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A gallium nitride-based thin film is grown on a multicrystalline Si substrate by a molecular beam epitaxy apparatus. The microstructure of the crystalline film is closely examined by transmission electron microscopy (TEM). It is revealed that the film is composed of nanopillar-shaped-crystal grains with their diameters of 100 nm and heights of 400 nm approximately. Each nanopillar-crystal grain is based on highly-ordered wurtzite crystal structure and strongly textured with its c-axis oriented perpendicular to the substrate surface. The TEM observations also evidence that there are two kinds of basal stacking faults widely distributed in the nanopillar-crystal.

Precipitates formed in an Mg–0.5at%Ce alloy during age-hardening at certain temperatures ranging between 180 °C and 250 °C have been thoroughly investigated by a combined technique of TEM and HAADF-STEM. The precipitation sequence can be presented as Mg-solid solution → GP-zone → β 1 (Mg 3 Ce; BiF 3 -type) → β (Mg 12 Ce; Mn 12 Th-type). At an early stage of aging (180 °C for 2 h), fine precipitates of planar GP-zone with an ordered structure appear in parallel to (1 0 0) m planes of the Mg-matrix, having a thickness of sub-nm and an extension of 5–15 nm. With an advance of aging, the GP-zones increasingly grow larger and combine with the neighbors. When the GP-zones have reached as large as approximately 20 nm in diameter, the age-hardening effect is maximized (180 °C for 70 h). After the top-aging, the GP-zones begin to decompose and disappear, and instead precipitates of two other phases, i.e. the β 1 - and the β -phase come into sight in the matrix with definite crystallographic orientation relations of [0 0 1] m //[1 1 0] β 1 //[1 0 0] β and (1 1 0) m //(1 1 1) β 1 //(0 1 0) β , finally completing the aging effect with full of coarse β -precipitates.

Phase transformation of solid solution decomposition occurring in a 96 at%Mg-4 at%Dy alloy, which was solution-treated at 540°C and subsequently aged at 250°C for various lengths of time, has been investigated by conventional transmission electron microscopy (TEM) in combination with high-angle annular detector dark-field scanning transmission electron microscopy (HAADF-STEM). The atomic-scaled observations based on both techniques provide the evidence that the first appreciable change in microstructure caused by aging is the occurrence of a short-range ordered state in Dy-segregated regions and that the short-range ordered state allows full of the nuclei of β′ phase associated with an Mg7Dy-type structure to occur in the domains, just as in cases of Mg-Gd and Mg-Y systems. With an increase of age-hardening effect, the β′ precipitates become larger and increasingly anisotropic in morphology, accompanying three orientation variants in coherent with the Mg-matrix. When reaching at the stage of hardness maximum (as-aged at 250°C for 100 h), the β′ precipitates, which have an orthorhombic structure with lattice parameters of a=0.659 nm, b=2.231 nm, c=0.523 nm, take the form of a thin disk-shape with a thickness of 20∼100 nm and a diameter of 200∼400 nm. With an advance of over-aging effect, the β′ precipitates are gradually reduced in volumes and replaced by β precipitates of cubic structure.

Consumers often talk about consumer packaged goods (CPG) brands with their family and friends. One notable feature of word-of-mouth (WOM) communication is that a brand that has been purchased by all participants in the conversation often becomes a topic. For example, consumers who have purchased Red Bull often talk about the brand among themselves. Previous studies have actively examined the effect of WOM on the first purchase of a new brand (i.e., a brand that has not been purchased) in the categories of books (Chevalier and Mayzlin 2006), movies (Liu 2006), and games (Zhu and Zhang 2010). However, how WOM influences repeat purchases of a CPG brand has remained virtually unexplored, although some studies imply that consumer interactions promote repeat purchases (e.g., Baghurst, Record, and Leppard 2000).

Thin films of Al–Ni–Co alloy were produced by vacuum deposition technique using a substrate material of amorphous carbon thin-foil. Attempts were made to obtain a homogeneous decagonal quasicrystalline film, where the preparation technique was based on the direct evaporation of pre-alloyed ingot of Al 72 Ni 15 Co 13 onto the heated substrates. In order to explore early stages of the decagonal film growth, the Al–Ni–Co films with different thicknesses ranging from 2 nm to 30 nm were deposited on either substrates heated at 500 °C or non-heated substrates. The film samples so obtained were examined mainly by atomic force microscopy in combination with transmission electron diffraction and imaging techniques. On the basis of these observations, deposition conditions necessary for the growth of decagonal phase in the resulting films as well as the growth mechanism of the decagonal film will be discussed.

