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We formed n-type polycrystalline semiconducting BaSi2 films on insulating silicon nitride films by sputtering and investigated their electrical and thermoelectric properties. The electron concentration of the grown films was approximately 1015–1016 cm−3 at room temperature, and the electron mobility was higher than 103 cm2 V−1 s−1 despite the polycrystalline films being randomly oriented. The films contained a large concentration of oxygen (1.5 × 1021 cm−3). A large thermoelectric power factor of 386 μW m−1 K−2 was obtained at 309 K for B-doped n-BaSi2 films. This value is approximately 8.6 times higher than the previous highest power factor reported for n-BaSi2.

We developed a lanthanum-doped Pb(Zr0.4,Ti0.6)O3 (PLZT)-based ferroelectric capacitor (FE) aiming at low-voltage operation of ferroelectric random access memory at low temperatures down to −45 °C. High-temperature sputter-deposited IrO x (1 < x < 2) or HT-IrO x was employed as a top electrode (TE) instead of room-temperature (RT) deposited IrO x or RT-IrO x over two PLZT stacked layers. We observed that polarization characteristics drastically improved even at −45 °C by employing HT-IrO x and thinning PLZT, even though leakage current was increased by about one order of magnitude. Transmission electron microscopy observations showed that HT-IrO x has a columnar-like crystalline structure while RT-IrO x has a granular-like crystalline structure. Secondary ion mass spectroscopy indicated that Pb diffusion from PLZT into TE was suppressed by HT-IrO x , which is considered to cause the improvement of polarization characteristics.

A cavity-resonator-integrated guided-mode resonance mirror (CRIGM) consisting of a small-aperture grating coupler integrated in a waveguide cavity on a high-reflection substrate reflects an incident free-space wave with reflection-phase variation of 2π in a resonance condition. CRIGM has been investigated as a key component in surface mount packaging of VCSEL for future optical interconnects but the reflectance of a fabricated CRIGM was not sufficient. Matching of electric field distribution between an incident Gaussian beam and the reflected beam from the CRIGM is discussed for improving the reflectance. A new apodization method of grating-tooth shift is proposed for the field-distribution matching. CRIGMs with the new and a well-known fill-factor apodization methods are characterized by numerical simulation. It is predicted that the previously measured reflectance will be improved by more than 1.2 dB by introducing either of the apodization methods.

Aluminum alloy contains intermetallic compounds, which contribute to the improvement of strength properties. However, when it is exposed a to a corrosive environment, the area around the compounds is dissolved preferentially, resulting in the formation of pitting corrosion. Although this dissolution reaction is presumed to be caused by the potential difference (ΔV) between the matrix and the compounds, it has not been quantitatively clarified how ΔV is generated. In this article, we present our study on the effects of the compound composition on ΔV by using the technique of machine learning. The results showed that ΔV and the elemental concentration of the compounds have a linear relationship.

This paper reports the effectiveness of a novel imaging system, piezoelectric and laser ultrasonic system (PLUS), for the three-dimensional (3D) imaging of fatigue cracks with a high-resolution. The PLUS combines a piezoelectric transmitter and the two-dimensional (2D) mechanical scanning of a laser Doppler vibrometer, enabling the 2D matrix array with an ultra-multiple number of receiving points for 3D phased array imaging. After describing the principle and 3D imaging algorithm of PLUS, we show the fundamental 3D imaging capability of the PLUS in a flat-bottom-hole specimen with varying the number of receiving points under a fixed large receiving aperture. We then demonstrate that the PLUS with 4275 receiving points (i.e. 75 × 57) achieves high-resolution 3D imaging of a fatigue crack with a high signal-to-noise ratio, providing the outline of the fatigue crack geometry. We also discuss the effectiveness of the ultra-multiple receiving points for suppressing grating lobes and random noise.

