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The process for electroplating amorphous gold–nickel–tungsten alloy that we developed previously based on the addition of a gold salt to a known amorphous Ni–W electroplating solution was investigated further using the X-ray diffraction (XRD) method for the purpose of quickly surveying the effects of various experimental variables on the microstructure of the alloy. In this system the gold concentration in the plating bath was found to be critical; i.e., when it is either very low or very high, the deposit becomes crystalline to XRD. The deposit composition varies linearly with the mole ratio of Au to Ni in solution, and the alloy deposit is amorphous to XRD when the atomic ratio of Au/Ni in the deposit is between 0.5 and 1.5. At suitable concentrations of the metal ions, the deposit contains essentially no tungsten. By extending the work on the Au–Ni–W system, an amorphous Au–Co alloy plating process was also developed.

We have carried out X-ray absorption measurements with its magnetic circular dichroism (MCD) of perpendicular magnetic films of DyxCo100−x (15⩽x⩽33) at Dy M4,5 and Co L2,3 absorption edges to investigate electronic and spin states of the Dy 4f and Co 3d states, respectively. The replacement of major spin between Dy 4f and Co3d is clearly observed in the spectra between 20⩽x⩽25. The expected values of the orbital angular moment ∣〈Lz〉∣ of Dy 4f were estimated to be 1.4–0.8 μB while that of Co 3d was estimated to be around 0.2 μB.

Pd-Co was electrodeposited as a rough cathode catalyst for a direct methanol fuel cell fabricated using micro-electromechanical systems technology. Pd-Co was electrodeposited at -10 mA/cm2 for 60 s or -200 mA/cm2 for 5 s. The deposits were evaluated with respect to microstructures, electrochemical characteristics, and fuel cell performances. As a result, oxygen reduction activity of the sample prepared at -200 mA/cm2 was higher than that prepared at -10 mA/cm2, while the electrochemically active surface areas were almost the same. Microstructures of the former and the latter were observed dendritic and flat, respectively. We conclude that the difference of oxygen reduction activity is attributed to the difference of the microstructure. In addition, we modified the dendritic sample by depositing Pd-Co at -0.75 V vs. Ag/AgCl. The modification increased open circuit potential for oxygen reduction by 30 mV from 0.70 to 0.73 V.

Sputter-deposited SmCo5 thin films exhibiting high perpendicular magnetic anisotropy were studied for materializing ultra high density magnetic recording. This study put emphasis on the fabrication of SmCo5 double-layered perpendicular magnetic recording media. A double-layered medium with a Ru buffer layer introduced between a Cu/Ti intermediate layer and a Co-Zr-Nb soft magnetic underlayer exhibited high perpendicular magnetic anisotropy, whereas that without the Ru buffer layer did not. Auger electron spectroscopy revealed that the Ru buffer layer inhibited unfavorable interdiffusion between the Cu/Ti intermediate layer and the Co-Zr-Nb soft magnetic underlayer. In addition, the read-write characteristics of the SmCo5 double-layered perpendicular magnetic recording media were evaluated for the first time.

Different shapes (nanosphere or nanorod) of gold nanoparticles (Au-NPs) were synthesized with and without ultrasonic irradiation in the presence of citric acid. Spherical-shaped and rod-shaped Au-NPs showed different surface plasmon resonance (SPR) absorption bands. The Au-NPs with different shapes were immobilized on a monolayer of 3-aminopropyltriethoxysilane (APS) coated on an indium–tin oxide (ITO) electrode. The potential dependence of the SPR band of different shaped Au-NPs in an aqueous solution was explored. The SPR band and intensity changes of the Au-NPs were found to depend on the applied potential. The spherical-shaped and rod-shaped Au-NPs showed different SPR absorption behaviors when potential was applied. These behavior changes were interpreted as the result of the potential-induced changes of the local dielectric environment around the nanoparticles due to molecular absorption/desorption and the charging/discharging of the particles.

