菊池 丈幸

<p>We studied the fabrication of a TiO<sub>2</sub>/SiO<sub>2</sub> composite coating on Ti. At a temperature above 1100 K with oxygen partial pressure, a self-organized coating of rutile phase TiO<sub>2</sub> is formed on a Ti substrate. The thick TiO<sub>2</sub> coating (> 10 m) had a "piecrust-like" multilayer structure, which comprise TiO<sub>2</sub> monolayers and gaps. A composite coating containing SiO<sub>2</sub> was fabricated via a sol-gel method in vacuum to improve the exfoliation strength of the brittle, porous TiO<sub>2</sub> coating. Cross-sectional SEM images revealed sufficient amounts of SiO<sub>2</sub> in the gaps between the TiO<sub>2</sub> monolayers in the TiO<sub>2</sub>/SiO<sub>2</sub> 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 TiO<sub>2</sub> coating alone, and the composite coating's failure mode was interfacial compared with cohesive for the self-organized TiO<sub>2</sub> coating.</p><p> </p><p>Mater. Trans. <b>57</b>（2016） 2008-2014に掲載</p><p>本研究の背景をより正確にするため，実験方法，結果，考察の一部を修正し，文献の追加および順番を変更，Fig. 12を追加した．</p>

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

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

<p>Y-type ferrite substituted with a combination of non-magnetic lithium and aluminum, Ba<sub>2</sub>Zn<sub>2–2<i>x</i></sub>Li<sub><i>x</i></sub>Al<sub><i>x</i></sub>Fe<sub>12</sub>O<sub>22</sub>, 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 <i>x</i> = 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 <i>x</i>. As a result, the saturation magnetization at room temperature showed maximum at <i>x</i> = 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.</p>

© 2017 Elsevier Ltd and Techna Group S.r.l. 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 Mössbauer spectra were measured at room temperature with conventional constant-acceleration spectrometer. Obtained Mössbauer spectra were numerically separated into six discrete components. The relationship between Mössbauer parameters and magnetic properties has been discussed. From the values of the isomer shift, it was found that the iron ion in Sr3Co2-xZnxFe24O41is 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-xZnxFe24O41is 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.

A new synthetic route to prepare yttrium barium copper oxide superconductive fibers using electrospinning in conjunction with the polymerizable complex method was developed. The as-spun fibers exhibited wool-like tactility and were 5-7 mu m thick. The fibers therefore exhibited sufficient flexibility to be fabricated into arbitrary shapes. Although the fibers shrunk and exhibited brittle tactility because of the decomposition of organic compounds during heat treatment, the fibers predominantly maintained their fibrous form. Scanning electron microscopy observations revealed the growth of metal oxide grains during sintering. Powder X-ray diffraction pattern of the annealed fibers showed good agreement with the pattern of YBa2Cu3O7-delta. Magnetic property measurements of a ground fiber sample using a superconducting quantum interference device revealed that the superconducting transition temperature of the sample was 91 K. (C) 2017 The Ceramic Society of Japan. All rights reserved.

<p>SnO<sub>2</sub> quantum dot was successfully synthesized at ambient temperature via ozone bubbling to suspension including Sn<sub>6</sub>O<sub>4</sub>(OH)<sub>4</sub> under pH of 12. It was clarified that use of SnF<sub>2</sub> as starting material enables to obtain clear and stable SnO<sub>2</sub> quantum dot suspension. Possible formation mechanism of quantum dot was proposed and shift of fluorescence was predicted with use of varied basic solution for neutralization and pH adjustment based on the hypothesis that shift of fluorescence is attributed to change in size. And this prediction was confirmed by experiment. Finally addition of Zn as dopant gave improved luminescence intensity without shift of fluorescence.</p><p>SnO<sub>2</sub> quantum dot developed in this work does not include any cadmium, thus application as alternative to conventional CdSe and CdS is expected.</p>

Ferromagnetic magnetite (Fe3O4) thin films for magnetoelectric multiferroic applications were deposited on (200) (Bi3.25Nd0.65Eu0.10)Ti3O12 (BNEuT)/(101) Nb:TiO2 substrates by metalorganic chemical vapor deposition (MOCVD) using an iron(III) tris(2,2,6,6-tetramethyl-3,5-heptanedionato) precursor as the iron source. The BNEuT film utilized as a ferroelectric template material was in the form of freestanding nanoplates with narrow spaces between them. The effects of deposition conditions such as the deposition time and substrate temperature on the magnetic and structural characteristics of the Fe3O4/BNEuT composite films were investigated. All the films consisted of mostly single-phase Fe3O4 with a cubic inverse-spinel structure. When deposition was carried out at temperatures of 400-420 degrees C, the filling rates of particles introduced into the narrow spaces between the BNEuT nanoplates exhibited high values of 76-89% including the amorphous phase. This suggested that the deposition in this temperature range made progress according to the growth mechanism of MOCVD in the surface reaction rate determining state. Room-temperature magnetic moment-magnetic field curves for Fe3O4 thin films deposited at 400-500 degrees C for 60 min exhibited narrow rectangular hysteresis loops, indicating typical soft magnetic characteristics. (C) 2016 The Japan Society of Applied Physics

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 (>10 mu 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.

