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Atomic-scale relaxations of platinum nanoparticles (Pt NPs) for fuel-cell catalysts are evaluated by spherical-aberration corrected environmental transmission electron microscopy (ETEM) under reference high-vacuum and N2 atmospheres, and then under reactive H2, CO and O2 atmospheres, combined with ex situ durability test using an electrochemical half-cell. In high-vacuum, increasing roughness due to continuous relaxation of surface-adsorbed Pt atoms is quantified in real-space. Under H2 and N2 atmospheres at a critical partial pressure of 1 × 10−2 Pa the stability of the surface facets is for the first time found to be improved. The adsorption behaviour of CO molecules is investigated using experimentally measured Pt–Pt bond lengths on the topmost surface layer of Pt NPs. The deactivation of Pt NPs in the anode environment of a proton-exchange-membrane fuel-cell is demonstrated at the atomic-scale in the ETEM, and the transformation of NPs into disordered nanoclusters is systematically quantified using the partial size distribution of Pt atomic clusters under controlled heating experiments at 423, 573 and 723 K.

To generate a vibration-free zone in a designated region of a structure, cluster power flow control is presented. Unlike conventional modal-based vibration control, mainly used for augmenting structural damping, active wave control can render all the vibration modes inactive; the gain characteristic of a forced vibration response converges to the asymptote—to a far greater extent than augmenting structural damping; however, progressive waves still remain. Power flow control, advanced active wave control, allows the generation of a vibration-free zone when properly configured to handle all the governing structural variables. To implement power flow control, cluster control is introduced, which guarantees unconditional stability of a feedback system. To evaluate the vibration-free state, a vibration intensity is introduced; however, as a result of suppressing the vibration intensity, two extreme phenomena arise: suppression or excitation of structural modes. To overcome this problem, minimization of the dominant structural variables that are the counterparts of the vibration intensity elements is set up, with the result that a vibration-free zone is generated, together with the suppression of the vibration intensity. A numerical analysis is then conducted, followed by an experiment, demonstrating the capability of the proposed method for generating a vibration-free zone.

This paper is concerned with modal control of a rectangular plate using both smart sensors and smart actuators. Since filtering and actuation are related, discussion of a smart sensor comes first followed by that of the counterpoint?a smart actuator. This paper begins by discussing an ideal case of modal control comprising extraction and activation of a target structural mode of a plate. Then, for the purpose of implementing a modal control system, three-dimensional smart sensors and actuators are introduced, the design procedure being investigated. Taking into consideration the practicability, two-dimensional smart sensors and actuators for modal filtering and modal actuation, respectively, are presented, and then the number, location and shaping function of the two-dimensional modal sensors and actuators are clarified. Furthermore, the extraction and actuation of the (1, 3) mode of a simply supported rectangular panel using the smart sensors and actuators is shown. Finally, a modal feedback control system is constructed utilizing both the smart sensors and the smart actuators, demonstrating the effectiveness at suppressing the particular structural mode of interest without causing spillover.

This paper deals with active boundary control (ABC) of a rectangular plate using feedforward control. Conventionally, boundary conditions dominating the fundamental properties of a structure are obtained a priori. If it is possible to control the boundary conditions of a structure, its structural characteristics may be altered as wished. The ABC presented in this work enables one to generate the desired boundary conditions at a designated area on a target plate. Firstly, the principle of the ABC where the system is described using the transfer matrix method is presented. Then, the optimal feedforward control law for producing the desired boundary conditions on the plate is derived. It is found that, as a result of applying the ABC on an edge of the plate, global generation of a quiet zone around the edge can be achieved. Numerical simulations are conducted where the fundamental properties of the ABC system are investigated. In addition, implementation of the ABC using distributed parameter polyvinylidene fluoride film (PVDF) sensors introduced for modal filtering is discussed. Finally, experiments are carried out to demonstrate the validity of the ABC when generating a desired boundary condition at the target location, creating a global quiet zone within the target region of the plate.

