The phase transition behaviors of the [111] oriented barium titanate (BaTiO3) single crystals were investigated as functions of temperature, uniaxial stress and electric fields. For the phase transition by temperature, with decreasing temperature above Tc, the paraelectric phase changed to the intermediate phase with superparaelectric state, and finally change to the ferroelectric phase with randomly oriented spontaneous polarizations. Moreover, it was also found that the phase transition by uniaxial stress field above Tc was almost similar one by temperature. On the other hand, for the phase transition by electric field above Tc, with increasing electric field, the paraelectric phase changed to the intermediate phase, and finally changed to the ferroelectric phase with the oriented polar direction. These results suggested that above Tc, combination between uniaxial stress and electric fields might be effective for a poling treatment of BaTiO3 crystals. Thus, in this study, a new poling method for the BaTiO3 crystals was proposed using control of temperature, uniaxial stress and electric fields.

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Two-dimensional (2D) speckle patterns from the ferroelectric material PZN-9%PT have been observed successfully by coherent x-ray diffraction. The 2D-FFT image of the speckle pattern gives us a spatial autocorrelation function which contains the information of the domain arrangement in the crystal within a few micrometers scale. By the complementary use of an optical microscope and SEM, it has been concluded that there are some scales of higher-order structures (domains) from sub-J.tm to sub-mm in PZN-9%PT, i.e., a set of domains with a scale forms a higher order of domain. The nature of the pseudo-cubic X-phase is also discussed.

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Bismuth tungstate, Bi2W06 (BWO), mono-domain crystals were grown by a slow cooling method using L2B4O7 as a flux below the Curie temperature of 940°C. The growth conditions, which produced the maximum thickness, were investigated by a solidification technique based on the changing volumes of the starting material solution. We obtained plate-like crystals with sizes up to 1.0 mm thick. The relationship between the crystallographic abc and rectangular XYZ axes in the BWO crystals was clarified using etch pit observations and static piezoelectric measurements. According to the relationship, when the +Z axis was chosen such that the piezoelectric constant d33 is positive, it was found that both d31 and d32 are negative. The dielectric constant, epsilon iJ/ epsilon 0, of the BWO crystal was 70-100 at room temperature.

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The Bi4Ti3O12 (BIT) thin films with TiO2 layer were prepared on Pt/Ti/SiO2/Si substrates by two-dimensional RF magnetron sputtering using TiO2 and Bi2O3 targets. In order to prevent the interdifussion of BIT thin film, we inserted the TiO2 layer between BIT thin film and Pt electrode. The BIT thin film with TiO2 layer consists of small grain with a diameter of 80 nm. The orientation of BIT thin film depends on the film thickness ofTiO2 layer. When the thickness of TiO2 layer is 10 nm, the postannealed BIT thin film exhibited a good P-E hysteresis loop. The leakage current (IL) at voltage of 10 V was 10·6 A/cm2, although the IL of BIT thin film with no layer was 10·5 A/cm2

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The polarization dependence for the electronic structure of Bi4Ti3O12 (BIT) single crystal has been studied by soft-X-ray emission spectroscopy (SXES) and X-ray absorption spectroscopy (XAS). The valence band and conduction band are mainly composed of O 2p state and Ti 3d state, respectively. The SXES spectra measured at the Ti 2p absorption edge region exhibit three structures, which correspond to elastic scattering, fluorescence and soft-X-ray Raman scattering. The Raman scattering corresponds to the charge-transfer (CT) energy, which corresponds to the transition from O 2p state to unoccupied Ti 3d state. The CT energy in the a-c plane is different from that in the a-b plane. The difference of CT energy originates to the lattice constant and hybridization effect in BIT single crystal.

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Bi4Ti3O12 (BIT) thin films with TiO2 anatase layer were prepared on La0.05Sr0.95TiO3 (LSTO) substrates by metalorganic vapor deposition using Bi(CH3)3 and Ti(i-OC3H7)4 sources. When the substrate temperature was fixed at 500oC, the BIT thin films exhibited highly c-axis orientation. The c-axis orientation does not depend on layer created on LSTO substrate. The grain size of BIT thin film with TiO2 anatase layer is smaller than that with of BIT thin film with no-layer. The grain size of the BIT thin film accords with that of TiO2 anatase layer. This indicates that the TiO2 anatase layer acts not as barrier layer but as an initial nucleation layer of the BIT thin film. The postannealed BIT thin film with TiO2 anatase layer exhibited random orientation and P-E hysteresis loop.

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Domain switching process of bismuth titanate single crystals was investigated under application of electric field along the crystallographic c axis through polarization measurements and domain observations by optical microscope and piezoelectric force microscope. While unpoled crystals exhibited a poor polarization hysteresis, the crystals which were poled at 150°C showed a well-saturated polarization hysteresis with a remanent polarization of 4.4 micro C/cm2 and a coercive field of 4.7 kV/cm. Domain observations reveal that lenticular domain acts as an initial nucleus both in the poled and unpoled crystals during polarization switching of the c-axis component. The sidewise motion of the lenticular-domain walls and resultant single domain state were easily established for the poled crystals, while the lenticular domains observed in unpoled crystals were clamped even though a high electric field was applied to them.

