A new technique, referred to as rolling-assisted-biaxially-textured-substrates (RABiTS) has recently been proposed by Goyal et al., to fabricate long-range, biaxially textured substrates with suitable metal/ceramic surfaces for epitaxial growth of electronic devices [1]. Using standard thermomechanical processing, long lengths of flexible, biaxially oriented substrates with smooth surfaces (rms∼50nm) are obtained [1]. Epitaxial metal and/or oxide layers which can serve both as a chemical as well as a structural buffer are deposited on the biaxially textured metal. The metal with a suitable set of epitaxial, multi-layers comprises the substrate which is expected to have many potential applications, including superconductivity, photovoltaics and ferroelectrics [1].

When high temperature superconductors are deposited on a set of epitaxial multilayers on biaxially textured RABiT substrates, extremely high critical current densities, approaching 106 A/cm2 at 77K have been obtained [2].

The thermo-mechanical response of single crystals has been studied in detail since the discovery of X-ray and electron diffraction. While an extensive knowledge exists on the effect of crystallographic orientation on deformation and recrystallization behavior of single crystals, the thermo-mechanical response of grains of different orientations embedded in a polycrystalline matrix are not well understood. With the emergence of microstructure based models predicting the structure evolution during deformation or recrystallization, data validating the predicted structure changes are essential. This requires to study the evolution of microstructural attributes such as morphology or orientation of an individual grain within a specific grain neighborhood during mechanical or thermal exposure. Interrupted coupon scale testing, with a separation of testing and microstructural observation is not sufficient due to the small size of the objects to be observed. Thus, the structure evolution of selected grains has to be followed in-situ.

The quality of the Kikuchi patterns obtained for example by electron backscattered diffraction decreases when the dislocation density increases in strained materials, and consequently, it can theoretically be correlated to the strain through the average dislocation density measurement particularly for monotonic deformation paths. For that purpose, in a first step it is necessary to define a quality factor defined in the Hough space or with the Burns method currently used when the Kikuchi patterns are automatically analyzed. Then, and it is the most important point, the quality factor must be linked to the strain through a calibration curve independent of crystallographic orientation.

The main objective of this study is to test the reliability of this method in the simple case of the hardness test. This test is simulated using the finite element method and the obtained results are compared to those measured by electron backscattered diffraction. Several calibration methods are defined.

Automated electron backscatter diffraction pattern (EBSP) measurements were conducted in an attempt to relate low cycle fatigue (LCF) behavior to underlying microtexture in alpha-beta forged and heat treated Ti-6242 materials. Conventional load control, R=0 LCF tests were conducted with two wave forms, 30 cycles per minute (30 cpm), and 2 minute hold at peak stress, (dwell). The fracture surfaces and adjacent microstructures of the LCF specimens were examined using light microscopy, scanning electron microscopy (SEM), and orientation imaging using automated EBSP.

Fracture surfaces of dwell LCF specimens frequently contained large macroscopically flat, shiny facets, while 30 cpm specimens showed no such evidence of facets. Additionally, the dwell LCF specimens that contained facets had very low lives, typically around 1000 cycles at 126 ksi maximum stress. EBSP measurements directly on the facets, and on cross-sections through the facets revealed that the facet fracture plane was on, or close to (0001) of the primary alpha grains, Fig. 1, and was approximately perpendicular to the stress axis.

Intergranular degradation processes (e.g., corrosion, stress corrosion cracking) are a frequent cause of premature and unpredictable service failure of engineering components. Since these processes cause component failure via propagation through the intercrystalline network, they are strongly dependent upon the distribution of specific grain boundary structures in the material. Previous studies have shown that grain boundaries crystallographically described by low Σ (Σ≤29) Coincidence Site Lattice (CSL) relationships can often selectively display a high resistance (and often immunity) to corrosion and fracture. Recent advances in automated microdiffraction techniques (e.g., EBSP) in SEM have now made it possible to readily evaluate grain boundary character distributions in conventional polycrystalline materials. by utilizing this technique, and by formulating and applying simple stochastic models for the propagation of intergranular cracking and corrosion processes, the opportunity now exists for (1) improved component lifetime prediction, and (2) the optimization of materials synthesis techniques to yield intergranular-degradation resistant microstructures.

