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A new scheme of calculation of high-angle annular dark-field STEM image, capable of including both elastically diffracted and thermal diffuse scatter- ing waves, has been presented by a combination of Pennycook's and Nakamura's methods. The new scheme has been demonstrated for image simulations of Si(011) as functions of thickness, defocus values and detec- tor angles. In the present method, the TDS electron intensities are treated in the same way as in Pennycook's method, having a clear physical picture of its origin and reflecting the atom configuration in the systems. For the case of Si(011), it has been confirmed that at the detector angle of 60 to 160 mrad, which is usually applied, the image becomes highly incoherent, and even the image formed only from SOLZ beams becomes incoherent at the detector angle. At a low detector angle, however, the image has coherent features indicating the necessity of a simulation for individual systems.

The irradiation effects of Ar ions into solid Xe precipitates embedded in an Al matrix were observed using high-resolution transmission electron microscopy (HRTEM). Al TEM thinned specimens were implanted with 50 keV Xe at room temperature to a dose of 1×10 16 ion/cm 2 and successively implanted with Ar ions of 25 keV to a dose of 1×10 16 ion/cm 2 . After 5×10 15 ion/cm 2 Ar irradiation, the maximum size of the crystalline precipitate becomes 27% larger than that before irradiation. The lattice constants of Xe precipitate before and after the Ar irradiation were also measured. However, no change in lattice constant was detected.

Pure Al powder was sintered by spark plasma sintering (SPS) process at various sintering temperatures and loading pressures. The density, electrical resistivity, tensile properties and microstructure of powder compacts were investigated. The powder compacts with the similar properties as base aluminum metal was obtained at sintering temperature above 873 K, loading pressure above 23.5 MPa. For the powder compacts with the similar density but with the large difference in the electrical resistivity and tensile properties, the interfaces between Al powder particles were investigated using high resolution transmission electron microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDS). Two types of interfaces, with metal/metal bonding and metal/oxide film layer/metal bonding, were observed in Al powder compacts. The properties of powder compacts were mainly subject to the behavior of oxide film between the powder particles.

A phase transformation in γ-TiAl intermetallic alloy was found to be induced with 50 keV Xe-ion irradiation-implantation at doses larger than 2.2 x 10 18 ions m -2 at room temperature. The structure and the chemical composition of the induced phase were investigated with high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy. The zones of the induced phase have sizes up to about several tens of nanometres. The phase has a hexagonal structure with a = 0.286 nm and c = 0.462 nm. The crystallographic orientation relationship between the phase (P) and the γ-TiAl matrix is (001) p //(111) γ and [100] p //[011] γ . The [Al]/[Ti] atomic composition ratio in the phase is analysed to be 56/44, slightly different from that of the matrix, 51/49. These results suggest that the induced phase is an Al solid solution of α-Ti alloy phase, which has different structural parameters and chemical composition from those of the reported phase. It is suggested that the size of the ions is important in the phase transformation.

The phase transformation of γ (fcc) to α (bcc) is observed in thin film specimens of austenitic 304 stainless steel implanted with 100 keV ions at room temperature. The orientation relationships between the induced α (bcc) and the austenitic γ (fcc) matrix are determined to be (0 1 1 ) α //(1 1 1) γ and [1 1 1] α //[0 1 1] γ . The relationship is followed by the Kurdjumov–Sachs (K–S) rule rather than the Nishiyama–Wasserman (N–W) rule in this experiment, though the latter relationship was well observed in the previously reported experiments of implantation of austenitic stainless steels with noble gases or other heavy ions.

In situ high-resolution electron microscopy has been used to observe nanoprecipitates of crystalline Xe in faceted cavities in Al during coalescence induced by 1.0 MeV electron irradiation at 300 K. Atomic-level fluctuations of cavity facets result in shape changes and precipitate motion leading to coalescence. There is no apparent elastic interaction between precipitates separated by as little as 0.5 nm. After coalescence, crystalline Xe conforms by plastic deformation without melting to changes in cavity shape. Cavity volume, not surface area, is conserved during coalescence, implying that cavity pressure is not determined solely by the interface tension.

