研究者業績

Takeyuki Kikuchi

  (菊池 丈幸)

Profile Information

Affiliation
Graduate School, of Engineering, University of Hyogo
Degree
(BLANK)

J-GLOBAL ID
200901008411341436
researchmap Member ID
1000296293

Research Interests

 1

Papers

 55
  • Eri Miura-Fujiwara, Hiroshi Harada, Yoshinobu Tanaka, Takeyuki Kikuchi, Thoru Yamasaki
    Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals, 82(3) 70-77, 2018  
    We studied the fabrication of a TiO2/SiO2 composite coating on Ti. At a temperature above 1100 K with oxygen partial pressure, a self-organized coating of rutile phase TiO2 is formed on a Ti substrate. The thick TiO2 coating(&gt 10 m)had a "piecrust-like"multilayer structure, which comprise TiO2 monolayers and gaps. A composite coating containing SiO2 was fabricated via a sol-gel method in vacuum to improve the exfoliation strength of the brittle, porous TiO2 coating. Cross-sectional SEM images revealed sufficient amounts of SiO2 in the gaps between the TiO2 monolayers in the TiO2/SiO2 composite coating, even at the interface between the oxide coating and the substrate. Exfoliation stress of the composite coating was up to 10-15 times higher than for the self-organized TiO2 coating alone, and the composite coating's failure mode was interfacial compared with cohesive for the self-organized TiO2 coating.
  • Yasuhiro Yoneda, Eri Takada, Haruka Nagai, Takeyuki Kikuchi, Masao Morishita, Masafumi Kobune
    JAPANESE JOURNAL OF APPLIED PHYSICS, 56(10), Oct, 2017  
    A monoclinic ferroelectric phase with the space group Pm has been discovered in lead-free (Na0.5K0.45Li0.05) NbO3 solid solution ceramics synthesized by a malic acid complex solution method. At ambient temperature, the lattice parameters of this monoclinic structure were (a(m), b(m), c(m); beta) = (4.002 angstrom, 3.935 angstrom, 3.980 angstrom, 90.32 degrees). The average and local structures of this monoclinic phase were analyzed by synchrotron X-ray measurements. The average structure maintained the monoclinic structure down to 20 K, although the local structure changed below room temperature. The distinct short-range order structure was found to be rhombohedral. The results demonstrate the presence of an order-disordertype phase transition structurally bridging between the rhombohedral local structure and the low-symmetry monoclinic average structure in a (Na0.5K0.45Li0.05) NbO3 solid solution system. (C) 2017 The Japan Society of Applied Physics
  • Masafumi Kobune, Takuya Nishimine, Takuya Matsunaga, Satoshi Fujita, Takeyuki Kikuchi, Hironori Fujisawa, Masaru Shimizu, Kensuke Kanda, Kazusuke Maenaka
    JAPANESE JOURNAL OF APPLIED PHYSICS, 56(10), Oct, 2017  
    Regardless of the deposition time (30-90 min), almost single-phase magnetite (Fe3O4) films with a cubic inverse-spinel structure were produced at a substrate temperature of 500 degrees C by metalorganic chemical vapor deposition (MOCVD). The Fe3O4/(Bi(3.25)Nd(0.65)Eu(0.1)0) Ti3O12 (BNEuT) composite film deposited at 500 degrees C for 90 min by MOCVD exhibited excellent room-temperature magnetic properties, such as a saturation magnetization of 480 emu/cm(3), a residual magnetization of 160 emu/cm(3), and a coercivity of 297 Oe. Ferromagnetic Fe3O4 electrodes micropatterned using a combination of photolithography and reactive ion etching were fabricated after MOCVD, and their structural, leakage current, and ferroelectric characteristics were investigated. The room-temperature leakage current density-applied electric field and polarization-electric field (P-E) characteristics of the composite films were successfully measured using Fe3O4 electrodes. The room-temperature P-E hysteresis loop for a sample with the structure Fe3O4/BNEuT/Nb: TiO2/Ti had a relatively good shape, with a remanent polarization of 8 mu C/cm(2) and a coercive field of 193 kV/cm. (C) 2017 The Japan Society of Applied Physics
  • Makoto Nakanishi, Saori Ono, Tatsuo Fujii, Takeyuki Kikuchi
    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy, 64(7) 378-382, Jul 1, 2017  
    Y-Type ferrite substituted with a combination of non-magnetic lithium and aluminum, Ba2Zn2-2xLixAlxFe12O22, was synthesized by polymerized complex method and the effects of substitution on their magnetic properties were investigated. The monophasic Y-Type ferrite was obtained at the composition range up to x = 0.6 and their lattice parameters decreased isotropically by the substitution. The saturation magnetization at 10 K decreased and Curie temperature increased with increasing composition x. As a result, the saturation magnetization at room temperature showed maximum at x = 0.2 and the relative complex permeability of sintered Y-Type ferrite also showed same tendency. The substituion with a combination of non-magnetic ions could enhanced the magnetic properties of Y-Type ferrite through lattice contraction and/or site occupation of iron ions.
  • Takeyuki Kikuchi, Masafumi Kobune, Makoto Nakanishi, Tatsuo Fujii
    CERAMICS INTERNATIONAL, 43 S386-S390, 2017  
    Polycrystalline powder samples of the zinc-substituted strontium cobalt Z-type hexaferrite: Sr3Co2-xZnxFe24O41 (x = 0, 0.5, 1.0, 1.5 and 2.0) were prepared by the polymerizable complex method. Their Mossbauer spectra were measured at room temperature with conventional constant-acceleration spectrometer. Obtained Mossbauer spectra were numerically separated into six discrete components. The relationship between Mossbauer parameters and magnetic properties has been discussed. From the values of the isomer shift, it was found that the iron ion in Sr3Co2-xZnxFe24O41 is trivalent with high spin. The value of the quadrupole splitting increased and changed the sign from negative to positive for the sample with x = 1.5. From the results mentioned above and the analysis of the complex permeability spectra, the magnetocrystalline anisotropy of Sr3Co2-xZnxFe24O41 is changed from c-plane to c-axis at Zn content between x = 1.0 and 1.5. The compositional dependence of the areas of each subspectra showed that Zn2+ ions occupy the sites with down spin at the compositional range of x = 0.0-1.0.

Misc.

 12

Presentations

 136