The specific features of structural transformations in lanthanum manganite are analyzed in terms of the macrosymmetry conservation principle. The possible mechanisms of phase transformations are proposed reasoning from a sequence of structural transitions, including the restoration of a virtual configuration of cubic perovskite with double the lattice parameter. It has been synthesized and investigated three phases Pnma I, Pnma II, R3c. It has been shown by X-ray diffraction analysis and Mössbauer spectroscopy that the transition from the Pnma I to Pnma II phase in LaMnO3+d compound occurs through the intermediate phase Pnma II* virtually by “jump”. The HEED investigations of the synthesized phases have shown that the Pnma I and R3c phases have the expected simple pattern whereas the electron-diffraction pattern of the Pnma II phase strongly differs.

A transmission electron microscope (TEM) is much more than just a tool for imaging the static state of materials. To demonstrate this, we present work on studying the mechanical and electrical properties of carbon nanotube devices. Multiwall carbon nanotubes are concentrically stacked tubular sheets of graphite, where the spacing between each cylinder is simply the natural spacing of graphite. Using a custom-built in-situ nanomanipulation probe, we have shown that it is possible to slide the nanotube layers in a telescopic extension mode that exhibits low friction, demonstrating the potential of nanotubes as the ultimate synthetic nanobearing. During this telescopic extension, the electrical resistance of the nanotube devices increases, opening the possibility that these devices can also be used as nanoscale rheostats. We also briefly describe work on using electron holography inside a TEM to study the electric field distribution in nanotube field-emission devices and on using a nanotube itself as a biprism for electron holography. These measurements together demonstrate the wealth of information that can be obtained and frontiers that can be opened by putting operational nanodevices inside an electron microscope.

Measuring material properties is critical to understanding the behavior of contemporary nanostructured materials. In this paper, we show that as a consequence of the universal binding energy relation (UBER), universal features and strong scaling correlations exist between the volume plasmon energy and cohesive energy, valence electron density, elastic constants and hardness of various materials with metallic and covalent bonding. Based on these relations, we propose novel techniques that allow direct measurement and imaging of material properties in situ using valence electron energy-loss spectroscopy combined with energy-filtering transmission electron microscopy. This is illustrated by evaluation of elastic and cohesive properties of individual metastable nanoprecipitates in structural alloys and hardness of diesel-engine soot particles. The results demonstrate that new plasmon spectro-microscopic techniques have the potential to determine quantitatively and image multiple solid-state properties at the nanoscale, establishing a new capability for material research.

The presence of impurities in aluminum alloys is of great interest with respect to microstructural properties, specifically, the effect of solute on texture and anisotropy. This paper presents new evidence of the pronounced effect of solute drag based on in-situ annealing and Electron Backscatter Diffraction experiments of Zr-rich Al alloys subject to prior strain. A compensation effect was found for grain boundary mobility maxima for specific boundary types. Trends in activation energy as a function of boundary type support the observations of a compensation effect with respect to temperature. Evidence for irregular motion of boundaries from in-situ observations is discussed in reference to new theoretical results that suggest that boundaries migrating in the presence of solutes should move sporadically provided that the length scale at which observations are made is small enough. A study of both boundary motion and solute segregation to specific boundary types using Scanning Transmission Electron Microscopy and in-situ TEM is presented.

Self-assembled InAs/GaAs quantum dots (QDs) were grown by the atomic layer epitaxy technique and the structure and the thermal stability of QDs have been studied by using high resolution electron microscopy with in-situ heating experiment capability. The QDs were found to form a hemispherical structure with {136} side facet in the early stage of growth. The average height and diameter of the QD were found to be ∼ 5.5 nm and ∼ 23 nm, respectively. Upon capping by GaAs layer, however, the apex structure of QD changed to a flat one. In-situ heating experiment within TEM revealed that the uncapped QD remained stable until 580°C. However, at temperature above 600°C, the QD structure became flat due to the fast decrease of QD height. After flattening, the atoms diffused from the InAs QD to the GaAs substrate, resulting in the total collapse. The density of the QD decreased abruptly by this collapse and most QDs disappeared at above 600°C.