© 2015 The Japan Society of Applied Physics. (Bi3.25Nd0.65Eu0.10)Ti3O12 (BNEuT-0.1) films with a- and b-axis orientations and thicknesses of 1.8-2.3μm were sputter-deposited on conductive Nb:TiO2(101) substrates containing 0.79 mass% Nb. The deposition temperature was fixed at 650 °C, and the sputtering gas pressure was varied from 0.4 to 5.0Pa in order to examine its effect on the structural, ferroelectric and piezoelectric properties of the films. The films were found to have a mostly single-phase orthorhombic structure, with a high degree of a- and b-axis orientations (93-98%). The films had a nanoplate microstructure, with the plates being aligned along the [100]/[010] direction, and porosities of 15-25%. A maximum room-temperature remanent polarization (2Pr) of 93 μC/cm2 was obtained for a sputtering gas pressure of 5.0 Pa. All the films were strongly a-axis oriented, according to the results of X-ray diffraction measurements and vertical amplitude images in piezoresponse force microscopy. The optimal sputtering gas pressure for heteroepitaxial growth of BNEuT-0.1 nanoplates with a high degree of a-axis orientation of 96.5%, a maximum orthorhombicity of 0.0017, a comparatively large remanent polarization of 2Pr = 66 μC/cm2, and a high porosity of 24% was found to be 0.4 Pa.

The piezoelectric properties of high-temperature-poled high-density solid solutions with compositions of xPb(Mn1/3Nb2/3)O-3 yPbZrO(3)-zPbTiO(3) (xMnN-yPZ-zPT; PNInNZT) with x = 0.020 - 0.180, y = 0.420 - 0.580, and z = 0.400 - 0.560 were investigated by using the resonantantiresonant frequency method. The two optimal compositions that exhibited large values of d(33).Q(m)(p), where d(33) is the piezoelectric coefficient (longitudinal length mode) and Q(m)(p) is the mechanical quality factor (radial mode) for high-power piezoelectric applications were x = 0.040, y = 0.540, and z = 0.420 in the rhombohedral and the morphotropic phase boundary (MPB) regions and x = 0.095, y = 0.435, and 2 = 0.470 in the MPB and the tetragonal regions. By comparing the maxima in d(33).Q(m)(p) for high-temperature (HT)-poled PIVInNZT samples with the maxima in d(33) . Qm(p) for room-temperature (RT)-poled PMnNZT samples that had been previously reported, the ratio of d33 Qm(p)HT/d33 .Qm(p) RT was approximately 1.8, exhibiting a significant iniprovement due to HT-poling treatments.

High-density solid solutions with compositions of (1-x)(Bi1/2Na1/2)TiO3-xBa(Mn1/3Nb2/3)O-3 (BNT-BMN), with x = 0 - 0.06, were prepared by using the conventional ceramic fabrication process. The optimal composition that yielded the best piezoelectric properties for high-power piezoelectric applications was investigated. X-ray diffraction (XRD) analyses of BNT-BMN with x = 0 - 0.06 suggested that the rhombohedral-pseudocubic morphotropic phase boundary (MPB) for this material system is in the compositional region 0.035 a parts per thousand currency sign x a parts per thousand currency sign 0.04 at room temperature. A hard-mode BNT-BMN with x = 0.03, which lay on the rhombohedral side near the MPB region, exhibited excellent piezo- and ferroelectric properties.

© 2014 The Japan Society of Applied Physics. Sr2Bi4Ti5O18(SBTO) films with a- and b-axis orientations, and thicknesses of 0.9-1.2μm were sputter-deposited on conductive Nb:TiO2(101) substrates containing 0.79 mass% Nb. The deposition temperature was varied from 575 to 700 °C under a fixed gas pressure of 0.4 Pa, and the structural and ferroelectric characteristics of the films were investigated. SBTO films deposited at 625-700 °C had a mostly single-phase orthorhombic structure, with a high degree of a- and b-axis orientations [α(h00)/(0k0)] of 99.0-99.8%. In addition, the full width at half maximum of the (200) diffraction peak was 0.69-0.86°, which indicated good crystallinity. SBTO films deposited at 625-650 °C had a nanoplate-like microstructure with the plates aligned along the [010] direction. The real room-temperature remanent polarization (2P∗r), taking the porosity between the nanoplates into account, exhibited a maximum of 40 μC/cm2at 650 °C. Thus, the optimal deposition temperature for heteroepitaxial growth of SBTO nanoplates with a high α(h00)/(0k0)of ≥99.0% and excellent ferroelectric properties on conductive Nb:TiO2substrates is 650 °C under a gas pressure of 0.4 Pa.

