ZnO powders were heated in different atmospheres at 800 and 1400°C, of which the characterization was studied by X-ray diffraction, and hydrogen peroxide generated from the surface of ZnO powder was measured. The diffraction peaks corresponding to zinc oxide with hexagonal type structure were detected in all samples. From the results of calculating lattice constants, a₀ and c₀, it was found that the value of c₀ in hexagonal structure increased with the increase in the oxidizability of atmosphere. However, no change of the a₀ value showed, irrespective of atmosphere and temperature. Hydrogen peroxide was found to generate from all samples, of which the generation amount increased with the increase in the oxidizability of atmosphere.

Lead impurities on Si surface after the chemical etching and cleaning process were evaluated by measuring the work function in the silicon chip of the mesa structure. The ultraviolet rays photoelectron analysis in the air and the Maxwell stress microscope analysis were used for the evaluation. The values of the work function on Si surface are influenced by the cleaning technique. The part of low work function corresponds to Pb impurities observed by SEM.

The Li/Na carbonate is expected to be the one of the candidates for the advanced electrolyte of Molten Carbonate Fuel Cells (MCFC) especially under the pressurized operation. After the long-term operation of cells with the Li/Na carbonate, the Ni deposition in matrices, degradation of cathodes, matrices and cathode current collectors were analyzed. With the Li/Na carbonate, the amount of the Ni deposition and the particle growth of NiO in cathodes were suppressed by the less solubility of NiO. Moreover, there were no detectable differences on both the particle growth and the phase transformation of γ-LiAlO₂ in the matrices. The extraordinary effects on the corrosion penetrations and the electrolyte losses of the cathode current collectors by the Li/Na electrolyte were not detected. Therefore, the MCFCs with the Li/Na carbonate are expected to have a longer endurance and a lower decay rate compared with conventional cells with the Li/K carbonate, because of less dissolution of the NiO cathode related to both the short circuiting and the lower increase of polarization due to the structural changes of cathodes.

A smart carbon dioxide gas sensor applicable for the gas monitoring has been successfully realized by the conjunction of trivalent cation and divalent anion conducting solid electrolytes with a water insoluble Li and Ba codoped Nd₂O₂CO₃ solid solution as an auxiliary detecting electrode. The present sensor shows a rapid and continuous response and the sensor output obeys the Nernst relationship, showing a theoretical response. The sensor possesses such unique characteristics not to be interfered with the coexisting gas species such as water vapor, nitrogen oxides and also oxygen, etc. demonstrating a satisfactory performance for a practical in-situ application.

Magnesium hydroxide powder for flame retarder of plastics must have hydrophobic property for providing good dispersion state during mixing the powder and plastics having hydrophobic property. In order to evaluate the character as a flame retarder of magnesium hydroxide powders treated with stearic acid and a silane coupling reagent, potentiometric titrations were done for dispersions consisting of the powder and aqueous solution of LiClO₄ and TritonX-100 as a wetting agent. The acid-base reaction was Mg(OH)₂ + 2HNO₃ → Mg(NO₃)₂ + 2H₂O which proceeded for the powder without the surface treatment reagents in the pH range between 10 and 10.5. The titration curves obtained for the powders with the reagents shifted to the pH reagion below 10 due to inhibition of the reaction by the reagents at the powder surface. The shifting degree was greater with increase in the amounts of the reagents at the surface. The powders yielding greater shifting, viz., serious reaction inhibition were found to be excellent flame retarder, which can be easily compounded with ethylene-ethylacrylate copolymer as a covering plastic for electric wire under lower torque of mixing machine to provide composites having better characteristics on elongation, tensile strength and electrical resistance per unit volume as the physical poroperties. The potentiometric titration method used was found to be very useful for evaluation of the magnesium hydroxide powder for flame retarder.

The wastewater treatment system using denitrification apparatus by the electrolytic method was developed. The bench-scale-size system which capacity is 1～2 m³/day and tank volume is 55 L, was produced by experiment. The conversion of nitrate ion, nitrite ion and ammonium ion to nitrogen gas was 90% after 60 minutes of reaction. The concentration of nitrate ion, nitrite ion and ammonium ion in the initial reaction solution was 1860 mg L⁻¹, 330 mg L⁻¹ and 540 mg L⁻¹ (Total-N 900 mg L⁻¹). In this method, the highly-activated electrodes were used as a Cu-Zn cathode and a Pt/Ru/Ti anode. The main electrolytic reaction of nitrate removal involved cathodic reduction of NO₃⁻ to NH₃ (NO₃⁻ + 6H₂O + 8e → NH₃ + 9OH⁻) and anodic oxidation of Cl⁻ to HClO (2Cl⁻ → Cl₂ + 2e⁻, Cl₂ + H₂O → HClO + HCl), and finally got N₂ by redox reaction (2NH₃ + 3HClO → N₂ ↑ + 3HCl + 3H₂O). Ampholyte element (Al, Zn) contributed to the rise of cathodic reduction. The performance of denitrification apparatus was analyzed by the measured data. As a result, it was concluded that the power consumption for denitrification was 20≫60 kWh/kg-N by this method.