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We performed X-ray diffraction topography on a BaTiO3 single crystal by high-coherent synchrotron X-rays. Since the domain configuration of the BaTiO3 crystal was unstable and fluctuated as temperature fluctuated, an excellent temperature control system is needed for the domain observation. We used a milli-Kelvin (mK) cell, which can control a BaTiO3 crystal within ±lmK. By combining the coherent X-ray and the mK-cell, one can detect the lattice strain very sensitively around the domain boundary. The lattice strain reduced as temperature increased, and disappeared at 100°C, which is much lower than the phase transition temperature of the BaTiO3, and the BaTiO3 crystal still remained in the ferroelectric tetragonal phase. This behavior can be interpreted by the existence of the so-called ‘non-strain-free style domain’, which is reported firstly by Takashige et al.

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The magnetic and structural properties of FINEMET [Fe73.5Si13.5B9Nb3Cu1 wt %] amorphous powder were investigated after nitrification and mechanical milling. Fe-based amorphous powder was nitrified and crystallized simultaneously at 550oC by using ammonia(NH3) gas. Nitrified powder exhibits iron nitride phases such as Y'-Fe4N, Fe3N and alpha’’-Fe16N2. Nitrified particles were more brittle than raw particles. As a result, nanometer sized nitride powder was fabricated by a high energetic ball milling method. The saturation magnetization (Ms) and coercivity (He) of nitrified powder were increased due to nitride phases.

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Transmission electron microscopy (TEM) observation was used to study a polycrystalline BiFeO3 film fabricated by a chemical solution deposition (CSD) on Pt/Ti/SiO2/Si(l00) substrates. Cross-sectional TEM images and corresponding selected area diffraction patterns (SAED) as well as x-ray diffraction (XRD) patterns indicated that the polycrystalline single phase of the BiFeO3 film was formed after annealing at 823 K for 10 min. Interfacial structural analysis making use of a high resolution cross-sectional TEM observation showed that a 1-2-nm-thick amorphous layer was formed only at the interface of the bottom electrode, and we found this amorphous layer deteriorates the leakage current quality. Ferroelectric hysteresis loops were measured by using a high frequency of 100 kHz system in order to suppress the leakage current component. The remanent polarization and the electrical coercive field of the BiFeO3 film were around 46 micro C/cm2 and 230 kV/cm, respectively at room temperature. At 10 K, the remanent magnetization and a magnetic coercivity were around 2 emu/cm3 and 0.5 kOe, respectively. However each parameter disappears at least 40 K. A broad peak was observed at 70 K in zero-field-cooling curve, which indicates a spin glass behavior of the BiFeO3 film.

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Ferroelectric (l-x)BiFeO3-xPbTiO3 thin films with near the morphotropic phase boundary (MPB) composition have been prepared by the chemical solution deposition. Perovskite BiFeO3-PbTiO3 single-phase thin films on Pt/TiO2/SiO2/Si substrates with good surface morphology were successfully fabricated by optimizing several processing conditions. Typical polarization (P)-electric field (E) hysteresis loops were observed for (l-x)BiFeO3-xPbTiO3 (x=0.2, 0.3, 0.4) thin films, although some leakage current components were included at room temperature. Since the electrical resistivity of the BiFeO3-PbTiO3 films was improved in the low temperature region, those films exhibited well-saturated ferroelectric P-E hysteresis loops. The remanent polarization (Pr) and coercive field (Ec) of the 600°C-prepared 0.7BiFeO3-0.3PbTiO3 thin films at -190°C were approximately 60 micro C/cm2 and 300 kV/cm, respectively.

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Perovskite BiFeO3-SrTiO3 ceramics have been prepared by the solid state reaction. The effect of SrTiO3 content in BiFeO3-SrTiO3 system on the crystal structure was investigated. Single phase of perovskite BiFeO3-SrTiO3 ceramics were successfully fabricated, whereas pure BiFeO3 ceramics contained a small amount of second phase in perovskite BiFeO3. Crystallographic symmetry of BiFeO3-SrTiO3 changes from rhombohedral to cubic when the amount of SrTiO3 exceeded 20 mol%. Mn doping to BiFeO3-SrTiO3 is very effective in controlling the grain growth and improving the sintered density. The dielectric properties of resultant ceramics were also improved by the Mn doping. Furthermore, rhombohedrally distorted Mn-doped BiFeO3-SrTiO3 show weak ferromagnetism at room temperature.

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Magnetic and dielectric properties of the ruthenium double perovskites R2MRuO6 were studied (R=La, Pr and Nd, M=Mg, Co, Ni and Zn). For R=La, the materials with the magnetic M2+ ions (M=Co and Ni) showed magnetic ordering and large dielectric constants (~5000). On the other hand, for the non-magnetic M2+ ions (M=Mg and Zn), magnetic ordering was not observed. In addition, their dielectric constants were found to be small (~100-200). Together with the imaginary part and the tan delta component of the dielectric response, the large dielectric constants for M=Co and Ni may be related to a smooth response of polar regions. Brief discussion for related materials R2MRuO6 with R=Pr and Nd is also described.

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Effects of the solid solution and aging treatment on microstructure, hardness and electrical conductivity of the Cu alloy containing 1.1 wt% Cr were investigated. The Cu-Cr alloy contains Mn as an alloying element. The horizontal continuous casting process was applied to obtain the unidirectionally solidified billets. The solid solution treatment of the alloy was carried out at 990 oC and the aging treatment was performed in the range 420-520 oC. The electrical conductivity generally increased as the aging temperature increased from 420 oC to 520 oC.