An extremely enhanced enantioselectivity was achieved for the detection of enantiomers of alanine (Ala), leucine (Leu), and 3,4-dihydroxyphenylalanine (DOPA) based on the voltammograms for the deposition of Cu from Cu complexes of the amino acids at an Au electrode modified with a self-assembled monolayer (SAM) of l-homocysteine (Hcy). The enantioselective current density peak for the Cu deposition was found to change with increasing number of potential cycles after the addition of Cu(II), and the highest enantioselectivity was observed immediately after the addition of Cu(II). Besides, enantioselectivity was not observed with proline, whose five-membered ring contains the nitrogen atom of a secondary amino group, while some amino acids with a primary amine group such as Ala, Leu, and DOPA exhibited enantioselectivity. These results suggest that the chiral ligand exchange reaction at the l-Hcy SAM-modified Au electrode, namely, the enantioselective formation of diastereomeric complexes of Cu(II) with target enantiomers and l-Hcy self-assembled on the Au electrode, plays an important role in the chiral discrimination based on the Cu deposition. Keywords: d-amino acids, Chiral ligand exchange, Cu underpotential deposition, Self-assembled monolayers, Solid/liquid interfaces, Voltammetry, Chiral discrimination

We have investigated the effects of the etching method of a Ti substrate for a metal oxide electrode on the electrochemical characteristics of the electrode. The preparation method and electrochemical characterization of zirconium oxide films on etched Ti substrate has been also studied. The HCl etching was developed a fine and homogeneous roughness on the Ti substrate. Fabrication and material properties of the metal oxide electrode, which is known to be so effective to generate ozone and sodium hypochlorite (NaOCl) as power oxidant, were studied. A proper metal oxide material focus zirconium oxide through reference paper. A coating method to enhance the fabrication reproducibility of the zirconium oxide electrode was used dip-coating method by zirconium oxychloride. Zirconium oxide films on the Ti substrate were analyzed by SEM, XPS and cyclic voltammetry.

The filling of trenches in ULSI interconnect structure by electroless copper deposition was investigated for the effect of bath additives. The additive effect was found to depend strongly on the reducing agent used in the bath. Void-free trench-filling was achieved by using polyethylene glycol (PEG) as an inhibiting additive in the bath containing glyoxylic acid as the reducing agent, while the combined addition of 8-hydroxy-7-iodo-5-quinoline sulfonic acid (HIQSA) and PEG was necessary for achieving void-free filling in the bath containing formaldehyde as the reducing agent. The effect of PEG on trench filling in the former bath was studied in detail based on electrochemical measurements. It is suggested that the rinse water remaining in trenches before electroless deposition causes a decrease in PEG concentration at the trench bottom during copper filling. The addition of PEG was found to shift the deposition potential in the negative direction. A new potential measuring apparatus was devised and used in model experiments, which revealed that the deposition potential depends on the local concentration of PEG at the trench bottom, where it is expected to be low. The observed preferential growth of copper deposit at the trench bottom is thus attributed to the effects of the variation of PEG concentration within the trenches on the deposition rate and potential.

The enantioselectivity imparted to a gold electrode by modifying its surface with a self-assembled monolayer (SAM) of cysteine (Cys) was investigated for the electrochemical redox reaction of 3,4-dihydroxyphenylalanine (DOPA). A cyclic voltammetric study of the redox reaction revealed that the enantioselectivity was determined by the surface coverage of the gold electrode with Cys molecules. The electrode modified with ∼1.8 × 1014 Cys molecules cm−2 exhibited enantioselectivity in the voltammogram for the oxidation and reduction of DOPA, while the voltammograms obtained by the electrodes with either more or less surface coverages did not exhibit significant enantioselectivity. It is suggested that the accessibility of DOPA to that area of the gold surface which is not blocked by Cys molecules at an optimum surface coverage, is required for the enantioselective redox reaction of DOPA to proceed. Chirality, 2007. © 2007 Wiley-Liss, Inc.

The lifetimes of ionic vacancies created in ferricyanide-ferrocyanide redox reaction have been first measured by means of cyclotron magnetohydrodynamic electrode, which is composed of coaxial cylinders partly exposed as electrodes and placed vertically in an electrolytic solution under a vertical magnetic field, so that induced Lorentz force makes ionic vacancies circulate together with the solution along the circumferences. At low magnetic fields, due to low velocities, ionic vacancies once created become extinct on the way of returning, whereas at high magnetic fields, in enhanced velocities, they can come back to their initial birthplaces. Detecting the difference between these two states, we can measure the lifetime of ionic vacancy. As a result, the lifetimes of ionic vacancies created in the oxidation and reduction are the same and the intrinsic lifetime is 1.25 s and the formation time of nanobubble from the collision of ionic vacancies is 6.5 ms.