We have developed a spherical aberration corrected transmission electron microscopy (Cs-corrected TEM) technique that allows us to obtain clearer images in real space than ever before. We applied this technique to titanium oxide, in which light elements such as oxygen are difficult to observe using TEM because of its small cross section and electronic damage. In the present study, we successfully observed oxygen atoms in rutile TiO2. In addition, this direct observation of oxygen atoms enabled us to study the Magn?li structure (TinO2n?1), which is caused by oxygen vacancies. These vacancies caused an atomic relaxation of the titanium and oxygen atoms. The relaxed atoms formed a characteristic shear structure of rutile titanium dioxide phase. This shear structure of the Magn?li structure (TinO2n?1) was visualized with a spatial resolution of 0.119?nm. At the same time, the selected area diffraction (SAD) pattern of the defect structure was obtained. Additional spots were shown inside the rutile [110] spot. We made structural models of the shear structure and simulated the diffraction pattern and images using a multi-slice simulation. Additional spots in the simulated diffraction patterns accurately reconstructed the experimental data. We also considered the possibility of the real-space analysis of local structures using spherical aberration corrected transmission electron microscopy.

This paper concerns the active vibration control of a flexible beam using smart sensors from the viewpoint of an active wave control theory. The objective of this paper is to present a new type of sensor which enables one to measure the wave amplitude of a flexible beam in real time for the application of use in an adaptive feed-forward control system. Firstly, a novel wave filtering method using distributed parameter PVDF sensors is proposed. It integrates an infinite number of point sensors and has an integral calculation ability based on a proposed shaping function. Furthermore, the characteristics of the wave filter and the performance of the adaptive feed-forward control system using the wave filter are discussed. Finally, experiments adopting the active wave control theory which use the wave filter are conducted, demonstrating the validity of the proposed method in suppressing the vibration of a flexible beam.

Vanadium clusters with a size of several nanometres can be dispersively distributed in ZnO films by using co-deposition. EELS mapping of V-L2,3, HRTEM images, SAD patterns and EELS are a good combination for characterizing nanometre-sized V clusters embedded in a ZnO system. There is no obvious orientation relationship between V and ZnO lattices due to a less good match between ZnO and V atomic planes. The ratio of the vanadium L-white lines of vanadium clusters embedded in ZnO becomes bigger than that of the bulk. The samples were observed in situ from 298 to 923 K with a heating holder so as to study the aggregation process of vanadium clusters in the ZnO crystalline matrix. First, the size of the ZnO crystal grains becomes bigger after the sample is heated at 623 K for an hour; second, the size of ZnO and vanadium particles grows bigger after the sample is heated at 723 K for half an hour, and another orientation relationship between ZnO and vanadium appears; third, after the sample is heated at 873 K for half an hour, the size of vanadium becomes smaller, while V particles and ZnO begin to react and form another phase; finally, Zn2V O7 phase is formed after the sample is heated at 923 K for half an hour.

We have studied in situ direct observations of depositing Au onto InSb{111}A,B -(2 ? 2) surfaces up to monolayer (ML) thickness and their reaction processes by using high-resolution transmission electron microscopy in the profile-imaging geometry. During Au deposition up to ?ML coverage, the In-vacancy and Sb-trimer outermost layers of the surfaces change their (2 ? 2) structures to (1 ? 1) periods, and the deposited Au atoms form the regions which agglutinate in the vicinity of their surfaces. Further, Au deposition (e.g.??ML) leads to a partial disruption of the substrate and to an infiltration of the substrates inside. The difference between the (111)A and the (111)B substrates is that the infiltration in the latter slowly progresses in comparison with the former. The difference in growth of gold in these systems is probably due to the polarity and the surface structures of their substrates.

Ultraviolet light was used to irradiate hydrocarbons on TiO2 thin film in high-resolution transmission electron microscopy (TEM). The hydrocarbon was decomposed by photocatalysis of titanium oxide. Reaction processes were studied by using an in situ TEM observation system which was newly constructed for the present study. For measuring photocatalytic activities, electron energy loss spectroscopy (EELS) was used. We developed a new TEM method for observing crystal structures of TiO2 and quantifying photocatalytic activities concurrently. We succeeded in measuring the photodecomposition activity of hydrocarbons on TiO2 films in a submicron area. The spatial resolutions of the present method were compared with those of other methods for measuring photocatalytic activity.