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Single crystals of K0.47Na053NbO3 (KNN) and Mu-substituted KNN (Mn-KNN, K0.53Na0.47Mn0.004Nb0.996Oy) were grown by a flux method, and the influence of lattice defects on the polarization and leakage current properties was investigated. As-grown KNN did not show an apparent polarization hysteresis loop due to its large leakage current (~10-3 A/cm2). 0.4 at.%-Mn-KNN annealed at 1100oC in air exhibited a low leakage current ( ~ 10-8 A/cm2), a relatively large remanent polarization of 40 microC/cm2 and a coercive field of 12 kV/cm at 25oC. The oxidation of Mn and Nb ions during annealing in air was found to play an essential role in the low leakage current in Mn-KNN. Mn substitution followed by annealing under moderate oxidation condition was effective for reducing leakage current in addition to enhancing polarization property.

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We synthesized the perovskite-type oxides with A-site vacancies, Sr0.5NbO3, Sr0.5TaO3 and Sr0.5Nb0.5Ta0.5O3, via nanosheet process using (SrNb2O7)2- nanosheets and/or (Sr1.5Ta3O10)2- nanosheets. Raman scattering demonstrates that nanosheet-processed Sr0.5Nb0.5Ta0.5O3 have a novel structure composed of the alternate stacking of the several layers of Sr0.5NbO3 and Sr0.5TaO3 along the c axis. Dielectric measurements (1 MHz) of pressed powder exhibited that nanosheet-processed Sr0.5TaO3 showed a much higher permittivity of 52 compared with solid-state-reacted Sr0.5TaO3 (33). Nanosheet-processed Sr0.5Nb0.5Ta0.5O3 with B-site-cation ordering had a lower permittivity of 42 than that with B-site-cation disordering (65). These results suggest that the stacking faults induced by nanosheet process and the arrangement of B-site cations play an important role in dielectric permittivity.

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Single crystals of PbTiO3 (PT) were grown by a self-flux method, and the influence of lattice defects on the leakage current properties at 25 oC of the PT crystals was investigated. While PT crystals annealed in air at 700 oC showed a leakage current density of the order of 10-5 N/cm2, annealing under a high oxygen partial pressure of 35 MPa at 700 oC increased the leakage current density to 10-4 N/cm2. This increase in leakage current by the oxidation treatment provides direct evidence that electron hole plays a dominant carrier for the leakage current property in the PT system. The conductivity at 800 oC of the PT crystals proportionally increased with an increase in oxygen partial pressure, and electron hole is revealed to be a detrimental carrier even at 800 oC. Thermogravimetric analysis showed that a larger weight loss due to PbO vaporization was observed under a higher oxygen partial pressure at high temperatures above 1000 oC. The enhanced vacancy formation of Pb under a higher oxygen partial pressure demonstrates that the surface reaction between Pb atoms and O atoms adsorbed onto the PT surface, which leads to PbO (g), is the limiting factor for the vacancy formation in the PT system. It is suggested that Pb vacancies act as an electron acceptor for generating electron holes, leading to a higher leakage current.

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We report electronic conduction of polycrystalline and epitaxial Sr(Ti,Ru)O3 (STRO) thin films and fabrication of ferroelectric gate transistors using STRO as a channel and Pb(Zr,Ti)O3 (PZT) as a ferroelectric gate insulator. Polycrystalline and epitaxial STRO films were prepared on SiO2/Si and SrTiO3(100) by sputtering using an STRO ceramic target (Ti/Ru=40/60). Hall effect measurements revealed that polycrystalline STRO films prepared at 560 oC in a pure argon atmosphere had carrier densities of 1021-1022cm·3 and mobilities of 0.l-0.3cm2V-1s-1, respectively. When STRO films were sputtered in a mixture of argon and oxygen gases, the carrier density decreased to an order of 1020cm-3 due to an increase of Ti/Ru ratio. The mobility barely changed with an addition of oxygen. Epitaxial STRO films on SrTiO3(100) substrate showed similar carrier density and mobility to those of polycrystalline films. Hall effect measurements also indicated that polycrystalline and epitaxial STRO films had n-type conduction. Ferroelectric gate transistors with a 6nm-thick-STRO layer as a channel showed a non-volatile field effect by two opposite polarization states of PZT. The change of channel conductance was approximately 40%.

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(Bax, Sr1-x)TiO3 (BST) films have been widely investigated because of expectations of their applications in microwave devices. In particular, there has been intense interest in new devices that use their nonlinear properties such as tunable devices and frequency mixers. In order to realize such devices, detailed evaluation of their nonlinear properties and numerical mode ling are important. In this paper, capacitance-voltage (C-V) characteristics of BST films prepared by sputtering were measured, and numerical fitting of a polynomial to the voltage-charge (V-Q) characteristics calculated from the C-V data was carried out. The results show that the measured data can be expressed with precision by a simple equation containing only linear and third order components, revealing that a practical experimental equation for the design of electrical circuits was obtained. Furthermore, a new equivalent circuit of the nonlinear dielectric film was proposed, and calculation of generation of third order frequency from a BST film capacitor was also performed. The measured third order component agreed exactly with the calculated results, revealing that our equivalent circuit is useful as an analysis method for circuits using nonlinear capacitors.

