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Nano- or micro-tube mat has a large surface area and small pore size distribution, suitable for adsorption and controlled release of biologically active species. PVA fiber mat derived from the electrospinning was soaked in the Stöber solution at room temperature for 2h, which was fired at 500°C for 2h to derive the silica-tube mat. The characteristics of surface structure of PVA fiber and silica tube mat were investigated by Scanning electric microscope (SEM) and pore size distribution of silica tube mat was investigated by GEMINI2370 Micromeritic. The silica tube mat has 1.5–27 nm pore size.

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The present study focused formation of hydroxyapatite (HAp) from calcium phenylphosphate (CaPP) in simulated body fluid (SBF) containing alkaline phosphatase (ALP). ALP acts as a catalyst to hydrolyze phosphate esters, and results in gradual formation of phosphate ions. The emitted orthophosphate ion reacted with calcium ion to form HAp crystals, which have scale-shaped crystals in SBF. Transformation rate of CaPP to HAp was increased with increasing ALP concentrations in SBF. The increased rate of transformation is attributed to enhanced hydrolysis of the phenyl phosphate by increasing with the amounts of ALP.

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x mol% Li-doped BaTiO₃ (x = 0, 0.4, 0.6, 0.8, 1.2) particles were synthesized by a solvothermal approach at 200^oC. The obtained powders were 50-100 nm in diameter, and could be sintered to almost full theoretical density ( > 95%) at low temperature such as 1100^oC. The sinterability and piezoelectric property of Li-doped BaTiO₃ were improved by doping with Li ion. The highest piezoelectric constant d₃₃ was 260 pC/N with x = 0.6.

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We formed c-axis-oriented (Sr,Ca)2NaNb5O15 (SCNN) sheets using the green sheet process and the high-magnetic-field method, and we succeeded in realizing c-axis-oriented single plates (O-SP) and c-axis-oriented multilayer piezoelectric ceramics (O-MLPC) for SCNN. From the measurement results of displacement induced by electric field, it was clarified that effective d33 of the O-SP was 240 pm/V. This value was about 3 times larger than that of the randomly oriented single plate, which was 70% of that of single crystal. Moreover, it was confirmed that O-MLPC indicated displacements 3 times as large as that of the conventional multilayer piezoelectric ceramics. In this study, we clarified that piezoelectric properties in bulk and multilayer structure can be drastically enhanced using the green sheet process and the high-magnetic-field method.

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Piezoelectric actuator devices become increasingly important with widespread use of mechatronics devices. We propose a lead-free (K,Na)NbO3-based multilayer ceramic with nickel inner electrodes for piezoelectric actuator devices. In this study, the reduction resistance of (K,Na)NbO3 system was clarified to be cofired with base metal nickel inner electrodes. As a result, sufficiently high electric resistivity was obtained for the (K,Na)NbO3-based composition in reducing firing. The d33 constant was 160 pC/N and the Curie temperature was 260 degree Celsius. A multilayer specimen with nickel inner electrodes was fabricated. Its normalized electric-field-induced thickness strain was 360 pm/V.

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Evaluation on ferroelectric domain structures is described in piezoelectric ceramics composed of alkali bismuth niobate and alkali bismuth titanate. Ferroelectric domain switching and domain rotation could be explained by DC poling field dependence of dielectric piezoelectric prpperties. In addition, Young's modulus and Poisson's ratio toward poling field in piezoelectric ceramics were investigated by measuring longitudinal and transverse acoustic wave velocities to clarify the relationships between high piezoelectricity and the values. Basically, increasing domain alignment by applying DC poling field, the Young's modulus decreased and Possion's ratio increasd.

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Piezoelectric ceramics, which are vibrated under high alternating current (AC) field, show strong nonlinearities through a shift of the resonance frequency. This behavior is called as "jump phenomenon". This phenomenon should be considered for the design of high-power driving devices. We have constructed the theoretical formula of piezoelectric displacement including nonlinear effect under high electric field. The measured resonance curves of soft- and hard-type PZT ceramics were simulated using the theoretical equations. Using the material constants evaluated by the simulation, the domain's contribution to jump phenomenon was discussed.

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Solvothermally synthesized strontium titanate (SrTiO3, ST) or barium titanate (BaTiO3, BT) nanocubes were accumulated and the dielectric properties were studied. Initially, the BT or ST nanocubes were pressed into pellets. BT and ST were deposited on the pellets by a solvothermal method. P-E hysteresis loops and S-E curves of BT- ST accumulation ceramics (BT on ST) showed ferroelectric responses. The dielectric constant of the accumulation ceramics was measured to be 70.6.

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Lead-free (Na,K)NbO3(NKN) ceramics were synthesized by a 2-step sintering method under an atmospheric pressure or low oxygen partial pressures to investigate the effect of such atmosphere on the grain growth behavior. It was found that the NKN ceramics sintered under lower oxygen partial pressure showed better uniform microstructures, and demonstrated different grain growth exponent n constant from the samples sintered in an atmospheric pressure.

