Scanning tunneling microscopy (STM) images of the cleaved surfaces of Bi2Sr2CaCu2O8 (2212), Bi2Sr2CuO6 (221), and the Pb-substituted Bi1.5Pb0.5Sr2CuO6 (Pb-substituted 221) at room temperature have been obtained. On the 2212 (Tc=85 K) compound, high resolution images show striations ˜10 Å to 30 Å wide. Similar striations of a periodicity of ˜27 Å are also observed on the 221 (Tc=10 K) compound. On the Pb-substituted 221 (Tc=25 K) compound, no periodic structure can be observed. On samples oriented with Laue reflection, the striations are observed to run parallel to the a or b axis of the crystal. These striations are likely to be associated with the undulations along the b axis of the Bi layer observed in recent transmission electron micrographs. For the 2212 compound, comparison of the dependence of scan line characteristics on tunneling bias with calculations on the density of states of each elemental component around the Fermi energy also suggests that tunneling occurs on the Bi face. The topographical and tunneling bias dependence results show that the Bi-rich surfaces of these new superconductors is essentially a termination of the bulk structure even though structural or chemical defects are common.

High resolution electron micrographs have been obtained in various orientations for δ2-Y2Si2O7 using the Atomic Resolution Microscope (ARM) at the National Center for Electron Microscopy (NCEM). These ARM images were processed by masking the diffractogram of the digitized image in Fourier space and applying an inverse transform (using the SEMPER program at the NCEM Image Analysis Facility) in order to reveal details obscured by amorphous contrast originating in the glassy matrix. Processed experimental images from very thin regions of the crystalline phase were compared with images simulated from postulated models (SHRLI images); close agreement was obtained.

A progress report is given on our attempt to image non-metallic materials using the field ion mciroscope. Field ion images have been obtained for different forms of graphite and a Y-123 compound, and preliminary interpretations of these images are presented. While the quality of field ion images of these materials is not too bad, it is not yet good enough to observe the atomic arrangements.

The use of high-resolution electron microscopy in the study of ceramic materials is illustrated with examples from current research. Particular emphasis is placed on the preparation of the sample and the difficulties in interpretation which may result from the techniques which are necessary for these hard, chemically inert materials.

A new high resolution electron microscopy investigation of indentationinduced hexagonal silicon has been carried out using the JEOL 4000EX electron microscope. The better resolution of the microscope enables one to extract more structural information about this intriguing phase and its interface with the cubic phase. A new structural model for the cubic/- hexagonal interface is presented. Image simlations are carried out over a wide range of thickness and defocus for the new model and also a previous model due to Tan et al.

This paper describes the application of high-resolution electron microscopy (HREM) to the determination of phase diagrams. Using a heating holder in a high-resolution transmission electron microscope (TEM), the chemical stability of a CdTe/GaAs interface is confirmed, as predicted by the Ga-As-Cd-Te quaternary phase diagram. Crisp, near-atomic-resolution video imaging is obtained at an annealing temperature of 500°C. Not only are the above results in complete agreement with ex situ annealing of the CdTe/GaAs heterojunction, but also direct observations of dynamic events occuring at the atomic level are recorded in real-time. Sublimation at the edge of a CdTe {111} thin film occurs via a ledge mechanism. Instead of a steady progression of this solid-vapor reaction, one obtains a real-time impression of dynamic equilibrium between vaporization and recondensation as atoms from the surface disappear and reappear several times before their ultimate removal.

In this investigation, multislice image calculations were used to determine the effects of point defects on image contrast in ARTEM. It is shown that point defects with an atomic number different from the matrix produce a regular change in image contrast. The minimum detectable defect concentration for any system of matrix and solute can be predicted from a simple formula based on a rule of mixtures and the atomic numbers of the matrix and solute. The effects of lattice distortions associated with point defects appears to have minimal effect on image contrast in ARTEM. Optimum specimen and microscope conditions for observing point defects in crystals and the possibility of extending the analyses to interpret atomic-resolution images of larger defects are discussed.

The growth characteristics of Co/Cr multilayers have been studied in cross-section with a 400kV high-resolution electron microscope. The growth directions for bcc Cr were predominantly <110> while the axes of the observed crystallite fringes were mainly <100> and <111>. The hcp Co crystallites grew predominantly in the <10.1> direction while the areas with strong fringes were along a <10.0> projection. This observed structure was in agreement with that obtained from analysis of large angle X-ray scattering spectra. The columnar structure was found to be present with the layers growing right through the columns.

High resolution scanning transmission electron microscopy (HRSTEM) and the nanodiffraction patterns of the high Tc superconductor of Yba2Cu3O7−x were studied with the use of a dedicated VG-HB5 STEM microscope. STEM imaging on the YBa2Cu3O7−x [100] shows atomic resolution image of the heavy atoms. Approximately 750 diffiaction patterns were recorded with the nano-probe electron beam of 3Å in diameter scanned over a region of 20Å×12Å on the specimen. Simulation of the diffraction patterns is employed to recognize the patterns for beams centered on Cu(1), O(4), Ba and Y. The local symmelry around an individual atom can then be studied. STEM images of the Yba2Cu3O7−x[001] show the edge dislocations temlinating at the grain boundary and the microdiffraction patterns show the 2-fold symmetry for the core of the dislocation and the (110) plane symmetry for the grain boundary.