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The systematic investigation on the piezoelectric properties of lanthanum-substituted lead zirconate titanate (PLZT) films was carried out. Polycrystalline PLZT films with La-contents of 0, 3, 6, 9 and 12 mol% were formed on Pt/Ti/SiO2/Si substrates at 700 oC by chemical solution deposition (CSD). 111 preferred oriented PLZT films were directly grown on the substrates, and PZT seeding layers were introduced onto substrates for randomly oriented PLZT films. The longitudinal displacement curves were measured with D-E hysteresis loops simultaneously at ±300 kV/cm by AFM probing system. The maximum longitudinal displacements were attained at La content of 6 mol% in both orientations. The change in optical length induced by the longitudinal displacement was estimated to be from 0.2 to 0.4%. On the other hand, the shift in resonant wavelength induced by applying DC bias voltage is typically to be 0.5 to 1.0% in PLZT films. Therefore, we concluded that the influence of piezoelectric displacements on electrooptic effect is not small.

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Pyrochlore-type ferroelectric La2Ti2O7 thin films were prepared on SrTiO3 (100) substrate by metalorganic deposition. The high-quality La2Ti2O7 thin film was obtained using pre-crystallization, which keeps at 660°C for 5 min before final crystallization from 700 to 1100°C. The La2Ti2O7 thin film crystallized at 900°C consisted of small surface roughness of 3 nm and small grain size with a diameter of 100 nm against the film thickness of 400 nm. The valence band measured by soft-X-ray emission spectroscopy, which reflects the electronic structure in the bulk state, accords with band calculation of La2Ti2O7. The resistivity was approximately 109 ohm. These findings are considered to be due to the activation of nuclear creation for growth of thin film with pre-crystallization.

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To investigate the compositional dependence of the piezoelectric properties in lead zirconate titanate (PZT) thick films, 2-micro m-thickness Pb(ZrxTi1-x)O3 (x=0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8) films were prepared on Pt/Ti/SiO2/Si substrates by a chemical solution deposition process. The prepared thick films were fabricated into disk shape structure using reactive ion etching with a diameter of 10 micro m and 20 micro m. The ferroelectric properties and longitudinal displacement of the PZT thick film disks were measured simultaneously with an atomic force microscope (AFM) connected with a ferroelectric test system (FCE). Piezoelectric constants, referred to as AFM d33, were calculated from unipolar driven strain-field curves. For ferroelectric properties, the coercive field Ec increased with decreasing Zr content, x, and remnant polarization Pr showed a peak at x= 0.4. On the other hand, the AFM d33 showed two peaks at x= 0.5 and 0.7. These tendencies are consistent with a simulation result for PZT ceramics (Yamamoto 1998 [1]). We suggest that the AFM d33 peak at x= 0.7 corresponds to the rhombohedral phase boundary between the high temperature, Rh (HT), and low temperature, Rh (LT) phases.

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It is anticipated that Pb(Zrx,Ti1-x)O3 (PZT) films will be used in various next-generation high performance devices, such as ferroelectric memories and microelectromechanical systems (MEMS). However, PZT films show degradation problems due to the presence of crystal defects. In order to solve this problem, it is necessary to elucidate the degradation mechanisms. In this paper, PZT films containing excess lead content at the interface between the electrode and the PZT layer were evaluated by thermally stimulated current measurements, which is one of the evaluation methods for crystal defects. Although, defects at the interface increased with increasing excess lead content, fatigue performance was reduced. The number of defects in usual PZT films increase due to fatigue, and inversely, a decrease in defects with progress of fatigue was also observed in the excess-lead film. Based on these results, a very thin excess PbOx layer containing crystal defects seems to exist at the interface, and compensates for the decrease in lead and oxygen content in the PZT layer by out-diffusion caused by fatigue.

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The unoccupied electronic structure at low temperature of SrTiO3-delta has been studied by resonant-inverse photoemission spectroscopy (RIPES). The RIPES spectra show two peaks whose the energy separations match with the t2g- and eg-subbands of unoccupied Ti 3d state. A new peak clarified by the Ti 3p - 3d resonance effect is observed at 6.1 eV above Fermi level (EF). The 6.1 eV peak is not found in the O ls X-ray absorption spectrum, which reflects the electronic structure of the bulk state. The existence of the 6.1 eV peak suggests the correlation effect at low temperature of SrTiO3.

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Polycrystalline Pb(Zr,Ti)O3 thin film was prepared on SrTiO3/Pt/CeO2/SiO2/Si substrate by pulsed laser deposition with in-situ magnetic field (Dynamic Aurora PLD method). SrTiO3 and CeO2 layers were also prepared by this method, and Pt layer (bottom electrode was prepared by rf magnetron sputtering). Dynamic Aurora PLD method enabled to lower crystallization temperature for CeO2 (below 300 oC, even at room temperature), SrTiO3 (400 oC) as well as PZT (400 oC). CeO2 layer was used to improve the crystallinity of Pt bottom electrode. SrTiO3 layer was used as a seed layer to help the crystallization of PZT. In case of CeO2, amorphous film was obtained without application of magnetic field. This indicates that application of magnetic field has the key to lower the crystallization temperature. Under 2000 G of magnetic field, clear CeO2(111) peak was observed. For SrTiO3, it was also found that the crystallinity of SrTiO3 changes with the atmosphere during deposition; the crystallinity is not necessarily high in O2 atmosphere and the crystallinity was high in N2O atmosphere. Similar effect was also observed on the preparation of PZT thin film. Since it is known that N2O decomposes into N2 and atomic oxygen, and the atomic oxygen is very active. Therefore, application of magnetic field in the N2O atmosphere would enhance the formation of atomic oxygen to lower crystallization temperature of SrTiO3 and PZT thin films.