The preparation technique to obtain purely inorganic silica doped titania fibers using electrospinning together with sol-gel method was proposed. For the system without silicon doping, fibers were too brittle to form long fiber. And it was clarified that small amount of doped silicon could modify the flexibility of fibers drastically and long fibers with appropriate mechanical property could be obtained. After calcination at 500 degrees C for 2 h anatase phase was appeared and the specific surface area of fibers with composition of [Ti]/[Si] = 6 showed highest value 71.9m(2)/g among all the samples tested, which is even higher than typical fine particles. The result of decomposition experiment of Rhodamine B dye solution showed that the silica doped titania fiber has adequate photocatalytic activity to decompose organic matters. (C)2014 The Ceramic Society of Japan. All rights reserved.

a- and b-axis-oriented (Bi3.25Nd0.75-xEu x)Ti3O12 (BNEuT, x = 0-0.75) films of 3.0μm thickness were fabricated on conductive Nb:TiO2(101) substrates containing 0.79 mass-Nb by high-temperature sputtering at 650°C, and their structural and piezoelectric characteristics were investigated. The room-temperature remanent polarization (2Pr) and effective piezoelectric coefficient (d33) values for the BNEuT films exhibited maxima of 87 μC/cm2 and 15pm/V, respectively, at x = 0.10, which were approximately 1.3 times larger than those (2Pr = 65 μC/cm2 and d33 = 12pm/V) of the nondoped (Bi 3.25Nd0.75)Ti3O12 (BNT) nanoplate. The BNEuT film with x = 0.10 had a high a-axis orientation judging from the X-ray diffraction measurement and the observation of the phase image by piezoresponse force microscopy. It is shown that adequate Eu3+ doping of BNT nanoplates produces a larger displacement magnitude of the octahedra than that in the nondoped BNT nanoplate, resulting in an improvement of piezoelectric properties in addition to the ferroelectricity. © 2014 The Japan Society of Applied Physics.

The morphotropic phase boundary (MPB) for high-density solid solutions with compositions of xPb(Mn1/3Nb2/3)O-3-yPbZrO(3)-zPbTiO(3) (PMnNZT) with x = 0.02-0.16, y = 0.42-0.56, and z = 0.42-0.56 has been refined on the basis of an analysis of the dielectric and piezoelectric properties of the fabricated samples. An X-ray diffraction analysis of the PMnNZT solid solutions suggested that the refined rhombohedral-tetragonal MPB in this material system is in the compositional region x = 0.02-0.134, y = 0.42-0.54, and z = 0.44-0.485. It was found that a hard-mode solid solution with x = 0.10, y = 0.45, and z = 0.45, which lies in the refined MPB region, exhibited excellent piezo- and ferroelectric properties highlighting its potential as a high-power piezoelectric material for ultrasonic vibrators and piezoelectric transformers. (C) 2013 The Japan Society of Applied Physics

a- and b-axis-oriented (Bi3.25Nd0.75-xEu x)Ti3O12 (BNEuT, x = 0-0.75) films of 3.0 μm thickness were fabricated on conductive Nb:TiO2(101) substrates containing 0.79 mass% Nb by high-temperature sputtering at 650 °C, and their structural and ferroelectric characteristics were investigated. All the films had a mostly single-phase orthorhombic structure, with high degrees of a- and b-axis orientations of 99.0-99.8%. The lattice parameters (a-, b-, and c-axis lengths) and the calculated orthorhombic lattice distortion decreased monotonically with increasing Eu content. The microstructure of BNEuT films with x = 0-0.50 was nanoplate-like, whereas that of films with x ≥ 0:60 was significantly more bulklike. The real room-temperature remanent polarization (2Pr*), taking the porosity between the nanoplates into account, had a maximum value of 2Pr* = 87 μC/cm2 at x = 0.10, which was approximately 1.3 times larger than that (65 μC/cm2) of the nondoped BNT film. It is shown that lattice distortion caused by rotation of octahedra in the a-b plane due to the Eu substitution plays a significant role in the improvement of ferroelectricity. © 2013 The Japan Society of Applied Physics.

a- and b-axis-oriented Bi3. 25Nd0. 75Ti3O12 (BNT) nanoplates, 3. 0-μm thick, were fabricated on conductive Nb:TiO2(101) substrates with 0. 79 mass% Nb at 650 °C by high-temperature sputtering. Successively, the fabrication of inorganic-organic composites was carried out by introducing an epoxy resin to the spaces between the BNT nanoplates. The fourier transform infrared spectroscopy (FTIR) and the energy dispersive X-ray (EDX) elemental mapping results confirmed that the fabricated composites were inorganic-organic hybridized materials with cured epoxy resin introduced into the spaces between the BNT nanoplates. Piezoelectric response measurements of the fabricated BNT-epoxy resin composites by using piezoresponse force microscopy (PFM) showed that the composites have potential as piezoelectric microelement materials. © 2013 The Korean Physical Society.

Synthesis of U-type hexaferrite was investigated in the various strontium-based systems (Sr-Me-Fe-O system, Me = Co, Zn, Cu, and Ni). Precursors of ferrites were prepared by polymerizable complex method. Sr4Me2Fe36O60 (Me = Co and Zn) U-type hexaferrites were synthesized at the temperature range between 1423 and 1483 K in air. Coercivity of obtained ferrite was decreased with increasing heat treatment temperatures. Cu substitution reduced formation temperature of U-type hexaferrite.