The study of texture and grain boundary misorientation in multiphase materials has been greatly benefited from the recent automation of the electron back-scattered diffraction (EBSD) technique. With this technique, each phase in a multiphase material can be individually sampled and analyzed. This is of great significance and interest in the study of thin films, inclusions and multiphase alloys. Spatial resolution, which depends on experimental conditions such as beam energy and specimen tilt, and the material being studied, is critical in order to determine the orientation of different phases in multiphase materials.

The Monte Carlo (MC) method has been effectively used to investigate spatial resolution in single phase materials. In this paper, the MC simulation is modified and applied to two-phase geometries. For a bulk two phase (Al/Au) specimen, the coordinate system was defined such that the x-axis was normal to the electron beam and the interface, y-axis parallel to the interface and coplanar to the beam direction, and z-axis perpendicular to the specimen surface which was tilted 70°, as shown in Fig. 1.

Metal surfaces undergo structural change by the dissociative adsorption of O2, where the reconstructuring is caused by either of the two distinctive mechanisms depending on the temperature and/or the crystalographic planes, one is the “adsorption induced reconstruction” and the other is the “formation of quasi-compounds and their array over the surface”.

The oxygen induced reconstruction of Cu(100) is the former case. When a Cu(100) surface is exposed to O2, oxygen atoms are adsored by making nano-size c(2x2) structure to avoid the convergence of the stress induced by the adsorption. When the oxygen coverage exceeds a critical value of ca 0.3 ML, Cu atoms are missed from the substrate surface to release the stress and the R45 reconstruction is established. In contrast to the Cu(l00) surface, an entirely different process takes place on a Cu( 110) surface exposed to O2, where the (-Cu-O-) string is formed and by a chemical array over the terrace occur.

Recent developments in techniques of real space observations of surfaces are notable. In them reflection electron microscopy (REM) is a unique technique where in-situ real time observations of wide areas of surfaces are possible. In the present paper recent studies of surface dynamic processes on Si surfaces are reviewed. Observed dynamic processes are adsorption induced successive phase transitions, adsorbate induced facet formations and step rearrangements induced by a reversal of specimen heating current direction(so called current effect) and by a reversal of the sign of the surface strain(strain effects).

Figure 1 reproduces a series of REM images and RHEED patterns taken during successive phase transition induced by Au deposition on a clean Si(lll) surface at 780°C[l]. (a) shows a REM image taken before Au deposition. Line images with zigzag in shape are atomic steps on the surface. The surface steps up to the right as indicated by a step mark. The corresponding RHEED pattern in (b) shows that the surface has the 7×7 structure.

Clear understanding of the structural and morphological transformations on the crystal surfaces can only be extracted from considerations of the dynamical properties of surface evolution. So ultra high vacuum reflection electron microscopy (UHV REM) has been applied to in situ studies of step behaviors on the silicon surfaces during various treatments. Dependence of the surface morphology on the number of parameters is reviewed with new results. Special attention is paid to influence of the electromigration phenomena and strain fields on structural evolution of the surfaces during sublimation, phase transition and epitaxial growth. The stability of the atomic step distributions is discussed in the frame of kinetical morphological transitions on silicon surfaces during DC heating of studied crystal [1].

The step motion during sublimation shows a strong influence of stress fields on the step configurations [2]. The importance of surface stress is obvious because in equilibrium conditions there is a residual stress on the surface due to existence of broken bonds.

We studied the beginning oxidation stage of a model metal system by in-situ transmission electron microscopy (TEM) in order to gain insights into the initial kinetics of oxidation. In-situ TEM experiments can distinguish between nucleation and growth since individual oxide islands are imaged. We chose to investigate Cu, since it is a simple face-centered cubic metal. Also, Cu is a highly promising metal interconnect material because of its low resistivity and good electromigration properties as compared to Al.

