Abstract: Structural aspects of ramp-type Josephson junctions based on REBa2Cu3O7-delta high-T-c superconductors, are investigated by cross-section transmission electron microscopy and results related to fabrication process or physical properties. The barrier layer material is PrBa2Cu3-xGaxO7-delta. The ramp-geometry depends on the etching conditions. High levels of Ga doping (x>0.7) influence the microstructure of the barrier layer thereby changing the junctions properties.

Abstract: Recent developments in the field of TEM characterisation of Si device materials are discussed and illustrated by a few case studies of material in different stages of various kinds of processing. Important challenges are the ever decreasing defect densities and device feature sizes. Defect delineation techniques using large area inspection tools yielding accurate coordinates of the defects to be studied have therefore become an essential part of the TEM analysis procedure. The possibility to transfer these defect coordinates without loss of accuracy to tools for local TEM specimen preparation is also a conditio sine qua non for a successful analysis. Insitu TEM remains important as dynamic processes can be observed and analysed under well defined experimental conditions. As case studies illustrating new developments, results are presented on defects in as-grown Ct silicon, on in-situ studies in processed silicon, on problem sites in advanced integrated circuit structures and on assessment of localised strain fields in the nm size scale.

Abstract: Analytical and high resolution electron microscopy have been used to study the effect of Zn- and Fe-doping on the micro structure of [001] YBa2Cu3O7-x thin films on [001] MgO substrates grown by magnetron sputtering. Special attention was paid to the presence of second phase inclusions and surface outgrowths such as CuO, Y2Ba1Cu1O5-x, Y2O3 in order to establish a relationship with the critical current density.

Abstract: The properties of the shape memory behaviour of Ni-rich binary NiTi are strongly dependant on the thermal history of the material. In this respect the changing of transformation temperatures of the underlying martensitic transformation and the occurrence of multiple step transformations are the most important phenomena. Part of the explanation is found in the presence of Ni4Ti3 precipitates in the B2 matrix after particular heat treatments. The formation of these precipitates changes the Ni concentration of the matrix and induces a strain field, with both of these aspects expected to be of importance. In this work atomic resolution and analytical TEM (transmission electron microscopy) techniques are used to obtain quantitative information concerning these two main features. Furthermore, the known structure of Ni4Ti3 is refined by a least squares optimization of quantitative electron diffraction data. The high-resolution TEM results show that there are strains up to 2% in the matrix surrounding the precipitates and they gradually increase until a maximum is reached when moving away from the interface. Analytical results reveal a global decrease of Ni content in the matrix when sufficient precipitates are present and a gradient in their close vicinity. The refinement of the structure shows atomic displacements, thereby increasing our understanding of the shrinking of the precipitate lattice with respect to the matrix.

Abstract: Multishell tabular grains have a higher speed than pure AgBr tabular grains. Usually the shells differ in size and iodide content, but also the precipitation method for the iodide containing shells has an influence on the iodide incorporation. A TEM investigation was performed to determine the defect structure of multishell AgBr (111) tabular crystals containing a shell with a low iodide concentration and one with a high iodide concentration. The twins that induce tabular growth and stacking fault contrast in the region of the iodide shells have been observed, similar to previously studied AgBr/Ag(Br,I) coreshell crystals. Moreover in some of the crystals dislocations have been observed, sometimes even an entire network. The number of dislocations formed varies for the different methods of iodide addition. Also variations in average thickness between the different iodide addition methods have been observed. A higher number of dislocations and thicker crystals point towards a higher local concentration of iodide. These observations allow deciding which iodide incorporation method is most useful for a preferred dislocation pattern.

Abstract: The basics of the interpretation of high resolution images showing detail of the order of 0.1 nm are shortly explained here. The use of a field emission source, a CCD camera and an adapted reconstruction method for restoring the projected crystal potential (focus variation method) allows a quantitative interpretation of HREM images. Examples of partially disordered alloys and carbonate ordering in high Tc superconductors are presented.

Abstract: Electron continement and its effect on the superconducting-to-normal phase transition driven by a magentic field and/or a current is studied in nanowires. Our investigation is based on a self-consistent numerical solution of the Bogoliubov-de Gennes equations. We find that in a parallel magneitc field and/or in the presence of a supercurrent the transition from the superconducting to the normal phase occurs as a cascade of discontinuous jumps in the superconducting order parameter for diameters D < 10 divided by 15 nm at T = 0. The critical magentic field exhibits quantum-size oscillations with pronounced resonant enhancements as a function of the wire radius.

Abstract: Ag/ZnO and Au/CuxO (x = 1, 2) nanocomposites supported on Si(100) and polycrystalline Al2O3 were synthesised by hybrid approaches, combining chemical vapor deposition (either thermal or plasma-assisted) of host oxide matrices and subsequent radio frequency-sputtering of guest metal particles. The influence of the adopted synthetic parameters on the nanocomposite morphological and compositional features was investigated by field emission-scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. Results confirm the synthesis of ZnO and CuxO nanoarchitectures, characterized by a tailored morphology and an intimate metal/oxide contact. A careful control of the processing conditions enabled a fine tuning of the mutual constituent distribution, opening thus attractive perspectives for the engineering of advanced nanomaterials.

Abstract: Porous Ni50.8Ti49.2 bulk material was prepared by powder metallurgy sintering. Solid solution and aging treatments were applied to improve the phase homogeneity and phase transformation behavior. Scanning and transmission electron microscopy, aided by energy dispersive X-ray analysis, were used to study the microstructure and chemical phase content of the alloys. In-situ cooling was carried out to observe the phase transformation behavior. As-received material contains dispersed Ni2Ti4O particles while Ni4Ti3 precipitates appear after aging. Close to pore edges, the latter have a preferential orientation due to the induced stress fields in the matrix.

Abstract: Quantitative atomic resolution annular dark field scanning transmission electron microscopy (ADF STEM) has become a powerful technique for nanoparticle atom-counting. However, a lot of nanoparticles provide a severe characterisation challenge because of their limited size and beam sensitivity. Therefore, quantitative ADF STEM may greatly benefit from statistical detection theory in order to optimise the instrumental microscope settings such that the incoming electron dose can be kept as low as possible whilst still retaining single-atom precision. The principles of detection theory are used to quantify the probability of error for atom-counting. This enables us to decide between different image performance measures and to optimise the experimental detector settings for atom-counting in ADF STEM in an objective manner. To demonstrate this, ADF STEM imaging of an industrial catalyst has been conducted using the near-optimal detector settings. For this experiment, we discussed the limits for atom-counting diagnosed by combining a thorough statistical method and detailed image simulations.

Abstract: The main bottlenecks for high-resolution biological imaging in electron microscopy are radiation sensitivity and low contrast. The phase contrast at low spatial frequencies can be enhanced by using a large defocus but this strongly reduces the resolution. Recently, phase plates have been developed to enhance the contrast at small defocus but electrical charging remains a problem. Single particle cryo-electron microscopy is mostly used to minimize the radiation damage and to enhance the resolution of the 3D reconstructions but it requires averaging images of a massive number of individual particles. Here we present a new route to achieve the same goals by hollow cone dark field imaging using thermal diffuse scattered electrons giving about a 4 times contrast increase as compared to bright field imaging. We demonstrate the 3D reconstruction of a stained GroEL particle can yield about 13.5 A resolution but using a strongly reduced number of images.