Papers by Author: Nobuyasu Adachi

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Authors: Takashi Yoshiguchi, Toshitaka Ota, Nobuyasu Adachi
Abstract: By the solution-dropping method imitating the growth of stalagmite in nature, piezoelectric KNbO3 crystal was prepared onto a substrate by dropping metastable K2NbO3F aqueous solution. The transformation from K2NbO3F to KNbO3 was accelerated by separately dropping H2O2 solution at the same time. Under the conditions of K2NbO3F concentration of 4.2×10-2 mol/l, H2O2 concentration of 9mol/l, dropping rate of 1.7ml/min, dropping time of 2 h, and substrate temperature of 20°C, KNbO3 crystals of 2 to 5μm and polycrystalline film composed of KNbO3 crystals of < 1μm were grown at aqueous temperatures of 20°C and 60°C, respectively.
Authors: Toshitaka Ota, Takahiro Eitsuka, Haruki Yoshida, Nobuyasu Adachi
Abstract: Porous calcium phosphate ceramics (apatite and TCP) with wood-like microstructures, analogous to that of silicified wood, were prepared from natural woods as templates. The production of these ceramic woods was performed by the following process: (1) infiltration with an ethanol solution containing tri-ethyl phosphate and calcium nitrate tetra-hydrate into wood specimens, (2) drying to form a calcium phosphate gel in the cell structure, (3) firing in air to form apatite and TCP. The microstructure of the obtained ceramic woods retained the same structure as that of the raw woods: with the pore sizes corresponding to those of the original wood, and the major pores being unidirectionally connected.
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