Microcapsules made of hard carbon films were fabricated for electron microscopic observations of liquid-like samples such as biological cells/molecules in water solution and liquid crystals. 4-(1-methylheptyloxycarbonyl) phenyl--octyloxybiphenyl-4-carboxylate (MHPOBC) liquid crystals housed in the capsule were observed by transmission electron microscopy at 120 kV accelerating voltage. From the series of electron diffraction patterns, the rate of electron irradiation damage was estimated for the cases of changing sample temperature, beam current density and accelerating voltage. Phase transitions from a crystalline phase to liquid crystalline phases such as an isotropic-A phase of a smectic state (Sm-IA) and a chiral-A phase of a smectic state (Sm-CA*) were successfully observed and the rotation fluctuation of the molecules in the phase was measured by using the electron diffraction patterns.

As-quenched icosahedral Al55Si7Cu25.5Fe12.5, its 1/1 approximant of the same composition, and icosahedral Al62.5Cu24.5Fe13 alloys have been studied using x-ray diffraction, scanning transmission electron microscopy and the high-angle annular dark field technique, zero-field and in-field 57Fe Mossbauer spectroscopy, and electrical resistivity. The crystal structure of the 1/1 approximant Al55Si7Cu25.5Fe12.5 has been refined with the Rietveld method and shown to be compatible with the measured high-angle annular dark field images. The distribution of the principal component of the electric field gradient tensor has a bimodal character with a dominant negative sign in the icosahedral Al–Cu–Fe system. The local order of the Fe structural environment is compared in icosahedral Al55Si7Cu25.5Fe12.5, its 1/1 approximant, and icosahedral Al62.5Cu24.5Fe13. The average quadrupole splitting decreases with temperature as T3/2 for all alloys studied, and its value is significantly larger for the icosahedral alloys. The vibrations of the Fe atoms in the alloys studied are well described by a Debye model, with characteristic Mossbauer temperatures of 468(25), 487(19), and 455(6) K for icosahedral Al55Si7Cu25.5Fe12.5, its 1/1 approximant, and icosahedral Al62.5Cu24.5Fe13, respectively. The electrical resistivity is discussed in terms of quantum interference effects and structural disorder.

The structural evolution of high-quality 3.3–73.2-nm-thick tetragonal-like BiFeO3 (T-BFO) thin films grown on LaAlO3(001) substrates and the bulk photovoltaic effect of the films were investigated. The T-BFO films were grown by rf magnetron sputtering, showing the Peudellösung fringes around the T-BFO (001) diffraction peak in X-ray diffraction θ–2θ patterns. These indicate the structural coherence between the surface and the interface in the surface normal direction of the films. High-resolution synchrotron X-ray diffraction analysis and transmission electron microscopy reveal that the lattice relaxation behavior from the MA monoclinic to MC monoclinic structure occurs as the film thickness increases. The domain structure was partly controlled by using a vicinal LAO (001) substrate along [100]. Regarding the current–voltage characteristics of the Pt/T-BFO/Pt coplanar capacitor under violet laser illumination, T-BFO films show an anomalous photovoltaic effect with an open-circuit voltage of 6.1 V and a short-circuit current of −290 pA along the [100]T-BFO direction.

This paper presents a new methodology of realizing an active wave control for an orthotropic rectangular panel. In general, an ideal wave controller is expressed by non-causal function which is impossible to be realized practically. The static direct feedback is introduced to overcome this problem. Firstly, a transfer matrix method for an orthotropic rectangular panel is introduced to describe the wave dynamics of the structure. This is followed by the derivation of feedback control laws for absorbing reflected waves. Then, static direct feedback is presented to realize the perfect wave absorption at single frequency. Finally, from a viewpoint of numerical analyses, control effects of the proposed method are verified by evaluating the absolute displacement distribution. It is found that the reflected wave absorbing control enables the inactivation of all vibration modes in the controlled direction.