Particulate matter (PM) that is composed of a complex mixture of organic compounds, soot, transition metals, sulfates, nitrates, and other trace elements has been associated with a range of adverse health effects. The effect of the separate components of PM and their interaction with each other is important in order to understand the origins of toxicity in these materials. Iron and soot are common environmental contaminants occurring in ultrafine particulate matter in the air, and have been experimentally generated, in a manner simulating high-temperature, industrial processes, through the combustion of iron pentacarbonyl in a mixture of acetylene and ethylene. Nanoprobe electron energy-loss spectroscopy (EELS) in the transmission electron microscope was used to collect Fe L3:L2 white line-intensity ratios from the interiors and surfaces of iron oxide nanoparticles present in samples generated under low and high soot conditions. This ratio is sensitive to any change in the iron oxidation state, and indicated that iron oxide nanoparticles co-generated with large quantities of soot during combustion processes show a subsurface layer (of thickness 2–3 nm) of decreased iron oxidation state. A quantitative analysis of the iron L32 EELS ionization edge measured in nanoprobe mode indicated that in these particles, the oxidation state of iron at the surface is decreased from Fe3+ to Fe2+, possibly explaining the toxicity of these materials in the respiratory tract. The application of EELS to understanding the nanoscale distribution of the various components and their chemical interactions in these samples, and correlation of these results with acute respiratory toxicity studies of the laboratory-generated particulate matter, are discussed.

The effect of simulated body fluid (SBF) on the structure and microstructure of ferrimagnetic bioglass ceramics (FBC) was investigated in series of samples in the system of the oxides [0.45(CaO, P2O5) (0.52-x)SiO2 xFe2O3 0.03Na2O], with X = 0.05, 0.10, 0.15, 0.20. Physical properties of the materials were studied as a function of processing parameters and time of immersion in SBF by x-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS). The in vitro experiment showed that bioactivity of the FBC varies with the composition of the oxides, heat treatment, and time of exposure in SBF in a non-systematic way. A surface layer of Si, P, Ca partially covers the Fe, O dendrites, while formation and size of pores is determined by the specific processing parameters of the materials.

The optimized surface termination of SrTiO3 (111) substrates was investigated and the effects of the terminated SrTiO3 (111) substrate on the growth characteristics of epitaxial Bi4−xLaxTi3O12 (BLT) films were evaluated. It was found that etching in buffered HF (BOE) solution for 2min provides a stable etching condition for SrTiO3 (111) substrates and that etching is an important factor for the formation of terrace structures. The microstructure of BLT films grown on the terminated substrate revealed a flat surface morphology and well-defined interfacial structure in comparison with BLT films grown on non-terminated substrate. Therefore, surface termination is a crucial factor for determining the quality of film morphology and interfacial structure.

Two recent developments related to the application of off-axis electron holography to the characterization of magnetic and electrostatic fields in nanoscale materials and devices are described. The first is based on the design and implementation of a three-contact electrical biasing specimen holder that allows electron holograms to be recorded from samples as they are tilted to angles of up to ±70° with voltages applied to them in situ in the electron microscope. The second relates to the prospect of characterizing magnetic vector fields in materials in three dimensions using electron holography.

The paper concentrates on in situ transmission electron microscopy of nano-sized Mo and Nb clusters. In particular, this contribution presents challenges to control the microstructure in nano-structured materials via a relatively new approach, i.e. using a so-called nanocluster source. An important aspect is that the cluster size distribution is monodisperse and that the kinetic energy of the clusters during deposition can be varied. The deposited Mo clusters with sizes 5 nm or larger show a body-centered crystal (bcc) structure. The cubic clusters are self-assembled from smaller ones and forming distorted cubes of typical size 7.8 nm or larger. With reducing cluster size to ≤3 nm, the face centered crystal (fcc) structure appears due to dominance of surface energy minimization, while self-assembly into large cubes with sizes up to 20 nm is still observed. In situ TEM annealing leads to cluster coalescence at temperatures ∼800 °C, with the crystal habit changing to rhombic dodecahedron for isolated clusters, while large cubes change to faceted polyhedra. In situ TEM annealing studies on Nb clusters showed that cluster coalescence events were not observed even at rather elevated temperatures because of the formation of oxides.

