Makio Naito

Fabrication of Bi(Pb)SrCaCuO Thin Film of High-Tc Phase

Lead-added Bi-Sr-Ca-Cu-O (BSCCO) thin film of high-Tc phase has been successfully prepared by means of rf-magnetron sputtering and the post annealing process. The content of lead in the BSCCO thin film was decreased during an ordinary annealing process. In order to minimize the decrease of lead, the BSCCO thin film was placed on a bulk ceramics whose composition was similar to that of the film, and annealed for 50 hours at 855°C in air. As the result, the content of lead in the thin film was almost unchanged during the annealing process. The intensity ratio of the X-ray diffraction lines due to the (002) of high and low-Tc phases was about 4/1. The film showed a superconducting transition at 110 K; a long tail of some residual resistance remained down to 90 K.

Additive Manufacturing and Strategic Technologies in Advanced Ceramics: Ceramic Transactions

Stereolithographic additive manufacturing was customized successfully to create micro ceramics components. Photo sensitive acrylic resin with alumina of 170 nm in diameters was spread on a glass substrate with 5 to 10 m in layer thickness by using a mechanical knife edge. Cross sectional layers patterned by ultraviolet laser scanning of 10 to 100 m in variable diameter were laminated to create composite precursors. Dense components could be obtained through dewaxing and sintering heat treatments. Photonic crystals with periodic arrangements in magnetic permeability were created to control electromagnetic waves in terahertz frequency range by Bragg diffraction. The terahertz waves can synchronize with vibration modes of various biochemical molecules. Efficient terahertz wave resonators to excite the molecule vibrations will be specifically applied for novel analyzers and reactors. The photonic crystals including micro cavities were designed and fabricated successfully to resonate with microwaves in terahertz frequency range. The wave transmittances through the photonic crystals including the liquid cells were measured by using a terahertz time domain spectroscopy, and cross sectional profiles of electric field intensities were calculated by a transmission line modeling method. INTRODUCTION Periodic arrangements in dielectric constants can reflect electromagnetic waves through Bragg diffraction. Especially called photonic crystals theoretically exhibits forbidden gaps prohibiting wave transmissions1. The diffraction wavelengths are comparable to the lattice constants. Diamond type micro lattices with isotropic periodicities were processed as the perfect structure to open the photonic band gaps for all crystal directions2. However, special lattice propagations were difficult to create by conventional machining of molding processes. In our investigation group, ceramics photonic crystals with diamond structures were created by stereolithographic additive manufacturing and nanoparticles sintering. The band gap formation in the terahertz frequency ranges had been observed3. In this investigation, single and double cavities were introduced into the diamond photonic crystals in order to study the characteristic resonance modes by using computer aided design, manufacture and evaluation. These structural misfits can localize the electromagnetic waves strongly through multiple reflections, and wave amplification can realize transmission peak formations in the photonic band gaps according to the defect size3.

Electrostatic Dry Coating of Cathode Materials for Li ion battery

Organic solvents are widely used in wet coating for manufacturing Li ion batteries. This study focused on switching to environmentally benign solvent-free process, and examined a possibility of electrostatic dry coating (EDC) of cathode materials which are generally composed of active oxides, conductive and binder additives. Firstly, the composite particles containing the three components were prepared by dry mechanical treatment, and then EDC experiment was performed for the composite particles. Interestingly, the composite particles could be tribo-charged enough for electrostatic deposition on an earthed Al foil in air, with relatively high deposition rate. The as-deposited film was further dry-pressed to increase the film density (3 × 103kg/m3). A half cell was assembled using the pressed film as cathode electrode, and it was demonstrated that the initial charge-discharge characteristics were comparable to those obtained for wet-coated films. The results obtained indicate that there are some opportunit...

Direct Filament Formation of Biological Carbon Nanotube Suspensions

In this study, aqueous carbon nanotube (CNT) suspensions were prepared using biological surfactant of sodium deoxycholate (NaDC). The influence of NaDC concentration on the NaDC self-association in water and the rheological responses of the NaDC-CNT-water system were investigated. It has been found that the yield stress of the suspension increased with NaDC concentration, which was strongly related to the NaDC self-association of lyotropic liquid crystals. Due to the enhanced rheological properties at high NaDC concentration (30%), it allowed the shear-induced filament formation in which the CNTs were aligned along to the shear direction. This filament formation may be attractive for transferring aligned CNTs on substrates in a controlled manner.

CONTROL OF NANOSTRUCTURE OF MATERIALS

Publisher Summary This chapter summarizes process technologies for nanostructural controls using mainly fine particles including nanoparticles as a starting material. The assembly structures of nanoparticles are discussed, introducing nanobiotechnologies and colloid processes. In addition, there is an explanation of fractal structures, rather than periodic or random structures, and optical properties. The chapter looks at nanoporous structures and their control technologies, including zeolite, creation technologies of nanoporous structures by dry processes, control technologies of nanoporous structures, and the control of tubular porous structures. The relation between nanocomposite structures used in catalysts and fuel cell electrodes and their functions is explained together with polymer nanocomposite technologies. In addition, plastic deformation technologies are discussed for controlling the nanostructures of metal and alloy. The distinctive process technologies of sintering and bonding of nanoparticle assembly and self-organization of nanoparticles are covered. The latest information is also introduced on various technologies useful for forming nanostructures, including sintering technologies of nanoparticles, low temperature sintering technologies of ceramics, aerosol deposition, colloid chemical processes, self-organization phenomena of nanoparticles in liquid phase, assembly patterning technologies, and organic/inorganic mesoporous materials.

Effect of mechanical stirring of YBaCuO mixed powder during heat treatment on superconductive properties

This paper deals with a new apparatus for the simultaneous processing of mechanical stirring and calcining of superconductive powder materials to achieve a simpler process for the fabrication of superconductive oxides. As the first step, the change of the mechanical motion of a powder bed at elevated temperature was visualized by use of a transparent mixing tube. Consequently, it was possible to analyze the effect of temperature on the dynamic motion of the powder bed. From the analysis, it was found that there was less increase in cohesiveness of mixed powder of Y2O3, BaCO3 and CuO below 400°C. Above this temperature, the cohesiveness increased considerably, which produces a negative effect of mechanical stirring. Furthermore, the powder calcined in the tumbling bed at the lowering temperature step of calcining showed better superconductive properties than that calcined in the fixed bed.

Preparation of stainless steel/zirconia composite particles with a multi-phase coating layer

Abstract A novel technique for coating a multi-component layer of finer stainless steel/zirconia around spherical stainless steel core particles is described. Composite particles have been prepared by using our new two step mechanofusion process that is one of the mechanical combining processes. Spherical stainless steel particles of 35 μm in mean diameter are employed as core materials, and zirconia particles of 0.5 μm in diameter are used for coating around core particles in a primary mechanofusion process. Cu particles of

Preparation of Bi(Pb)SrCaCuO Thin Film with High-Tc Phase

The lead added BiSrCaCuO thin film of high-Tc phase has been successfully prepared by using rf-magnetron sputtering and post annealing process. The content of lead in the thin film was easily decreased during the ordinary annealing process. In order to minimize the decrease of lead, the Pb-doped BSCCO thin film was placed on the bulk ceramics and annealed for over 170 hours at 855°C in air. As the result, the content of Pb was almost unchanged and the film showed superconducting transition at 104 K.