Author
Toru Sekino
Bio: Toru Sekino is an academic researcher from Chubu Electric Power. The author has contributed to research in topics: Cubic zirconia & Ceramic. The author has an hindex of 6, co-authored 10 publications receiving 2301 citations.
Topics: Cubic zirconia, Ceramic, Sintering, Boron nitride, Elastomer
Papers
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TL;DR: In this article, a new route for the synthesis of a nanotube made of titanium oxide is presented, where needle-shaped TiO2 crystals (anatase phase) with a diameter of 8 nm and a length of 100 nm were obtained when sol−gel-derived fine TiO 2-based powders were treated chemically with a 5−10 M NaOH aqueous solution.
Abstract: Nanotubes composed of various materials such as carbon, boron nitride, and oxides have been studied recently. In this report, the discovery of a new route for the synthesis of a nanotube made of titanium oxide is presented. Needle-shaped TiO2 crystals (anatase phase) with a diameter of ≈8 nm and a length of ≈100 nm were obtained when sol−gel-derived fine TiO2-based powders were treated chemically (e.g., for 20 h at 110 °C) with a 5−10 M NaOH aqueous solution. It was found by observation using a transmission electron microscope that the needle-shaped products have a tube structure. The TiO2 nanotubes have a large specific surface area of ≈400 m2·g-1. TiO2 nanotubes obtained in the present work are anticipated to have great potential for use in the preparation of catalysts, adsorbants, and deodorants with high activities, because their specific surface area is greatly increased. If metallic-, inorganic-, or organic-based materials can be inserted into the TiO2 nanotubes, novel characteristics such as electr...
2,335 citations
Patent•
22 Jan 2004
TL;DR: In this paper, a sintered boby is described, which is a ZrO 2 -Y 2 O 3 -based zirconia-based body, and the porosity is 2% or lower; its manufacturing method is also provided.
Abstract: PROBLEM TO BE SOLVED: To provide a high strength conductive zirconia sintered body of which the conductivity is developed by adding a very small amount of conductive substance to a zirconia sintered body and controlling the conductive substance on a nano-level, a molecular level, or on an atomic level, fully differently from the conventional conductive ceramics, and of which the original characteristics are further improved whithout sacrificing the original mechanical characteristics and corrosion resistance of the matrix, and its manufacturing method. SOLUTION: This sintered boby is a ZrO 2 -Y 2 O 3 -based zirconia sintered body, (a) of which the crystal phase of ZrO 2 comprises mainly tetragonal zirconia, and which is characterised in that (b) the mole ratio of Y 2 O 3 /ZrO 2 is in the range of 1.5/98.5 to 4/96, (c) the atomic number ratio of Ti/Zr is in the range of 0.3/99.7 to 16/84, (d) the mean crystal particle size of zirconia is 2 μm or smaller, and (e) the porosity is 2% or lower; and its manufacturing method is also provided. COPYRIGHT: (C)2005,JPO&NCIPI
12 citations
Patent•
17 Feb 2005
TL;DR: In this article, a zirconia sintered compact consisting essentially of ZrO 2 and a stabilizer, the molar ratio of stabilizer to stabilizer was found to be 1.5/98.5 and the crystal phase was mainly tetragonal, 0.1-3.0 wt.
Abstract: PROBLEM TO BE SOLVED: To provide a zirconia sintered compact having a desired stable conductivity given with excellent dynamic properties (fracture strength, fracture toughness or the like) by adding a smaller quantity of a conductive material, and a method of manufacturing the same. SOLUTION: In the zirconia sintered compact consisting essentially of ZrO 2 and a stabilizer, the molar ratio of the stabilizer to ZrO 2 is 1.5/98.5-3.5/96.5, the crystal phase of ZrO 2 is mainly tetragonal, 0.1-3.0 wt.% carbon nanotube is contained in the zirconia sintered compact and the volume resistivity of the zirconia sintered compact is 10 -2 -10 9 Ωcm. The method of manufacturing the zirconia sintered compact is provided. COPYRIGHT: (C)2006,JPO&NCIPI
10 citations
Patent•
11 May 1992
TL;DR: In this paper, a composite ceramic sintered compact is composed of partially stabilized zirconia matrix grains contg. 5-30mol% CeO 2 and a dispersed phase of fine particles of one or more among Al 2 O 3, SiC, Si 3 N 4 and B 4 C. The fine particles have a higher m.p. than the sintering temp.