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We investigated the gasochromic coloration of amorphous tungsten oxide films having oxygen compositions between WO0.25 and WO3.0. The films were deposited by the reactive radio frequency (r. f.) magnetron sputtering with varying oxygen partial pressure. The oxygen and hydrogen concentration of the tungsten oxide films were determined using the Rutherford Backscattering Spectrometry (RBS) and the Elastic Recoil Detection Analysis (ERDA), respectively. The optical transmittance was examined for the films coated with palladium catalysis during the exposure of diluted hydrogen gas. Superior gasochromic properties were obtained for the films consisting of tungsten trioxide, WO3. For the films with lower oxygen concentration than WO3, the optical transmittance hardly changed during the hydrogen exposure. High concentration of hydrogen about 0.7 per a tungsten atom was found in the WO3 films. The hydrogen retention drastically decreased with a decrease of the oxygen concentration.

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Electrode-supported SOFCs exhibit highly electrochemical performance but they require gas-tight sealing between porous electrodes. Conventional sealing materials can sufficiently seal with dense materials such as ceramics and metals, but the sealing materials were much penetrated into porous electrodes and excess penetration caused severe gas-leakage. We have prepared insulating flexible sheets to realize gas-tight sealing against porous SOFC electrodes during fusion at 800°C. Amorphous Na2O-SiO2 spherical particles (NS particles) and amorphous SiO2 particles (S particle) were synthesized by sol-gel method, and thick sheets containing NS and S particles were obtained by tape-casting method. Porous La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) ceramics were used as a porous electrode to investigate penetration of sealing materials and identification of bonding phases. Fusion of the sheet against porous LSCF at 800°C resulted in gas-tight sealing and the formation of NaLa9(SiO4)6O2 (NLSO) phase. The formation of NLSO phase was controlled by the addition of S particles. TEC of NLSO did not show anomalous profiles which often result in severe cracks and are shown for some glasses at glass transition temperatures. Therefore, the NLSO phase would be valuable as the bonding phase between LSCF and glass seals.

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Si3N4-Si2N2O-MN (M=B, Ti) composite ceramics were hot-pressed (HP) by using following reactions of 2B2O3 + Si3N4 = 4BN + 3SiO2 (i), 3TiO2 + Si3N4 = 3TiN + 3SiO2 + 1/2 N2 (i)', Si3N4+ SiO2 = 2Si2N2O (ii). Reactions during sintering were followed by XRD and sintered composites were characterized by XRD, SEM, TEM, four-point bending test and Vickers indentation method. XRD results and TEM observations showed that h-BN and TiN were formed at about 1200°C by the reaction of (i) and (i)'. The Si2N2O phase formed by reaction (ii) was found above 1800°C. Si3N4-Si2N2O-BN composite consisted of Si2N2O grains of 2-10 micro m in size with Si3N4 and h-BN grains of about 0.5 micro m in size. Strength of Si3N4-Si2N2O-BN composite was lower than that of Si2N2O ceramics but hardness and toughness were comparable to Si2N2O. Si3N4-Si2N2O-TiN composites also consisted of 2-10 micro m Si2N2O grains with small TiN about 0.5 micro m. Hardness and strength of Si3N4-Si2N2O-TiN composites were comparable to those of Si2N2O ceramics but toughness was greater than Si2N2O.

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Synthesis conditions of melilite-type rare-earth silicon oxynitrides (RE2Si3O3N4; RE= La, Ce, Nd, Sm, Gd, Dy, Er and Yb) were examined using Si3N4 and rare-earth oxides as starting materials. The stoichiometric compounds could be synthesized by the solid-state reaction of equimolar RE2O3 (RE=Nd, Sm, Gd, Dy and Er) with Si3N4 at 1700°C for 2 h in N2 atmosphere. When near-ultraviolet light was irradiated to these compounds, only Gd2Si3O3N4 emitted yellow light without activator. The excitation and emission behaviors of Gd2Si3O3N4 were further examined by doping the activator (RE’3+; RE'= Ce, Sm, Tb, Dy and Er). Orange-colored light was emitted by doping S3+ to Gd2Si3O3N4; the relative emission intensity of Gd1.98Sm0.02Si3O3N4 achieved 1.8 (reference: Ca WO4). When Tb3+ was doped to Gd2Si3O3N4, the emission band of Gd2-2xTb2xSi30O3N4 was centered at 545 nm where the green-colored light was emitted; the maximum emission intensity achieved 3.5 (refernce:CaWO4) at x=0.06.

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Reactive grinding using a planetary ball-mill has been applied to the mechanochemical synthesis of lanthanoid ferrites, LnFeO3 (Ln: La, Pr, Sm, Gd, Dy, Yb). Colloidal lanthanoid hydroxides, Ln(OH)3, have first been formed from their oxides in organic liquids under grinding. The hydroxides not only promote the size reduction of the other reactant Fe2O3 in acting as the grinding aid but react with Fe2O3 to form hydroxide-complexes. The hydroxide complexes can be converted to LnFeO3 by the following stress-induced dehydration-condensation reaction. The reactivity strongly depends on the free energy change of hydroxide formation (delta GR) for the lanthadoid oxides and an electrostatic parameter of lanthanoid ions (Z/r), where Z is the ionic charge number and r the ionic radius. Although the delta GR values for all Ln2O3 are negative, the high Z/r value disturbs the formation of hydroxide-complexes. The adequate combination of the starting materials and the influence of the grinding stress have been discussed.