Synthesis of Sr3Zn2Fe24O41 Z-type ferrite was investigated. Precursors of ferrite were prepared by polymerizable complex method. Identification of formed phases in the obtained samples and determination of lattice parameters of Z-type ferrite were performed by powder X-ray diffraction (XRD). Single-phase of Sr3Zn2Fe24O41 Z-type ferrite was synthesized by heating at 1463 K for 5hours in air. M-H curve of prepared single-phase Sr3Zn2Fe24O41 Z-type ferrite was measured by using vibrating sample magnetometer (VSM). It was revealed that Sr3Zn2Fe24O41 Z-type ferrite has larger saturation magnetization (23.5 mu(B)/formula unit) than that of Sr3Co2Fe24O41 (22.7 mu B/formula unit) and shows characteristic two-step saturation of magnetization as well as Sr3Co2Fe24O41 Z-type ferrite.

Single-walled carbon nanohorns (SWCNHs) hybridized with palladium (Pd) nanoparticles were synthesized by a single-step gas-injected arc-in-water method (GI-AIW) with a Pd wire inserted inside the anode hole. In the arc zone, carbon and Pd were vaporized simultaneously, leading to the formation of hybrid material of SWCNHs and Pd nanoparticles due to effective quenching. Based on TEM and CO chemisorption analyses, Pd nanoparticles were found to be embedded inside SWCNH aggregates. The size of Pd nanoparticles, determined by X-ray diffraction, was in the range of 3-6 nm when Pd wires with diameters of 0.1 and 0.3 mm were used. Using a Pd wire with a diameter larger than 0.5 mm results in larger Pd nanoparticles which tend to be exposed to the outer surface of the hybrid material. According to thermogravimetric analyses, the weight fraction of Pd nanoparticles is increased by increasing the Pd wire diameter although the yield of Pd nanoparticles decreased. SWCNHs hybridized with dispersed Pd nanoparticles, synthesized with 0.1 mm Pd wire, exhibited strong anti-oxidation resistance with a highly graphitic structure. (C) 2011 Elsevier Ltd. All rights reserved.

Synthesis of single-phase Sr3Co2Fe24O41 Z-type (Sr(3)CO(2)Z) ferrite was realized by adopting the polymerizable complex method. Crystal structure of samples has been investigated by powder X-ray diffraction (XRD). Single-phase Sr(3)Co(2)Z ferrite was obtained by heating at 1473 K for 5 h in air. Magnetic properties were discussed by measurements of M-H curves with vibrating sample magnetometer (VSM). Sr(3)CO(2)Z ferrite prepared by polymerizable complex method showed typical M-H curve of soft ferrite, with a saturation magnetization of 21.5 mu(B)/formula unit (50.5 emu/g) and a coercive force of 0.0141 at room temperature. (C) 2011 Elsevier Ltd. All rights reserved.

Synthesis of La-Co substituted M-type Calcium hexaferrite was studied. Samples were prepared by polymerizable complex method. High purity reagent of strontium carbonate, iron (III) nitrate ennnahydrate, cobalt (II) nitrate hexahydrate and lanthanum oxide were used as starting materials. Prepared aqueous solution was heated for dehydration and gelling. Thermal pyrolysis was carried out by heating the gel. The obtained precursor powders were ground with an alumina mortar and compacted by uniaxial pressing into disk specimens and then heated at temperature range between 1173 K and 1573 K in air. Phase identification and determination of lattice parameters were carried out by powder X-ray diffraction (XRD). Scanning Electron Microscope (SEM) was utilized to investigate the microstructure of the polycrystalline ferrites. Magnetic properties were discussed by magnetization measurements by measuring of M-H curve with vibrating sample magnetometer (VSM). Single-phase of M-type hexaferrite was obtained at lower temperature relative to by conventional synthesis. © Published under licence by IOP Publishing Ltd.

Magnetic properties of La-Co substituted M-type strontium hexaferrites were studied. The samples were prepared by polymerizable complex method. Crystal structure of samples has been investigated by powder X-ray diffraction (XRD). Single-phase M-type strontium hexaferrites with chemical composition of Sr(1.05-x)La(x)Fe(12-x)Co(x)O(19) (x = 0-0.4) were formed by heating at 1173 K for 24 h in air. Magnetic properties were discussed by measurements of M-H curves with vibrating sample magnetometer (VSM). La-Co substituted M-type strontium hexaferrites prepared by polymerizable complex method showed typical magnetic hysteresis of hard ferrite. The coercive force increased significantly by La-Co substitution with polymerizable complex method. Maximum coercive force achieved in this study is 8.0 kOe (640 kA/m). Scanning electron microscopy revealed that the prepared ferrite particles have plate-like shape of diameter range between 20 and 500 nm. (C) 2010 Elsevier B.V. All rights reserved.