Xe ions were implanted into Al in a high-voltage transmission electron microscope at temperatures 423 and 473 K to a dose up to 2.6×1021 ions m−2. Electron energy loss spectroscopy (EELS) and energy filtered imaging (EFI) were employed to characterise Xe cavities over the temperature range 300–858 K. The precipitates grew up to about 30 nm when Xe ions were introduced at 473 K. The crystalline precipitates start to change to a non-crystalline state at 623 K and converted completely to the non-crystalline state at a temperature up to 773 K. Energy filtered images of Xe were taken with Xe-M4,5 core loss electrons to get the two-dimensional distribution of Xe for both crystalline and non-crystalline Xe cavities. Low energy loss peaks at about 14.6 and 15.3 eV were identified in the EELS spectra obtained at 300 and 773 K, respectively. These peaks are thought to be related to the Xe precipitates in Al. The analysis of Xe-M4,5 edge in EELS spectra suggests that Xe-precipitates exist in the gaseous state at 773 K.

Defect introduction processes in two differently sized Xe nanocrystals embedded in Al were observed with in situ high-resolution electron microscopy. The imaging conditions made it possible to follow the apparent movement of Xe atom columns within a nanocrystal. The positions of individual atom columns were measured on captured video images, before and after defect introduction, from intensity traces along the rows of atom columns. For each of these precipitates, a planar defect appears on {1 1 1}. The observed displacement of Xe atom columns approximately corresponds to the projected displacement produced by a Shockley partial dislocation, bounding an intrinsic stacking fault. Comparison of the displacements of atoms in the two nanocrystals shows that the displacements are reduced at the precipitate/matrix interfaces. This implies that there will be a displacement at interfaces that represents some compromise between the strain field of the partial dislocation and the interface compatibility requirement.

We report the fabrication of submicron GaAs/AlAs double-barrier resonant tunneling diodes (RTDs) using wet etching with In droplets as a mask. Uniform mesas about 400 nm in size were formed and showed a clear resonance feature in current–voltage (I–V) characteristics, indicating that the mesa worked as a RTD. This simple technique can be applied to the fabrication of various submicron diodes.

The effects of water vapor and oxygen addition to an iron pentacarbonyl precursor on the formation of iron oxide deposits were studied to understand the mechanism of iron oxide formation in electron beam-induced deposition. The water vapor addition markedly reduced the carbon content in the deposits and led to the formation of crystalline iron oxide. However, the oxygen addition had little effect on the composition and structure of the deposits. This suggests that iron acts as a catalyst and a chemical reaction similar to the water gas reaction occurs during the electron beam-induced deposition.

A fabrication technique combining electron-beam-induced deposition and low energy ion milling is suggested. Nanosized deposits fabricated by electron-beam-induced deposition are used as masks for low energy ion milling so that the substrate regions covered with the nano-sized deposits form nanostructures. A check by high-resolution electron microscopy showed that the method can be used to fabricate nanometer-sized structures from various materials with high crystallinity which is very important for device applications.

To fabricate organic nanofibers that function as active optical waveguides with semiconductor properties, a facile procedure was developed to grow single crystalline nanofibers via π–π stacking of the polycyclic aromatic molecule, coronene, through solution evaporation on a substrate. The fabricated nanofibers with millimeter-scale lengths have well-defined shapes, smooth surfaces, and low-defect structures. The nanofibers are demonstrated to function as efficient active waveguides that propagate their fluorescence (FL) along the fiber axis over their entire length. We further demonstrate that the nanofibers can be highly aligned on the substrate when solution evaporation is conducted in a magnetic field of 12 T. The mechanism of the magnetic alignment can be elucidated by considering the anisotropy of the diamagnetic susceptibility of a single coronene molecule and the crystal structure of a nanofiber. Owing to the high degree of alignment, the nanofibers rarely cross each other, allowing for measurement of the waveguiding properties of single isolated nanofibers. The nanofibers propagate their FL of λ > 500 nm with a low propagation loss of 0–3 dB per 100 μm, indicating that the nanofibers function as sub-wavelength scale, low-loss waveguides. Thus, they are promising building blocks for miniaturized optoelectronic circuits.

