JAEA
  • help
  • PC | SP
  • JP | EN
          
Refine your search：     
Report No.
 - 
Clear All
Search Results: Records 1-20 displayed on this page of 26

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Blister formation in rutile TiO$$_{2}$$(100) films by helium irradiation

Yamamoto, Shunya; Nagata, Shinji*; Takeyama, Akinori; Yoshikawa, Masahito

Nuclear Instruments and Methods in Physics Research B, 249(1-2), p.374 - 376, 2006/08

https://doi.org/10.1016/j.nimb.2006.04.032
 Times Cited Count：8 Percentile：50.27(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Characterization of sulfur-doped TiO$$_{2}$$ films by RBS/C

Yamamoto, Shunya; Takeyama, Akinori; Yoshikawa, Masahito

Nuclear Instruments and Methods in Physics Research B, 242(1-2), p.377 - 379, 2006/01

https://doi.org/10.1016/j.nimb.2005.08.077
 Times Cited Count：9 Percentile：53.55(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Blister formation in rutile TiO$$_{2}$$ (100) thin films by helium ion implantation

Yamamoto, Shunya; Nagata, Shinji*; Takeyama, Akinori; Yoshikawa, Masahito

Transactions of the Materials Research Society of Japan, 30(3), p.789 - 792, 2005/09

no abstracts in English

Journal Articles

${it In-situ}$ optical spectroscopy of ablation plume for preparations of nanostructured TiO$$_{2}$$ thin films by pulsed laser deposition

Kitazawa, Shinichi

Japanese Journal of Applied Physics, Part 1, 43(9A), p.6335 - 6341, 2004/09

https://doi.org/10.1143/JJAP.43.6335
 Times Cited Count：17 Percentile：54.92(Physics, Applied)

Nanostructured TiO$$_{2}$$ thin films on $$alpha$$-Al$$_{2}$$O$$_{3}$$ (0001) substrates prepared by pulsed laser deposition (PLD) were analyzed and evaluated in terms of the buffer O$$_{2}$$ gas pressure (0 - 80 Pa) dependencies by optical spectroscopy and surface morphology. Optical emission spectra of the ablation plume from Ti and TiO$$_{2}$$ targets were measured in-situ. The contribution from TiO molecules was observed by narrow-band photometry. The surface morphology was observed by an atomic force microscope (AFM), revealing the pressure dependence of nanostructures. The crystallographic structures of prepared TiO$$_{2}$$ thin films were observed by X-ray diffraction (XRD). The optically observed band-gaps of the prepared thin films show that the crystallographic structures are mixed crystals of rutile and anatase. Evaporated Ti particles combine with buffer O$$_{2}$$ gas thereby producing TiO molecules, which affect the formation of nanostructures on TiO$$_{2}$$ thin films.

Journal Articles

Preparation of highly oriented TiO$$_{2}$$/ZnO films by pulsed laser deposition

Yamamoto, Shunya; Choi, Y.; Umebayashi, Tsutomu; Yoshikawa, Masahito

Transactions of the Materials Research Society of Japan, 29(6), p.2701 - 2704, 2004/00

no abstracts in English

Journal Articles

Optical spectroscopy of plasma plume induced by pulsed laser deposition of TiO$$_{2}$$ thin films

Kitazawa, Shinichi; Yamamoto, Shunya

Transactions of the Materials Research Society of Japan, 28(4), p.1133 - 1136, 2003/12

The epitaxial growth of high quality TiO$$_{2}$$ films has attracted much interest from the viewpoints of basic science and applications. In the synthesis process of TiO$$_{2}$$ films, the pulsed laser deposition (PLD) method is widely employed because of its advantage for materials with high melting point. The laser irradiation generates plasmas from Ti bulk targets, and the evaporated Ti particles have interactions with buffer dioxide gas before/after the epitaxial growth. We observed the optical emission spectra from the plumes generated by laser ablation in order to improve on the epitaxial growth under proper conditions. The spectra show dependences of energy densities and wavelengths of the laser. The spectra are investigated for relevancies to the quality of films and crystallographic relationships that were assessed by x-ray diffraction, x-ray pole figures and Rutherford backscattering spectroscopy.

Journal Articles

Nanoparticle formation by pulsed laser ablation of TiO$$_{2}$$

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$$_{2}$$ rutile pellet with a KrF excimer laser ($$lambda$$ = 248 nm). The ablation was performed in atmospheres of Ar and O$$_{2}$$ 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$$_{2}$$. 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$$_{2}$$ with a small amount of a less oxidized phase such as Ti$$_{2}$$O$$_{3}$$. 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.

