Electrochemistry
Online ISSN : 2186-2451
Print ISSN : 1344-3542
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77 巻 , 8 号
選択された号の論文の53件中1~50を表示しています
論文特集号 溶融塩 • イオン液体 — 新しい液体材料の体系化をめざして
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  • Klaus FUNKE, Monika MUTKE, Ana ŠANTIĆ, Radha D. BANHATTI, ...
    77 巻 (2009) 8 号 p. 573-581
    公開日: 2012/03/22
    ジャーナル オープンアクセス
    Conductivity and fluidity spectra of two room temperature ionic liquids, BMIm-BF4 and HMIm-BF4, taken at different temperatures, are presented and compared with each other. BMIm-BF4 and HMIm-BF4 are short for 1-butyl-3-methyl-imidazolium tetrafluoroborate and 1-hexyl-3-methyl-imidazolium tetrafluoroborate, respectively. In their temperature and frequency dependences, flow of charge and shear flow are found to display close similarities. The distinguishing features of the ion dynamics in fragile ionic liquids as compared to ionic solids are seen to arise from the absence of a network that provides pre-formed vacant sites for the ions to move in. In ionic liquids, the dispersive behaviour of the frequency-dependent conductivity is thus characterized by a temperature-independent end frequency. This key feature, along with Arrhenius activated elementary displacements, is shown to yield the well-known non-Arrhenius temperature dependence of the DC conductivity. In Arrhenius-type plots, DC conductivity and fluidity can be superimposed over the entire temperature range above the glass transition. As a consequence, ionic conduction and shear flow can be traced back to elementary displacements with identical activation energy. On the inverse temperature axis, a small positive shift, Δ=(1/T−1/T), is required for the superposition. Remarkably, fluidities taken at temperature T correspond to conductivities taken at the slightly lower temperature T not only at DC, but in the entire frequency range studied. Indeed, according to the data as well as to our modelling, the entire conductivity and fluidity spectra superimpose when considered at T and T, respectively, with identical values of their end angular frequency. The still unknown time correlation function for shear flow is hence expected to have significant features in common with the current density autocorrelation function.
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  • Takatoshi HIJIKATA, Masaki KURATA
    77 巻 (2009) 8 号 p. 702-708
    公開日: 2012/03/22
    ジャーナル フリー
    Low-temperature chlorination of zirconium dioxide using molybdenum pentachloride has been investigated below 773 K. The chlorination ratio was measured by chemical analysis, and the products were identified by powder X-ray diffraction. The results indicated that substitution of chlorine using molybdenum pentachloride significantly reduces the reaction temperature. Almost all the zirconium dioxide was converted to chloride in 30 minutes at 668 K when the molar ratio of molybdenum pentachloride to zirconium dioxide exceeded two. The chlorination reaction between zirconium dioxide and molybdenum pentachloride was shown to be a three-dimensional diffusion reaction satisfying the Jander equation, and the activation energy was 67 kJ/mole. Chlorination at a practical reaction rate using molybdenum pentachloride was realized at much lower reaction temperature than that using chlorine gas and carbon.
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  • Yasushi TABEI, Mikito UEDA, Toshiaki OHTSUKA, Toshiharu YAMASHITA
    77 巻 (2009) 8 号 p. 709-712
    公開日: 2012/03/22
    ジャーナル フリー
    To make functional glasses, ion-exchange treatment of the glass surface was carried out in TlNO3-NaNO3 molten salt at 673 K and 723 K for various time periods, and then the Tl ions embedded in the glass were reduced to metallic Tl nanoparticles by hydrogen gas. The color of the glass containing metallic Tl nanoparticles changed to brown or black. The Tl nanoparticles were detected by a qualitative TEM analysis. The optical absorption spectra of these treated glasses showed a peak at about 370 nm. With increases in the temperature of the molten salt, the band intensity of the absorption is enhanced. The absorption increase may correspond to larger particle sizes and densities with the increase in temperature. The Tl nanoparticles with 10–150 nm diameter were observed at neighboring parts of the glass surface by TEM and FE-SEM.
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  • Tomohiro ISOGAI, Takaaki NAKAI, Kenta NAKANISHI, Minoru INABA, Akimasa ...
    77 巻 (2009) 8 号 p. 713-720
    公開日: 2012/03/22
    ジャーナル フリー
    The effects of HF content on the ionic conductivity and the viscosity of low temperature molten fluorides, (CH3)4NF·mHF, (CH3)3mHF, KF·mHF, and NH4mHF melts, were investigated. The ionic conductivity of the (CH3)3mHF and (CH3)4NF·mHF melts increased, whereas their viscosity decreased with increasing the m value. The ionic conductivity and the viscosity of the (CH3)3mHF melts were lower and higher, respectively, than those of the (CH3)4NF·mHF melts at a given m value and a given temperature. The activation energy for ionic migration decreased with increasing the m value in both systems. Similar effects of the m value on the conductivity and viscosity were obtained for the KF·mHF and NH4mHF melts. The KF·mHF melts exhibited lower conductivity and higher viscosity than the NH4mHF melts at a given m value and a given temperature. It was concluded that these effects of the HF content can be explained in terms of the concentration change of molecular HF and the resulting change in electrostatic cation-anion interactions.