The reduction of a copper oxide surface film by formic acid was investigated in situ using a spectroscopic ellipsometer. The activation energy of the reduction of the copper oxide film by formic acid was 97.4 kJ mol-1, and the reduction rate increased with increasing formic acid partial pressure. From experimental results, we assumed that the hydrogen atoms dissociated from the formic acid molecules that were adsorbed on the copper surface and reacted with the oxygen atoms, and the oxygen atoms desorbed as water. Furthermore, it was predicted that the reduction proceeds by the diffusion of oxygen atoms from bulk copper oxide to the copper surface, and the dissociation of hydrogen atoms from the formic acid molecules was the rate-determining step. Based on this prediction, the reduction rate was mathematically calculated, which was in good agreement with the experimental data.

This paper provides Pd-Ag solid solution nanoparticles (NPs) which were prepared by the simple solution method and their characteristic hydrogen storage properties. The solid solution between Pd and Ag was achieved on NPs with crystal sizes of 7–9 nm. The isotherms of these alloy NPs showed no typical plateau region and the PCT curve changed in increasing tendency in pressure as H/M increases even in a plateau region. More important findings included the increase of H/M at the very low H2 pressure conditions of 0.001 MPa. H/M was approximately 0.2 in the x range of 0.05–0.09 in Pd1-x Ag x NPs. Thus, the combination of the nanoparticular state and Ag doping in Pd brought better hydrogen storage and/or H2-related catalytic material which could be used at low H2 partial pressure condition.

We performed a size-controlled synthesis of Pd nanoparticles (NPs) by changing the initial concentration of Pd in a solution. The correlation between the hydrogen absorption isotherm (denoted as pressure–composition–temperature (PCT)) and the Pd particle size was examined by focusing on sizes between 5 and 10 nm in diameter. The PCT curves confirmed the characteristics of Pd NPs less than 10 nm in diameter, which were different from those of bulk Pd and strongly dependent on the crystallite size. The hydrogen isotherms of the 6.5 and 6.8 nm Pd NPs showed that the final amount of hydrogen was 0.3 at 0.1 MPa and their plateaus were shorter, with a steeper gradient. The hydrogen isotherm of the 5.5 nm NP showed no plateau and realized the nanoscale-regime phenomenon. For the hydrogen absorption of Pd, based on our experimental findings, the size-dependent tipping point between the bulk and NP regimes seems to lie at about 6 nm in diameter.

An environmental transmission electron microscopy (ETEM) was applied to the in situ observation of carbon contamination removal reaction on (100) crystal plane of catalytic CeO2 nanocubes. The distance between the surface of CeO2 and carbon layer (width) was quantitatively measured versus time at eleven points on three CeO2 nanocubes by observation at an oxygen pressure of 3.0 × 10−1 Pa at 400 °C. The carbon contamination removal rate in the time range of 100 to 460 s was 0.01 ± 0.002 nm s−1, not depending on the place. However, in the later stage, the rates of 0.057 ± 0.01 nm s−1 and 0.24 ± 0.02 nm s−1 were obtained for carbon contamination of different areas in the specimen even if the same crystal plane (100) was in contact with carbon. Carbon on the crystal surface in the inner area of the CeO2 aggregate was eliminated more quickly than contamination in the outer area. The result means that the local-environmental influence in nanoparticle aggregates is taken into account in a heterogeneous catalytic reaction as well as contamination reduction using ETEM.

Titanium oxide films grown on Ag(110) have been investigated by low-energy electron diffraction (LEED), photoelectron spectroscopy (PES), and X-ray absorption spectroscopy (XAS). As Ti atoms were deposited on Ag(110) in O2 at 5.0 × 10−6 Torr and the surface was subsequently annealed at 500 °C for 30 min, a film with a (1×1) periodicity with respect to Ag(110) was formed. The core-level PES study showed that the film was composed of TiO2 in which 1/6 of Ti atoms are reduced to Ti3+. The film gave a (1×1) LEED pattern when the thickness was less than 1 nm. The O K-edge and Ti L-edge XAS measurements showed that each Ti atom in the film was coordinated by 6 O atoms forming a distorted octahedron, as in the case of rutile and anatase TiO2. Analyses of XAS results suggested that the long-range order of the film was similar to that of anatase TiO2.