Lithium-ion batteries (LIBs) are generally constructed by lithium-including positive electrode materials, such as LiCoO2, and lithium-free negative electrode materials, such as graphite. Recently, lithium-free positive electrode materials, such as sulfur, are gathering great attention from their very high capacities, thereby significantly increasing the energy density of LIBs. Though the lithium-free materials need to be combined with lithium-containing negative electrode materials, the latter has not been well developed yet. In this work, the feasibility of Li-rich Li-Si alloy is examined as a lithium-containing negative electrode material. Li-rich Li-Si alloy is prepared by the melt-solidification of Li and Si metals with the composition of Li21Si5. By repeating delithiation/lithiation cycles, Li-Si particles turn into porous structure, whereas the original particle size remains unchanged. Since Li-Si is free from severe constriction/expansion upon delithiation/lithiation, it shows much better cyclability than Si. The feasibility of the Li-Si alloy is further examined by constructing a full-cell together with a lithium-free positive electrode. Though Li-Si alloy is too active to be mixed with binder polymers, the coating with carbon-black powder by physical mixing is found to prevent the undesirable reactions of Li-Si alloy with binder polymers, and thus enables the construction of a more practical electrochemical cell.

Structural and energetic investigations based on semiempirical PM5 and ab initio HF and MP2 calculations suggested that the self-assembled monolayer of an atropisomeric compound, (R)- or (S)-1,1′-binaphthalene-2,2′-dithiol (BNSH), on a gold (1 1 1) surface selectively adsorbs one enantiomer of phenylalanine (Phe), resulting in chiral discrimination, through hydrophobic, cation(− NH 3 + ) –π and NH(Phe)–π (BNSH) interactions in a nanometer-sized screw-hole-like pocket composed of three BNSH molecules in the monolayer.

LiNi1/3Mn1/3Co1/3O2 had been successfully prepared from spherical composite carbonate via a simple uniform-phase precipitation method [P. He, H. Wang, L. Qi, T. Osaka, J. Power Sources, in press] at normal pressure, using nickel, cobalt and manganese sulfate and ammonia bicarbonate as reactants. The preparation of spherical composite carbonate was significantly dependant on synthetic condition, such as the reaction temperature, feed rate, molar ratio of these reactants, etc. The optimized condition resulted in spherical composite carbonate of which the particle size distribution was uniform, as observed by scanning electronic microscopy (SEM). Calcination of the uniform composite carbonate with lithium carbonate at high temperature led to a well-ordered layer structured LiNi1/3Mn1/3Co1/3O2 as confirmed by X-ray diffraction (XRD), without obvious change in shape. Due to the homogeneity of the composite carbonate, the final product, LiNi1/3Mn1/3Co1/3O2, was also significantly uniform, i.e., the average particle size was of about 10 μm in diameter and the distribution was relatively narrow. As a result, the corresponding tap density was also high, approximately 2.32 g cm−3, of which the value is very near to that of commercialized LiCoO2. In the voltage range of 2.8–4.2, 2.8–4.35 and 2.8–4.5 V, the discharge capacities of LiNi1/3Mn1/3Co1/3O2 electrode were 159, 168 and 179 mAh g−1, respectively, with good cyclability.

We studied microscopic magnetic properties of each consistent atom in boron added CoNiFe electroless-deposited soft magnetic films, which is a promising candidate for the soft magnetic underlayer of the perpendicular magnetic recording medium, by X-ray absorption spectra (XAS) and magnetic circular dichroism (MCD) measurement. It was found that various monoxides and Fe sesquioxide coexisted with the metals at the upper part of the films. The results of MCD sum rule showed the expected values of orbital angular moment 〈Lz〉 for the film with macroscopic magnetic domain boundaries were larger than those of without domains at Co and Ni atoms and smaller at Fe atom. The appearance of macroscopic magnetic domain boundaries probably originated from the increase in 〈Lz〉 of Co and/or Ni atoms. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Pd nanocluster seeds were formed on a soft magnetic underlayer (SUL) using an electrochemical substitution reaction, and were utilized as an intermediate layer for a Co/Pd multilayered ([Co/Pd] n ) perpendicular magnetic recording medium. A CoNiFeB film prepared with electroless deposition was used as SUL, which was immersed into a PdCl 2 solution for the formation of Pd seeds. The Pd seeds were found to effectively reduce the size of magnetic domains in the [Co/Pd] n film deposited on them. The optimization of the concentration of the PdCl 2 solution and the use of the pretreatment process with a SnCl 2 solution were effective to obtain the smooth SUL surface with fine Pd seeds as small as 5 nm. The 20 nm-thick [Co/Pd] n film deposited on the optimized Pd seeds/CoNiFeB SUL exhibited a high coercivity of 7.8 kOe and a small magnetic domain size of 69 nm. These results indicated that the combination of the Pd seeds and the electroless-deposited SUL was desirable in terms of the improvement not only in the magnetic properties of [Co/Pd] n media but also in the mass productivity of the underlayer.