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Porous LaCoO3 films dispersed with La2O3 or Co3O4 and porous LaCoO3 film were prepared by sol-gel dip-coating, their average grain sizes being 40 nm, 160 nm, and 160 nm, respectively. These porous films were heat-treated by 1-15 cycles at a maximum temperature of 1273 K for 3.6 ks with a heating and cooling rate of 0.017 Ks-1. The grain size of LaCoO3 increased with increasing thermal cycle. The size of LaCoO3 grain in the La2O3-dispersed LaCoO3 film was smaller than that in LaCoO3 film and Co3O4-dispersed LaCoO3 film. Abnormal grain growth occurred in the LaCoO3 film. The grain growth of LaCoO3 in the films with La2O3 or Co3O4 obeyed a power-law relationship as given by dn – d0n = KN, where d is a grain diameter, N the cycle number, d0 the grain diameter at 0 cycle, K the grain growth constant, and n the grain growth exponent. The n value was 2.0 for the La2O3-dispersed LaCoO3 film, while the n was 4.2 for the Co3O4-dispersed LaCoO3 film, suggesting different grain growth is operative in these films.

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Pure copper (II) sulfide, CuS, was successfully prepared by a simple reaction of copper and sulfur powder in water at low temperatures (less than 60 °C), though the solid state reaction of the elements requires higher temperatures to complete the reaction. Pure Copper (I) sulfide (Cu2S) and silver (I) sulfide (Ag2S) were also prepared by similar reactions between the elements above 150 °C and 90 °C, respectively. Two phases (chalcocite-Q and chalcocite-low) were observed in the yielded Cu2S. Observation with the scanning electron microscope revealed that the CuS was composed of the particles of polyhedral frameworks with dimensions of 2 - 3 micro m. Whereas the particle sizes of the as-prepared Cu2S were similar to those of CuS, the particles had indefinite frameworks. For Ag2S, the as-prepared particles at 90 oC were like sharp thin blades and became duller with the increasing reaction temperature.

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In this paper, we focused on the fabrication of a opal-type photonic crystal from monodispersed SiO2 nano-spheres. Sol-gel derived colloidal solution of SiO2 nano-spheres with average diameter of about 300 nm were prepared by stober method. At first, zeta potentials of colloidal solutions were measured to decide the optimum pH value for obtaining a well-dispersed colloidal solution. At second, suitable drying conditions of SiO2 colloid particles on a glass substrate were investigated, where colloidal particles could arrange closely packed structures to form opal-type photonic crystals. The resultant samples were characterized by measuring the transmittance. As a result, transmittance drop at about 540 nm was observed to show the formation of the opal-type photonic crystals. This value is in good agreement with the result of calculation by using Bragg's law. From the results, it was concluded that self-assembled photonic crystals could be easily fabricated from colloidal solution of monodispersed SiO2 by controlling the capillary force during drying on the substrate.

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Spherical submicron-size copper powder was synthesized through condensation from a vapor phase with a significantly high degree of supersaturation in Ar-H2 plasma. The degree of supersaturation was increased by the relatively high rate feeding of raw copper powder of 40 micro m in size. The copper vapor concentration depended on the powder feed rate, reactor pressure and hydrogen flow rate. Relatively large particles of up to 0.1 micro m were prepared. Quench gas gave the formation of nanoparticles of 50nm in diameter even from a high concentration copper vapor. The quenching gas in the counter direction of the plasma flow restrain the particle growth due to increase of cooling rate. Also, Cu-W composite powders were synthesized through the Ar-H2 plasma treatment of mixture of Cu-WO3 powders. The starting temperature of shrinkage of Cu-20wt%W composite was significantly higher than pure Cu powders.

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The effect of annealing conditions on 0.7Pb(Mg1/3Nb2/3)O3 - 0.3PbTiO3 ceramics fabricated by spark plasma sintering (SPS) method were investigated. As-sintered samples were required a post annealing treatment for recovering their insulation from the conductive behavior caused by a partial reduction during SPS process. The treatment was necessary in a PbO-rich atmosphere for avoiding the decomposition of samples, and it not only removed oxygen vacancies but also promoted the crystal grain growth as well as the dielectric properties of samples. The higher anneal temperature and longer anneal duration were effective in the increase of the dielectric properties of samples.

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BaTiO3-SiO2 aerogels were prepared by sol-gel route with supercritical drying technique, after silica wet gel was dipped into BaTiO3 solution. In order to compare with the properties of compounded aerogels, pure BaTiO3 nanoparticles were also prepared by the sol-gel method. These BaTiO3-SiO2 aerogels and BaTi0O3 nanoparticles were characterized by X-ray diffraction (XRD), Raman spectra, transmission electron microscopy (TEM) and photoluminescence (PL) spectra. The size of compounded aerogel nanoparticles distributed from 7 to 20 nm when the BaTiO3-SiO2 aerogels were heated at 800 °C. The intensity of PL was obviously increased, comparing with the one of pure BaTiO3 heated at the same temperature.