We studied the correlations among the structural properties, valence band spectra, and electrical properties of (111)-oriented half-Heusler LaPtBi thin films. An increase in the C1 order parameter led to a marked change in the valence band spectra just below the Fermi energy, indicating the dominant role of ordering at the Pt sites in the electronic structure of LaPtBi. Magnetotransport measurements at 4.2 K showed that the linearity rather than the classic quadratic component of magnetoresistance becomes more evident with increasing C1 order parameter. The unique electronic structure of LaPtBi showed various quantum phenomena related to zero-gap semiconductivity.

Environmental transmission electron microscopy has recently emerged as topics of great interest as well as ultra-high resolution electron microscopy using aberration correctors. Current research in this area has been focusing on dynamic observation with atomic resolution under gaseous atmospheres and in liquids. Nagoya University has been developing a new 1-MV high voltage (scanning) transmission electron microscope, which can be used to observe nano-materials under conditions that include the presence of gases, liquids and illuminating lights, and it can be also used to perform mechanical operations to nm-sized areas as well as electron tomography and elemental analysis by electron energy loss spectroscopy.

There have been reports of challenges in designing platinum carbon (Pt/C) electrode catalysts for PEMFC. Pt/C electrode catalysts deactivate much faster on the cathode (in moisturized O2) than on the anode (in H2). To understand influences of moisture and oxygen on the deactivation of the Pt/C catalysts in proton-exchange-membrane fuel cells (PEMFCs), spherical-aberration-corrected environmental transmission electron microscopy (AC-ETEM) was applied with a high-speed CCD camera. Structural changes of the Pt/C electrode catalysts were dynamically recorded in moisturized nitrogen, oxygen and hydrogen. The mass spectrometry confirmed the moisture content (between 5 to 30 %) of nitrogen driving gas through a humidifier. Coalescence of platinum nanoparticles (D = 3.24 nm) was carefully evaluated in pure N2 and moisturized N2 atmosphere. The Pt/C showed considerable structural weakness in a moisturized N2 atmosphere. Comparable results obtained by AC-ETEM in different gas atmospheres also suggested ways to improve the oxygen reduction reaction (ORR). In this paper, the deactivation process due to moisture (hydroxylation) of carbon supports is discussed using for comparison the movement of platinum nanoparticles measured in moisturized nitrogen and pure nitrogen atmospheres.

The interfacial atomic structures of 3C-SiC/Si(0 0 1) and the dislocation core structures related to generation and annihilation of stacking faults are clarified by aberration-corrected transmission electron microscopy combined with image processing called the ‘image subtraction and improved deconvolution (ISD)’ method. Details of the intrinsic interfacial structure are explained in terms of a two-dimensional network of partial edge dislocations and Lomer dislocations. Around the junction of the interface and a {1 1 1} stacking fault, a seven-membered ring of Si and C atom columns and interfacial steps are observed. On the other hand, a six-membered ring is observed at the intersection of two {1 1 1} stacking faults. Based on the results, the formation mechanism of the intrinsic interfacial structure and stacking faults during the growth process is discussed.

We present a morphology study of ZnO tetrapods using aberration corrected TEM, HAADF-STEM and 3D HAADF-STEM cryotomography as an alternative to more conventional TEM and SEM techniques. We use 3D IMOD reconstructions to show that the {10} facets dominate the total surface area of uniform hexagonal prism tetrapods. Using HRTEM we show that the small tetrapods have a zincblende phase core from which the four legs extend. The facets and the edges of these legs were found to be atomically clean and flat with the potential for ZnO tetrapods as model substrates. We deposited ultrafine Pt/Pd nanoparticles onto the tetrapods and investigated the resulting morphologies. We found using HAADF-STEM cryotomography and reconstruction techniques that the nanoparticle coverage gave separate nanoparticles and overall uniform coverage. We believe these techniques and the results from them could be useful for the development of nanoparticle-ZnO tetrapod composite systems with applications in optoelectronics, gas sensing and catalysis.