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We report selective preparation of macroporous monoliths of conductive titanium oxides Ti_nO_2n-1 (n = 2, 3, 4, 6) as a single phase, by reducing a macroporous TiO₂ monolith using zirconium getter. All the reduced monoliths have uniform pore size distribution, retaining that of the precursor TiO₂ monoliths. Furthermore, their bulk densities of 1.8 g cm^-3 are about half smaller and their porosities of 60% are about three times larger than that of commercial porous Ebonex (shaped conductive Ti_nO_2n-1). The obtained Ti_nO_2n-1 (n = 2, 3, 4, 6) macroporous monoliths could find their applications as electrodes for many electrochemical reactions.

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Recently, we have succeeded in the development of superior conductive ceramics by the gel-casting method. To use this ceramics industrially and widely, the improvement of productivity of fabrication is needed. In this study, we fabricated the conductive ceramics using a granule making by suspension polymerization. The electrically conductive property and carbon structure in the conductive ceramics was evaluated. The electroconductivity was high in the high pressure. Therefore, it was suggested that the press condition affected on the forming of carbon network and its graphitization behavior.

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In order to find the percolation threshold for the electrical resistivity and to study the photocurrent density of metallic Ag-nanoparticle/titania composite thin films, different volumetric fractions of silver (0.00 ≤ φ_Ag ≤ 0.68) to titania thin films, were fabricated on a quartz glass substrate at 600°C using the molecular precursor method. The resistivity of the films was of the order of 10^-2 to 10^-5 Ω cm at 25°C. The percolation threshold was identified at a φ_Ag value of 0.30. Photocurrent density of the Ag-NP/TiO₂ composite thin films was drastically changed and depended on the volumetric fractions of silver.

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Electrical conductive porous alumina (CPA) fabricated by the combination of gel-casting and high temperature reductive sintering in Ar at 1700 oC attracts a surge of interest. CPA was firstly pre-treated with mixed-acids followed by deposition of Pt nanoparticles via reductive reaction in order to gain novel composite. Crystal structure of uniformly dispersed Pt nanoparticles was confirmed to face centered cubic. And it was proved that surface pre-treatment attributes to the selective deposition of matrix.

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Metal carbide and carbonitride, Sm2Fe17Cx and Sm2Fe17CxNy, were prepared from Sm2Fe17 powders by carbonizing and/or nitriding in CH4-H2 or N2-H2 mixed gas. The resultant powders were characterized by structural or compositional analysis and magnetic measurements, so that Sm2Fe17CxNy showed the uni-axial magnetic anisotropy along a c axis of hexagonal lattices in a similar manner as Sm2Fe17Nx and the remanence values were increased with the C and N contents, but Sm2Fe17Cx was still of the plane anisotropy like the starting material of Sm2Fe17. However, Sm2Fe17Cx was unchanged even by heating at the higher temperature than 600C.

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Although BiNiO₃ is an insulator with Bi³⁺_0.5Bi⁵⁺_0.5Ni²⁺O₃ oxidation state at ambient pressure, it undergoes a pressure-induced phase transition to metallic Bi³⁺Ni³⁺O₃ at 4GPa. In the case of Bi0.95La0.05NiO3, this charge-transfer transition occurs at ambient pressure on heating, and the volume shrinks due to the Ni-O bond shrinkage. This transition is essentially first order, however, changing proportions of coexisting low- and high-temperature phase results in colossal negative thermal expansion. In this study, in order to understand the mechanism of this unusual transition, the microstructure of Bi_0.95La_0.05NiO₃ was studied by transmission electron microscopy.

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We synthesized the Y₃Fe₅O₁₂ powder using a reverse coprecipitation method. The maximum heat generation ability was obtained for the sample calcined at 1100^oC. Heat generation ability of the Y₃Fe₅O₁₂ is proportional to the cube of the strength of magnetic field. The hysteresis loss value for the B-H curve agreed with the heat generation ability for the sample calcined at lower than 1100^oC.

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We synthesized La_xNd_18-xLi₈Fe₅O₃₉(x=0, 9, 12, 18) by a solid-state method and measured direct and alternating current magnetometry. From the result, the temperature dependence of the dc magnetic susceptibility indicated the decrease of spin-glass transition temperature with the increase of the amount of lanthanum. Furthermore, weak ferromagnetic-like transition was observed in La₁₂Nd₆Li₈Fe₅O₃₉ at 7.8 K. This behavior corresponded with that of La₁₈Li₈Fe₅O₃₉. In La₁₅Nd₃Li₈Fe₅O₃₉ and La₁₆Nd₂Li₈Fe₅O₃₉, weak ferromagnetic-like transition was also observed at 7.8 K.

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