Zr50Cu50-xAlx (X = 2 to 16) and Zr 90-YCuYAl10 (Y = 30 to 45) bulk metallic glasses (BMGs) have been prepared by tilt casting techniques. The viscosity of the supercooled liquids has been measured by using a penetration viscometer with a column-shaped tungsten indenter with 0.5mm in diameter and an applied load of 0.020N at a high-speed heating at a rate of 400K/min in a highly-purified He-gas atmosphere. In the Zr50Cu50-xAlx (X = 2 to 16) system, the viscosity of the supercooled liquids exhibited almost the same values when the Al-content was increased from 2 to 10 at %. When the Al-content increased to 12 at. %, the viscosity of the supercooled liquids increased largely. A large amount of the ZrCu (B2) phase after crystallization of this BMG system was detected when the Al-content was 10 at % and below. While, when the Al-content was increased to 12 at %, the main precipitation phase was changed to the ZrCu (B 19') phase. Similar increase in the viscosity of the Zr90-YCuYAl10 (Y = 30 to 45) supercooled liquids was also observed when the Cu-content was increased from 30 to 45 at. %. This may be due to the strong relationships between the compositional dependence of structure and the viscosity of the supercooled liquids in these BMG systems. © 2010 The Society of Materials Science, Japan.

The titanate nanostructures with high UV absorption characteristics could be fabricated by hydrothermal method within a temperature range of 90-150 degrees C. TEM, XRD, BET analyses, and UV-vis spectroscopy were employed to elucidate the synthesized titanate nanostructure characteristics which were microstructure, phase transformation, specific surface area, and band gap energy, respectively. With an increase in the hydrothermal treating temperature from 90 to 120 C, the specific surface area of titanate nanostructures was increased from 83 to 258 m(2)/g, while the band gap energy of titanate nanostructures was increased from 3.44 to 3.84 eV and then slightly decreased to 3.81 eV at 150 degrees C. The fabricated titanate nanostructures could exhibit higher UV adsorption capability but lower photocatalytic activity when compared with that of commercial TiO2 powders. (C) 2010 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Viscous flow behaviour of supercooled liquids and mechanical properties in Zr55+XCu30-XNi5Al10 (X=0, 5 and 10 at. %) and Zr65Cu18Ni7Al10, bulk metallic glasses (BMGs) have been examined. Viscosity has been measured by using a penetration viscometer at a high-speed heating rate of 400 K/min. With increasing Zr-content, T-g tended to decrease and T-x tended to increase, resulting Delta T-x (=T-x-T-g) increaseing up to about 170 K under a heating rate of 400 K/min by the DSC analysis. The viscosity lowered about one order of magnitude, e.g., minimum value of the viscosity decreased from 3 similar to 4x10(6) Pa-s for the Zr55Cu30Ni5Al10 and Zr60Cu25Ni5Al10 BMGs down to 5 similar to 6x10(5) Pa-s for the Zr65Cu20Ni5Al10 and Zr65Cu18Ni7Al10 BMGs under the same heating condition. Compression tests were also carried out at a slow strain rate of about 1 x 10(-4) s(-1) at room temperature. With increasing Zr-content, the apparent yield stress was decreased but the total strain at fracture was increased significantly, suggesting that there is a strong relationship between viscosity and the mechanical properties in these BMGs.

Titanate nanostructures were synthesized by hydrothermal technique. The sonication pretreatment and reaction temperature were employed to investigate the morphology and specific surface area of the titanate nanostructure. Transmission electron microscopy, dynamic light scattering, and nitrogen adsorption were used to characterize and elucidate the behavior of titanate nanostructures in each experimental condition. By the effect of sonication pretreatment, the length and BET surface area of titanate nanotubes (TNTs) were raised from 50 nm to 490-1760 nm and from 180 to 260 m2g-1, respectively, because of de-agglomeration of TiO2 particles in the precursor. The BET surface area of TNTs increased with increasing hydrothermal temperature from 90 to 150°C However, when the reaction temperature increased up to 180°C, BET surface area of TNTs inversely decreased. The reason of the decline in surface area could be explained by morphology of titanate formed. The nanotube structure (hollow) of titanate was transformed to nanofiber structure (non-hollow) at this high temperature. © 2009 The Society of Chemical Engineers, Japan.

The hydrothermal process coupled with sonication pretreatment has been employed to synthesize titanate nanostructures, including nanotubes and nanowires. By varying size of raw TiO(2) powder(400 nm and 1 mu m), reaction temperature (90-180 degrees C), and sonication power (0-38 W), morphology of titanate nanostructures, length of titanate nanotube, and phase of titanate nanowire could be adjusted. Transmission electron microscope (TEM), nitrogen adsorption, and X-ray diffraction (XRD) were employed to analyze structure, specific surface area, and crystalline phase of the synthesized products. The titanate nanostructures transformed from the smaller TiO(2) particles provided higher specific surface area and shorter tube-length than those transformed from the larger ones. Morphology of titanate product transformed from TiO(2) spherical particle to titanate nanosheet, nanotube and nanowire with the gradual increase in the reaction temperature. The surface area of the samples corresponded well with the amount of titanate nanotube (hollow) and nanowire (non-hollow), whilst the length of titanate nanotube became longer with the applying sonication pretreatment Interestingly. the formation of brookite phase was observed for the titanate nanowire synthesized at 180 degrees C with sonication pretreatment (C) 2009 Elsevier B.V. All rights reserved.

