A new apparatus for the evaluation of catalysts in the gas diffusion electrodes is proposed. A test specimen of catalyst loaded on carbon paper is mounted in Teflon holder and partially immersed in test solutions. The specimen is designed to revolve in the air and solution phases, thereby experiencing alternate contacts with gas | liquid phases. The reactant oxygen appears to be supplied mostly when the surface of the electrode is in the gas phase, which then brings about the cathodic current when the surface is in the liquid phase. After testing several kinds of catalysts, it is established that the apparatus successfully simulates the conditions of gas diffusion electrodes, and can be used in assessing such catalysts for fuel cells.
Metal oxide thin films such as TiO2, ZrO2 and ZrTiO4 were fabricated from metal oxide precursor solutions by a dip-coating method, and were tested as hydrocarbon gas sensors. The solutions were prepared by the dehydration and polymerization processes of metal alkoxides in a benzene-butanol-water solution. This preparation method of the precursor solution was named “advanced sol-gel method”. The transparent surface of ZrO2 film was homogeneous and uniform. The similar morphology was observed on other oxide films. When these films were tested as hydrocarbon gas sensors, TiO2 film showed good response and sensitivity. It exhibited better sensitivity to propane than to methane. The response and recovery times for both gases were less than 30 sec at 500°C.
The filling of deep-sub micrometer through-holes and trenches with a high aspect ratio by the high vacuum planar magnetron sputter deposition of copper, which even at pressures lower than 10−5 Pa the discharge can be sustained by the applying of a high magnetic field and high target voltage, is investigated. It is found that good filling is achieved in a 1% nitrogen atmosphere at a low sputter pressure of 0.1 Pa, yielding copper films with resistivity of approximately 2 × 10−8 Ωm, equivalent to that prepared by the pure argon sputter.
Damascene process has become a key technology as a manufacturing method of the semiconductor devices. In this research, copper filling of submicron vias and trenches on the silicon wafer by copper electroplating was examined. Complete void-free copper filling of submicron width trenches was obtained by the addition of polyethylene glycol (PEG) and bis (3-sulfopropyl) disulfidedisodium (SPS) as the additives to the copper electroplating bath. However, the overplate phenomenon was often observed in this case. This phenomenon may cause the improper polishing on the following chemical and mechanical polishing process (CMP). This paper describes the effect of additives on the copper filling by electroplating and eliminates the overplate phenomenon by the combination of the additives.
A study was conducted by using SEM and AFM to evaluate the micro-structure of the corroded surface of two kinds of graphitized carbon fibers with different graphite crystal orientation, i.e., the one of an onion-skin with random core structure and the other of simply a radial structure, respectively. It became clear that the former carbon fiber was corroded to increase its roughness on its surface slightly, while the latter was corroded to increase the surface roughness by more than three times (Ry) or six times (Ra) of the former. These results show that corrosion behavior of the carbon fiber changed by the orientation of graphite crystallite planes in both carbon fibers and the orientation of graphite crystallite planes is an important factor for corrosion resistance along the graphitizability of the carbon fiber. Also, it was considered that these results are useful for other electrochemical applications, i.e., polymer electrolyte fuel cells with phosphoric acid fuel cells.
Manganese dissolution from spinel LiMn2O4 cathode material is one of the origins of a significant capacity fading with cycling for rechargeable lithium ion batteries. To suppress the manganese dissolution, the Li1+xMn2−xO4 (0 ≤ x ≤ 0.1) spinels were prepared. Their cycle performances and the amount of manganese dissolution from the spinels in charged state into an electrolyte were investigated to confirm that the manganese dissolution was suppressed in the lithium-doped spinels system. As a result, it was found that the rate of manganese dissolution decreased and the cyclability was improved with increasing doping amount of lithium in the spinel compound due to stabilizing the spinel structure by substituting lithium for manganese in 16d sites.