Novel Fe2O3 nanowires have been successfully synthesized by a simple oxidation process of pure iron. The microstructure of the Fe2O3 nanowires have been systematically investigated by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM). The investigated materials are found to be stoichiometric rhombohedral α-Fe2O3 with typical diameters of 20–80 nm and lengths up to 20 μm. In addition to known single crystal Fe2O3 nanowires, a great amount of novel bicrystalline nanowires were found with ellipsoidal heads. Investigations indicate that most of the bicrystalline nanowires are twins and their orientation relationship is obtained to be (−1, 1, 10)M//(−1, 1, 10)T, [110]M//[-1-10]T. High resolution TEM with numerical reconstruction of the electron exit wave was used to investigated the atomic structure of the micro-twins. Their growth mechanism is briefly discussed on the basis of solid phase growth process.

Field Emission Gun Transmission Electron Microscopy (FEG TEM) is used to measure solute atom segregation to stacking faults in a Cu- 7.15 at% Si alloy annealed at temperatures of 275°C, 400°C and 550°C. A highly localised increase in the silicon concentration was detected at the stacking fault plane. Segregation of the higher valence silicon atoms increases the local electron to atom ratio in the crystal thereby lowering the stacking fault energy as expected for a Cu-Si alloy system. Measurements across low angle boundaries showed hardly any change in solute concentration, which suggests that the segregation observed at stacking faults is due to a genuine chemical interaction rather than an elastic interaction which can occur in for example high angle grain boundary segregation. The segregation was greatest for the 275°C annealed alloy, where the enrichment is more than 2 at% Si above matrix composition, and was found to decrease monotonically with increasing temperature. The binding energy, as determined from a McLean isotherm, was measured to be -0.021 eV/atom. This is significantly different to the theoretical estimate of -0.0022 eV/atom, as calculated by data on phase equilibria. This could be due to several reasons including experimental error, assigning thermodynamic data of a bulk phase to a stacking fault and inadequacies in the Suzuki segregation model itself.

In this paper, we have studied the relationship between medium-range order structures in and stress relaxation in amorphous diamond-like carbon films with fluctuation microscopy. Our preliminary results show strong correlation between stress relaxation and medium-range order. Our previous results showed that annealing films that had been through stress relaxation procedures caused great increase of medium-ranger order. In this paper, we have found that the increase of medium-range order in films that have been annealed before going through stress relaxation through removal of substrates is less pronounced than that of films that have been annealed after removal of substrates. We will discuss interpretations and implications of these results.

The present paper discusses two different active influences of an electron beam on a nanosize sample.

The first observed influence is the formation of nanoparticle agglomerates due to the beam charge. This can be likened to the formation of fine sand and it enables the determination of grain magnitude of the given nanomaterial. This also enables to get a clear picture of the sample, which is latent at first due to the coating of nanoparticles and their agglomerates. For example, removal of nanopowder coatings has enabled for the first time to find self - assembling systems in a shape of double chain spatial helixes from inorganic particles (as DNA).

The second type of influence is related to transformations, which distort the sample. Transformation of amorphous particles of metal into a crystalline state by means of local heating is the one of most importance.

Growth of thread-shaped hollow and solid nanowhiskers from nanoparticles and their further disintegration to a great number of small crystals under influence of electron beam in the chamber of electron microscope was observed. Therefore it can be confirmed that it is necessary to use an electron microscope with special precautionary measures, when working with nanoamorphous metals.

In aberration corrected scanning transmission electron microscopy, the depth of focus is of the order of a few nanometers, so that the three-dimensional shape of nanocrystals could so far not be determined with atomic resolution. Here we show that with the assistance of image simulations it is possible to achieve atomic-scale information in the depth direction by analyzing a through-focal series where the number of atoms in most columns can be determined by Z-contrast simulations. The error in this analysis is about two atoms in the thickest regions, and less in thinner regions.