It was experimentally confirmed that the average length of titanate nanotubes (TNTs) can be increased and controlled to a certain degree by applying sonication pretreatment to their titania precursors prior to hydrothermal synthesis. Without sonication, the average length of the TNTs synthesized by the hydrothermal process was much shorter due to constricted diffusion of the hydroxyl ion (OH(-)) and the sodium ion (Na(+)) through the narrow interparticle space of agglomerated titania precursors, thereby retarding the TNT formation mechanism. On the other hand, much longer TNTs with an average hydrodynamic size of 490-1760 nm were produced when the sonication pretreatment was applied. Based on microscopic observations on the transformation of the present precursors and the reported nanotube formation phenomena during the hydrothermal process, a mechanism contributing to length control is proposed.

Viscous flow behavior in supercooled liquid region of as-cast and pre-annealed Zr55Cu30Al10Ni5 bulk metallic glasses has been examined by using a penetration viscometer under high-speed heating rate of 20, 200 and 400°C/min. Applied load for the cylindrical-shaped penetration indenter with a diameter of 1 mm was varied from 0.049 N to 0.294 N. Viscosity was quite independent of these applied loads. By pre-annealing the bulk metallic glasses at 400°C, the density of the glasses increased, while the viscosity and the activation energy for viscous flow in their soopercooled liquid decreased with the pre-annealing treatments. Corresponding measurements of the differential thermal calorimetry (DSC) have been also done.

High-strength nanocrystalline Ni-W alloys containing 16.9 at. % W with average grain size of about 6 nm in diameter has been obtained by electrodeposition. At room temperature, the nominal tensile strength of the alloy was attained to about 1600 MPa, while the plastic strain before fracture was a very low value of 0.05 %. In this case, highly localized shear bands were observed near the fractured surface of the tensile test specimen. When the samples were annealed at 300°C under a static tensile stress of 327 MPa, the plastic strain was largely increased at the initial period of annealing and then tended to saturate, i.e., 0.54 % for 2 h, respectively. Grain size of the Ni-W alloys was almost saturated to 10-15 nm after annealing at 300°C for 2 h. It may be expected that the high tensile stress during grain growth might be effective to obtain the large uniform plastic deformation of nanocrystalline Ni-W alloys.

We have prepared Carbon/Fe-Ni-Cu ternary alloy composites by polymerized complex method. A single-phase Fe-Ni-Cu alloy could be obtained in carbon matrix by controlling pH of the citrate complex solution. It was revealed that the chemical compositions of metals in composites were maintained well by adding ethylene glycol into the complex solution. Crystallinity of both carbon matrix and Fe-Ni-Cu alloy particles were enhanced with increasing the carbonized temperature. The composite carbonized at 700°C had larger saturation magnetization and smaller coercivity than that carbonized at 500°C, which correlated with metal content and crystallite size of alloy. The composite carbonized at 700°C exhibited larger permeability and permittivity than carbon/Fe-Co alloy composites at frequency of GHz range.

A mixed ionic and electronic conducting hydrogen separation membrane, which consisted of proton-conductive oxide and metallic palladium, was fabricated. A porous alumina tube was employed as a support, and proton-conductive oxide particles were introduced into a microporous top layer of the support by an impregnation method. Palladium particles were deposited into the same porous layer by chemical vapor deposition. Hydrogen permeated preferentially via the membrane thus obtained with a hydrogen permeance (PH2) of 1.2 x 10(-9) mol.m(-2).s(-1).Pa-(1) at 873 K. Selectivity for hydrogen (PH2/PN2) increased with the operating temperature due to an increase in proton conductivity of the membrane, and PH2/PN2=5.7 was attained at 873 K. (C) 2007 Elsevier B.V. All rights reserved.

We have prepared Carbon/Fe-Ni-Cu ternary alloy composites by polymerized complex method. A single-phase Fe-Ni-Cu alloy could be obtained in carbon matrix by controlling pH of the citrate complex solution. It was revealed that the chemical compositions of metals in composites were maintained well by adding ethylene glycol into the complex solution. Crystallinity of both carbon matrix and Fe-Ni-Cu alloy particles were enhanced with increasing the carbonized temperature. The composite carbonized at 700°C had larger saturation magnetization and smaller coercivity than that carbonized at 500°C, which correlated with metal content and crystallite size of alloy. The composite carbonized at 700°C exhibited larger permeability and permittivity than carbon/Fe-Co alloy composites at frequency of GHz range.

Films consisting of carbon nanotubes containing iron (CNTs-Fe) were prepared on tungsten substrates for electron field emission. The films were prepared by drying the mixture of the CNTs-Fe with poly [3-octyl-thiophene] (P3OT) or toluene under a magnetic field using a permanent magnet of surface magnetic flux 340 mT. The field emission properties of the films were measured in comparison with the films prepared without the magnetic field. The films prepared under the magnetic field showed better field emission characteristics than those without the magnetic field, and the electric field to generate the required field emission current was significantly decreased by applying the magnetic field in the film preparation process. Microscopic analyses indicated that the magnetic field had the effect of forcing the CNTs-Fe to stand perpendicular to the substrate, which causes the enhanced field emission properties. (c) 2006 Elsevier Ltd. All rights reserved.