A highly sensitive and simple optical method for detecting the cantilever deflection in atomic force microscopy is described. The method was incorporated in an atomic force microscope and imaging and force measurements, in ultra-high vacuum and in air, were sucessfully performed.

Atomic force microscopes (AFM) have been designed and tested. A simple reliable version with high resolving power is described here. Materials of construction and operational parameters are reported. Applications to a range of materials has confirmed the general usefulness of AFM technology to materials research.

The high resolution electron microscope is powerful for modern materials science, because of its direct observation capability for the atomic structure of materials. The JEM-4000EX, a 400 kV accelerating voltage electron microscope whose objective lens has a 1 mm spherical aberration coefficient, has a 0.168 nm theoretical resolving power. Using this microscope, atomic structure images of high Tc superconductor such as Y-Ba-Cu-O, Bi-Ca-Sr-Cu-O and Tl -Ca-Ba-Cu-O were observed.

The CM30-Super TWIN Transmission Electron Microscope achieves a point resolution of 0.19 nm as shown by standard and Young's fringes diffractograms. Thanks to its unique TWIN lens concept, the instrument combines ultra-high resolution with excellent performance in numerous other operational modes, including scanning, diffraction and micro-analysis. Coma-free alignment, providing accurate objective-lens centring, is standard on the CM30. Complete microprocessor control yields ease of operation, accurate and reproducible microscope control and connection with peripheral equipment.

With the modern ultra high vacuum technology, it is easy to achieve 10−1 Torr vacuum. This is when a vacuum chamber has been designed and built specifically for this purpose. Electron microscope column is not a simple vacuum chamber. It is a precision equipment that allows electron microscopy of various specimens. The column is designed primarily for high resolution microscopy and it is not necessarily suitable for achieving ultra high vacuum condition. This is clear from a long TEM history. No dependable ultra high vacuum microscope has ever been built until very recently. Many attempts have been made so far to convert conventional microscopes into UHV-microscope, particularly specimen chamber area.

Simultaneous achievement of atomic resolution,

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zone axis alignment of crystals (>5nm), diffraction studies of crystals (>0.5nm), and x-ray analysis of precipitates (>1nm) have been possible in a unique new TEM (EM-002B) in its UHR configuration.

Recent modifications to the JEOL ARM-1000 microscope have markedly enhanced its performance. The point resolution limit at 1000kV is confirmed by optical diffractograms down to 1.7Å and there are firm indications of contrast transfer down to 1.4Å. The unique tilting capability of the ARM, ±40° biaxial tilt over the 800kV to 1000kV range, is preserved at this resolution. This paper presents the measured imaging parameters and results of resolution tests.

The initial oxidation stages of Cu-Ni alloys have been studied by atom-probe field ion microscopy (APFIM). Oxide layers were formed in-situ in the FIM chamber on the clean alloy surfaces. The Cu-Ni alloys were oxidized in-situ at 1×10−4 Torr O2 at 970 K for less than 1 min. The atom-probe analysis of the {111} and {100} surfaces of the oxidized alloys showed that the oxide was comprised of NiO. The concentration change at the oxide/metal interface was also analyzed by the atom-probe.

A Philips 430ST high-resolution electron microscope has been converted for ultra-high-vacuum operation by substitution with a novel specimen chamber, which also incorporates a flexible chamber for specimen preparation and treatment, and additional pumping facilities. Key features of the design include a single-tilt specimen holder with in situ heating to 1200° C, and liquid-helium-cooled cryofingers above and below the sample. Initial operating experiences indicate that the microscope performance has not been compromised by the UHV conversion. However, selection of optimum imaging conditions is difficult for a clean crystalline material.

A combined field ion (FIM) and scanning tunneling microscope (STM), which we call “FI-STM,” was designed and constructed with multiple surface analytical functions. The system is equipped with a LEED/AES system and a sputtering gun and/or heating devices for preparing and characterizing specimen surfaces. The field ion microscope (FIM) is operated at room temperature to observe the geometry of the STM scanning tip in-situ in the course of STM investigations. The instrument has been operated successfully by observing the structures of the graphite (0001), the Si (111) 7×7 and the Si (100) 2×1 surfaces.

A scanning tunneling microscope with a tunneling-current dynamic range of four orders of magnitude has been used in tunneling-spectroscopy studies of Au surfaces in moderate vacuum and in various gases at atmospheric pressure. Rapid scans of z-motion transducer voltage (Vz) were measured as a function of tunneling current (It) under computer control. Driftcorrected plots of log(It) versus Vz were essentially linear. The mean barrier potential was determined from the slope of these plots and the measured displacement-versus-Vzcalibration curve. Barrier potentials so determined are compared for different environmental conditions of the Au surface.