Abstract: PURPOSE: To enhance the strength and toughness of a zirconia-based ceramic sintered compact. CONSTITUTION: This composite ceramic sintered compact is composed of partially stabilized zirconia matrix grains contg. 5-30mol% CeO 2 and a dispersed phase of fine particles of one or more among Al 2 O 3 , SiC, Si 3 N 4 and B 4 C or one or more of the carbides nitrides or borides of the groups IVa, Va and VIa elements of the periodic table. The fine particles have a higher m.p. than the sintering temp. of the zirconia matrix and the dispersed phase has been dispersed as a second phase in the matrix grains. When this sintered compact is produced, a powdery mixture contg. partially stabilized zirconia powder contg. 5-30mol% CeO 2 and the above-mentioned fine particles having ≤1μm average particle diameter is sintered at a temp. below the m.p. of the fine particles. COPYRIGHT: (C)1993,JPO&Japio
10 citations
Patent•
14 Jun 2004
TL;DR: In this article, a pressure sensitive electrically conductive elastomer is proposed to provide a pressure-sensitively electricallyconductive elastic elastic material with high mechanical strength and reproducibility of electrical resistance change when subjected to repeated compressive deformation.
Abstract: PROBLEM TO BE SOLVED: To provide a pressure-sensitively electrically conductive elastomer high in mechanical strength and good in the reproducibility of electrical resistance change when subjected to repeated compressive deformation. SOLUTION: The pressure-sensitively electrically conductive elastomer is such that a flaky, needle or fibrous electrically conductive filler and ceramic particles of nanometer size are dispersed in an electrically nonconductive elastomer; wherein the ceramic particles are layered inorganic compound particles with an organic compound intercalated therein or with an organic compound and the electrically nonconductive elastomer prior to curing intercalated therein, and the electrically conductive filler is ≤10 6 Ω/cm in volume resistivity with its planar or length direction oriented nearly parallel to the planar direction of the electrically nonconductive elastomer formed in sheet. COPYRIGHT: (C)2006,JPO&NCIPI
7 citations
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9,432 citations
TL;DR: This review attempts to cover all aspects, including underlying principles and key functional features of TiO(2), in a comprehensive way and also indicates potential future directions of the field.
Abstract: TiO(2) is one of the most studied compounds in materials science. Owing to some outstanding properties it is used for instance in photocatalysis, dye-sensitized solar cells, and biomedical devices. In 1999, first reports showed the feasibility to grow highly ordered arrays of TiO(2) nanotubes by a simple but optimized electrochemical anodization of a titanium metal sheet. This finding stimulated intense research activities that focused on growth, modification, properties, and applications of these one-dimensional nanostructures. This review attempts to cover all these aspects, including underlying principles and key functional features of TiO(2), in a comprehensive way and also indicates potential future directions of the field.
2,735 citations
TL;DR: Analysis of photocurrent measurements indicates that the light-harvesting efficiencies of NT-based DSSCs were higher than those found for D SSCs incorporating NPs owing to stronger internal light-scattering effects.
Abstract: We report on the microstructure and dynamics of electron transport and recombination in dye-sensitized solar cells (DSSCs) incorporating oriented TiO2 nanotube (NT) arrays. The morphology of the NT arrays, which were prepared from electrochemically anodized Ti foils, were characterized by scanning and transmission electron microscopies. The arrays were found to consist of closely packed NTs, several micrometers in length, with typical wall thicknesses and intertube spacings of 8−10 nm and pore diameters of about 30 nm. The calcined material was fully crystalline with individual NTs consisting of about 30 nm sized crystallites. The transport and recombination properties of the NT and nanoparticle (NP) films used in DSSCs were studied by frequency-resolved modulated photocurrent/photovoltage spectroscopies. While both morphologies display comparable transport times, recombination was much slower in the NT films, indicating that the NT-based DSSCs have significantly higher charge-collection efficiencies than...
2,008 citations
TL;DR: In this paper, the fabrication, properties, and solar energy applications of highly ordered TiO 2 nanotube arrays made by anodic oxidation of titanium in fluoride-based electrolytes are reviewed.
1,905 citations
TL;DR: An overview of the state of the art in ferroelectric thin films is presented in this paper, where the authors review applications: micro-systems' applications, applications in high frequency electronics, and memories based on Ferroelectric materials.
Abstract: An overview of the state of art in ferroelectric thin films is presented. First, we review applications: microsystems' applications, applications in high frequency electronics, and memories based on ferroelectric materials. The second section deals with materials, structure (domains, in particular), and size effects. Properties of thin films that are important for applications are then addressed: polarization reversal and properties related to the reliability of ferroelectric memories, piezoelectric nonlinearity of ferroelectric films which is relevant to microsystems' applications, and permittivity and loss in ferroelectric films-important in all applications and essential in high frequency devices. In the context of properties we also discuss nanoscale probing of ferroelectrics. Finally, we comment on two important emerging topics: multiferroic materials and ferroelectric one-dimensional nanostructures. (c) 2006 American Institute of Physics.
1,632 citations