The kinetics of carbon nanotube (CNT) synthesis by decomposition of CH 4 over Mo/Co/MgO and Co/MgO catalysts was studied to clarify the role of catalyst component. In the absence of the Mo component, Co/MgO catalysts are active in the synthesis of thick CNT (outer diameter of 7-27 nm) at lower reaction temperatures, 823-923 K, but no CNTs of thin outer diameter are produced. Co/MgO catalysts are significantly deactivated by carbon deposition at temperatures above 923 K. For Mo-including catalysts (Mo/Co/MgO), thin CNT (2-5 walls) formation starts at above 1000 K without deactivation. The significant effects of the addition of Mo are ascribed to the reduction in catalytic activity for dissociation of CH 4, as well as to the formation of Mo 2 C during CNT synthesis at high temperatures. On both Co/MgO and Mo/Co/MgO catalysts, the rate of CNT synthesis isproportional to the CH 4 pressure, indicating that the dissociation of CH 4 is the rate-determining step for a catalyst working without deactivation. The deactivation of catalysts by carbon deposition takes place kinetically when the formation rate of the graphene network is smaller than the carbon deposition rate by decomposition of CH 4 .

The functions and structures of Mo/Ni/MgO catalysts in the synthesis of carbon nanotubes (CNTs) have been investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Thin 2-5-walled CNTs with high purities (over 90%) have been successfully synthesized by catalytic decomposition of CH(4) over Mo/Ni/MgO catalysts at 1073 K. It has been found that the yield of CNTs as well as the outer diameter or thickness correlates well with the contents of these three elements. The three components Mo, Ni, and MgO are all necessary to synthesize the thin CNTs at high yields since no catalytic activity was observed for CNT synthesis when one of these components was not present. The outer diameter of the CNTs increases from 4 to 13 nm and the thickness of graphene layers also increases with increasing Mo content at a fixed Ni content, while the inner diameter stays at 2-3 nm regardless of their contents. Furthermore, the average outer diameter is in good agreement with the average particle size of metal catalyst. That is, the thickness or the outer diameter can be controlled by selecting the composition of the Mo/Ni/MgO catalysts. XRD analyses have shown that Mo and Ni form a Mo-Ni alloy before CNT synthesis, while the Mo-Ni alloy phase is separated into Mo carbide and Ni. These alloy particles are supported on MgO cubic particles 15-20 nm in width. It has been found that only small Mo-Ni alloy particles 2-16 nm in size catalyze CNT synthesis, with larger particles over 15 nm exhibiting no activity. Mo carbide and Ni should play different roles in the synthesis of the thin CNTs, in which Ni is responsible for the dissociation of CH(4) into carbon and Mo(2)C works as a carbon reservoir.

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In recent years, it has become necessar y to develop lead substitutes, such as lead-free solder alloys, because of increased environmental concerns regarding the use of leaded materials. In addition, electronic components that use lead-free solder alloys will need to be smaller and usable at higher operating temperatures in next-generation semiconductor devices. Therefore, lead-free solder alloys must be made more reliable. In this work, tin-copper-nickel （Sn-Cu-Ni） solder alloys, Sn-Cu solder alloys, and Sn-Ni solder alloys, as well as 99.96 mass％ pure Sn, were subjected to tensile testing. The results showed the effects of adding Cu and Ni to Sn on the high-temperature deformation behavior of the Sn-Cu-Ni solder alloys. For each alloy and Sn, the stress exponent was estimated to be >5. This result indicated that, in each sample, the high-temperature deformation was controlled by dislocation creep. Furthermore, the creep activation energy was dependent on stress, and was affected to the greatest extent when adding Cu. ［doi:10.2320/jinstmet.J2016069］

Electroplating has been an important process to produce electronic devices, automotive parts, decorative materials and so on. In contrast to that, plating is endowed with environmental issues originated from exhaust fluids and acid mists. Therefore, it is limited to construct new production line in spite of necessity of plating. Moreover, it is difficult to improve productivity drastically due to completely established plating technology in 21th century. To break down demerits of conventional electroplating, we focus on the fundamental issue regarding with the plating process that can be performed in electrolyte bath. Recently, we have developed novel electroplating process named solid electrodeposition (SED), which is characterized by metal ion electrophoresis through solid electrolyte membrane1). This process has unique deposition behavior that the metal deposition on substrate proceeds only on contact area with the membrane, like a stamping process. The SED has a merit of reducing amount of exhaust fluids as well as direct patterned deposition reflecting the membrane shape. Therefore, we believe that SED is highly promising process to metallize the substrate instead of the conventional electroplating. In this study, we report on copper deposition mechanism and direct fine pattering process by applying SED. We evaluate the limitation of copper deposition rate under controlled process parameters. As a result of that, the maximum deposition rate reaches over 0.63A/dm2 (14μm/min), which should be relatively higher than conventional one. The impressive value is originated from metal transfer mechanism into membrane as well as the device configuration. The metal deposition proceeds on solid-solid interface between membrane and substrate so that no diffusion layer exist near the substrate2). Moreover, the distance between anode and cathode can be shorten because the membrane preserves electrolyte solution. The copper film deposited from electrolyte solution without additives exhibits relatively smooth and minute surface morphology. This may be because membrane contacted on substrate restricts abnormal Cu growth due to contact pressure. SED has a merit for direct patterned deposition reflecting membrane shape, but it is not easy to fabricate fine patterns without masking. Therefore, it is limited to apply high-end parts such as printed circuit boards and sensor devices. To overcome this problem, we have developed direct fine patterning process by combining SED with dry coating and etching technologies. Figure 1 shows schematic diagram and photographs of each step. Firstly, the metal thin layer is formed on substrate by means of sputtering (electrode layer). Secondary, silver nanoparticles are printed as fine circuit patterns and sintered at optimal temperature (seed layer). Thirdly, copper was selectively deposited on seed layer by means of SED, which utilizes the potential difference between electrode and seed layers. The SED proceeds through isotropic growth along vertical direction because the deposition occurs on the surface of seed layer contacted with the membrane. Therefore, SED can produce relative thick and fine patterns following line width of seed layers. Finally, the bear electrode layer is etched away by plasma exposure. We believe that this approach is highly promising process to fabricate circuit pattern in terms of cost (simple step) and environmental (no exhaust fluids) point of view. 1. H. Yanagimoto, R. Mori, K. Okamoto and J. Murai, F01-994, 236nd ECS Meeting. 2. Y. Narui, Y. Hoshi, I. Shitanda, M. Itagaki, H. Yanagimoto, M. Hiraoka and H. Iisaka, E01-920, 232nd ECS Meeting. Figure 1