Titanium dioxide (TiO2) with metal nanoparticles exhibits a high photocatalytic activity by a charge separation. Recently the size of the nanoparticles has been reduced to less than 1 nm. In contrast, the size of TiO2 support particles has been kept at sub-micron sizes to ensure stability for practical use at high temperatures. For visualizing and analyzing the metal nanoparticles which are supported on different positions of those complex substrates, a high voltage transmission electron microscope(HVEM) shows a strong performance because of its high transmission capability to view whole areas of the catalysts. Electron tomography is also important to quantify the three-dimensional morphology such as size, density, surface area and nearest particle distance. Here we report the data obtained by using He-cooled 3D TEM/STEM, a newly developed 1MV high voltage environmental TEM/STEM and a 200kV aberration corrected TEM/STEM. Nanostructures of catalytic samples are characterized using these EMs as well as measurement of their chemical activity.

Recent nanointegration of magnetic storage and spintronic devices is expected to lead to the development of systems that can analyze magnetic and spin states with a nanometer-order spatial resolution. Development of a polarized transmission electron microscope (SPTEM) that employs a spin-polarized electron source (PES) has commenced at Nagoya University. A spin-polarized electron beam is extracted from a photocathode that has a negative electron affinity surface. The temporal profile of the electron beam can be modulated by varying the temporal profile of the driving laser. The SPTEM can obtain temporal and spatial information about spin. The design and construction of the PES were optimized for the SPTEM. A beam energy of less than 40 keV (a low energy for a TEM) was used because the spin interaction with condensed matter is very small compared with the Coulomb interaction. A polarized electron gun was realized in an extreme high vacuum by applying a high field gradient of 4 MV/m to the photocathode surface. A 40-keV polarized electron beam with sub-millisecond pulses was generated using a backside-excited photocathode. The illumination system of the TEM was designed with the aim of producing a spin-polarized electron beam. The system contains two components that rotate spin: one performs azimuthal rotation and the other performs in-plane rotation in the condenser magnet system. The SPTEM has the potential to dynamically generate magnetic-field images with high contrast and high temporal resolution.

In order to study spin related phenomena in nano-size materials, spin-polarized electron source (PES) has been employed for the incident beam in transmission electron microscope (TEM). The PES has been designed and constructed with optimizing for spin-polarized TEM. The illuminating system of TEM is also designed to focus the spin-polarized electron beam emitted from a semiconductor photocathode with a negative electron affinity (NEA) surface. The beam energy is set to below 40 keV which is lower energy type as a TEM, because the spin interaction with condensed matters is very small corresponding with a Coulomb interaction. The polarized electron gun has realized in an extra high vacuum (XHV) condition and high field gradient of 4 MV/m on a surface of photocathode. Furthermore, it demonstrated that 40-keV polarized electron beam was operated with a sub-milli second pulse mode by using the backside excitation type photocathode. This high performance PES will make it possible to observe dynamically a magnetic field images with high contrast and highspeed temporal imaging in TEM.

This paper presents a novel smart film actuator based on the use of a biomass plastic as a piezoelectric film. Conventional polymeric smart sensors and actuators have been based upon synthetic piezoelectric polymer films such as PVDF. Almost all synthetic polymers are made from nearly depleted oil resources. In addition combustion of their materials releases carbon dioxide, thereby contributing to global warming. Thus at least two important sustainability principles are violated when employing synthetic polymers: avoiding depletable resources and avoiding ecosystem destruction. To overcome such problems, industrial plastic products made from synthetic polymers were developed to replace oil-based plastics with biomass plastics. This paper applies a biomass plastic with piezoelectricity such as poly-L-lactic acid (PLLA). As a result, PLLA film becomes a distributed parameter actuator per se, hence an environmentally conscious smart film actuator is developed. Firstly, this paper overviews the fundamental properties of piezoelectric synthetic polymers and biopolymers. The concept of carbon neutrality using biopolymers is mentioned. Then a two-dimensional modal actuator for exciting a specific structural mode is proposed. Furthermore, a biomass plastic-based cantilever beam with the capability of modal actuation is developed, the validity of the proposed smart film actuator based upon a biomass plastic being analytically as well as experimentally verified.