Journal Articles

Photocatalytic properties of S-doped TiO$$_{2}$$ under visibel light irradiation

Umebayashi, Tsutomu; Asai, Keisuke*; Yamaki, Tetsuya; Yoshikawa, Masahito

Kogyo Zairyo, 51(7), p.34 - 36, 2003/07

https://ci.nii.ac.jp/naid/80015964818

no abstracts in English

Journal Articles

Synthesis of sulfur-doped TiO$$_{2}$$ by ion implantation

Umebayashi, Tsutomu; Yamaki, Tetsuya; Yamamoto, Shunya; Tanaka, Shigeru; Asai, Keisuke*

Transactions of the Materials Research Society of Japan, 28(2), p.461 - 464, 2003/06

TiO$$_{2}$$ is promising as a photocatalytic material. However, it is active only under UV light irradiation because of its wide band gap ($$sim$$3.0 eV). We recently reported that sulfur (S) doping caused the optical absorption edge of TiO$$_{2}$$ to be shifted into the lower energy region. Based on the theoretical analyses using first principles band calculations, mixing of the S 3p states with the valence band was found to contribute to the bandgap narrowing. In this study presented here, S-doped TiO$$_{2}$$ was prepared by ion implantation and subsequent thermal annealing. S$$^{+}$$ was implanted into the single crystals of rutile TiO$$_{2}$$ with a fluence of 8 $$times$$ 10$$^{15}$$ ions/cm$$^{2}$$. According to the results of RBS/channeling analysis, irradiation damage recovered after the annealing at 600 $$^{circ}$$C in air. In the annealed crystal, S atoms occupied O sites to form Ti-S bonds, as assessed by XPS.

Journal Articles

Sulfur-doping of rutile-titanium dioxide by ion implantation; Photocurrent spectroscopy and first-principles band calculation studies

Umebayashi, Tsutomu; Yamaki, Tetsuya; Yamamoto, Shunya; Miyashita, Atsumi; Tanaka, Shigeru; Sumita, Taishi*; Asai, Keisuke*

Journal of Applied Physics, 93(9), p.5156 - 5160, 2003/05

https://doi.org/10.1063/1.1565693
 Times Cited Count：300 Percentile：98.63(Physics, Applied)

Sulfur (S)-doped titanium dioxide (TiO$$_{2}$$) was synthesized by ion implantation and subsequent thermal annealing. Compared to the pure TiO$$_{2}$$, a photocurrent was observed in the lower energy regions for the S-doped TiO$$_{2}$$. Based on the theoretical analyses by the first principles band calculations using the full potential linearized augmented plane wave methods within the generalized gradient approximation, the mixing of the S 3p states with the valence band (VB) was found to contribute to the increasing width of the VB. This leads to the bandgap narrowing in the S-doped TiO$$_{2}$$. Therefore, the photon-to-carrier conversion was induced during irradiation by visible light above 420 nm ($$<$$ 2.9 eV).

Journal Articles

UV-ray photoelectron and ab initio band calculation studies on electronic structures of Cr- or Nb-ion implanted titanium dioxide

Umebayashi, Tsutomu; Yamaki, Tetsuya; Sumita, Taishi*; Yamamoto, Shunya; Tanaka, Shigeru; Asai, Keisuke*

Nuclear Instruments and Methods in Physics Research B, 206, p.264 - 267, 2003/05

https://doi.org/10.1016/S0168-583X(03)00740-7
 Times Cited Count：24 Percentile：81.79(Instruments & Instrumentation)

Chromium (Cr) and niobium (Nb) were implanted into single-crystalline titanium dioxide (TiO$$_{2}$$; rutile). After annealing at 600$$^{circ}$$C for the Cr-implanted sample or at 1000$$^{circ}$$C for the Nb-implanted sample, the radiation damage was recovered. The implanted metals occupied titanium (Ti) sites in TiO$$_{2}$$ to form metal-oxygen bonds. According to the ultraviolet-ray photoelectron spectra, a localized level due to the implanted metals was formed in band gap of both the crystals. This position was close to the VB edge for the Cr-doped TiO$$_{2}$$, while the Nb-doped TiO$$_{2}$$ had the small peak far from the edge. This is in good agreement with the ab-initio band calculation results. It is considered that the midgap states of Cr- and Nb-doped TiO$$_{2}$$ consist of the Cr t$$_{2g }$$ or Ti t$$_{2g }$$ state, respectively.