In the stability region of the Ni-rich Al–Co–Ni decagonal quasicrystals, phase relationships among three different modulations, i.e. the so-called Ni-rich basic, S1-state and Type-I phases, and their phase changes have been thoroughly investigated by various transmission electron diffraction and imaging techniques in combination with thermal analysis. Electron diffraction experiments have clearly indicated that the S1-state phase formed in the Al 70 Co 12 Ni 18 alloy, which is stable at 900 °C, transforms into the Type-I phase by annealing at 650 °C and that the Ni-rich basic phase formed in the Al 71.5 Co 9 Ni 19.5 alloy, which is stable at 900 °C, transforms into the S1-state phase by annealing at 650 °C. In addition, differential scanning calorimetry measurements have evidenced for the first time that both phase changes occur reversibly at certain temperatures ranged between 700 and 800 °C. The structural features of the modulations mentioned above have been distinguished and uniquely characterized by making the best use of high-angle annular detector dark-field scanning transmission electron microscopy as well as high-resolution transmission electron microscopy.

Dissolution patterns essential for Al–Co–Cu and Al–Co–Ni decagonal quasicrystals (d-QCs) have been investigated in detail by chemical etching using a HF–HNO3–H2O solution followed by scanning electron microscopy (SEM) observations. The chemical etching of definite surface areas of the samples, which are either normal or parallel to the tenfold axes, using a solution with HF–HNO3–H2O (1 : 5 : 4 in volume ratio; 0°C; 5–10 min), produces a large number of microfacet pits of decagonal prismatic shape. In addition, the same etching test in combination with SEM observations was carried out on a deformed sample of the Al–Co–Ni d-QC, which had been subjected to concentrated mechanical stress at an elevated temperature of 850°C by means of the Vickers indentation technique. The morphological features of the resulting micropits and their possible origins are discussed on the basis of results obtained by SEM observations.

The structures of an Al–Pd decagonal quasicrystal and an Al 3 Pd crystal are characterized as two-dimensionally quasiperiodic and periodic arrangements of the same columnar clusters of atoms, respectively. In order to study the transformation process from quasiperiodic to periodic arrangements of the atom clusters, melt-quenched Al 3 Pd alloys, annealed at various temperatures, have been examined by electron diffraction and high-resolution electron microscopy. In the intermediate state of the transformation, we have found locally periodic arrangements with special intervals, some of which are not in the Al 3 Pd crystal. Based on the periodic arrangements in the intermediate state of the transformation, metastable structures between the quasiperiodic to periodic arrangements of the atomic clusters have been discussed.

Dissolution patterns caused by anodic etching of an Al–Pd–Mn icosahedral quasicrystal and chemical etching of an Al–Cu–Co decagonal quasicrystal were examined by optical and electron microscopy as well as by atomic force microscopy. Appropriate etching treatments of these quasicrystals, i.e. the anodic etching of the Al–Pd–Mn quasicrystal in a solution of CH 3 OH–HNO 3 , and the chemical etching of the Al–Cu–Co quasicrystal in a solution of HF–HNO 3 –H 2 O resulted in occurrence of dissolution patterns composed of a number of well-facetted micropits (and hillocks for the Al–Cu–Co alloy as well) on low-indexed surfaces of the specimens. The morphological features of these etch-figures are discussed in relation to the internal structural symmetries.

Stabilization of Guinier-Preston zones (GP-zones), which have been found in an Mg 97 Gd 2 Zn 1 alloy annealed at 200°C for 150 h, is studied. Single formation of the GP-zones without other precipitates is found in Mg 98 Gd 1 Zn 1 and Mg 97.5 Gd 1.5 Zn 1 alloys annealed at 200°C for 100h. The GP-zones at this aging stage are distributed widely and separately from each other, but they change into many groups of band-shaped GP-zones by prolonged annealing.

Faceted micropits obtained by electrochemical etching of a single quasicrystal of an Al-Pd-Mn icosahedral phase have been examined by optical and electron microscopy. Anodic etching of the flat surface of a fivefold plane in a solution composed of CH3OH and HNO3(3:1 in volume ratio) reveals a variety of icosahedrally faceted micropits which originated from pre-existing microvoids and etch pits of pentagonal pyramid shape due to the other origins, probably structural defects inside the specimen. As the dissolution progresses, the micropits make successive changes in their shapes, ending in pentagonal pyramids before they vanish.