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  • Minoru MIZUHATA, Tatsuo OHTA, Shigehito DEKI
    77 巻 (2009) 8 号 p. 721-724
    公開日: 2012/03/22
    ジャーナル フリー
    Raman spectra and the polarization behaviors of molten alkali carbonates coexisting inorganic powder were measured. The deformation and the change of polarization properties by the coexisting with the solid phase are discussed. The symmetry of the band shape of the Raman spectra for CO32− stretching band (ν1) was deformed asymmetrically by coexisting with α-Al2O3 powder. The deconvolution of spectra of mixtures exhibited two band components. The observed bands are evidence of the existence of two different types of CO32− ions in these systems. Raman depolarization ratio for molten carbonate systems increases from the base line with the decrease of the apparent average thickness. The degree of the anomalous behavior of the molten carbonate by the solid phase have been observed in the order of α-Al2O3>γ-LiAlO2>ZrO2 which is related to the surface acidity defined by the value of point of zero charge (pzc). Consequently, the carbonate ion is deformed asymmetrically by coexisting with inorganic oxide powder.
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  • Minoru MIZUHATA, Takeshi MINOWA, Shigehito DEKI
    77 巻 (2009) 8 号 p. 725-729
    公開日: 2012/03/22
    ジャーナル フリー
    The effects of secondary cationic species on the ordering structure in room temperature ionic liquids (RTILs) are discussed. Binary RTILs refer to mixture of trimetyl-n-octylammonium bis(trifluoromethanesulfonyl)imide (N1118[TFSA]) and alkali or alkali-earth metal bis(trifluoromethanesulfonyl)imide (M[TFSA]y; M=Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba) in an appropriate molar ratio (x=0.1, 0.2, 0.3, 0.5), denoted as Mx[N1118]1−x[TFSA]1−x+xy. From SAXS and WAXS measurements of Mx[N1118]1−x[TFSA]1−x+xy, the intensity of first peak derived from the ordering structure increases with addition of M[TFSA]y. It is suggested that the metal cation has an intensive interaction with TFSA anion and cationic structural ordering are enhanced. We discussed the relationship between ionic size and the formation mechanism of the local ordering structure in binary ionic liquids containing alkali metal and alkali earth metal based on aliphatic quaternary ammonium (AQA) cations is clarified.
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  • Hongtao JIANG, Ning AI, Min WANG, Dengxiang JI, Jianbing JI
    77 巻 (2009) 8 号 p. 730-735
    公開日: 2012/03/22
    ジャーナル フリー
    Pyrolysis of biomass in molten salt media have been conducted in a stainless steel reactor. Five kinds of mixed molten salts were used as thermal pyrolysis media and six kinds of biomass as feedstock. The experiments were carried out under atmospheric pressure and 400–600°C. The pyrolysis oils were examined using some spectroscopic and chromatographic analysis techniques. The effects of the type of molten salts and feeding conditions, reaction conditions, including temperature and space velocity, on yield of liquid product were investigated. This paper reports the feasibility for producing bio-fuels and bio-chemicals through the pyrolysis of biomass in molten salt media.
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  • Yasuhiko IWADATE, Haruaki MATSUURA, Akihiko KAJINAMI, Keiichi TAKASE, ...
    77 巻 (2009) 8 号 p. 736-740
    公開日: 2012/03/22
    ジャーナル フリー
    Local structure of molten lanthanum trichloride—alkali chloride ternary systems was analyzed in terms of Raman spectroscopy and pulsed neutron diffraction in order to accelerate the realization of pyrochemical reprocessing of nuclear spent fuels. In particular, not only vibrational modes of ionic species existing in molten LaCl3-ACl-NaCl (A=Li, K, Rb, and Cs) systems but also short range structure in molten LaCl3-CsCl-NaCl system on behalf of the systems described before were reported in some detail, the salt combinations of which could be of prototype in the reprocessing of UO2 and/or PuO2.
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  • Yasuhiko IWADATE, Takumi HARADA, Takahiro OHKUBO, Kazuko FUKUSHIMA, Ma ...
    77 巻 (2009) 8 号 p. 741-744
    公開日: 2012/03/22
    ジャーナル フリー
    The short-range structural parameters for NaNO2 and KNO2 pure melts were determined by the time-of-flight neutron diffraction. The precise analyses of structural parameters obtained such as coordination number, interatomic distance, and temperature factor allowed us to conclude that (1) there exist stable NO2 anions in the melts, (2) NO2 anions behave like NO3 anions due to the existence of lone pairs of electrons, (3) the short-range structure of KNO2 pure melt is similar to that of NaNO2 pure melt but the cation site relative to anion is a little different from each other in terms of the cation size effect.
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