We demonstrate the formation of InAs quantum dots (QDs) on InAlAs/InP(111)A by means of droplet epitaxy. The C3v symmetry of the (111)A substrate enabled us to realize highly symmetric QDs that are free from lateral elongations. The QDs exhibit a disk-like truncated shape with an atomically flat top surface. Photoluminescence signals show broad-band spectra at telecommunication wavelengths of 1.3 and 1.5 μm. Strong luminescence signals are retained up to room temperature. Thus, our QDs are potentially useful for realizing an entangled photon-pair source that is compatible with current telecommunication fiber networks. © 2014 AIP Publishing LLC.

We discuss the advantages of V2O5-P2O5-Fe2O3-Li2O glass-ceramics as a cathode for lithium-ion batteries. The glass was prepared by using the melt quenching method. The glass-ceramics were produced by heat treatment in air. LixV2O5 crystal was only confirmed as the precipitated phase and the degree of crystallinity was approximately 90%. The total capacity of the glass-ceramics was 340 Ah/kg at a C/20 rate for 1.5-4.2 V cutoff ranges. It is 10% higher than the capacity of the glass cathode. Moreover, the charge-discharge performance of the glass-ceramics cathode showed good cycleability similar to that of the glass. The glass-ceramics had a 83% capacity retention after 40 cycles. These results show that glass-ceramics is a potential candidate for lithium-ion cathode materials.

The evolution of the structural and optical properties of a silicon core in oxidized nanowalls is investigated as a function of oxidation time. The same individual nanostructures are characterized after every oxidation step in a scanning electron microscope and by low-temperature photoluminescence, while a representative sample is also imaged in a transmission electron microscope. Analysis of a large number of recorded single-dot spectra and micrographs allows to identify delocalized and localized exciton emission from a nanowire as well as confined exciton emission of a nanocrystal. It is shown how structural transitions from one-to zero-dimensional confinement affect single-nanostructure optical fingerprints. QC 20130204

O3-NaFe1/2Co1/2O2 shows initial capacity of 160 mAh/g and an average operating voltage of 3.1 V (vs. Na) with good cyclability, and is a promising candidate of the cathode materials for sodium-ion secondary batteries (SIBs). Here, we found that the cyclability of the slowly-cooled sample is much worse than that of quenched one, even though the former sample keeps the O3-type structure. The energy dispersive X-ray spectroscopy (EDX) images suggest that the slow-cooled sample (Nax Fe1–yCoy O2) is inhomogeneous in the Fe concentration (1 – y), perhaps triggered by the Na deficiency (1 – x). We ascribed the poor cyclability in the slowly-cooled sample to the concentration inhomogeneity (Δy). The Δy is further responsible for the fluctuation of the lattice constants (a and c), as revealed by the Williamson–Hall plot. (© 2016 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)

Electron-beam-induced deposition was performed to fabricate nanostructures using a subnanometer-sized probe of high-energy electrons emitted by a 200 kV transmission electron microscope equipped with a field emission gun. We fabricated nanometer-sized dots with a diameter of less than 5 nm, controlling their position and size by the introduction of a organometallic precursor gas near the substrate surface. The relation between the size of the deposit and the deposition time was studied, and, in addition, the effect of the substrate thickness was examined.

The magnetic susceptibility of cold-rolled Zr–14Nb was evaluated to apply a new metallic medical device used for magnetic resonance imaging (MRI). The magnetic susceptibility of cold-rolled Zr–14Nb decreased up to the reduction ratio of 30%, then gradually decreased up to the ratio of 90%. Transmission electron microscopic observation revealed the strain-induced formation of ω phase after cold rolling at the reduction ratio of 5%, indicating that the initial decrease in magnetic susceptibility was caused by the formation of the ω phase. The ω phase was saturated at the reduction ratio of 30%. The formation of the ω phase could be explained on the basis of the increase in the Young’s modulus and Vickers hardness of cold-rolled Zr–14Nb. The effect of texture formation on these properties was not obvious in the cold-rolled Zr–14Nb. Because of the strain-induced formation of the ω phase, the magnetic susceptibility of Zr–14Nb can be reduced by cold rolling to as low as that of as-cast Zr–9Nb, which is one-third that of Ti and Ti alloys. Therefore, cold-workable Zr–14Nb with low magnetic susceptibility could be a promising alloy for medical devices under MRI.