This paper provided a simple preparation method of Pd–Pt solid solution nanoparticles (NPs) and demonstrated their hydrogen storage properties. The mixture of Pt and Pd precursors led to the formation of a solid solution in the system of Pd–Pt by the present one-pot solution method. A series of alloy NPs were characterized by X-ray diffraction, transmission electron microscopy and X-ray absorption fine structure measurement. The mean diameters of Pd and Pd–Pt nanoparticles in aqueous solution were ca.4 nm. The atomic ratio of hydrogen per metal at 0.1 MPa H2 was 0.2 (Pd), 0.08 (Pd0.75Pt0.25), 0.07 (Pd0.7Pt0.3) and 0.04 (Pd0.65Pt0.35). The hydrogen storage phenomenon strongly depends on alloying Pt to Pd, and hydrogen per metal extremely decreased by adding Pt to Pd in solid solution NPs.

Metal-dispersed Pd/ZrO2 composites were derived from amorphous Zr65Pd35 alloy and their catalytic behavior for diesel soot combustion was studied. X-ray diffractograms and scanning electron micrographs indicated that mixtures of ZrO2 phase and the dispersed metallic phase were formed in the resulting material after heat treatment at 800°C in air. The oxidized alloy resulted in the enhanced soot combustion activity. The combustion processes were observed by in situ high temperature optical microscopy (HTOM) and ex situ electron microscopy with different scales. This work provided a new type of catalytic material prepared from amorphous alloys which was effective soot combustion catalysis.

This paper provided the controlled synthesis of Pd–Au nanoparticles (NPs) by a facile solution method, and demonstrated the novel hydrogen storage properties of Pd NPs. The addition of a small amount of Au led to the suppression of growth in Pd NPs, making size control possible. The mean diameters of Pd and Pd–Au NPs before filtering the solutions ranged from 7.3 to 5.0 nm. The hydrogen storage phenomenon strongly depends on particle size. The amount of hydrogen absorbed in NPs under 0.1 MPa H2 was 0.6 H Pd−1 for 10.7 nm NPs, 0.38 H Pd−1 for 9.3 nm NPs, and 0.17 H Pd−1 for 6.5 nm NPs. Also, the presence of Au may influence the hydrogen absorption of Pd NPs. The possibility of a higher hydrogen storage capacity, tuned by particle size and Au modification to Pd NPs, was proposed in the present work.

Although ferroelectric random access memory (FRAM) has superior electric properties, its downside is that it has a relatively larger cell area in comparison other non-volatile memories. We tried to apply TiOx, and AlOx to an underlying layer (TiOx-UL, AlOx-UL) instead of our previously used Ti underlying layer (Ti-UL) for the La-doped lead zirconate titanate (PLZT) capacitor to obtain a high polarization value aiming to a lowering cell area. The failed bit ratio of the FRAM with TiOx-UL was found to be higher than that with AlOx-UL even though polarization values of the PLZT capacitor with both underlying layers are almost the same and much higher than that with Ti-UL. It is strongly suggested that the imprint induced in PLZT by charged defect is a main cause of bit failure by fail-bit analysis. X-ray diffraction and atomic force microscopy observations shows that charged defect density in PLZT over TiOx-UL is possibly higher than that in PLZT over AlOx-UL due to surface roughness of underlying layers.