Crystallization of chiral amino acid, leucine, on the gold substrate modified with a self-assembled monolayer (SAM) was investigated with X-ray diffraction (XRD) and atomic force microscopy (AFM). It was found that the formation of enantiomeric crystalline phase occurred enantioselectively when the specimen modified with the SAM, to which one enantiomeric form of leucine molecules was covalently attached, was immersed in a pure enantiomeric solution of leucine. On the contrary, a racemic crystalline phase was formed on both d - and l -leucine-attached SAMs after soaking in a racemic leucine solution. In non-racemic solutions, both enantiomeric and racemic crystalline phases were formed on the enantiomer-attached SAM when the one enantiomeric form with the same chirality as the attached enantiomer was contained in excess, while neither of the crystals was formed with the other enantiomeric form in excess. Changes in the surface morphology of the specimens accompanied with the growth of crystalline phases on the SAM, reflecting the crystallinity suggested from the XRD method, were observed by using AFM.

Fabrication of electroless NiMoB thin films as a diffusion barrier layer and capping layer for Cu interconnects in ULSI with low-k inter level dielectrics were developed. The films containing the Mo were expected to improve the barrier property for Cu diffusion and thermal stability of the films. This study included the novel wet formation process, i.e. we use self-assembled monolayer and catalyzing process to obtain the uniform catalyzed surface to initiate the electroless deposition reaction. The deposition rate was strongly dependent on the MoO3 concentration in the solution. The content of Mo in the deposit increased as the concentration of MoO3 in the solution increased. Thermal stability of the NiMoB film for Cu diffusion was evaluated. The obtained films (Mo concentration = 20 to 25at %) was stable against vacuum annealing under 400{degree sign}C

LiCoO2 had been successfully prepared from spherical basic cobalt carbonate via a simple uniform-phase precipitation method at normal pressure, using cobalt sulfate and urea as the reactants. The preparation of spherical basic cobalt carbonate was significantly dependant on synthetic condition, such as the reactant concentration, reaction temperature and impeller speed, etc. The optimized condition resulted in spherical basic cobalt carbonate with uniform particle size distribution, as observed by scanning electron microscopy. Calcination of the uniform basic cobalt carbonate with lithium carbonate at high temperature led to a well-ordered layer-structured LiCoO2 without shape change, as confirmed by X-ray diffraction. Due to the homogeneity of the basic cobalt carbonate, the final product, LiCoO2, was also significantly uniform, i.e., the average particle size was of about 10 μm in diameter and the distribution was relatively narrow. As a result, the corresponding tap-density was also high approximately 2.60 g cm−3, of which the value is higher than that of commercialized LiCoO2 of Hunan Ruixing, co. In the voltage range 2.8–4.2, 2.8–4.3, and 2.8–4.4 V, the discharge capacities of LiCoO2 electrode were 153, 159, and 168 mAh g−1, respectively, with better cyclability.

The soft x-ray absorption and magnetic circular dichroism spectra at the Co L2,3-edges of [Co/Pd]20 and [CoB/Pd]20 multilayered films, which were sputter-deposited in Ar gas containing N2 at room temperature, were measured to investigate the electronic and spin states of the films. The macroscopic magnetic properties, such as coercivity and saturation magnetization, and microstructural properties, such as grain size and preferred orientation, were markedly changed for the [Co/Pd]20 film by the B doping and N2 addition. The B doping and/or the addition of N2 gas caused appreciable changes not only in macroscopic magnetic properties but also in microscopic properties, such as the spin angular momentum and orbital angular momentum, throughout the multilayered film. On the other hand, a new spectral feature at the high energy side of the Co L3-edge peak in x-ray absorption spectra was found in only the films with N2 added. Thus, the microscopic properties, such as electronic and spin states, of the Co 3d electronic state for the [Co/Pd]20 and [CoB/Pd]20 films were changed by only the sputtering process with additive N2 gas.