Optical sectioning using scanning confocal electron microscopy (SCEM) is a new three-dimensional (3D) imaging technique which promises improved depth resolution, particularly for laterally extended objects. Using a stage-scanning system to move the specimen in three dimensions, two-dimensional (2D) images sliced from any plane in XYZ space can be obtained in shorter acquisition times than those required for conventional electron tomography. In this paper, a double aberration-corrected SCEM used in annular dark-field mode was used to observe the 3D structure of SiO(2) hollow spheres fabricated by a carbon template method. The double-shell structure of the sample was clearly reflected in both XY- and XZ-sliced images. However, elongation along the optical axis was still evident in the XZ-sliced images even when double aberration correctors were used. Application of a deconvolution technique to the experimental XZ-sliced images reduced the elongated shell thicknesses of the SiO(2) sphere by 40-50% and the selectivity of information at a certain sample depth was also enhanced. Subsequently, 3D reconstruction by stacking the deconvoluted slice images restored the spherical surface of a SiO(2) sphere.

Energy filtered scanning confocal electron microscopy (EFSCEM) in an aberration-corrected transmission electron microscope offers an approach for three-dimensional imaging and chemical analysis of nanoscale materials related to the well-established technique of confocal scanning optical microscopy. Here, we apply EFSCEM to the compositional analysis of the core structure in candidate structures for targeted drug delivery. Element-specific optical sectioning along the specimen depth direction demonstrates the presence of additional Si in a nominal Fe 2O 3 core. The presence of Si in the core is consistent with a specific formation mechanism for the hollow structure of the core. © 2012 American Institute of Physics.

The scattering matrix method combined with the layer-doubling method is applied to n-beam dynamical calculations at 100 and 300 kV for aluminum, copper, and gold and the validity of the method has been critically examined in comparison with multi-slice and Bethe's eigenvalue methods. The method is shown to be an efficient dynamical method for high resolution electron microscopy (HRTEM). Die Streumatrix-Methode in Kombination mit einer Schichtverdoppelung wird auf dynamische Berechnungen des n-Strahlfalles bei 100 und 300 kV fur Aluminium, Kupfer und Gold angewendet. Die Gultigkeit der Methode wird kritisch untersucht durch Vergleich mit „multi-slice”-Rechnungen und Auswertung der Betheschen Eigenwert-Gleichungen. Dabei erweist sich die Methode als alternativ und effizient zur dynamischen Berechnung der Abbildung in der Hochauflosungs-Elektronenmikroskopie (HREM).

Optical transitions in silicon nanocrystals with different surface passivations were probed at low temperatures on a single-particle level. A type of quasidirect recombination process, different from the quantum-confined exciton transition, is identified. The luminescence spectra have different emission energies, but the contribution of a no-phonon transition is significantly higher than expected from the quantum-confinement model. Its relative strength was found to be temperature dependent, suggesting spatial localization of excitons as a possible origin. QC 20111103

Mean free path of elastic electron scattering λ(el) has been measured with a 200 keV transmission electron microscope for a wide range of stable elemental solids. An oscillating behavior versus atomic number Z has been revealed, such that, within one row of the periodic table, λ(el) exhibits minimum (maximum) for elements with completed (empty) outer d shells. These λ(el)(Z) oscillations are attributed to Z dependence of the atomic density, and their importance for the interpretation of electron microscope images is demonstrated.

The structure of individual nanodiamond grains produced by the detonation of carbon-based explosives has been studied with a high-vacuum aberration-corrected electron microscope. Many grains show a well-resolved cubic diamond lattice with negligible contamination, thereby demonstrating that the non-diamond shell, universally observed on nanodiamond particles, could be intrinsic to the preparation process rather than to the nanosized diamond itself. The strength of the adhesion between the nanodiamond grains, and the possibility of their patterning with sub-nanometer precision, are also demonstrated.