The epitaxial growth technique of ultrahigh density (>1012 cm-2) Fe3Si nanodots (NDs) on Si(111) substrates was developed using an ultrathin SiO2 film technique. Low temperature (3Si NDs was needed to suppress the interdiffusion between Fe atoms deposited on the sample surface and Si atoms in the substrate. The ND shape changed drastically from sphere to discontinuous films as the Fe content was increased slightly from a stoichiometric ratio of Fe:Si of 3:1. For almost-spherical NDs with the ultrahigh density, a transition from superparamagnetism to ferromagnetism was observed at specific temperatures, the ferromagnetism of which included the magnetic dipole interactions in ultrahigh density ND system. These ND structures with ND size dependence of the coercive force were expected to be selectively used as both magnetically fixed and free layers in magnetic tunneling junction structures only by changing the ND size.

This paper concerns the active vibration control of a rectangular panel using smart sensors from the viewpoint of an active wave control theory. The objective of this paper is to present a new type of filter which enables the measurement of the wave amplitude of a rectangular panel in real time for the application of an adaptive feedforward control system which inactivates vibration modes. Firstly, a novel wave filtering method using smart PVDF sensors is proposed. It is found that the shaping function of smart sensors is a complex function. To realize the smart sensor in a practical situation, a Hilbert transformer is utilized to implement a phase shifter of 90° for broadband frequencies. Then, from the viewpoint of a numerical analysis, the characteristics of the proposed wave filter and the performance of the adaptive feedforward control system using the wave filter are discussed. Finally, experiments implementing the active wave control theory which uses the proposed wave filter are conducted, demonstrating the validity of the proposed method in suppressing the vibration of a rectangular panel.

We applied the cryo-HAADF-STEM tomography (cryogenic Tecnai G2 Plara) for analysing three-dimensional nano-structures of platinum (Pt) and gold (Au) nanodots synthesised on titanium dioxide. The structural parameters such as particle size, density and volume were successfully evaluated and compared between macroscopic properties (methylene blue dissolution and CO oxidation). The atomic structures of metallic clusters on the TiO2 surface were also carefully investigated by using double aberration corrected TEM/STEM (double AC JEOL JEM-2200FS) in order to study the quantum size effect of these noble metals.

We report the development of technologically important nickel (Ni) nanodots (nanoparticles) dispersed in amorphous silica (SiO2) for high-temperature permselectivity for hydrogen separation membranes, crucial in hydrocarbon reactions and H(2) production, and present the systematic reconstruction of the three-dimensional (3D) structures of the nanodots using electron nano-tomography. 3D structures using cryogenic high-angle annular dark field scanning transmission electron microscopy (Cryo-HAADF-STEM), which is a more accurate method for nanoparticle morphology than conventional chemisorption, are correlated with experimental reversible hydrogen adsorption properties. The correlations provide the first direct evidence of very high activity on the nanoparticle surface and the nature of adsorption sites. The results have important implications in general for the use of electron nano-tomography in the design of supported metallic nanoparticles for hydrogen separation membranes.

We first tried to determine the thickness of both Si-on-Mo and Mo-on-Si interdiffusion layers inherent in the Mo/Si multilayer films by taking high angle angular dark-field-scanning transmission electron microscopy (HAADF-STEM) images. Secondly, the origin of 2–5% shortage of the measured extreme ultraviolet (EUV) reflectivity relative to that expected from the Fresnel equation has been investigated from two possible viewpoints: one, the presence of residual Xe gas atoms incorporated into the film during deposition in the reduced Xe gas atmosphere, and the other, a gradual shift of the layer periodicity over an entire cycle of repeated depositions. By analyzing the grazing incident X-ray reflectivity (GIXR) spectra for the 50-layer films, we were able to demonstrate that the latter is responsible for lowering the EUV reflectivity.

Ge/Si structures with a layer of Ge islands grown on oxidized Si surfaces and covered with Si were recently found to exhibit intense photoluminescence (PL) in the D1 region (~0.8 eV) after annealing at high temperatures. We show that this PL is a property of the Ge/Si structures grown at low temperatures from about 400 to 500 °C, at which crystal defects are introduced through the coalescence of strained three-dimensional islands. PL features are found to be independent of Ge thickness over a wide range from 0.7 to 3 nm. A monotonic increase in PL with annealing temperature is observed up to 1000 °C, but PL completely vanishes after annealing at higher temperatures. The transmission electron microscopy data show the presence of dense arrays of crystal defects in the Si layer capping the layer of Ge islands.