The covalent attachment of alkyl groups to silicon surfaces, via carbon–silicon bond formation, has been attempted using gas-surface reactions starting from Cl-terminated Si(1 1 1) or H:Si(1 1 1) under ultraviolet light irradiation. The formation of Cl-terminated Si(1 1 1) and its resulting stability were examined prior to deposition of organic molecules. High-resolution electron energy loss spectroscopy (HREELS) was utilized for detecting surface-bound adsorbates. The detection of photo-deposited organic species on Cl:Si(1 1 1) from gas-phase CH4 or CH2CH2 was not significant. On H:Si(1 1 1), it was evident that after the photoreaction with gas-phase C2H5Cl, C2H5 groups were chemically bonded to the surface Si atoms through single covalent bonds. The C2H5 groups were thermally stable at temperatures below 600 K. Alkyl monolayers prepared on silicon surfaces by dry process will lead to a new prospective technology of nanoscale fabrication and biochemical applications.

X-ray absorption and magnetic circular dichroism spectra (XAS–MCD) of the Dy M 4,5 -edges of Dy x Co 100− x ( x = 15–33) thin films are measured. The advantage of element and orbital selectivity in the XAS–MCD measurements enables us to directly observe the magnetic moments of specified elements. The MCD intensity at the Dy M 5 -edge is maximum when the incident X-ray is normal to the surface and the incident angle dependence of the MCD intensity shows a sine curve. That gives us information about the angular distribution of the Dy magnetic moments with respect to the total magnetization direction and the opening angle of the cone. Applying the sum rule, the expectation value of orbital magnetic moment was estimated. The half opening angle of the random distribution of the moments were estimated and it was found that the angle has its minimum value around x = 20.

Mesoporous intermetallic Pt–Ni alloys with various compositions have been produced by the chemical reduction of two metal (nickel and platinum) salts dissolved in aqueous domains of a lyotropic liquid crystalline (LLC) phase. The mesoporous Pt–Ni alloys are small particles less than 100 nm in size and exhibit high specific surface areas higher than 40 m2 g−1. The ordering of the mesostructure decreases with increasing Ni content in the alloys. The high resolution scanning electron microscopic (HR-SEM) images show that the porous nanostructures are indeed formed over the entire area on the external surface of the particles. The lattice parameters of the alloys decrease with the increasing Ni content, implying the incorporation of Ni. The X-ray photoelectron spectroscopic (XPS) data show that Ni atoms in the alloys are thought to be in the zerovalent metallic state (Ni0). The transmission electron microscopic (TEM) images prove that the lattice fringes assigned to a fcc structure are randomly oriented in the pore walls. The energy-dispersive X-ray spectroscopic (EDS) mapping shows uniform distribution of Ni atoms in the porous matrix. These results indicate the formation of mesoporous intermetallic Pt–Ni alloys.

We have developed an excellent process for selective deposition of mesoporous Pt through tailored microfabrication steps via the “Solvent-Evaporation-mediated Direct Physical Casting (SEDPC)” method. The direct observation by high-resolution scanning microscopy (HR-SEM) shows the formation of an ordered mesoporous structure in a very confined area. The cyclic voltammogram of the mesoporous Pt reveals a typical feature of Pt surface. The surface morphology and ordering of the mesostructure strongly depend on the electrodeposition conditions (constant-current and constant-potential depositions). The roughness factors are greatly enhanced as the charge densities in the constant-current deposition are increased. These findings are important for the morphological design of mesoporous metals in a micrometer scale.

The relationship between human sensation experienced in the use of a material and its physical properties was investigated for the case of writing with a ball-point pen containing water-based ink. Friction force microscopy (FFM) and a writing tester were used to measure friction in nano- and macro-scale, respectively, and their results were correlated with the smoothness of the act of writing. FFM allowed the determination of the optimum concentration of a specific lubricant to be incorporated in the ink to minimize the wear of the bearing material, although no significant relationship was observed with the writing tester. The nano-tribological measurements by FFM provide a significant means to understand the relationship between materials and the smoothness of the act of writing.

This article reviews results of our investigations, performed over the period of a decade, on gold plating for electronics applications. Three different topics are covered: (1) development of a new, non-cyanide, soft-gold electroplating bath containing both thiosulfate and sulfite as ligands; (2) evaluation of a known cyanide-based, substrate-catalyzed electroless bath for depositing pure soft gold, and subsequent development of an alternative, non-cyanide, substrate-catalyzed bath; and (3) development of a new process to electroplate amorphous hard-gold alloys for probable future applications as a contact material on nano-scale electronic devices.