We experimentally examined the characteristics of bright-field (BF) scanning confocal electron microscopy (SCEM) images by changing the observation conditions and comparing the images with those obtained by BF transmission electron microscopy (TEM) and BF scanning TEM (STEM) modes. The observation of 5-nm-diameter Au nanoparticles demonstrated that BF-SCEM produces object elongation of more than 2000 nm along the optical axis, as do BF-TEM and BF-STEM. We demonstrated the relationship between elongation length and geometric effects such as convergence and collection angles of a probe and the lateral size of an object; the relationship is consistent with previous theoretical prediction. Further, we observed interesting features that are seen only in the BF-SCEM images; the film contrast was strongly enhanced, compared with that of BF-STEM. In addition, a bright contrast appeared around the object position in the elongated images. Using this characteristic, we could determine the object position and structure.

We report propagation of exciton polaritons (EPs) in photoexcited nanofibers of thiacyanine dye over a few hundred micrometers at room temperature. We determine the complex refractive index along the nanofibers by fluorescence microscopy measurements on single nanofibers and observe its anomalous behavior due to the EP effect. The longitudinal-transverse splitting energy ($\ensuremath{\Delta}{E}_{L\ensuremath{-}T}$) is evaluated to be $\ensuremath{\sim}1\text{ }\text{ }\mathrm{eV}$. The large $\ensuremath{\Delta}{E}_{L\ensuremath{-}T}$ and waveguide function of the nanofibers allow a millimeter propagation of EPs at room temperature, which is hardly realized in other systems.

A novel top-down approach for the controllable fabrication of semiconductor nanostructures exhibiting quantum effects is described. By decomposing metal-rich precursor gas molecules with an electron beam, a sub-10 nm metal pattern can be formed and subsequently transferred to a semiconductor substrate. In such a way monocrystalline silicon nanodots and nanowires are produced as revealed by transmission electron microscopy. It is also shown how through controlled thermal or chemical oxidation the nanostructure surface can be passivated. By providing direct access to the sub-10 nm size range this method possesses promising potential for application in the quantum dot and nanoelectronics fields. QC 20111129

We demonstrate that a transmission electron microscope fitted with two spherical-aberration correctors can be operated as an energy-filtered scanning confocal electron microscope. A method for establishing this mode is described and initial results showing 3D chemical mapping with nanoscale sensitivity to height and thickness changes in a carbon film are presented. Importantly, uncorrected chromatic aberration does not limit the depth resolution of this technique and moreover performs an energy-filtering role, which is explained in terms of a combined depth and energy-loss response function.

We evaluated the depth resolution of annular dark-field (ADF) scanning confocal electron microscopy (SCEM) with a stage-scanning system by observation of nanoparticles. ADF-SCEM is a three-dimensional (3D) imaging technique that we recently proposed. An ADF-SCEM instrument involves a pinhole aperture before a detector for rejecting electrons from the out-of-focal plane in a specimen and an annular aperture under the specimen for collecting only scattered electrons. The stage-scanning system enables us to directly obtain optical slice images perpendicular and parallel to an optical axis at a desired position. In particular, the parallel slices visualize the elongation of nanoparticles along the optical axis, which depends on the depth resolution. ADF-SCEM effectively reduced the elongation length of the nanoparticles sufficiently to demonstrate depth sectioning, in comparison with scanning transmission electron microscopy and bright-field SCEM. The experimentally obtained length was nearly equal to the theoretically estimated one from the probe size considering the experimental conditions. Furthermore, we applied this ADF-SCEM technique to analysis of the 3D position of catalytic nanoparticles on carbon nanostructures.

The process of electron-beam-induced deposition (EBID) was simulated with a dynamic Monte Carlo profile simulator, and the growth of carbon, silver, and tungsten supertips was investigated to study the dependence of material composition on the spatial resolution of EBID. Because light atoms have a smaller scattering angle and a longer mean free path, the carbon supertip has the smallest lateral size and the highest aspect ratio of a bottom tip compared to silver and tungsten supertips. Thus the best spatial resolution of EBID can be achieved on materials of low atomic number. The calculation also indicated a significant contribution of primary electrons to the growth of a supertip in EBID, which is consistent with the experimental observations. These results lead to a more comprehensive understanding of EBID, which is a complex interaction process between electrons and solids.

