motion. A high interfacial tension on the front side of the droplet is caused by an occurrence of electrodeposition as reported before, whereas a low interfacial tension on the rear side is attributed to an occurrence of hydrogen evolution reaction on the electrode surface. The velocity increase is due to the increase in the rate of hydrogen evolution reaction. We have also found another factor affecting the velocity; the velocity increases as the density of aqueous solution increases.
Electrochemical Oscillation during H2O2 Reduction in Basic Solutions
Authors: Mukouyama Yoshiharu , Hasegawa Mitsuhisa , Nakanishi Shuji
Published: May 2015

A new type of electrochemical oscillation has been found to appear as a current oscillation in the H2O2-NaOH-Pt system. The oscillation, named oscillation I, appears within the potential region where an N-shaped negative differential resistance (N-NDR) is observed. The N-NDR is attributed to the formation of under-potential deposited hydrogen (upd-H) which suppresses the reduction of HO2
- produced from H2O2. Moreover, oscillation I also appears in the H2O2-H2SO4-Pt system when the salts such as Na2SO4 and K2SO4 are added to electrolytes, because the local pH at the electrode surface even in H2SO4 solutions becomes basic during the H2O2 reduction. Electrochemical impedance measurements indicate that oscillation I is classified into an NNDR oscillator, and also that the N-NDR plays a crucial role in the positive feedback loop in oscillation I. The surface concentration of HO2
- plays a role as the slow process in the negative feedback loop.
New Insights on Naproxen Quantification Using Voltammetry and Graphite Electrodes: Development of an Optimized and Competitive Methodology
Authors: Aguilar-Lira Guadalupe Yoselin , Álvarez-Romero Giaan Arturo , Rojas-Hernández Alberto , Páez-Hernández María Elena , Rodríguez-Ávila Jose Antonio , Romero-Romo Mario Alberto
Published: May 2015

The present work describes a novel, simple and fast electroanalytical methodology for naproxen determination in pharmaceutical formulations. Naproxen’s indirect quantification through an adsorption anodic wave was performed at a graphite bar electrode using differential pulse voltammetry. An anodic current maximum was recorded at a potential of -0.3 V referred to a saturated Ag/AgCl electrode, in the presence of 0.1 mol L-1 phosphates buffer at pH 7 as supporting electrolyte. The naproxen’s oxidation is an irreversible diffusion-controlled process. A calibration plot was done from which a correlation coefficient of 0.990 was obtained with a sensibility of 4.19 ± 0.62 µA L µg-1, detection and quantification limits of 2.99 and 9.97 µg L-1 respectively.
Oxygen Reduction Reaction in Alkaline Solution: Influence of Catalyst Loading and Carbon Support Characteristics
Authors: Kasatkin Piia Ereth , Härk Eneli , Jäger Rutha , Lust Enn
Published: May 2015

Oxygen electroreduction reaction in 0.1 M KOH aqueous solution has been investigated varying the catalyst loading deposited onto glassy carbon electrode. It was found that with increasing the catalyst loading the electrocatalytic activity increased. Comparable current density values obtained for 1.0 mg cm-2 Pt-Vulcan electrode could be achieved for Pt-C(Mo2C) electrode with approximate loading of 0.3 mg cm-2, indicating that Pt-C(Mo2C) catalyst has noticably higher activity towards ORR than Pt-Vulcan catalyst.
Electrochemical and Physical Characterization of Ru Nanoparticles Activated Carbon Supported Electrodes in Alkaline Solution
Authors: Steinberg Vahur , Härk Eneli , Jäger Rutha , Rauwel P , Lust Enn
Published: May 2015

Carbide derived carbon synthesized from tungsten carbide and commercially available VulcanXC72® were used as support materials for Ru nanoparticle catalysts. The synthesized electrocatalysts have been characterized with scanning electron microscopy, X-ray diffraction, (high resolution) transmission electron microscopy and low temperature N2 adsorption methods. Ru nanoparticles modified carbon supports have been investigated as oxygen reduction catalysts in alkaline solution by the rotating disc electrode and cyclic voltammetry methods. The synthesized materials exhibited high specific surface area, dependent strongly on the carbon support used. Ru nanoparticles deposited onto the carbide derived carbon (C(WC)) formed agglomerated mesoporous clusters. The surface area of Ru metallic particles were 71.3 and 167.9 m2g-1 for Ru-C(WC) and Ru-C(Vulcan), respectively.
Electrochemical Oxidation of Phenol Using Boron-Doped Diamond Electrodes
Authors: Hangarter Carlos M , O'Grady William E. , Stoner Brian R. , Natishan Paul M.
Published: May 2015