Journal Articles

Characterization of metal-doped TiO$$_{2}$$ films by RBS/channeling

Yamamoto, Shunya; Yamaki, Tetsuya; Naramoto, Hiroshi; Tanaka, Shigeru

Nuclear Instruments and Methods in Physics Research B, 206(1-4), p.268 - 271, 2003/05

https://doi.org/10.1016/S0168-583X(03)00742-0
 Times Cited Count：13 Percentile：64.64(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Fluorine-doping in titanium dioxide by ion implantation technique

Yamaki, Tetsuya; Umebayashi, Tsutomu; Sumita, Taishi*; Yamamoto, Shunya; Maekawa, Masaki; Kawasuso, Atsuo; Ito, Hisayoshi

Nuclear Instruments and Methods in Physics Research B, 206(1-4), p.254 - 258, 2003/05

https://doi.org/10.1016/S0168-583X(03)00735-3
 Times Cited Count：136 Percentile：98.9(Instruments & Instrumentation)

Single crystalline titanium dioxide (TiO$$_{2}$$) rutile were implanted with 200keV F$$^{+}$$ at a nominal fluence of 1$$times$$10$$^{16}$$ to 1$$times$$10$$^{17}$$ ions cm$$^{-2}$$ and then thermally annealed in air up to 1200$$^{circ}C$$ for 5h. The radiation damage and its recovery during the subsequent annealing were analyzed by Rutherford backscattering spectrometry in channeling geometry and variable-energy positron annihilation spectroscopy. The lattice disorder was completely annealed at 1200$$^{circ}C$$ by the diffusion of point defects to the surface acting as a sink. According to the secondary ion mass spectrometry, the F depth profile was shifted to a shallower region along with the damage recovery, finally producing an F-doped layer where the impurity concentration increased steadily towards the surface. The F doping proved to provide a small modification to the conduction-band edge of TiO$$_{2}$$, as assessed by theoretical band calculations.

Journal Articles

Semiconducting properties of polycrystalline titanium dioxide

Kuratomi, Takashi*; Yamaguchi, Kenji; Yamawaki, Michio*; Bak, T.*; Nowotny, J.*; Rekas, M.*; Sorrell, C. C.*

Solid State Ionics, 154-155, p.223 - 228, 2002/12

https://doi.org/10.1016/S0167-2738(02)00436-8
 Times Cited Count：14 Percentile：57.54(Chemistry, Physical)

no abstracts in English

Journal Articles

Analysis of electronic structures of 3d transition metal-doped TiO$$_{2}$$ based on band calculations

Umebayashi, Tsutomu; Yamaki, Tetsuya; Ito, Hisayoshi; Asai, Keisuke*

Journal of Physics and Chemistry of Solids, 63(10), p.1909 - 1920, 2002/10

https://doi.org/10.1016/S0022-3697(02)00177-4
 Times Cited Count：627 Percentile：99.67(Chemistry, Multidisciplinary)

The electronic structures of titanium dioxide (TiO$$_{2}$$) doped with 3d transition metals (V, Cr, Mn, Fe, Co and Ni) have been analyzed by ab-initio band calculations based on the density functional theory with the full-potential linearized-augmented-plane-wave methods. When TiO$$_{2}$$ is doped with V, Cr, Mn, Fe or Co, an occupied level occurs and the electrons localized around each dopant. As the atomic number of the dopant increases, the localized level shifts to lower energy. In contrast, the electrons from Ni dopant are somewhat delocalized, thus significantly contributing to the formation of the valence band with O p and Ti 3d electrons. Based on a comparison with the absorption and photoconductivity data previously reported, we show that the t$$_{2g}$$ state of the dopant plays a significant role in the photoresponse of TiO$$_{2}$$ under visible light irradiation.

Journal Articles

Photo-induced surface charge separation in Cr-implanted TiO$$_2$$ thin film

Sumita, Taishi*; Yamaki, Tetsuya; Yamamoto, Shunya; Miyashita, Atsumi

Thin Solid Films, 416(1-2), p.80 - 84, 2002/09

https://doi.org/10.1016/S0040-6090(02)00618-1
 Times Cited Count：22 Percentile：69.58(Materials Science, Multidisciplinary)

Surface charge separation efficiencies of uniformly Cr-distributed rutile grown by pulse laser deposition(PLD) using Cr/TiO$$_2$$ multi-targets and rutile with Cr concentration gradient produced by ion implantation with the appropriate post-annealing process were characterized by photo-induced transient charge separation (PITCS) measurement. Cr depth profiles were obtained by secondary ion mass spectrometry(SIMS) and X-ray photoelectron spectroscopy(XPS) was used to determine that both surface Cr concentrations were the same. PITCS can be measured without direct contacts and without an externally applied field, and demonstrate the inherent property of charge separation without disturbing spontaneously formed surface band bending. There was a large charge separation for implanted rutile with Cr gradient, even in the visible light region ($$sim$$520nm), which was more remarkable than that of uniform rutile and epitaxial anatase films.