Quantitative High Resolution Electron Microscopy (HREM) is used to characterize the in-plane displacements of atoms around a screw dislocation core in bcc molybdenum. The in-plane displacements have an important effect on the bulk mechanical properties of bcc metals and alloys. However, the largest displacements are predicted to be less than 10 pm, requiring that the atom positions in an HREM image be determined to sub-pixel accuracy. In order to calculate the displacements the positions of the atom columns in the undistorted crystal must be determined precisely from the information available in the HREM image. An algorithm for such a task is briefly discussed and the technique applied to several HREM images. It is seen that the atomic displacements are predominantly due to surface relaxation (i.e. Eshelby twist) of a thin TEM foil, thereby masking the finer displacements of the dislocation core. Nye tensor plots, which map the resultant Burgers vector at each point of a distorted crystal, are also used to characterize the core structure. Although the large displacements from the Eshelby twist were completely removed, no signal from the dislocation core region was observed.

We used electron holography to analyze the dopant profile in a MOS transistor. The overall performance of the holography electron microscope at our laboratory has been confirmed by recording a maximum of 16, 000 numbers of electron interference fringes on a conventional electron microscope film. For thin film specimen preparation, we have developed an FIB system with a modified beam scanning scheme in which a high-frequency analog modulation signal is added to the digital signal of the beam deflector. This has enabled us to smooth the residual surface roughness presumably caused by the glitch-noise of D/A converter and we proved that a nearly atomically smooth surface was obtained as estimated with an AFM and TEM. We used this optimized system to characterize the dopant profile in MOS transistors, and comparisons with the calculated profiles from device simulator have proved that they are in good agreement.

A transmission electron microscopy study has been carried out on the domain structures of SrBi2Nb2O9 (SBN) ferroelectric ceramics which belong to the Aurivillius family of bismuth layered perovskite oxides. SBN is a potential candidate for Ferroelectric Random access memory (FeRAM) applications. The 90° ferroelectric domains and antiphase boundaries (APBs) were identified with dark field imaging techniques using different superlattice reflections which arise as a consequence of octahedral rotations and cationic shifts. The 90° domain walls are irregular in shape without any faceting. The antiphase boundaries are less dense compared to that of SrBi2Ta2O9(SBT). The electron microscopy observations are correlated with the polarization fatigue nature of the ceramic where the domain structures possibly play a key role in the fatigue- free behavior of the Aurivillius family of ferroelectric oxides.

The measurement of potentials associated with dopant atoms in semiconductors at nanometer spatial resolution using off-axis electron holography is known to be affected by the presence of the surfaces of thin specimens. In particular, the potential across a p-n junction is often found to be lower than would be expected from predicted properties of bulk devices. Here we present simulations of two-dimensional potential profiles within a thin (<1 µm) parallel-sided specimen containing a p-n junction. We find that the potential across the p-n junction is always smaller, when projected through the specimen, than would be expected from the properties of the bulk material. Crucially, the step in potential across the junction is independent of the value of the potential on the surface of the specimen for high dopant concentrations (>1017 cm−3). The simulations are compared with experimental data. Although they can account for some of the reduction in the observed potential, they do not fully explain the experimental results.

Low-resolution tomography requires recording images every few degrees. As a consequence, the sample is often degraded after such a procedure. However the required input can be reduced drastically by using knowledge about the position and the number of atoms in each atomic column. This concept has been tested in the present investigation where HREM image simulation (MacTempas) together with exit wave reconstruction (FEI Trueimage) have been performed. A cubeoctahedral nanoparticle is used for the simulation with different compositions i.e., pure solid Ga and In-Ga particles. Six different zone axes ([111], [111], [001], [110], [110], [011]) have been used and the parameters of an aberration corrected microscope (200kV, Cs = 0 mm, resolution = 0.5Å). The discrete grid data were determined by constructing a channeling map from the reconstructed exit wave images. In this special case only three projections [001], [110], [110] were sufficient to find a unique volumetric reconstruction, illustrating the potential of the method. The other projections were used for checking the solution. The comparison between the projected potentials (simulated input) and the final result shows that discrete tomography reconstructs the exact position of all 309 atoms and the three-dimensional shape of the nanocrystal.