High-resolution transmission electron microscopy (HRTEM) of multi-wall carbon nanotubes using a spherical aberration correction of the objective lens has shown a new possibility for the observation of nanometre-sized tubular materials. Improvement of the image resolution along a direction parallel to that of electron incidence enables one to obtain some information on the local height of the tubes, and in lateral directions better than 0.14 nm at 200 kV accelerating voltage, the possibility of direct determination of the chirality of the tubes and the observation of finer atomic structures of carbon atoms such as ‘hexagon’ ones is suggested. Spherical aberration corrected HRTEM begins a new stage of the structural study of nano-tubular materials.

The temperature-concentration dependences of the Raman spectra in the high-temperature region above the Burns temperature and the electron diffraction at room temperature were investigated in the (1-x)Pb(Zn1/3Nb2/3)O3–xPbTiO3 mixed crystal system. It was found that in the concentration range below x=0.8, the Raman active modes exist in the cubic phase and the intensities of the Raman lines in the cubic phase decrease with increasing temperature. A finite region where the Raman active modes are observed in the cubic phase was determined in the temperature-concentration phase diagram. On the other hand, no (1/2, 1/2, 1/2) superlattice diffraction was observed in the mixed crystal with the content above x=0.2. The present result indicates that the Raman active modes in the high-temperature phase cannot be explained by the zone folding for the superstructure with the Fm3m symmetry.

Single-wall carbon nanotubes (SWNTs) have been produced for the first time using the high-temperature pulsed arc-discharge technique, which has been developed recently in this laboratory, as reported in the conventional steady arc discharge method. Scanning electron microscopic (SEM) and transmission electron microscopic (TEM) observations reveal significant production of bundles of SWNTs in soot. The pulsed arc production of SWNTs favors a high-temperature (≥1000°C), long pulses (≥1 ms) and a heavy rare gas such as Ar or Kr as a buffer gas.

Small Fe particles of nm size were formed in MgO films by a codeposition technique. Static magnetization and ferromagnetic resonance were measured. Magnetic couplings between the particles are discussed on the basis of experimental data of ferromagnetic resonance and magnetization measurement. The data show that the particles in high Fe concentration film are strongly coupled, while those in low concentration films consist of two types of particles: strongly coupled ones and independent ones. Static magnetization measurement strongly suggests enhanced magnetism at the interface of the Fe particles and MgO matrix, which has been theoretically predicted.

The relationship between superconducting transition temperature, T c, and Cu valence as well as Cu–Cu and Cu–O bond lengths for Ba2- x Eu1+ x Cu3O7-δ and Ba2EuCu3O7- y compounds as functions of x and y was investigated. For Ba2- x Eu1+ x Cu3O7-δ compounds, Cu(2) valences decreased from 2.3 to 2.2 as x varied from 0 to 0.5, and Cu(1)–Cu(2) and Cu(2)–O(3) bond lengths were almost constant for 00.3. For Ba2EuCu3O7- y compounds, the Cu(2) valences decreased from 2.3 to 1.9 as y varied from 0.14 to 0.6, and Cu(1)–Cu(2) and Cu(2)–O(3) bond lengths increased with increasing y. T c of Ba2- x Eu1+ x Cu3O7-δ compounds decreased rapidly with increasing x; on the other hand, that of Ba2EuCu3O7- y compounds decreased gradually with increasing y. The behavior of T c for Ba2- x Eu1+ x Cu3O7-δ and Ba2EuCu3O7- y compounds cannot be accounted for by the change of Cu(2) average valence. The change of T c depended on the bond length of Cu(2)–O(3), and the maximum T c for these compounds was obtained at the optimum bond length of Cu(2)–O(3).

