Papers by Author: Makoto Kuwabara

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Authors: Yong Jun Wu, Juan Li, Makoto Kuwabara
Abstract: Electron beam lithography combined with electrophoretic deposition was investigated to fabricate micropatterned barium titanate (BTO) with nanostructures. High quality resist molds with micropatterns of microgrids and microdot arrays were prepared on Pt/Ti/SiO2/Si substrate by electron beam lithography. BTO nanocrystallites in a pseudo-cubic perovskite phase with an average particle size of about 10 nm were synthesized by a high-concentration sol-gel process. Well-dispersed and stable suspensions of barium titanate nanocrystallites were synthesized. Then, BTO microlines, microgrids and microdot arrays were electrophoretically deposited on micropatterned Pt/Ti/SiO2/Si substrate from these suspensions. The microstructure and properties of the BTO micropatterns were evaluated.
Authors: Shigeru Fujino, Makoto Kuwabara
Abstract: Dielectric constants were measured for phosphate and silica glass systems in the frequency region of 1 to 10 GHz using the resonance cavity method. Compositional dependence of dielectric constant and tangent loss were discussed. The effect of the cations on the ε indicates that ε increases in the order, R:Mg
Authors: Teruhisa Makino, Masashi Arimura, Yoko Yamashita, Kunitaka Fujiyoshi, Makoto Kuwabara
Authors: Juan Li, Yong Jun Wu, Makoto Kuwabara
Abstract: Praseodymium (Pr3+)-doped BaTiO3 was synthesized by a high concentration sol-gel process and sintered at different temperatures from 800oC to 1200oC. The emission was due to intra-4f transitions of Pr3+ which were mainly from the excited states 3P0 and 1D2 to the ground states of 3H4 of Pr3+, respectively. Enhancement of the luminescent properties of Pr-doped BaTiO3 was also investigated via adding Mg. For BaTiO3: Pr phosphor added with 0.5 mol% Mg, the emission intensity was about 60 times higher than that of samples without Mg addition. The emission enhancement may caused by the improved crystallinity, the charge compensation and the change of the substitution site of Pr3+ with the addition of Mg.
Authors: Tsuyoshi Aoki, Masao Kondo, Mineharu Tsukada, Kazuaki Kurihara, Makoto Kuwabara
Abstract: Two-dimensional Pb0.865La0.09Zr0.65Ti0.35O3 (PLZT) photonic crystals with hexagonal arrays of air holes on (001) Pt-sputtered magnesium oxide substrates were fabricated using a sol-gel process with resist molds. The PLZT photonic crystals have a thickness of 200 nm, and the period of hexagonal array and the radius of air holes were 400 or 450 nm and 135 or 165 nm, respectively. The PLZT photonic crystals were primarily orientated along the c-axis. The strain hysteresis loop of the photonic crystals suggested that the photonic crystals are ferroelectric. Several peaks within range of wavelength between 500 nm and 1000 nm appeared in the optical reflection spectra from the cleaved facet of the photonic crystals. The peaks have polarization dependence and the frequency bands of the each peak were close to that of photonic band gaps (PBGs) expected by the calculations.
Authors: Tsuyoshi Aoki, Kazuaki Kurihara, Makoto Kuwabara
Authors: Hirofumi Matsuda, Takayuki Kobayashi, H. Shiibashi, Makoto Kuwabara
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