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Various oxide nano-sized powders were successfully prepared by ultrasonic spray pyrolysis using arc plasma under the air atmosphere. Particle size, morphology, crystal phase and crystallinity of as-prepared powders were characterized by SEM and XRD. They had spherical morphology with narrow size distribution.

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TiO2-SiO2 nano-hybrid particles were prepared by the sol-gel method. TiO2 nano-layer was nano-coated on the surface of SiO2 mono dispersed nano-particles. In this study, we changed the [CH3COOH]/[Ti] (RA) and [H2O]/[Ti] (Rw) to control the hydrolysis and following condensation rate of titanium alkoxide to coat the SiO2 nano-particles uniformly. In addition, the different hydrolysis conditions were applied to deposit the TiO2 nano-layer on the SiO2 nano-particles (Step wise hydrolysis method and One step hydrolysis method). The resultant TiO2-SiO2 hybrid sol was evaluated by measuring the particle size distribution using the dynamic light scattering method to determine the thickness of TiO2 layer on the SiO2 surface. The surface morphology and the crystal structure of the calcined nano-hybrid particles were observed by high resolution transmission electron microscope (HR-TEM) and X-ray Diffraction (XRD).

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Tungsten tri-oxide (WOa) thin films are prepared by magnetron sputtering and subsequent thermal treatment. Ion irradiations with 4He+ at 350 keV were performed for the films. Gasocbromic coloration of the irradiated films was observed by a measurement of optical transmittance with the exposure of 1 % hydrogen. The extent of coloration level of the irradiated film with the fluence of lxl017 ions/cm2 is 7.5 times lager than that of non-irradiated film. W 4f photoemission spectra for the films were measured by x-ray photoelectron spectroscopy. From the fitting analysis for the spectra, the non-irradiated film has only W6+. In the irradiated film with the fluence of lxl017 ions/cm2, it is estimated that 17% and 4% of the W6+ change into W5+ and W4+, respectively. The irradiation for the films breaks the chemical bonds between tungsten and oxygen, and makes atomic sites of oxygen-deficient tungsten such as W5+ and W4+. The improvement of the gasocbromic coloration for the WO3 films relates to the increment of the W5+ and W4+ sites induced by the irradiation.

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Mullite exhibits low dielectric constant, high strength and relatively low thermal expansion coefficient, and therefore, is useful as a substrate for high-speed computer. Mullite is also a candidate material for high-performance low-temperature co-fired ceramic (LTCC) substrate because of the same reasons mentioned above. To apply the mullite substrate to LTCC, the reactivity of the mullite with elements that are contained in the glasses for low-temperature sintering should be investigated to choose the sintering aid for LTCC. In this paper, effect of the small amount of solution-derived yttoria addition on the sinterability of the mullite was investigated for the low-temperature sintering as well as the optimum amount of the alumina addition. The amount of the alumina addition was restricted within the solubility limit in mullite. As a result, faint amount of solution-derived yttria addition greatly enhanced the sinterability of the mullite because of the promotion of the liquid phase sintering by the uniformly dispersed yttria phase. In this paper, the relation between microstructures and the mechanical properties of the resultant mullite ceramics was discussed.

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In the latest few years, ‘arc in liquid method’ has been developed as a cost-effective technique to fabricate various kinds of carbon nanomaterials. In liquid nitrogen, especially high-quality multi-wall carbon nanotubes were observed. So, our research aims at creating carbon nanomaterials using contact arc method in liquid nitrogen and in liquid helium. For this research, a special evaporation cryostat, which has moving parts at low temperature part, is prepared. Experiments in liquid nitrogen were carried out at current density 8kA/cm2, 10kA/cm2, 12kA/cm2 and 14kA/cm2. At current density 10 and 12kA/cm2 ample fibrous carbon nanomaterials could be obtained. As for contact arc experiments in liquid helium, however, any carbon nanomaterials were not still obtained at current density 10kA/cm2.

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The effect of annealing temperature of Pd films on the gasochromic performance for hydrogen gas has been investigated. The Pd films prepared using an rf magnetron sputtering on quartz glass and glassy carbon substrates were annealed at temperatures range from 300 to 900°C in air. The films are characterized by Rutherford backscattering spectrometry (RBS) and X-ray diffraction (XRD). The gasochromic performance of palladium oxide films coated with a 15 nm thickness Pd catalyst is examined by optical transmittance in hydrogen. The polycrystalline PdO film which is thermally oxidized at 600°C in air shows the superior gasochromic performance. The optical transmittance of the film is rapidly decreased down to 10 % within 2 minute exposures to 1 % H2/Ar at room temperature. It is found that the gasochromic coloration of palladium oxide films for hydrogen is strongly influenced by annealing temperature.

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We report on the temporal and spatial resolved spectroscopic characteristics of the tungsten tri-oxide (WO3) plasma plume generated by Nd:YAG laser ablation. Emissions are dominated by mono-atomic neutral tungsten (W I), and there are no emission species such as W ions, 0 neutrals and molecular species. W I emission species move with high speed of 8.9 x103 m/s at the delay time (tau d) from 200 to 1000 ns after the laser irradiation. Two-dimentional images of expanding plasma plume were observed trough an ICCD camera.

