The viscosities of 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF 6 ]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF 4 ]) were measured by using a rolling-ball viscometer. The experimental temperatures were from 293.15 to 353.15 K, and the pressures were from 0.1 to 20.0 MPa.

Thermal conductivities are reported for a series of 1-alkyl-3-methylimidazolium hexafluorophosphates having butyl, hexyl, and octyl groups, which are expressed by [bmim][PF 6 ], [hmim][PF 6 ], and [omim] [PF 6 ], respectively. The experimental method used was a transient short-hot-wire method. Since only a small amount of sample liquid is required, this method was found to be effective for the thermal-conductivity measurements of ionic liquids (ILs). The experimental temperatures ranged from 294 to 335 K at pressures up to 20 MPa. The values of the thermal conductivities of ILs at normal pressure are similar to those of benzene. It was found that an effect of the length of the alkyl chain on the thermal conductivities in ILs is negligible. From the data for the thermal conductivity and viscosity at 293.15 K and 0.1 MPa of ILs and normal alkanes, a simple correlation was developed based on the Mohanty theory. From comparisons between the thermal conductivities of ILs and those of organic liquids (n-hexane, benzene, and methanol), the temperature and pressure dependences of the thermal conductivity of ILs are relatively weak.

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The reaction mechanism of the most commonly used anode material, Ni/yttria-stabilized zirconia ͑YSZ͒ cermets, in H 2 -H 2 O solid oxide fuel cells ͑SOFCs͒ was investigated. Because the reaction mechanism for the Ni/YSZ anode in H 2 has not been conclusively determined, we investigated the detailed dependence of dc polarization and interfacial conductivity of Ni/YSZ cermet anode on the partial pressure of hydrogen (p H 2 ). Based on our experimental results, we developed a model that links the chemical reactions on the anode with the electrical characteristics of the anode such as the dc polarization and the interfacial conductivity. In our model, we assumed competitive adsorption equilibrium of H 2 , H 2 O, and O on Ni surfaces at the three-phase boundary, and assumed the rate-determining step to be Langmuir-type reactions of H with O. In SOFCs with Ni/YSZ anodes, reported dependencies of the current and interfacial conductivity on p H and p H 2 O differ among previous studies. Both our measured dependencies and previously published dependencies were successfully reproduced by our Langmuir reaction model. Furthermore, possible reasons for these different observed dependencies include the different adsorption equilibrium constants.

The viscosities of 1-hexyl-3-methylimidazolium hexafluorophosphate ([hmim][PF 6 ]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([omim][PF 6 ]) were measured with a rolling ball viscometer. The experimental temperatures were from (293.15 to 353.15) K and pressures were up to 20.0 MPa. The experimental values were correlated with a Vogel-Tamman-Fulcher (VTF) equation and a Tait-form equation.

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