To enhance the write performance of a CF-SPT head, a smaller main pole of Co-Ni-Fe and a finer coil were fabricated by using the electrodeposition method. Fine coils with 2.5 μm pitch were obtained by the damascene process. The magnetic domain structure of the 15-μm-high and 20-μm-wide main poles could be controlled by changing their taper angles. A head with a favorable domain except at its tip exhibited stable write performance and no pole erasure. Thus, it was concluded that a control of the magnetic domain was necessary for write heads.

A series of our studies on sputter-deposited SmCo5 thin films exhibiting very high perpendicular magnetic anisotropy is reviewed. Introduction of a Cu underlayer is a key to imparting perpendicular magnetic anisotropy to SmCo5 thin films. Perpendicular magnetic anisotropy was enhanced by depositing the Sm-Co layer with the alternate lamination of Sm and Co sublayers and by using the Cu/Ti dual underlayer for producing a smooth film surface. As a result, under an optimized condition, the magnetic anisotropy constant was as large as 4.0 x 107 erg/cm3, which is greater by a factor of ten than that of material used for conventional magnetic recording media. Furthermore, we found that high perpendicular magnetic anisotropy was obtained even in very thin films and that the coercivity was controllable in a wide range when the films were prepared using an ultra-high vacuum sputtering system. Microstructural analysis suggested that the Cu-rich region in the initial growth stage of the Sm-Co layer played an important role in generating perpendicular magnetic anisotropy. In addition, we tested SmCo5 thin films for use in conventional and heat-assisted magnetic recording media.

The effects of the thicknesses of a Cu/Ti underlayer and a Sm-Co layer on the magnetic properties and domain structure of SmCo5 perpendicular magnetization films prepared by using an ultra-high-vacuum sputtering system were investigated. By adjusting the thicknesses of both the Cu/Ti underlayer and the Sm-Co layer, the coercivity was controlled to be a moderate value, allowing the films to be used in magnetic recording media while maintaining a squareness ratio of unity. As the Sm-Co layer thickness was reduced, the magnetic cluster size decreased and the magnetization reversal process varied from wall motion mode to a rotation mode. It is suggested that the Cu-rich region in the initial growth stage of the Sm-Co layer functions as the pinning site of the magnetic domain wall and plays an important role in controlling the magnetic domain structure.

We have proposed a novel convenient pathway via solvent-evaporation-mediated direct physical casting (SEDPC) for the fabrication of mesoporous metals in a micrometer scale. We have presented the successful deposition of highly ordered mesoporous Pt into micrometer channels prepared by lithography. The direct observation by a high-resolution scanning microscope (HR-SEM) showed the formation of highly ordered 2D-hexagonal (p6mm) mesoporous metals onto such substrates. The cyclic voltammogram of the mesoporous Pt in sulfuric acid revealed a typical feature which can identify the clean Pt surface. Moreover, mesoporous Pt exhibits an effective reduction of dissolved dioxygen molecules. It is proved that mesoporous Pt deposited in a very confined area via the SEDPC method possesses electrocatalytic performance owing to Pt. Keywords: Mesoporous metal, Electrocatalyst, Microchannel, Lithography, Platinum

Two-dimensional hexagonally ordered mesoporous Pt particles are prepared by Pt deposition in the aqueous domains of lyotropic liquid crystals (LLC) by chemical reduction with Zn powders. Interestingly, the framework is composed of connected nanoparticles of about 3 nm in size. Moreover, it is proved that the lattice fringes on the atomic crystallinity are coherently extended across the several nanoparticles in the framework. Such a framework composed of connected nanoparticles with extended crystallinity is uniquely created by using LLC as a soft template, which is not attainable by a traditional approach using mesoporous silica as a hard template. Through the structural identification, the formation mechanism of mesoporous Pt in the presence of LLC is thought to be continuous deposition of Pt nanoparticles from one nanoparticle.

A process for electroplating amorphous gold–nickel alloy with the atomic ratio of unity was developed. The plating bath was prepared by adding potassium cyanoaurate(I) into a known plating bath which produces amorphous nickel-tungsten alloy. At a sufficiently high gold concentration, the alloy deposit did not contain any tungsten. The amorphous nature of the Au–Ni alloy produced in the new bath was confirmed by using TEM and THEED. Hardness, resistivity, and contact resistance of this new alloy were determined, and the results are discussed for applications as an electrical contact material.