Electromagnetic wave absorption characteristics and electrical resistivity of the 3-5 mm thick ceramic specimens containing 14-20 mass% of Bincho-charcoal powder and 4-8 mass% of carbon black powder were measured by free space method and four probe method, respectively. The 3-5 mm thick specimens containing 16% of Bincho-charcoal powder absorbed remarkably (about 30 dB) the electromagnetic waves of 4-7 GHz. The 3-5 mm thick specimens containing 5% of carbon black powder absorbed excellently (25-40 dB) the electromagnetic waves of 4-8 GHz. The electrical resistivities of the specimens containing16% of Bincho-charcoal powder and 5% of carbon black powder were 5 × 103Ω ·cm and 1 × 104Ω·cm, respectively.

The formation process of Z-type hexagonal ferrite, Ba3Co 2Fe24O41, prepared by polymerized complex method and the effects of pH control of citrate complex solution were investigated. By heating a precursor, a pyrolyzed complex polymer, spinel phase, M-type ferrite and Y-type ferrite were formed sequently with increasing the heating temperature. By heating up to 1200°C, monophasic Z-type ferrite was not synthesized in usual preparation procedures. So pH of citrate complex solution was changed and the effects on formation process were examined. As ammonia solution was added to change the complex solution from acidic to basic, the phases in the pyrolysate changed form barium carbonate to barium nitrate and the crystallinity of the constituent phases decreased. By controlling pH to 11, monophasic Z-type ferrite was obtained by heating at 1200°C. On the other hand, pH control of the complex solution toward basic condition suppressed the formation of Y-type ferrite. It was revealed that the optimum conditions for preparing the complex solution depended on phases even for same Ba-Co-Fe-O system.

A porous nickel tubular support of 1 mm diam was successfully created by heat-treating a commercial nickel tube. The resulting tube contained uniform pores, whose diameters ranged from 0.5 to 2.5 mu m, depending on treatment temperature. The porous metal obtained is a promising candidate for support materials for microfuel cells or gas separation membranes because it has the necessary gas permeability and mechanical strength. It was also confirmed that a solid oxide fuel cell design employing the porous nickel tube as a supporting anode could be operated. (c) 2006 The Electrochemical Society.

We have successfully prepared Carbon/Fe-Co alloy composites starting from metal organic precursors synthesized by polymerized complex method. The carbon/Fe-Co alloy composites were obtained after the carbonization of the precursors heat-treated at ambient pressure and lower temperatures ranging from 500 to 700°C in N2gas flow. Crystalline sizes of both carbon matrix and Fe-Co alloy particles were determined by X-ray diffraction measurements as a function of the Co concentration and the carbonized temperature. The alloy particles were widely dispersed in the carbon matrix and the particle size carbonized at 600°C was about 20-50nm observed by scanning electron microscopy. The composite carbonized at 600°C had very small coercivity of 14 Oe and exhibited relatively large permeability spectra at frequency of GHz range.

Electromagnetic wave absorption characteristics and electrical resistivities of the unsaturated polyester specimens containing 20-60 mass% of Bincho-charcoal and 10-42.5 mass% of bamboo charcoal powders were measured. The specimens containing 33.3-50.0% of Bincho-charcoal powder absorbed remarkably the electromagnetic wave of the frequency range of 2.5-3.5 GHz and the specimens containing 12.1-18.0% of bamboo charcoal powder also absorbed remarkably that of the frequency range of 4.0-15 GHz. The specimens which showed the remarkable absorptions had the electrical resistivities of the range of 103-102Ω · cm and therefore these electrical resistivity values seems to have been suitable for converting the energy of the electromagnetic wave at the above frequency range into the energy of heat.

Electromagnetic wave absorption characteristics and electrical resistivity of the 2-6 mm thick cement mortar board specimens containing 6-16 mass% of Bincho-charcoal powder were measured by free space method and four probe method, respectively. The 2-4 mm thick specimens containing 8-10% of Bincho-charcoal powder absorbed remarkably the electromagnetic waves with frequencies of 3-8 GHz. Especially about 2.5 mm thick specimen containing 10% of Bincho-charcoal powder absorbed remarkably the electromagnetic wave of 5.8 GHz, which is used for intelligent transportation systems (ITS). It is clarified that these specimens are dielectric absorbers with the electrical resistivities of above 108 Ω · cm.

Electromagnetic wave absorption characteristics, electrical resistivity and micro pore structure (specific surface area and micro pore size distribution) of the powder-method woodceramics, which were prepared by carbonizing the compacted mixtures of wood powder and 10-30 mass% of phenolic resin powder, were examined in comparison with those of the conventional MDF-method woodceramics, which were prepared by carbonizing the medium density fiber (MDF) boards impregnated with phenolic resin solution. The powder-method woodceramics carbonized at 650°C showed remarkable electromagnetic absorption characteristics as same as MDF-method woodceramics, namely the absorption values of 10%, 20% and 30% phenolic resin specimens were 35 dB at 11 GHz, 40 dB at 9 GHz and 50 dB at 2 GHz, respectively. These remarkable absorptions were mainly due to the suitably high electrical resistivities (10<sup>1</sup>-10<sup>3</sup> Ωcm) of these woodceramics. The specific surface area of these woodceramics became to the maximum in the case of the carbonization at 700°C, namely 380 m<sup>2</sup> · g<sup>-1</sup> in the 30% phenolic resin powder specimen, 300 m<sup>2</sup> · g<sup>-1</sup> in the MDF specimen and 230 m<sup>2</sup> · g<sup>-1</sup> in the 10% phenolic resin powder specimen, respectively.