Single crystal -1000Å 99.999% purity copper films were grown on irradiated NaCl in an UHV e-beam evaporator system. The free-standing copper film was placed on a specially designed holder, which permits resistive heating of the sample. The microscope used for this experiment is a modified ultra-high vacuum, with base pressure of 10−9 torr, JEOL200CX, operated at l00kV. To remove the native oxide formed during exposure in air, the Cu film was annealed at ∼350°C

Tiny magnetic vortices hold the key in practical applications of superconductors, since the dynamic behaviors of vortices at pinning centers determine the critical current. These vortices have become observable directly and dynamically by using a “coherent” field-emission electron beam: The magnetic lines of force of vortices can be quantitatively observed as contour fringes in an electron-holographic interference micrograph. The change in the vortex radius could actually be measured when the temperature of a superconducting thin film changed. Vortices were also dynamically observed in a Lorentz micrograph. Both vortices and defects in the thin film can be observed simultaneously with this method, though the defects image is blurred.

This paper reports the dynamic observation of vortices at defects when the applied magnetic field changes. A superconducting Nb thin film, set on a low-temperature stage, is tilted 45° to an incident beam of 300kV electrons (see Fig. 1), and an external magnetic field is applied in the horizontal direction. When an electron beam passes through the vortices, their magnetic fields deflect the electron beam. Therefore, when observed in the lower plane, a vortex can be viewed as a pair of black and white spots.

Due to spatial constraints and small dimensions (<1 μm), the ferroelectric domain statics and dynamics in thin films can be significantly different from their bulk counterparts. Further, it has been recognized that electrode-film interfaces play a key role in the fatigue and retention phenomena in the thinfilms for ferroelectric memory applications, which are closely associated with barrier formation and charged defects trapped at various interfaces including the domain boundaries. Thus, it is imperative to utilize in-situ TEM to directly observe the domain switching at a length-scale which is essential (i.e. 1-10nm) for better understanding of the domain dynamics and their interactions with microstructure in thin filmferroelectrics.

We have successfully carried out in-situ TEM observations of domain dynamics in Pb(Zr.5Ti.5)O3 (PZT) thin films using PZT-based capacitor structures. The capacitors were produced by growing PZT layers (∼550 nm thick) on SrRuO3 bottom electrode layers (∼100 nm thick) on (001) SrTiO3 substrates using MOCVD. The top electrode consisted of an ∼200 nm silver layer.

The ability to control the environment inside the electron microscope is a very desirable general capability and one long pursued for higher vacuum or chemical reactions (1,2) Here we are primarily concerned with providing the essential facilities for realistic in-situ dynamic studies of chemical reactions between gases or vapors and solids. The compromises with microscope performance have been reduced substantially compared with previous gas experiments (2,3).

The primary applications for the present instrument are to reaction catalysts and the products of reactions where they are solid state materials of commercial value. Firstly, the catalyst may have to be (re)processed after transfer through the air or other hostile (i.e. non-reactor) environment. Secondly, the high vacuum atmosphere in a typical TEM may not be a compatible environment for the catalyst or other material (e.g. if it is solvated). Thirdly, the sequence of events in changes in the microstructure of a chemically active species will likely depend on the atmosphere in which those changes take place or are promoted (e.g. by heating).

The palladium-rhodium system has been extensively studied for its hydrogen absorption characteristics. However, the phase diagram of the palladium-rhodium system has not been conclusively determined below 800 K. Shield and Williams have experimentally determined the incoherent miscibility gap in Pd-Rh alloys using electrical resistivity studies, however the coherent miscibility gap and spinodal have not been determined. Recently work by Noh and Flanagan has suggested that hydrogen enhances metal atom mobility and may increase the kinetics of phase separation in Pd-Rh alloys. Field and Thoma found that hydrogen causes a Pd-10%Rh alloy to decompose during an in situhydrogen charging experiment in an environmental cell TEM. According to the calculations by Gonis et al. of the miscibility gap for the palladium-rhodium system, the Pd-10%Rh alloy may be within the chemical spinodal at room temperature.

In this work, two palladium-rhodium compositions were investigated. The first was a Pd-10 at.% Rh alloy produced by melt-spinning, and the second was a Pd-30at.

%Rh alloy which had been arc-melted and cold rolled followed by an annealing treatment to homogenize the material. TEM specimens were prepared by punching 3 mm disks from the material.