Fabrication process for picoliter volume SiO 2 glass tube array partially embedded in Si wafer was developed. As a template for the glass tubes, macropore array was formed at the surface of n-Si(1 0 0) wafer by photo-assisted electrochemical etching process. The area-selective formation of the array was achieved by applying Au/Cr micropatterns formed at the back-side surface of the substrate as the shade mask, which controls the illumination condition to optimize the etching reaction conditions. Subsequently, surface of the macropores was wet-thermally oxidized to form glass layer, and the bulk Si region was removed by alkaline etching, remaining the “glass tubes”. As a result of complete removal of the bulk Si, released glass tubes were obtained. By partial removal of the bulk Si part, the glass tubes were exposed, fixed in the remaining Si substrate in the form of well-ordered array. It was confirmed that the depth, the exposed region and the wall thickness of each glass tube were controllable by adjusting the parameters such as the duration of the Si electrochemical etching, the alkaline etching and the wet-thermal oxidation, respectively. In order to demonstrate microreaction in the glass tube, aqueous rhodamine B solution was injected into the tubes and excitation light was irradiated to them. As a result, the fluorescence of rhodamine B was clearly detected, confirming the applicability of the glass tubes for various kinds of devices and systems such as microreactors.

An investigation was carried out on the surface modification of γ-Fe2O3 nanoparticles with aminopropylsilyl (APS) groups in 3-aminopropyltriethoxysilane and the interparticle linkage with α,ω-dicarboxylic acids (succinic acid and suberic acid) through the terminal amino groups of APS moiety at the surface of γ-Fe2O3 nanoparticles. It was demonstrated that the change in interparticle distance caused by these surface modifications influences the magnetic property of the composites. When γ-Fe2O3 nanoparticles were modified with APS groups, coercivity increased and when they were further modified with α,ω-dicarboxylic acids, the larger decrease in coercivity was observed with the longer dicarboxylic acid.

The oxidation mechanism of aldehydes, which are commonly used as reductants for an electroless deposition process, was studied by using Density Functional Theory (DFT) calculations. The reaction pathway of the three aldehydes, i.e., formaldehyde, acetaldehyde and glyoxylic acid, with different functional groups, were examined by calculating energy profiles of all intermediate species. It was indicated that the pathway in an isolated system proceeds via dianion-free intermediate species. Taking the solvation effect into consideration, it was indicated that the oxidation reactions of the three aldehydes preferably proceed at the solid/liquid interface. In combination with a Cu metal cluster as a model of metal surface, it was also indicated that the oxidation reactions proceed preferentially at the Cu surface. It was expected that the adsorption/desorption energy at the Cu surface of glyoxylic acid, which has an electron-accepting carboxyl group, was smaller and substituent effect lead to its high reducibility.

Using first-principles total energy calculations within density functional theory (DFT), we investigated the surface properties, especially focusing upon the surface reactivity, of strained Si layer deposited onto SiGe underlayer, in comparison with normal (non-strained) Si surface. We used a cluster model as the surface of the strained Si and normal Si, and results of our calculation indicate that, when the Si possessed strained condition, the total energy is destabilized and the value of the gap between HOMO and LUMO became smaller than that of normal Si. In addition, we estimated the reactivity of the strained Si and normal Si surfaces with trace metal ion species in solution. As a result of the adsorption energy calculation of Cu 2+ , Ni 2+ and Fe 2+ to Si (100) surface, it was suggested that the adsorption energy of the metal ion species to the strained Si surface is more stable than that of the normal Si.

Maskless and electroless fabrication was demonstrated to form patterned nanostructures of various metal species, based upon the process previously developed by the authors. In this process, the metallic nanostructures were formed on the surface of clean, hydrogen terminated p-(1 0 0) Si wafer with pre-patterned nanoscopic defects, which were confirmed to possess higher activity for the reductive deposition reaction of the metal ion species. The deposition was achieved spontaneously and selectively at the defect sites on the wafer surface by immersing into dilute aqueous fluoride solution containing trace amount of metal ion species. By optimizing the formation condition of the patterned defects and composition of the solution, fabrication of patterned nanostructures of various metallic species such as Au, Ag, and Co, was achieved. Formation of the patterned nanostructures to 10 μm2 in extent, as well as control of the feature size of the deposits by adjusting the formation condition of the patterned defects were also attempted.