The shapes of micro-pits formed in an Al-Pd-Mn icosahedral quasicrystal have been examined by alternating sequence of electrochemical etching and scanning electron microscopy (SEM) observations. Anodic etching was executed on fivefold and twofold surfaces of the single-quasicrystal. Prolonged anodic etching in a solution of CH 3 OH + HNO 3 (volume ratio 3 : 1) followed by SEM observations has revealed that two different types of micro-pits, i.e. pre-existing micro-voids and electrochemical etch-pits, develop into the same regular shape. The micro-pits develop into a pentagonal pyramid on the fivefold surface, and a flat-bottomed rhombic pyramid on the twofold surface. It is shown that these two polyhedral etch-figures correspond to two different sections of a regular rhombic triacontahedron.

When (111) wafers of Te-doped GaP were etched in H 2 SO 4 + H 2 O 2 + H 2 O (5 : 1 : 1 in volume ratio) at a temperature above 70°C for a period longer than 3.6 x 10 3 s, abnormal etch pits of asymmetric shape formed on the (111) P surface in minor density compared to those of normal triangular pits and spiral pits. From microscopic observation, the abnormal pit had an etch beak projecting from its apex. In order to clarify the origin of abnormal etch pits, structural defects in the wafers were examined by transmission electron microscopy after thinning. As a result, they were classified into several types such as dislocations, dislocation loops, precipitates and lineage defects composed of a dislocation bundle. As the lineage defects often take such a peculiar configuration as a zigzag pattern, we suppose that the abnormal etch pit with a beak would nucleate owing to preferential dissolution along the lineage defect.

The crystal structure of a gamma-(Al-Cu-Ru-Si) cubic phase (Al Cu Ru Si ), considered to be closely related to that of the Al-Cu55.1 14.6 20.2 10.1 Ru icosahedral quasicrystal, has been determined by single-crystal X-ray diffraction. The atomic model, refined to a final R value of 0.0346, has about 262 atoms with an atomic ratio of Al Cu Ru in a cubic unit cell with a 66.3 13.5 19.8 lattice constant a = 1.538 0(2) nm and the space group Fm 3. The fundamental structure is characterized by a sc arrangement of dodecahedral atom clusters with an interval of 0.77 nm, which corresponds to a lattice constant of a 1/0 cubic approximant phase for the icosahedral quasicrystals. The chemical ordering of the constituents in the dodecahedral cluster produces a superstructure with a lattice constant twice that of a 1/0 cubic approximant phase.

HAADF (high-angle annular detector dark-field) images with Cs-corrected scanning transmission electron microscopy (STEM) have been observed for a W-(AlCoNi) crystalline phase and two-types of decagonal quasicrystals in Al71.5Co25.5Ni3 and Al72.5Co17.5Ni10 alloys. We have secured positive evidence that three-dimensional arrangements of transition-metal (TM) atoms of decagonal quasicrystals can be directly derived from the arrangements of bright dots in HAADF-STEM images, which correspond to individual TM atoms, by reference to results on HAADF-STEM observation and the structure of W-(AlNiCo) determined by X-ray diffraction analysis. We could conclude that pure TM atomic sites and mixed TM sites (with Al atoms) on A and B planes stacking along the periodic axis are located at the lattice points of a Penrose lattice with a bond length of 0.25 nm. In both planes atomic sites form pentagonal tilings with bond lengths of 0.47 nm and 0.76 (=0.47⋅τ) nm, respectively, in both the Al71.5Co25.5Ni3 and Al72.5Co17.5Ni10 decagonal quasicrystals, whose structures were formally characterized as rhombic and pentagonal tilings of atom columnar clusters with a bond length of 2 nm.

It was recently found that the electrochemical dissolution of an n-GaP (111) surface proceeded selectively or uniformly in an aqueous KOH solution, depending on an anodic high-voltage above ten volts. In the present study we report the formation of whiskers at dislocation sites of the n-GaP (111) surface that remain undissolved at an anodic voltage of 16 V in the 0.5 kmol·m−3 KOH solution.

