津田 哲哉

The electrodeposition of AlIn, AlSb, and AlInSb alloys was examined at copper rotating wire electrodes in the Lewis acidic 66.7-33.3 mol.% (m/o) aluminum chloride-1-ethyl-3-methylimidazolium chloride room-temperature ionic liquid. The Sb content in the AlSb binary electrodeposits depended on the applied current density, but the In content in the AlIn alloys was quite low, similar to 1 at.% (a/o), and independent of the current density. Variation of the partial current densities for the In and Sb during AlInSb deposition suggested that the deposition of a second phase rich in In and Sb, possibly InSb, occurs simultaneously at higher applied current densities. However, no X-ray diffraction patterns are apparent in these deposits other than that for face-centered cubic Al. Thus, the AlInSb deposit most likely consists of a non-equilibrium mixture of Al(x)In(y)Sb(100-x-y) and amorphous or nanocrystalline InSb. The AlInSb alloy semiconductor deposits prepared during this investigation exhibited photocatalytic behavior and could catalyze the photodecomposition of water under illumination with visible light. (C) 2007 Elsevier B.V. All rights reserved.

The anodic electrode behavior for a p-type silicon single crystal electrode ((10 0), p = 0.01-0.02 Q cm, boron doped) was examined in the 1-ethyl-3-methyl imidazolium fluorohydrogenate, EtMeIm(FH)(2.3)F, room-temperature ionic liquid (RTIL). The electrochemical behavior was very similar to that in conventional HF aqueous solution. After the anodic electrode reaction, the Si electrode was uniformly covered with a mesoporous Si layer having a pore size of similar to 25 nm. The mesoporous layer did not exhibit a photoluminescence spectrum in the visible region due to the lack of Si-H termination. However, after chemical treatment with an ethanolic HF solution, a subset of the porous Si samples showed a very weak photoluminescence. (c) 2007 Elsevier Ltd. All rights reserved.

Investigation on alkali fluoride-HF system has been initiated in the 19th century. The technique is currently utilized in fluorine-chemical industry. But, the problem is that this system readily releases hazardous HE Although organic base, e.g., amine, with HE which is mainly applied to fluorination treatment for organic compound, reduces the HF release, the solution still requires careful handling because of limited amount of free HE Recently family of fluorohydrogenate room-temperature ionic liquid, XF(HF)(2.3), that consists of heterocyclic ammonium cation (X+), F(HF)(2)(-), and F(HF)(3)(-), has gotten a lot of attentions due to the interesting physicochemical properties such as negligible vapor pressure (<7.5 x 10(-3) Torr (=1 Pa) at 298 K), high conductivity, and low corrosiveness. This novel solvent will greatly contribute to development of fluorine chemistry. In this article, fundamental techniques and physicochemical data on the fluorohydrogenate RTIL are summarized, and molecular science in the dialkylimidazolium fluorohydrogenates leading to the understanding of the unusual properties is reviewed based on recent experimental and theoretical considerations. (C) 2007 Elsevier B.V. All rights reserved.

The electrodeposition of Al-Mo-Ti ternary alloys was examined in the Lewis acidic 66.7-33.3% mole fraction aluminum chloride-1-ethyl-3-methylimidazolium chloride (AlCl3-EtMeImCl) room-temperature ionic liquid containing (Mo6Cl8) Cl-4 and TiCl2. The Mo content in the alloys varied with the applied current density and the Mo(II)/Ti(II) concentration ratio. The content was small and constant at 0.6 +/- 0.2% atomic fraction (a/o) and was independent of the deposition conditions. All the electrodeposited Al-Mo-Ti alloys were dense and compact and adhered well to the copper substrate. The deposit surface morphology depended on the applied current density and the Mo content of the alloys, as reported previously for the amorphous binary Al-Mo alloys. However, no amorphous glass phase could be detected in the Al-Mo-Ti ternary alloy samples; this behavior may be related to the presence of Ti. In summary, the addition of a small amount of Ti ( similar to 1 a/o) to the binary Al- Mo alloys resulted in a ternary alloy with a substantially improved chloride-induced pitting corrosion resistance compared to the related Al- Mo alloy. (c) 2008 The Electrochemical Society.

Urea-EtMeImCl mixtures have melting points from 333 to 363 K at 10-80 mol% urea, and, at temperatures > 343 K, these melts show the highest conductivity reported to date for urea-based binary melts.

Because aluminum is a less-noble metal which has the standard electrode potential of -1.676 V vs normal hydrogen electrode, it is impossible to obtain the electrodeposition of aluminum from an aqueous solution. No one has reported an electroless plating method of aluminum. We succeeded in demonstrating the electroless plating of aluminum from a room-temperature ionic liquid (RTIL). It was found from measurements of inductively coupled plasma, X-ray diffraction, scanning electron microscopy (SEM), SEM-energy-dispersive X-ray analysis, and glow discharge optical emission spectroscopy that dense, smooth, and pure aluminum plating was obtained from the RTIL by the electroless plating method. Moreover, the reaction mechanism of the electroless plating of aluminum from the RTIL electrolyte was electrochemically analyzed. (c) 2007 The Electrochemical Society.

The direct electrolytic reduction of solid SiO2 has been investigated in molten CaCl2 at 1123 K aiming at the production of solar grade Si (SOG-Si). The target impurity levels for Si in the present study were calculated from the acceptable impurity levels for SOG-Si and the segregation coefficients for the impurity elements. New types of SiO2 contacting electrodes, in which SiO2 directly contacts with only Si, were devised to reduce metal contaminations in the produced Si. By using the new SiO2 contacting electrodes and a quartz vessel, most of the metal impurities were significantly reduced to be below the target levels. When NH4OH/H2O2/H2O, HCl/H 2O2/H2O and HF/H2O 2/H2O were used as a cleaning solution, remaining CaCl2 and some metal impurities in the produced Si were removed effectively. A basket type electrode was also tested for the reduction of granular SiO2. ©The Electrochemical Society.

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