In this study, we investigated the antimicrobial activity of silver nanoparticles (Ag-NPs) and platinum nanoparticles (Pt-NPs) aqueous solution, which were prepared using different stabilizer, such as sodium dodecylsulfate (SDS) and poly-(N-vinyl-2-pyrrolidone) (PVP), for Staphylococcus aureus (S. aureus) and Escherichia coli (E.coli) by measuring the minimum inhibitory concentration (MIC). Antimicrobial effect of Ag-NPs for S. aureus and E. coli was investigated using cup diffusion method. The growth of Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria were inhibited by Ag-NPs. The MIC of Ag-NPs for S. aureus and E. coli were 5 and 10 ppm, respectively. But the Au-NPs stabilized with SDS did not show antimicrobial activity. Also, the Pt-NPs stabilized with PVP (or SDS) did not show antimicrobial activity for the test organisms.

A microscale Bi electrodeposition process was developed and applied to the three-dimensional fabrication of a highly sensitive X-ray imaging sensor, so called X-ray microcalorimeter, which has an array of sensing elements with a mushroom-shaped X-ray absorber. The composition and operating conditions for Bi electrodeposition were optimized and flat, smooth Bi deposits were obtained by applying additives such as diethylenetriamine pentaacetic acid (DTPA) and sodium n -dodecyl sulfate (SDS). The results of ultraviolet (UV)–visible absorption spectroscopy and polarization curves from the Bi electrodeposition solution indicated that the formation of a DTPA–Bi(III) complex and an increase of overpotential for Bi electrodeposition in the presence of SDS improved the solution stability as well as the surface morphology of the deposited film. The mold for the mushroom-shaped microstructure array was formed from a single-layered photoresist coating by applying sequential exposure steps for the “stem” part and the “roof” part. The absorber array was successfully fabricated by the Bi electrodeposition into the mold, precise polishing, and mold removal processes.

This overview describes our recent study on fabrication processes of high-performance magnetic thin films for high-density magnetic recording. Particularly, it is emphasized that electrochemical processes play significant roles in fabricating the recording heads and media used for the high-density recording. Newly developed electrodeposition methods for fabricating CoNiFe and CoFe soft magnetic thin films with high-saturation magnetic flux density are shown, and the key points for obtaining them are highlighted. It is summarized that the effective seedlayers for the sputter-deposited [Co/Pd] n multilayered films, which are promising candidates as magnetic recording media with strong perpendicular magnetic anisotropy for the high-density magnetic recording, have been developed. We have recently succeeded in developing the novel electroless deposition methods for the CoNiFe-based soft magnetic underlayers of double-layered perpendicular magnetic recording media and for the patterned medium consisting of CoNiP magnetic nano-dot arrays, which are briefly explained.

We have reported in our past work that electrodeposited Sn–Ni alloy with different composition show considerably different performance as anode materials for Li-ion batteries, and the performance was remarkably well (ca. 650 mAh g−1 at 70th cycle) when the composition was controlled to Sn62Ni38. In this work, structural changes during charge discharge cycling of Sn–Ni alloy with different composition were investigated to evaluate their differences in the cycle performance. From the XRD result, Ni3Sn4 phase was the main phase seen in Sn62Ni38, and its reversible reactivity with Li was confirmed. We suggest that this is the key phase for its high capacity and lengthened cycle life. From Sn54Ni46, which showed low capacity, only a metastable phase close to the structure of SnNi was confirmed. The results from Sn84Ni16 indicated the presence of pure Sn and Sn rich metastable phase would lead to relatively fast electrode degradation.

Field effect transistors (FETs) modified with various functional monolayers, such as organosilane monolayer, were formed on the identical substrate by precise control of the fabrication processes. The devices showed a typical transistor property with a good stability in aqueous solutions. The amino monolayer-modified FET acted as an ion sensitive FET with a good pH sensitivity of 58 mV/pH, and the perfluoro-alkyl monolayer-modified FET worked as a reference device. Moreover, the device with enzyme immobilized onto amino modified gate electrode enabled to detect trace concentration (10 −9 to 10 −6 M) of urea with a high sensitivity of 64 mV/decade. These monolayer-modified devices were expected to be applied as working and reference electrodes for on-chip ion and biosensing.