The oxidation of phenol is compared for two different boron doped diamond (BDD) electrodes; a niobium supported BDD planar electrode and a BDD coated Ti mesh. Raman spectroscopy and cyclic voltammetry were used to compare the two electrodes. Continuous oxidation of phenol utilized a flow cell configuration that circulated a fixed volume of solution, scaled to the electrode area, with an initial concentration of 10 mM phenol in 0.1M H2SO4. The conversion of phenol to CO2 was monitored by scheduled collection of aliquots and subsequent total organic carbon (TOC) analysis. The two electrodes were found to have similar conversion rates, with the total carbon decreasing from ~1% to <0.1%. Treatment of a more concentrated solution, 87 mM phenol in 0.1M H2SO4, was examined for the planar electrode and resulted in greater efficiency, which was attributed to greater localization between reactants and hydroxyl radicals in the kinetic limited regime.
Morphology Controlled Magnetic Interactions of Porous Silicon Embedded Nanostructures
Authors: Rumpf Klemens , Granitzer Petra , Koshida Nobuyoshi , Poelt Peter , Michor Herwig
Published: May 2015

In the frame of this work porous silicon templates with different morphologies, especially with respect to the roughness of the pore-walls have been fabricated and subsequently filled with diverse ferromagnetic metals to fabricate self-assembled three dimensional arrays of nanostructures (wires, particles) with distinct magnetic properties. The fabricated templates offer a quasi-regular self-assembled pore-arrangement with oriented pores. Also the pore-filling is self-assembled by electrochemical deposition and there are multiple possibilities to tailor the magnetic behavior of these systems such as material, morphology, inter particle distance or interfaces. One critical parameter for this purpose is the roughness of the pore walls and the surface of the metal structures, respectively. Within the pores of these templates ferromagnetic metals have been deposited and the modification of the magnetic properties correlated to the morphology of the different templates has been figured out.
Silver Nanoparticles Study for Application in Green Housing
Authors: Küünal Siim , Kutti Sander , Guha Mithu , Rauwel Protima , Wragg David , Nurk Gunnar , Rauwel Erwan
Published: May 2015

We report on the antibacterial and antifungal properties of silver nanoparticles in applications related to straw bale construction. Humidity related growth of microorganisms in green constructions is of concern as it can cause health problems among the house residents and reduce the durability of ecologically friendly construction materials. We provide a comparative analysis of the effects of silver nanoparticles on some of the most common house-colonizing fungi and bacteria. Outdoor tests demonstrate the efficiency of the silver nanoparticles for fighting micro-organisms. Indoor tests in petri dishes are compared with the outdoor tests, and the possible nature of the biocidal properties of the silver nanoparticles is probed. In contrast to the commonly reported results, we observe that antifungal properties of silver nanoparticles against common fungi in outdoor conditions show great potential in related applications.
Lower-body negative pressure restores leg bone microvascular flow to supine levels during head-down tilt
Authors: Siamwala Jamila H. , Lee Paul C. , Macias Brandon R. , Hargens Alan R.
Published: May 2015

Skeletal unloading and cephalic fluid shifts in microgravity may alter the bone microvascular flow and may be associated with the 1-2% bone loss per month during spaceflight. The purpose of this study was to determine if lower-body negative pressure (LBNP) can prevent microgravity-induced alterations of tibial microvascular flow. Head-down tilt (HDT) simulates the cephalad fluid shift and microvascular flow responses that may occur in microgravity. We hypothesized that LBNP prevents HDT-induced increases in tibial microvascular flow. Tibial bone microvascular flow, oxygenation, and calf circumference were measured during 5 min sitting, 5 min supine, 5 min 15° HDT, and 10 min 15° HDT with 25 mmHg LBNP using photoplethysmography (PPG), near-infrared spectroscopy (NIRS), and strain-gauge plethysmography (SGP). Measurements were made simultaneously. Tibial microvascular flow increased by 36% with 5 min 15° HDT [2.2 ± 1.1 V; repeated-measures ANOVA (RMANOVA) P < 0.0001] from supine (1.4 ± 0.8 V). After 10 min of LBNP in the 15° HDT position, tibial microvascular flow returned to supine levels (1.1 ± 0.5 V; RMANOVA P < 0.001). Tibial oxygenation did not change significantly during sitting, supine, HDT, or HDT with LBNP. However, calf circumference decreased with 5 min 15° HDT (−0.7 ± 0.4 V; RMANOVA P < 0.0001) from supine (−0.5 ± 0.4 V). However, with LBNP calf circumference returned to supine levels (−0.4 ± 0.1 V; RMANOVA P = 0.002). These data establish that simulated microgravity increases tibial microvascular flow and LBNP prevents these increases. The results suggest that LBNP may provide a suitable countermeasure to normalize the bone microvascular flow during spaceflight.