Tadahiko Mizuno

Controlled formation of metallic nanoballs during plasma electrolysis

Formation of spherical nanoparticles (hereafter “nanoballs”) in a gas/liquid mixed dual phase system during plasma electrolysis is reported. A gas/vapor sheath is formed at the electrode/electrolyte interface when the applied voltage is high enough to induce discharge plasma. Through this nonequilibrium process, the authors have produced Ni, Ti, Ag, and Au metallic nanoballs from the cathode mother materials with a certain size controllability. The electrode surface is partially melted by the local current concentration induced by electrothermal instability followed by an immediate cooldown, yielding nanoballs without contamination from electrolyte.

Hydrogen Evolution by Plasma Electrolysis in Aqueous Solution

Hydrogen has recently attracted attention as a possible solution to environmental and energy problems. If hydrogen should be considered an energy storage medium rather than a natural resource. However, free hydrogen does not exist on earth. Many techniques for obtaining hydrogen have been proposed. It can be reformulated from conventional hydrocarbon fuels, or obtained directly from water by electrolysis or high-temperature pyrolysis with a heat source such as a nuclear reactor. However, the efficiencies of these methods are low. The direct heating of water to sufficiently high temperatures for sustaining pyrolysis is very difficult. Pyrolysis occurs when the temperature exceeds 4000°C. Thus plasma electrolysis may be a better alternative, it is not only easier to achieve than direct heating, but also appears to produce more hydrogen than ordinary electrolysis, as predicted by Faradays laws, which is indirect evidence that it produces very high temperatures. We also observed large amounts of free oxygen generated at the cathode, which is further evidence of direct decomposition, rather than electrolytic decomposition. To achieve the continuous generation of hydrogen with efficiencies exceeding Faraday efficiency, it is necessary to control the surface conditions of the electrode, plasma electrolysis temperature, current density and input voltage. The minimum input voltage required induce the plasma state depends on the density and temperature of the solution, it was estimated as 120 V in this study. The lowest electrolyte temperature at which plasma forms is ~75°C. We have observed as much as 80 times more hydrogen generated by plasma electrolysis than by conventional electrolysis at 300 V.

Titanium concentration in FeTix (l ⩽ x ⩽ 2) alloys and its effect on hydrogen storage properties

Abstract The effect of the surface and bulk properties of FeTix (1 =⩽ x ⩽ 2) on its hydrogen storage characteristics was investigated by X-ray photoelectron spectroscopy, Mossbauer spectroscopy and metallographic observations. It is shown that several problems encountered with FeTi, such as the necessity of employing activation treatment and the surface sensitivity resulting from poisoning by impurity gases, can be reduced if alloys with a non-equilibrium structure are prepared by the addition of excess titanium.

Production of Heat during Plasma Electrolysis in Liquid

Plasma was formed on the surface of an electrode in a liquid solution when metal cathodes underwent high-voltage electrolysis. A real-time heat calibration system was designed for detecting the amount of heat generated during plasma electrolysis. The measured heat exceeded the input power substantially, and in some cases 200% of the input power. The heat generation process depended on the conditions for electrolysis. There was no excess heat at the beginning of plasma electrolysis. However, after plasma electrolysis for a long time, a large amount of heat was generated. The reproducibility would be 100% if all factors such as temperature, voltage and duration were optimized. Based on the heat and the products, we hypothesize that some unique reaction occurs on the cathode surface. This reaction may not occur at energy levels available during electrochemical electrolysis.

Light Emission from Pt during High‐Voltage Cathodic Polarization

Light emission from cathodically polarized Pt electrodes was investigated at cell voltages up to 200 V in aqueous electrolyte solutions. The emission of light was observed when intense cathodic polarization caused the temperature of the Pt electrodes to exceed the boiling temperature of the electrolyte. A thin vapor layer was formed at the metal‐electrolyte interface in which a high electric field ionized vapor molecules to generate a plasma state. The emission of light was caused by the glow discharge at relatively low cell voltages and by the spark discharge at high cell voltages. The spectra of the emitted light were assigned to the constituents of the electrolyte solution, electrode material, and gaseous hydrogen evolved at the electrode.

