Papers by Author: Kazumi Kato

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Authors: Xiang Ju Meng, Tatsuo Kimura, Tatsuki Ohji, Kazumi Kato
Abstract: Semi-crystalline mesoporous titania films were prepared by the reactions of titanium isopropoxide (TTIP) in acidic aqueous solutions containing EO106PO70EO106 triblock copolymer (F127) and 1,3,5-triisopropylbenzene (TIPBz). Adsorption experiments of dye molecules over the mesoporous films calcined at different temperatures and prepared with different TTIP/F127 molar ratios showed that adsorption property of the dye molecules would be related to the crystallinity of the frameworks and the macroporosity at the surfaces.
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Authors: Kazuyuki Suzuki, Yi Ping Guo, Kaori Nishizawa, Takeshi Miki, Kazumi Kato
Abstract: The Y0.5Yb0.5MnO3 ferroelectrics/HfO2 stacking layer was constructed on Si(100) substrate through the chemical solution deposition. The HfO2 insulating layer crystallized on Si(100) substrates consisted of uniform grains and had smooth surface. The Y0.5Yb0.5MnO3 film prepared on the HfO2 insulator layer had preferred orientation along c-axis. The Y0.5Yb0.5MnO3 film consisted of uniform grains and had smooth surface. The clockwise C-V hysteresis induced by ferroelectric polarization switching was observed in the MFIS structure. The memory window of the MFIS structure was about 2 V and the retention time was over 105 s.
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Authors: Kazuyuki Suzuki, Kiyotaka Tanaka, Tatsuo Kimura, Kaori Nishizawa, Takeshi Miki, Kazumi Kato
Abstract: The (Y,Yb)MnO3 films were crystallized on Y2O3 layers using alkoxy-derived precursor solutions. As a result of investigation of the effect of the Y2O3 layer on the dielectric properties of the (Y,Yb)MnO3/Y2O3/Si, the crystallographic properties such as the orientation and surface morphology of the (Y,Yb)MnO3 thin films depended on the crystallographic appearance of the insulator layer. Following that, the dielectric properties of the MFIS structures varied. For the construction of excellent MFIS structure, the improvement of the orientation, crystallinity, and surface smoothness of the (Y,Yb)MnO3 film by the optimization of the microstructure and dielectric property of the insulator is necessary.
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Authors: Yi Ping Guo, Kazuyuki Suzuki, Kaori Nishizawa, Takeshi Miki, Kazumi Kato
Abstract: BaTiO3 films with thickness of ~1 2m were prepared by chemical solution deposition on LaNiO3/Pt/TiOx/SiO2/Si substrate with a thin highly (100)-oriented and high crystallinity BaTiO3 thin film (~140 nm) as a buffer layer. The BaTiO3 films prepared by using a 0.5 mol/L solution have high crystallinity and still show (100) preferred orientation. The electrical properties of the (100)-oriented BaTiO3 films prepared by this process have been studied. A dielectric constant of ~910 and a loss tangent of ~3.5% (1 kHz) were obtained. The remanent polarization (2 Pr) and coercive field (2 Ec) are 4.0 μC/cm2 and 35 kV/cm, respectively.
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Authors: Kiyotaka Tanaka, Kazuyuki Suzuki, De Sheng Fu, Kaori Nishizawa, Takeshi Miki, Kazumi Kato
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Authors: Kazuyuki Suzuki, Kiyotaka Tanaka, De Sheng Fu, Kaori Nishizawa, Takeshi Miki, Kazumi Kato
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Authors: Kaori Nishizawa, Takeshi Miki, Kazuyuki Suzuki, Kazumi Kato
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Authors: Kaori Nishizawa, Takeshi Miki, Kazuyuki Suzuki, De Sheng Fu, Kazumi Kato
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Authors: Tsutomu Sonoda, Akira Watazu, Kazumi Kato, Tadashi Asahina
Abstract: The deposition of Sn-5wt.%Al alloy onto pure aluminum powder in its self-convective motion by magnetron DC sputtering was examined in order to prepare Al-Sn composite particles, aiming not only at the development of highly uniform sintered binary compact materials but also at the improvement of the bonding between the aluminum particles after sintering at low temperature such as 250°C. The self-convection phenomenon of the aluminum powder in the vacuum chamber occurred when a perpendicular vibration was applied to the powder. The sputter-deposition of the Sn-Al alloy was carried out during the self-convection of the aluminum powder. Under SEM and according to EPMA analysis, as well as according to thermal analysis with DSC, it was confirmed that the obtained particles were coated with the Sn-Al deposits. Therefore it was found that Sn-Al composite powder could be produced by this processing, and thereby not only the development of highly uniform sintered binary compact materials but also the improvement of the bonding between the aluminum particles after sintering at low temperature were expected.
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Authors: Kiyotaka Tanaka, Kazuyuki Suzuki, Tatsuo Kimura, Kaori Nishizawa, Takeshi Miki, Kazumi Kato
Abstract: Lead-free Ba(Ti1-xZrx)O3 (BTZ) thin films were fabricated on Pt(111)/Ti/SiO2/Si(100) substrates by the chemical solution deposition (CSD) process. The microstructure of the BTZ (x = 0.00 to 0.20) thin films was improved by additional sintering process, and their crystallite sizes were increased in each composition. The dielectric constant er and piezoelectric constant d33 of the BTZ thin films depended on the crystallite size. We give a guide for further investigation to improve the characteristics of BTZ thin films.
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