The ionized beam deposition (IBD) technique has been developed to fill quarter-micron contacts with TiN/Ti/TiSi2 barrier metal. IBD shows lower contact resistance and higher throughput than a collimated sputtering (CSP) technique. The bottom coverages of IBD and CSP are 50% and 10%, respectively, at a contact aspect ratio of 4. Non-equilibrium higher axial and lower radial velocity profiles of depositing particles can account for this bottom coverage difference.

The four-ring probe method which was devised as a method of measuring resistivity is described. This method is applicable to the system consisting of a circular disk sample and a four-ring probe array. The resistivity correction factor (RCF), which is necessary for correcting data measured by means of the four-ring probe method and for obtaining the resistivity of the sample, is derived analytically. The properties of the RCF are discussed on the basis of the theoretical analysis. It is demonstrated by the experimental results that (i) the RCF corrects data accurately, (ii) it is insensitive to the shape of the sample and the measurement position as long as the thickness of the sample is less than the probe spacing, and (iii) the four-ring probe method is compatible with the four-point probe method.

Lattice bending around the interfaces of strained InP/InGaP/InP superlattices was analyzed by using thickness fringes in the dark-field electron microscopy and nanometer-area electron diffraction patterns. The present paper is complementary to a previous paper about strain detection by using thickness fringes in the bright-field electron microscopy (Jpn. J. Appl. Phys. 30 (1991) L52). By using the two methods, lattice bending around the interfaces of the superlattices with a lattice misfit of 1% was quantitatively evaluated in a three-dimensional form. Comparison between the methods and the usual lattice-imaging method in high-resolution electron microscopy(HREM) is discussed.

Infrared transmission spectra were measured for single crystalline composite films of nm-sized metal (Au, Fe and Cr) crystallites and magnesium oxide (MgO). The absorption lines of the TO phonon of MgO were observed around 400 cm-1. The widths of absorption lines in Fe-MgO and Cr-MgO composite films are about three times wider than those of vacuum-deposited MgO films, whereas they are twice as wide in the Au-MgO composite films. These features are tentatively understood in terms of the difference in the bonding strength of the metals and oxide.

A new method for analyzing interfaces of semiconductor superlattices such as GaAs/Ga1-x Al x As is reported: An electron probe of 1–2 nm in size of formed in a transmission electron microscope is incident in the [100] direction on a {110} cleaved crystal of the superlattices and scanned around the interfaces like the cross-sectional observation. The nanometer-area diffraction patterns are recorded continuously by scanning the probe. The local compositional and structural information of the interfaces in the superlattices can be obtained using the method.

Composite films of titanium and magnesium oxide are prepared by simultaneous deposition technique on sodium chloride (001) surfaces and characterized by electron microscopy and electron diffraction technique. Small crystallites of around 1 nm in size with the structure of titanium oxide with ordered vacancies embedded epitaxially in magnesium oxide single crystal films are observed in as grown films. The structure of the composite films remains unchanged by heat treatment at 500°C for a few hours. Heat treatment of the composite films at 1000°C for a few minutes brings about the formation of Mg2TiO4 with the spinel structure.

Composite films of iron and magnesium oxide are prepared by a simultaneous deposition technique. An important feature of the films is that iron is grown epitaxially and separately with the size of around 1 nm inside (001) and (11̄0) magnesium oxide films of about 25 nm thickness. The structures of the films are studied by high resolution electronmicroscopy. The heat treatment of the composite films brings about the grain growth and the phase transformation of iron crystallites from α-iron to γ-iron.

Composite films of gold crystallites embedded in magnesium oxide (001) and (110) single crystalline films are prepared by the simultaneous vacuum deposition technique for the study of metal-magnesium oxide composite films. The epitaxially grown gold crystallites of a few nm in size are analyzed from the contrast of the lattice images by using computer-simulated images. The lattice fringes at the crystallites are observed with two kinds of spacing of gold or magnesium oxide depending on the defocus condition, which suggests that the thickness is a few atomic layers. The result is also inferred from the growth condition in the simultaneous deposition. The fact that no strain contrast is apparent shows that gold crystallites grow almost coherently inside the magnesium oxide. The imaging characteristics of the composite films are studied in detail on the thickness and the depth of the gold crystallites.