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Yamaki, Tetsuya; Ito, Hisayoshi; Matsubara, Masakazu*; Abe, Hiroaki*; Asai, Keisuke*
Transactions of the Materials Research Society of Japan, 28(3), p.879 - 882, 2003/10
Titanium oxide nanoparticles were formed by pulsed laser ablation of a TiO rutile pellet with a KrF excimer laser (
= 248 nm). The ablation was performed in atmospheres of Ar and O at total pressures ranging from 0.2 and 10 Torr. At a higher pressure than 1 Torr, Ti in the nanoparticles had an oxidation state of 4+ to form TiO. According to the X-ray diffraction analyses, the nanopartiles were found to contain both the anatase and rutile phases, which crystallized through extremely energetic, non-equilibrium reactions in an ablation plume. In contrast, at pressures of 0.2 and 0.5 Torr, the nanoparticles were composed of dominant TiO with a small amount of a less oxidized phase such as TiO
. The important result is that the XRD patterns of the samples prepared at 1 and 5 Torr showed the different anatase-to-rutile ratio of the peak intensities. This indicates that the weight fraction of the rutile/anatase crystalline phases can be controlled by the ambient gas pressure.
Kimata, Tetsuya*; Kato, Sho*; Yamaki, Tetsuya; Yamamoto, Shunya; Hakoda, Teruyuki; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
Platinum (Pt) nanoparticles prepared by Pt-ion implantation in a glassy carbon (GC) substrate exhibited high durability as oxygen reduction catalyst. This result would originate from chemical and electronic interaction between the Pt atoms at the particle surface and the lattice defects in the GC substrate introduced by the ion implantation. We prepared Pt nanoparticles by RF magnetron sputtering on the GC substrate modified by Ar-ion irradiation, and then investigated the influence of Ar-ion irradiation on their electronic structure. X-ray photoelectron spectroscopy demonstrated that the formation of the Pt-C bonding at the interface was promoted by the pre-deposition Ar-ion irradiation of the GC substrate.
Yamaki, Tetsuya; Kato, Sho*; Yamamoto, Shunya; Hakoda, Teruyuki; Kawaguchi, Kazuhiro*; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
A glassy carbon (GC) substrate was implanted with 100 keV tungsten (W) and platinum (Pt) ions at different fluences in order to prepare nanoparticles of W-carbides and Pt-metal, respectively, with diameters of 
10 nm. We discuss a detailed study of compound formation and binding interaction resulting from the W or Pt implants in GC for the first time, emphasizing the importance of chemical effects in determining the final properties of the implanted layer. The chemical effects between the implanted species and the GC substrate were investigated mainly by X-ray photoelectron spectroscopy (XPS) while the morphological properties, i.e., the dispersion states of the implants or the size and shape of the precipitated nanoparticles, were observed by transmission electron microscopy (TEM).
Yamaki, Tetsuya; Kato, Sho*; Kimata, Tetsuya*; Yamamoto, Shunya; Hakoda, Teruyuki; Kobayashi, Tomohiro*; Suzuki, Akihiro*; Terai, Takayuki*
no journal, ,
We have a strong motivation to pursue the possibility of using ion beam technology for the creation of nano-structured catalytic materials and their electrochemical device applications. My talk includes (1) the preparation of noble-metal nanoparticles in a glassy carbon (GC) substrate by the metal-ion implantation method, (2) heavy-ion-induced lattice defects in the GC substrate and their effect on the oxygen reduction reaction activity of the deposited platinum nanoparticles, and (3) the formation of polymer nanostructures and their potential as a catalyst support.