Electromagnetic wave absorption characteristics, electrical resistivity and micro pore structure (specific surface area and micro pore size distribution) of the powder-method woodceramics, which were prepared by carbonizing the compacted mixtures of wood powder and 10- 30mass% of phenolic resin powder, were examined in comparison with those of the conventional MDF-method woodceramics, which were prepared by carbonizing the medium density fiber (MDF) boards impregnated with phenolic resin solution. The powder-method woodceramics carbonized at 650°C showed remarkable electromagnetic absorption characteristics as same as MDF-method woodceramics, namely the absorption values of 10%, 20% and 30% phenolic resin specimens were 35 dB at 11 GHz, 40 dB at 9 GHz and 50 dB at 2 GHz, respectively. These remarkable absorptions were mainly due to the suitably high electrical resistivities (101-10 3Ωcm) of these woodceramics. The specific surface area of these woodceramics became to the maximum in the case of the carbonization at 700°C, namely 380m2·g-1 in the 30% phenolic resin powder specimen, 300m2·g-1 in the MDF specimen and 230m2 · g-1 in the 10% phenolic resin powder specimen, respectively.

A novel nanocarbon structure, carbon nanohorns (CNHs) particle which includes one Ni-contained carbon nanocapsule (CNC) in its center, is produced by submerged arc in liquid nitrogen using Ni-contained (0.7 mol%) graphite anode. Transmission electron microscopy revealed that each CNHs particle in nearly spherical shape of diameter around 50-100 nm has one Ni nanoparticle of diameter 5-20 nm encapsulated by graphitic shells as CNC. (C) 2003 Elsevier Ltd. All rights reserved.

Synthesis of multi-walled carbon nanotubes (MWCNTs) by an arc discharge between two graphite electrodes submerged in water under controlled pressure (from 400 to 760 Torr) is reported. Transmission and scanning electron microscopy investigations of the arc discharge product collected from the bottom of the reactor revealed high concentrations of MWCNTs at all pressures. Dynamic light scattering (DLS) on suspensions containing MWCNTs showed that the mean diameter of the nanotubes increases with decreasing pressure. Raman spectroscopy analysis reveals that the relative amount of disordered carbon is significantly less in the low-pressure samples. Furthermore, the yield of the deposit was found to be independent of the pressure. These results suggest that the physical properties of MWCNTs formed by the submerged arc can be controlled by varying the pressure. (C) 2003 Elsevier B.V. All rights reserved.

High-purity Fe-containing carbon nanocapsules (CNC) and carbon nanotubes (CNT) were prepared by pyrolysis of ferrocene in pure hydrogen flow. The CNTs and CNCs were, respectively, formed at the 988 °C zone and colder downstream zone of < 625 °C. The CNCs were observed to have an iron carbide core. Typical CNC particle sizes were in the 11-30 nm diameter size range with 2-40 graphitic shells.

The phase diagram of the BaO(BaCO3)-CaO-CuO system, especially in the barium-rich region at 900°C in air, was studied. Two new different oxycarbonates were observed: Ba8Ca16/15Cu64/15O11.20(CO 3)2.66 and a solid-solution series with a chemical composition of Ba2Cax+yCu1+(x/2)-yO2+δCO 3)1-z (where 0 ≤ x ≤ 2/39 and 0 ≤ y ≤ 16x/5). The oxycarbonate solid solution was formed in a region of the compositional triangle Ba:Ca:Cu (in moles) = (2:0:1)-(39:l:20)-(65:7:28). The solid-solution structure had P4/mmm symmetry, with lattice parameters a ≈ ap and c ≈ 2ap, where ap represents the perovskite cell. The Ba8Ca16/15Cu64/15O11.20(CO 3)2.66 compound, which had Pm3m symmetry with a lattice parameter a = 0.8116(2) nm, had no chemical-solubility range.

Bi-2223 bulk superconductors were irradiated with 290MeV/n40Ar18+ions.40Ar18+irradiation effects on flux pinning of Bi-2223, which were estimated as ΔM from magnetic hysteresis loops measured by SQUID and VSM, were discussed. Irradiated samples had enlarged magnetic hysteresis loops than unirradiated samples. Moreover, the increment of ΔM depended on depth from the irradiation surface. Microstructure of irradiated samples were observed by high-resolution transmission electron microscopy (HR-TEM). However, irradiation defects such as the columnar defects were not observed in these samples.

The effects of lithium doping by solid state reaction on the electrochemical intercalation into the Bi-2212 phase with lithium were investigated through the structure and superconducting properties. The expansion rates of lattice parameters with respect to the amount of lithium intercalated by electrochemical reaction decreased with increasing the amount of lithium doped by solid state reaction. The change of superconducting critical temperature with respect to average valence of copper became small with increasing the amount of lithium doped by solid state reaction. The electrochemical reaction removed lithium from Bi-2212 phase as much as the amount of lithium intercalated by electrochemical reaction. The result supports the possibility that lithium doped by solid state reaction and electrochemical reaction occupies the different sites in the Bi-2212 phase.