A sensitive nanosized molybdenum oxide (MoO(x)) photodetector is manufactured at a desired position by electron-beam-induced deposition (EBID). As-deposited MoO(x) had a conductivity approximately 300 S cm(-1). After 2 h annealing at 573 K, the conductivity of nanowires decreased 10 times to approximately 30 S cm(-1) and MoO(x) had photoconductivity. Nanosized MoO(x) wires enhanced the sensitivity of optical devices due to an increased surface area to volume ratio.

Cross-sectional transmission electron microscopy with elemental analysis was used to investigate shape and composition of nanostructures fabricated by electron beam induced deposition. The nanostructures were deposited on a thin edge of the silicon membrane allowing characterization without intermediate distorting preparation steps, such as focused ion beam milling. The effect of the surface carbon contaminants and the electron beam focusing on nanostructure composition was studied. It is shown how carbon content of nanostructures can be reduced by sample preheating, forming metal nanostructures with higher purity advantageous for circuitry and lithography applications. QC 20111129

A novel method for electrostatic potential measurements at the interface is described. It involves placing a two-dimensional grid below the sample and observing it in a scanning electron microscope. Primary electron beam displacement, caused by surface charges, can be then measured for every grid knot. Using geometric parameters of the setup, a quantitative mapping of the potential can be extracted. It is shown that this method can achieve a tens of millivolt sensitivity and a submicron spatial resolution in electrostatic potential measurements. QC 20111129

The production of nanometer-sized oxide structures is of significant interest due to the potential application to nanoelectronics, nanomagnetics and optoelectronics. It is important to place nano-dots or nano-wires at desired positions for the production of nanodevices. Electron beam-induced deposition (EBID) is a promising technique to produce such dots and wires [1]. The resolution of EBID is now reaching down to subnanometers [2]. Recently, Shimojo et al. reported that carbon-free crystalline iron oxide was deposited at room temperature by EBID [3]. In this paper, effects of water and oxygen addition to iron pentacarbonyl on nanostructure are studied.

Crystalline and amorphous xenon nanoparticles were produced in aluminum by Xe+ ion implantation and were characterized with high-resolution electron microscopy combined with electron energy loss EEL spectroscopy. Unusual distributions of the aspect ratio and of the diameter of the crystalline particles were observed and explained, respectively, by minimization of the surface energy and of the strain energy due to the specific lattice mismatch between Al and Xe. Matrix oxidation was revealed as an important phenomenon accompanying the amorphization of Xe particles. Significant variation of relative EEL peak intensities with Xe particle size was observed and associated with unequal pressure inside different particles. The thus revealed variation was utilized to map the pressure distribution inside individual particles with a nanometer spatial resolution.

The structure and composition of the 1/4{110} twin boundary in alpha-Zn7Sb2O12 have been determined by using quantitative high-angle annular dark field scanning transmission electron microscopy (HAADF STEM) analysis. The noise in the experimental HAADF STEM images is reduced by using the maximum entropy method and average processing, and the parameters used in dynamical simulations are experimentally determined. From the analysis, it has been found that octahedral sites in the twin boundary slightly shift parallel to the [110] direction, and a reduction of the Sb concentration at the octahedral sites on the plane adjacent to the twin boundary was detected. The reduction was measured from three regions in the same twin boundary, and the Sb concentrations were 4 +/- 3, 8 +/- 3 and 19 +/-2 at% from 33 at%.

Mean free path of inelastic electron scattering {lambda} has been measured with a 200 keV transmission electron microscope for the majority of stable elemental solids and their oxides. An oscillating behavior vs atomic number Z has been revealed, such that within one row of the Periodic Table, the minimum (maximum) of {lambda} is observed for elements with completed (empty) outer d shells. A significantly weaker {lambda}(Z) dependence is observed for the oxides. The {lambda}(Z) variation is ascribed to the three major factors: atomic density, number of 'free' electrons per atom, and contribution of atomic core-loss transitions.

In this paper, nanowires were fabricated by electron beam induced deposition using tetrakis(trifluorophosphite)-metal precursors. The microstructure and composition of the nanostructure were characterized by transmission electron microscopy (TEM).