Monitoring of Hydrogen Absorption into Titanium Using Resistometry

Hydrogen absorption into Ti electrodes during electrochemical cathodic polarization was monitored using resistometry. Electric resistance of Ti increased with H absorption due to growth of a hydride layer from the surface toward the inside. The growth rate of the hydride layer was estimated from resistance data and was found to depend on the polarization current density, existence of a preformed anodic oxide film, and shape of the specimen. For example, preformation of an anodic oxide film at a potential higher than the breakdown potential, rather, promotes hydrogen penetration. In the case of a thin wire electrode, the hydride layer grew in a nonuniform manner because the volume expansion induced cracking on the surface. Therefore, the average thickness of the hydride layer was estimated from the change in resistance.

Production of Stable Isotopes by Selective Channel Photofission of Pd

A conservative modeling and analysis were attempted to explain the presence of nonradioactive fission-like products with nonnatural isotopic ratios observed in some D2O/Pd electrolysis experiments. The collective deformation of a Pd nucleus by multiphoton E1 resonance absorption in a dynamic PdDx lattice was assumed to induce low-energy photofissions via the selective scission channels within the lowest band (11–20 MeV) of channel-dependent fission barriers. Values of channel dependent fission barriers were calculated by using liquid drop model potentials for Pd isotopes. Fission products were analyzed in detail. Major fission products (FPs) are stable isotopes and the isotopic ratios of FP elements are very different from those of natural abundances. The present theoretical results have shown good agreement with the experimental data of Mizuno et al.. [Denki Kagaku 64 (1996) 1660] and others in terms of Z-distribution, mass distribution and isotopic ratios. Selective channel photofissions with positive Q-values are possible for A>90 nuclei, which may provide us with a clean method for the incineration for the radio isotope (RI) waste of nuclear plants.

Effect of far-infrared light irradiation on water as observed by X-ray diffraction measurements

X-ray diffraction measurements were made on water irradiated with far-infrared (FIR) light. It was found that the X-ray diffraction intensity at a 2θ angle of 30° increased by about 2 times with the irradiation. The increase in the X-ray diffraction intensity was interpreted in terms of the destruction of water clusters.

Transmutation in the Electrolysis of Light Water—Excess Energy and Iron Production in a Gold Electrode

The identification of some reaction products possibly produced during the generation of excess energy is attempted. Electrolysis is performed for 7 days with a constant current intensity of 1 A. The electrolytes used are Na{sub 2}SO{sub 4}, K{sub 2}SO{sub 4}, K{sub 2}CO{sub 3}, and KOH. After the electrolysis, the elements in the electrode near the surface are analyzed by Auger electron spectroscopy and electron probe microanalysis. In every case, a notable amount of iron atoms in the range of 1.0 x 10{sup 16} to 1.8 x 10{sup 17} atom/cm{sup 2} (true area) are detected together with the generation of a certain amount of excess energy evolution. The isotopic abundance of iron atoms, which are 6.5, 77.5, and 14.5% for {sup 54}Fe, {sup 56}Fe, and {sup 57}Fe, respectively, and are obviously different from the natural isotopic abundance, are measured at the top surface of a gold electrode by secondary ion mass spectrometry. The content of {sup 57}Fe tends to increase up to 25% in the more inner layers of the electrode. 8 refs., 11 figs., 3 tabs.

Photon Emission from Ice during Fracture

We performed the first demonstration of photon emission from ice during deformation and fracture. Emission of visible photons was confirmed in accordance with crack generation and fracture. Time-resolved photon emission signals are presented along with load changing. Emission intensity roughly increased with increasing strain energy released by fracture, while scattering in the intensity data showed that emission intensity was strongly dependent on thc characteristics of an individual crack. Experimental evidence indicates that the generated electric charge on crack surfaces and at crack tips should have higher energy than that of electromagnetic emissions reported by Fifolt, Petrenko and Schulson. [rf23]