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The present paper reviews recent extensions of the X-ray reflectivity technique, which is a powerful tool for the non-destructive exploration of layered films and which can provide data on density, layer thickness, interface roughness, interdiffusion etc. With conventional X-ray reflectivity measurement, samples need to be sufficiently stable, and analysis is basically concerned with the static structure. In view of the growing need to observe changes to the buried interfaces of a variety of thin films and multilayers, it is crucial to develop novel methods and instruments that enable reflectivity measurements to be carried out much more quickly, preferably without any motion of the sample, the detector or the optics, i.e., without a theta/2theta scan. One can observe structural variations by noting changes in the position of critical angles, the frequency of interference fringes, or the degree of decay of the curve. This paper introduces recent developments in such rapid X-ray reflectivity techniques, as well as some interesting applications.

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X-ray reflectivity around the Bragg point has been applied to reveal the heterostructures and interfaces of many semiconductor materials combinations. We started with a simple structure of As delta-doping to test the capability of the technique to reveal the structure of a buried sub-monolayer, where the crystal structure is not changed and the model is simple. It was extended to realistic structures, i.e., single quantum well with different materials combinations such as InP/GaInAs/InP, InP/ErP/InP, and ZnSe/GaAs. It is demonstrated, using GaInP/GaAs/GaInP double heterostructures as an example, that this technique is a very powerful tool to correlate the growth process and the device properties through atomistic elucidation of the buried heterostructures nondestructively.

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The higher-order structures of high-density polyethylene (HDPE) thin films on Si wafers have been investigated on lamellar and molecular levels by synchrotron grazing-incidence small-angle and wide-angle X-ray scattering (GISWAXS: GISAXS and GIWAXS) measurements, respectively. Annealing effect on molecular orientation and lamellar stacking structure of the thin films was clarified by in-situ GISWAXS measurements at BL40B2 in SPring-8 for the thin films in a stepwise annealing process from 378 K to 393 K under vacuum. The thin films with a thickness of ea. 400 nm were prepared by a dip-coating method. The two-dimensional GISAXS patterns of the thin films suggested that crystalline lamellae were alternately stacked with amorphous in the parallel direction to the substrate surface and the long period increased from ea. 26 nm to ea. 36 nm during annealing. Their two-dimensional GIWAXS patterns measured at the same time indicated that HDPE chains formed the orthorhombic crystal and the chain axis in a crystalline lamella oriented relatively parallel to the film surface.

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Most magnetic recording devices such as read heads and magnetic or magneto optical recording media have multilayer structures. In these devices, magnetic structural information on the interfaces is the key to achieve the high performance. Polarized neutron reflectometry is a unique and nondestructive tool to determine the magnetic interfacial structures. Recently the neutron reflectometer, SUIREN, was installed at the neutron guide hall in JRR-3 of Japan Atomic Energy Agency (JAEA). This reflectometer is capable of polarized neutron reflectometry, and is now open to users.

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Semiconductor devices will soon reach physical limitation and several new technologies have been proposed to overcome it. Among them are silicon-on-insulator (SOI) substrates, which are thought to be ideal substrates since they reduce the body effect and parasitic junction capacitance, which degrade device performance. Additionally, fabricating devices on SOI substrates less than several ten nanometers thick and operating them in the fully depleted mode offers further performance advantages. Several techniques have been proposed to fabricate SOI substrates, such as oxygen-ion implantation, wafer bonding with a thinning process or hydrogen-ion implantation. The remaining issue is how to improve the crystalline quality of SOI substrates using these techniques. Since the substrates are formed in the thermally equilibrium condition at high temperature, the difference of thermal expansion coefficients induces defects and interface strains during the cooling process. Grazing incidence x-ray diffraction (GIXD) is more sensitive to the internal strains of thin SOI since the penetration depths of x-rays can be controlled by changing incident angles. We have recently succeeded in observing the strain structures of various SOI substrates in real-time using the GIXD technique.

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Molecular beam epitaxial (MBE) growth of InAs/GaAs(001) quantum dots and their annealing after deposition were investigated by grazing-incidence X-ray diffraction using a diffractometer integrated with an MBE apparatus. Use of synchrotron radiation and a two-dimensional X-ray detector enabled X-ray diffraction intensity mapping in the reciprocal lattice space at a rate of less than 10 s per frame. Results suggest that the degree of alloying that depends on the growth temperature has a strong influence on the structural evolution during annealing.

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Grazing incidence X-ray fluorescence (GIXF) was used to obtain information on composition as a function of depth. Glancing-angular dependence of the fluorescence intensity from a layered sample typically shows Kiessing fringe similar to the X-ray reflectivity curves, and it can be explained by theory of the atomic resolution X-ray holography, which is recently developed structural analysis method, where fluorescence intensities are measured as a function of direction of a crystal sample. In the GIXF, X-rays directly reaching at a layer emitting fluorescence are regarded as reference waves in holography, and X-rays singly reflected at interfaces act as object waves. Therefore, the angular dependence of fluorescence intensity is considered to be a hologram. The aim of the present work is the real space reconstruction from the angular dependence of the fluorescence intensity obtained by the calculation. Here, I made a multilayer model whose top layer was monatomic, and calculated the angular dependence of the fluorescence intensity from the top layer. The calculated pattern showed holographic oscillation. In the Fourier transform of the oscillation, there exists peaks corresponding to the depths of the interfaces in the multilayer, revealing that the present technique can provide film structure information without a priori knowledge.

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