In our previous works on La-doped Pb(Zr,Ti)O3 (PLZT) growth on a Pt/Ti bottom electrode, the O2 content in postdeposition annealing (PDA) was found to play an important role in obtaining good electrical characteristics and high manufacturing yield of ferroelectric random access memory (FeRAM). The optimal O2 content of around 2% inhibits the growth of randomly oriented La-doped Pb(Zr,Ti)O3 (PLZT) grains near the PLZT surface, resulting in the growth of highly {111}-oriented PLZT. We found that the Pt bottom electrode grown on an AlO x layer can further suppress the formation of randomly oriented PLZT grains near the PLZT surface and increases the optimal O2 content range from 2 to 50%, which can enlarge the manufacturing process margin of PDA. It is proven that the AlO x layer blocks the diffusion of lead oxides (PbO x ) from PLZT to SiO2 interlayers through Pt and promotes pyrochlore-perovskite transformation near the bottom electrode during PDA.

A fluoropolymer membrane filter with through-holes was fabricated by photolithographic patterning and the dry etching method. 380,000 highly packed through-holes, each with a diameter of 7 µm were able to cover a whole area with a diameter of 13 mm. Ethylene tetrafluoroethylene (ETFE) was used as the membrane, which was suitable for the fluorescence detection of rare cells such as circulating tumor cells (CTCs) in human blood. The device fabrication for the size based capture of rare cells in blood such as CTCs is realized in this study.

The piezoelectric and dielectric properties of Pb(Mg1=3Nb2=3)O3–PbTiO3 (PMNT) ceramics with compositions near a morphotropic phase boundary (MPB) were investigated under pressures p up to 700 MPa at 25 � C. The resonance and antiresonance frequency characteristics of impedance and phase in the k31 mode for PMNT (67/33) and (69/31) ceramics were observed under various pressures. The effect of pressure on their responses were clearly observed. The electromechanical coupling coefficient k31 in the k31 mode increases and the electromechanical quality factor Q decreases with increasing p at pressures lower than 100 MPa. The decrease in Q with p is due to the scattering of ultrasonic waves from the domain boundary. The relative permittivity "r increases with increasing p. Such increases in both k and "r with p seem to be related to the increase in topographical domain-wall density associated with monoclinic distortions. At pressures higher than 100 MPa, their electromechanical suppression in PMNT ceramics occurs at each pressure, corresponding to the electromechanical coupling coefficient k. "r increases with pressure-induced electromechanical suppression. The change in "r with such suppression corresponds to k. Such a phenomenon seems to be due to the increase in piezoelectric load based on the increase in complex domain wall density coming from the increase in free energy with pressure. [DOI: 10.1143/JJAP.47.7650]

An electron beam recorder for optical disk mastering was improved for future storage media. One improvement was related to a formatter to record constant angular velocity formats like servo patterns of hard disks. The formatter draws patterns with constant linear velocity by controlling the translation stage, the rotation stage, the beam blanker, and the high-speed deflector synchronously. The operation of the formatter was demonstrated by test drawing standard servo patterns that aligned in the radial direction and along the arc trajectory of a swing-arm actuator. Another improvement was a reduction in electron beam size. An electron beam column with a 50 kV acceleration voltage for optical disk mastering was improved by incorporating a new objective lens, the magnification of which was about 40% of the former lens. As a result, 58.5-nm pitch land-and-grooves were resolved with a linear velocity of 0.55 m/s. Furthermore a 100 kV electron beam column was developed to reduce the beam size to 10 nm or less. The width of fabricated grooves drawn by the column was about 12 nm.

A molecular dynamics computer simulation has been carried out for a two-dimensional (2D) square lattice model crystal. Anharmonic central forces up to the third order are considered for the nearest neighbor and next nearest neighbor interatomic interactions. Pulse input displacements are applied simultaneously to all of the edge atoms at one end of the model crystal, and displacements, velocities, and energies of all atoms in the crystal are calculated as a function of time. Two types of wave are seen in the crystal depending on the excitation conditions. When the input pulse is small, the wave has characteristics of "phonon". When the input pulse is large, it has characteristics of "soliton". A slit-shaped or linear array of defect atoms is placed at the center of the crystal. The waves are scattered by the defect atoms. The dependences of the scattering on the mass of the defect atoms, the interatomic interaction parameters, and the size of the opening of the slit are studied. The experimental results are represented in 2D colored maps.