Masakazu Sakaguchi

Characterization of the Three‐Phase Equilibrium on a Porous Electrode for Fuel Cell

The stability of the three-phase interface involving the solid catalyst on carbon carrier, liquid electrolyte solution, and fuel gas found in a porous electrode was investigated by means of a radioisotope tracer method for the electrodes prepared from carbon carriers with various fine structures. Higher electrode activity was observed for the electrode prepared with a perovskite-type LaNi 0.99 Cu 0.01 O 3 catalyst and a carrier which consisted of a secondary particle crowd due to the aggregation of fine particles

Detection of latent finger-print by autoradiography

An autoradiographic method is described for the detection of latent finger prints. Radioactive compounds are allowed to react with substances contained in a latent print, after which the material is placed in contact with photographic film. Finger prints were detected after a week on metal, glass, paper, and textile fabrics. (C.H.)

Electrical Conductivity of Alkali Metal Sulfate Crystals

Department of Applied Chemistry, Faculty of Engineering Niigata University; Ikarashi, Niigata-shi 950-21 Japan The polarization phenomena of various samples of alkali metal sulfates: consisted of monocomponent and binary-component sulfates in the forms of 1) compound, 2) solid solution, and 3) mixture; were investigated in a DC electric field at 260° under various atmospheric conditions (vacuum, O2, and NH3). It is clear from Fig.5 that the surface electrical conductivity (σ) of each sample was affected by two kinds of polarization phenomena. One occurred immediately after applying a voltage then σ decreased abruptly in the sample which had the lower conductivity, another occurred slowly and the decrease of σ emerged remarkably in the sample which had the higher conductivity. Such polarization phenomena of all samples were most obviously found in vacuum. In O2 flow, σ of a Na2SO4 sample and a O2-pretreated Li2SO4 sample increased initialy (Fig.6). This can be interpreted, in terms of diffusion of O2 into the crystal as a carrier owing to Hedvall effect with the phase transition reaction. In NH3 flow, σ of mono-component samples increased in the order of Li2SO4<K2SO4<Cs2SO4(Fig.7). These facts are considered to result from an addition of electron conductivity caused by the formation of ammonia-complex. The formation of the complex was more easily achieved against the electronegativity of the positive element in the samples. Exceptionally, no polarization phenomenon was observed in a Na2SO4 sample. This suggests that Hedvall effect with the phase transition reaction promoted the formation reaction of ammonia-coinplex which had electron conductivity.

Formation Mechanism of the Chemical Vapor on the Vapor Transport of ZnS Crystal

In order to clarify the formation mechanism of the chemical vapor concerning the vapor trantsport of ZnS crystal using HCl as agent, the sorption of HCl on the surface of ctystal and the diffusion of chlorid ion into the bulk of crystal were investigated.Below 0.1atm of HCl, the amounts sorbed and diffused chloride ion increased exponentially with increasing pressure, but around 0.1atm, the amounts decreased suddenly, then increased again with incireasing pressure. By mixing He, the sharp decrease of the amounts of sorbed and diffused chloride ion around O.1atm was not recognized. Below O.1atm, the most of the diffused chloride ion was localized in the near surface of the crystal. Above O.1atm, the sintering of ZnS particles progressed remarkably and the chloride ion distributed uniformly throughout the bulk of crystal. On lengthening the firing time, the diffused chloride ion was segregated gradually on the grain boundaries of the crystal, then formed ZnCl2, which sublimed.From these results, the formation mechanism of ZnCl2 at the gas-solid interface corncerning the chemical vapor transport of ZnS crystal was discussed.