Hiroaki Yamamoto

The magnetic dipole interaction between the nuclear spin of the proton and the electronic spin of the magnetic catalyst is verified for the first time. The findings of this study will open a new direction in catalyst design aided by a magnetic field.

The preparation of cobalt-antimony thermoelectric film using pulse electrolysis was investigated in ethylene glycol (EG)-CoCl₂-SbCl₃ non-aqueous solutions at 393 K. The layered structures consisting of Co rich Co-Sb alloy layers and Sb rich Co-Sb alloy layers were obtained by applying alternately the potentials for electrodepositing the former, E_Co, and the latter, E_Sb, in the 90.0 mol%EG-9.09 mol%CoCl₂-0.91 mol%SbCl₃ bath, and were heat-treated at 673 K for 24 h in Ar gas atmosphere to prepare the Co-Sb alloy films with uniform composition. The composition of Co-Sb alloy film was found to be controlled by adjusting the ratio of applied duration at E_Co, t_Co, to one at E_Sb, t_Sb, in the potential rectangular wave used in the pulse electrolysis. At the (t_Sb / t_Co) ratio of 7.0, the Co-Sb alloy film with the composition of 26.1 mol%Co-73.9 mol%Sb was obtained after heat treatment. This alloy film was not the CoSb₃ single phase, but included it as constituent and exhibited a p-type thermoelectric conversion by the given temperature difference.

Thermoelectric materials of the Fe-Al binary system were prepared at 423 K by electrodeposition in molten salts of the AlCl₃-NaCl-KCl-FeCl₂ quaternary system. The effects of the current density at the constant content of FeCl₂ were investigated in addition to the FeCl₂ content at the constant current density on the compositions and morphologies of the electrodeposited Fe-Al alloy films. When the Fe-Al alloy films were electrodeposited in the 63.59 mol%AlCl₃-25.83 mol%NaCl-9.94 mol%KCl-0.64 mol%FeCl₂, the constant molar ratio for FeCl₂ to AlCl₃ was 1:100, the Al contents electrodeposited in the film were increased as a function of the applied current density followed by morphological change to a powder over 150 Am^－2, indicating that the current density for smooth film preparation was 100 Am^－2. At constant current density of 100 Am^－2, the various Al contents in the films were obtained as a function of the FeCl₂ content in the molten salt, resulting in the significant increase of Al content below 0.5 mol% FeCl₂ in the molten salt. Electromotive force was generated by a temperature difference on the obtained Fe-Al alloy films. The sign of generated electromotive force, the type of thermoelectric conversion, depended on the Fe-Al alloy film composition. These obtained results clarifying the condition of electrolysis to control the composition determining thermoelectric property of the film are expected to be useful to develop thermoelectric devices that use Fe-Al film.

Anodizing of magnesium was studied in sodium metasilicate with ortho-Cresol-4-sulfonic acid aqueous solution. A gray-colored anodic oxide film was obtained in 3.0mol·dm⁻³ sodium metasilicate-0.25mol·dm⁻³ o-Cresol-4-sulfonic acid aqueous solution at constant current density of 1000A·m⁻² for 6.0×10⁵C·m⁻² at 278K. This film mainly consisted of magnesium, silicon, and oxygen and contained small amounts of carbon and sulfur. In the wear test using #800 SiC waterproof abrasive paper, this anodic oxide film showed almost the same wear resistance as that obtained in 2.0mol·dm⁻³ sodium metasilicate aqueous solution. However, in 0.86mol·dm⁻³ NaCl solution at 308K, the former without sealing showed higher corrosion resistance than the latter with sealing. Moreover, its corrosion resistance was further improved by the sealing treatment in boiling distilled water.<br>