Journal Articles

Characterization of epitaxial TiO$$_{2}$$ films prepared by pulsed laser deposition

Yamamoto, Shunya; Sumita, Taishi; Yamaki, Tetsuya; Miyashita, Atsumi; Naramoto, Hiroshi

Journal of Crystal Growth, 237-239(Part1), p.569 - 573, 2002/04

The epitaxial growth of TiO$$_{2}$$ films has attracted much interest from the viewpoints of basic science and applications. In the present study, it is shown that TiO$$_{2}$$ films with anatase or rutile structure can be grown by pulsed laser deposition(PLD) with an ArF excimer laser under the controlled O$$_{2}$$ atmosphere. The TiO$$_{2}$$ films were prepared on the LaAlO$$_{3}$$, LSAT SrTiO$$_{3}$$ and $$alpha$$-Al$$_{2}$$O$$_{3}$$ single crystal substrates. The epitaxial films were analyzed by RBS and X-ray diffraction for investigating the crystallographic relationships with the substrates. The high quality anatase TiO$$_{2}$$(001) films have been successfully grown on the LaAlO$$_{3}$$ (001), LSAT (001) and SrTiO$$_{3}$$ (001) substrates at temperatures above 500$$^{circ}$$C. Also the high quality rutile TiO$$_{2}$$(100) and (001) films were obtained on the $$alpha$$-Al$$_{2}$$O$$_{3}$$ (0001) and (10-10), respectively.The optical properties were characterized by optical absorption measurements. The optical band gaps for anatase and rutile TiO$$_{2}$$ epitaxial films were evaluated to be 3.22 eV and 3.11 eV, respectively.

Journal Articles

Preparation of epitaxial TiO$$_{2}$$ films by pulsed laser deposition technique

Yamamoto, Shunya; Sumita, Taishi; Sugiharuto; Miyashita, Atsumi; Naramoto, Hiroshi

Thin Solid Films, 401(1-2), p.88 - 93, 2001/12

https://doi.org/10.1016/S0040-6090(01)01636-4
 Times Cited Count：129 Percentile：96.8(Materials Science, Multidisciplinary)

The epitaxial growth of high-quality TiO$$_{2}$$ films has attracted much interest from the viewpoints of basic science and applications. In this study, it is shown that TiO$$_{2}$$ films with anatase and rutile structure can be prepared by pulsed laser deposition (PLD) with a Nd-YAG laser under the controlled O$$_{2}$$ atmosphere. The TiO$$_{2}$$ films with 200 nm thickness were prepared on the SrTiO$$_{3}$$, LaAlO$$_{3}$$, LSAT and $$alpha$$-Al$$_{2}$$O$$_{3}$$ single crystal substrates. The epitaxial films were analyzed by Rutherford backscattering spectrometry (RBS) combined with channeling and X-ray diffraction for the crystallographic relationships with the substrates. The high quality anatase TiO$$_{2}$$ (001) films have been successfully prepared on the LaAlO$$_{3}$$ (001), LSAT (001) and SrTiO$$_{3}$$ (001) substrates about 500$$^{circ}$$C substrate temperature. Also the high quality rutile TiO$$_{2}$$ (100) and TiO$$_{2}$$ (001) films were obtained on the $$alpha$$-Al$$_{2}$$O$$_{3}$$ (0001) and (10$$bar{1}$$0), respectively.

Journal Articles

Formation of hybrid monolayers and langmuir-blodgett-type multilayers from ammonium cations and TiO$$_{2}$$ crystalline nanosheets

Yamaki, Tetsuya; Shinohara, Ryuji*; Asai, Keisuke*

Thin Solid Films, 393(1-2), p.154 - 160, 2001/08

https://doi.org/10.1016/S0040-6090(01)01063-X
 Times Cited Count：10 Percentile：50.69(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Surface modification of TiO$$_{2}$$ single crystals by nonmetal-ion implantation

Yamaki, Tetsuya; Sumita, Taishi; Yamamoto, Shunya; Miyashita, Atsumi

Dai-11-Kai Ryushisen No Sentanteki Oyo Gijutsu Ni Kansuru Shimpojiumu (BEAMS 2000) Hobunshu, p.131 - 134, 2000/11

no abstracts in English

26 (Records 1-20 displayed on this page)