Mitsuaki Takeuchi

Photoinduced hydrophilicity of TiO2 thin film modified by Ar ion beam irradiation

Abstract TiO 2 are applied widely as photocatalytic materials. In this study, we investigated preparation of TiO 2 thin film with photoinduced hydrophilicity under weak UV light in indoor environment. TiO 2 films were prepared by rf magnetron sputtering process in an atmosphere of pure oxygen. Ar ion beam irradiation treatment of TiO 2 film was carried out using a plasma cathode ion source. O–H absorption peaks as the wavenumber regions 3300–3400 cm −1 increased with increasing of Ar ion beam irradiation time. The improvement of photoinduced hydrophilicity of the film was independent of surface area of TiO 2 film. In XPS measurements, O 1s peaks of Ar ion beam irradiated TiO 2 films shifted 0.4–0.6 eV to higher binding energy side. Oxygen vacancies were induced in surface of the film by Ar ion beam irradiation. The TiO 2 films showed photoinduced hydrophilicity under weak UV light such as indoor environment.

Magnetostrictive characteristics of Fe-Al films formed by ion plating process

The crystal structure and magnetostrictive properties of Fe-Al thin films prepared by ion plating process were investigated. Film composition, structure, magnetization and in-plane magnetostriction were obtained by energy dispersive X-ray spectroscopy, X-ray diffraction, vibrating sample magnetometer and cantilever method respectively. The film showed higher magnetostrictive susceptibility and larger magnetostriction at low magnetic fields.

Giant magnetostrictive iron-based alloy thin film for optical scanner

To develop an optical scanning device, the magnetostrictive alloy thin films were prepared on silicon wafer and polyimide substrate by d.c. magnetoron sputtering process. The TbFe1.8 film shows a giant positive magnetostriction of about 1200 ppm at 5 kOe, whereas the SmFe2.5 shows a giant negative magnetostriction of about 1200 ppm. The magnetostrictive alloy thin films device showed reproducibility below 5 kOe of magnetic field.

Characterization of giant magnetostrictive composite materials prepared under magnetic field

Giant magnetostrictive (GM) composite materials with high corrosion resistance and high electrical resistivity were developed. Magnetostriction of the composite material prepared under magnetic field at 19 kOe was about 880 ppm, and the TbFe2 particle size in the sample was 100-150 μm. Shape anisotropy of the TbFe2 particles induced by compression and magnetic field caused to increase the magnetization and magnetostriction measured for y axis of the composite samples formed with magnetic field. The composite materials showed high resistivity in order to 10-2 Ωm and exhibited in order to 10-2 g hour-1 of corrosion rate. The corrosion rate of the composite samples increased with increasing TbFe2 particle size. The corrosion rate of the composite materials may be affected to volume fraction of the TbFe2 particles exposed area in surface of the composite materials.

Magnetostrictive characteristics of Tb-Fe-Si thin films prepared by magnetron sputtering

Giant magnetostrictive (GM) Tb-Fe-Si films were prepared by magnetron sputtering system. X-ray diffraction pattern showed film samples were in amorphous state. The Tb-Fe-Si film (Tb : Fe : Si = 1 : 2.7 : 0.2) prepared at 373 K showed 30 MPa tensile stresses generated by magnetostriction along in-plane direction. The film sample showed about 4.3 μΩm of electrical resistivity that is about 100 times larger than that of TbFe2 film shown about 5.9 × 10-2 μΩm. The film sample coercivity was 360 Oe. Magnetization of the film sample at 15 kOe of applied magnetic field in parallel direction to the film surface exhibited 81.0 emu/cc. We prepared giant magnetostrictive thin film with higher electrical resistivity than that of TbFe2 thin film.