The magnetization of a stable single-grained Al 70 Pd 21 Mn 9 icosahedral quasicrystal has been investigated in the temperature region between 2 and 600 K below the magnetic field 80 kOe. The susceptibility yields a Curie constant 1.75×10 -4 cgsemu·K/g, a Curie temperature -1.62 K, and a constant susceptibility contribution -0.25×10 -8 cgsemu/g. Magnetization curves at low temperatures suggest that only about 1% of the Mn atoms are magnetic. The temperature dependence of the susceptibility above 300 K shows a positive T 2 contribution, which has been first observed in magnetic quasicrystals and is considered to originate from a pseudogap in the electronic density of states at E F causing the stability. Temperature- and magnetic-field-dependencies of the electrical conductivity are well accounted for by a weak localization theory including spin and spin-orbit scattering. The agreement between the experimental data and the fitting is not improved by adding the diffusion channel contribution of electron-elec...

A formula is given of the conductivity with explicit temperature-independent term in a weak-localization theory. Correct subtraction of the quantum terms yields a Boltzmann conductivity about three times as large as the one without correct subtraction for an Al 66.3 Cu 20.4 Fe 13.3 icosahedral phase. Parameters V F τ, τ/τ so , τ e /τ so , and A inthe theory could be obtained by the fit of the formula.

Magnetic properties of two kinds of Ga–Mg–Zn alloy samples were studied. One is Ga 20 Mg 40 Zn 40 icosahedral phase which was thermally stable below about 615 K, the other is Ga 18.5 Mg 41.5 Zn 40 alloy which exhibited amorphous-like X-ray diffraction pattern with no sharp peaks. The icosahedral phase showed a linear relationship between the magnetic susceptibility and the square of temperature. The improvement of the specimen quality resulting from heat treatment made the temperature dependence enhanced and the paramagnetism reduced. The amorphous-like sample did not show the temperature dependence of the magnetic susceptibility. These facts afford the experimental evidence that, in terms of Pauli paramagnetism, the electronic density of states at Fermi level of the icosahedral phase is strongly affected by the band-structure originating from the quasiperiodicity.

In order to characterize the molecular mechanism of blister formation of oral mucosa in pemphigus vulgaris (PV), we observed the effects of PV serum on the arrangement of keratin intermediate filaments (KIFs) and desmosomes of cultured human gingival keratinocytes by transmission electron microscope.The arrangement of KIFs in contol cells showed a radiating pattern of filament bundles to the cell periphery, and these bundles ended at well developed desmosomes.After incubation with PV serum for 96 hrs at 37°C, the arrangement of bundles of KIFs became unclear and the number of desmosomes decreased, and amorphous dotted structures were observed.These dotted structures seemed to be formed by structural changes of KIFs and these structures were often associated with distrupted desmosomes.These results support our hypothesis that PV serum induces structural changes in KIFs and also in desmosomes.

In magnetic skyrmion crystals (SkXs), the quality of skyrmion ordering affects the motion under electric current and temperature gradient. However, the crystalline nature itself remains an open issue. We report the observation of skyrmion polycrystallization in FeGe1−xSix as a function of x by Lorentz transmission electron microscopy. With increasing x, the SkX changes from single crystalline to polycrystalline, concomitantly with the formation of the interfaces referred to as domain boundaries. In situ observations have revealed that the domain boundary formation competes the tendency to accommodate the differences between orientations of the SkX.

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

The H2SO4–H2O2–H2O system, typically a solution with five parts H2SO4, one part H2O2 and one part H2O in volume ratio, is currently used for chemical polishing of a GaAs crystal to obtain microscopically smooth surfaces. However, the etching of the (111)Ga surface in this etchant leads to the formation of etch pits. In this study, the etching behavior of the (111)Ga surface in various compositions of the H2SO4–H2O2–H2O system at temperatures of 0–70°C is mainly re-examined. It is found that a microscopically smooth {111} surface can be obtained by etching in the solutions with 78+x parts H2SO4, two parts H2O2 and 20-x parts H2O (x=0–4) at 70°C. In contrast, dark and light pits are formed on the (111)Ga surface etched in a solution with two parts H2SO4, one part H2O2 and seven parts H2O at 0°C. Their origin is predicted on the basis of double-etching test results.

A thin-film sample of Al–Pd–Mn ternary alloy has been produced by a vacuum deposition technique using dual evaporation sources, followed by thermal annealing. The microstructure of the film has been examined by transmission electron microscopy (TEM) and by atomic force microscopy (AFM). The TEM observations reveal that the film has a granular texture of highly ordered icosahedral phase islands embedded in the matrix consisting mainly of multiple-twinned crystals exhibiting a pseudo-tenfold symmetry. It is shown by AFM that the icosahedral islands form protuberant structures with the average height of approximately 50 nm.