Masayuki Nagai

Nano-characterization of a nafion thin film in air and in water by atomic force microscopy

Surface structures of nafion films under various conditions were studied using an atomic force microscope (AFM). First, we observed that nanosize pores formed on a nafion film surface when the film was prepared on a glass substrate; however, such pores did not appear on a metal surface. Second, in the case of a hybrid film of nafion and platinum/carbon (Pt/C), the surface morphology in water was different from that of a pure nafion film; however, it was not significantly different from that in air. Third, nanosize cracks appeared when a nafion film was heated at around 100 °C. Last, the effect of hydration on AFM nanolithography in liquids is discussed.

Intermediate Temperature Fuel Cell Using Gypsum Based Electrolyte And Electrodes

The proton conductive electrolyte membrane and the electrodes for intermediate temperature fuel cell were made from the phosphoric acid treated gypsum as a proton conductor. The membrane and the electrodes were built into single cell and tested at intermediate temperature region. The power density of the fuel cell was 0.56 mW/cm−2 at 150 °C without any humidification and 1.38 mW/cm−2 at 150 °C, 5% relative humidity. The open circuit voltage of the cell was increased higher than 0.7 V when the electrodes were annealed at 150 °C, 5%R.H., however the reasons for this are still to be further investigated. The results show that the potential of the phosphoric acid treated gypsum for the intermediate temperature proton conductor.

Dissolution of Sparingly Soluble Inorganic Compound to Aqueous Suspension with Ion Exchange Resin (Part 11)-Octacalcium Phosphate-

The dissolution process of octacalcium phosphate (Ca8H2(PO4)6•5H2O, OCP) using a strongly acidic ion exchange resin with a hydrogen form (H-R) suspended in water was examined in detail to confirm the formation of CaHPO4•2H2O (DCPD) as an intermediate. The reactivity of OCP, α- or β- tricalcium phosphate (α- or β-TCP), or tetracalcium phosphate (Ca4(PO4)2O, TetCP), with Ca(H2PO4)2 solution to form DCPD was compared using calorimetry and chemical analysis. The reactivity increased in the order of TetCP=α-TCP»OCP≥β-TCP. The structure of OCP consists of “apatite layer” and “hydrated layer.” The “apatite layer” of OCP was examined by comparing the reactivity of DCPD+hydroxyapatite (HAp) and DCPD+β-TCP with H-R where HAp and β-TCP imitated the “apatite layer.” The results suggested that the “apatite layer” in OCP would be similar to β-TCP rather than HAp in terms of the reactivity.