Progress on the development of an in-situ nanoindentation specimen holder for the Kratos 1.5MeV HVEM located at the National Center for Electron Microscopy, Berkeley, CA, USA, is reported. There is currently considerable work being reported on the mechanical properties (i.e., hardness, delamination, wear, etc.) of single and multicomponent thin films, nanoclusters and fibers by techniques such as nanoindenting, ref. [1] are recent examples. However, with all of these tests there has not been direct, unambiguous observation of the response or evolution of the microstructure. With many of these reports, there has been little “post-mortem” TEM characterization and there has been no real attempts to simulate these dynamically in the TEM. For the case of nano-testing of the materials the interaction volumes are often on the scale of the natural sampling volume of the HVEM. It seems natural that post-mortem and in-situ TEM characterization techniques be applied.

The optimization of currently available catalysts and the development of new ones requires a detailed understanding of the effects of both microstructure and composition on their function. Previous work has demonstrated that information at the atomic-scale on heterogeneous catalysts can be derived using high resolution transmission electron microscopy (TEM). Under favorable conditions, the morphology of heavy metal catalytic particles can be related to catalytic activity. It has been shown that preoxidation can disrupt the surface of small metal particles causing altered activity and selectivity in reactions such as alkane hydrogenolysis. Metals such as Pt, Rh, or Ru are noble and pick up no more than a monolayer of oxygen when exposed to air during sample preparation for microscopy. This oxygen monolayer is not imaged in the microscope, most likely because the oxygen desorbs during exposure to the high energy electron beam. However, when metals such as Fe, Co, Ni, Pd or Cu are exposed to air, there is a corrosive interaction that alters particle structure quite dramatically.

UHV(ultrahigh-vacuum) TEM has long been used as a powerful tool for studying crystal surfaces, particularly for both the direct imaging of the surface structure and for in-situ observation of surface reaction processes with atomic resolution.

This paper reports a newly developed 200kV UHV TEM equipped with a field emission gun(FEG). The instrument is designed to obtain information about elemental or bonding states of surfaces in addition to observation of surface atomic structure with high contrast. Basic performances of the UHV FE-TEM includes a specimen vacuum of 2.0X10-8Pa, probe size less than 1.0nm Ø with 0.5nA probe current, point-to-point resolution of 0.21 nm, and a lattice resolution of 0.10nm.

A UHV Energy Dispersive X-ray Spectrometer (EDS) originally developed by JEOL Ltd. and a Parallel Electron Energy Loss Spectrometer (PEELS) are attached to the UHV FE-TEM, which combined with a fine focused probe of 1.Onm Ø allows atomic scale spectroscopy of surfaces.

Transition and rare earth metal elements have played a vital role in synthesis of functional and smart materials because of their unique electronic structures and mixed valences. Experimental measurement of the valence states is thus important for understanding the mechanism which drives the functional properties. Lai1.xSrxCoO3-y(LSCO), for example, is an ionic conductor with potential applications in fuel cells and many other fields. In this type of materials, the anion deficiency is directly associated with the ratio of Co2+/Co3+ (or Co3+/Co4+) present in the specimen. It is known that the anion deficiency of the material depends on the operation temperature, but a direct measurement of anion deficiency is a challenge to existing microscopy techniques. In this paper, we present the in-situ analysis of Co valence in LSCO using electron energy-loss spectroscopy (EELS) in a transmission electron microscope.

LSCO thin films (with x = 0.5) were grown on polished MgO(00l) substrate by liquid source metal-organic chemical vapor deposition (MOCVD) method [1].

The interaction of radiation produced point defects with a dislocation microstructure at high temperature is of considerable interest and careful high voltage microscopy experiments can provide valuable insight into the mechanisms. Veyssière and Westmacott carried out in-situ experiments monitoring the partial dislocation climbs in Ni3Al induced by thermal vacancies as well as by Frenkel pairs produced during irradiation.1 We report here the results of some preliminary experiments we performed on alumina (A12O3) single crystals with high dislocation densities to study the modification of the microstructure by electron irradiation at high temperature.

The dislocation microstructures were produced by shock wave deformation using a high-velocity impact technique. The technique is capable of producing a very high density of defects consisting primarily of basal twins, and slips on the basal, pyramidal and rhombohedral planes in alumina. The dislocations are all of glide type, mostly forming shear bands. A typical microstructure prior to irradiation is shown in figure la.

Metal oxide films are are an emerging sensing technology for the identification of gas phase species. Metalorganic chemical vapor deposition (MOCVD) on microhotplate structures provides a method of fabricating gas sensing layers in self-patterned structures. Investigation of the morphological characteristics of film growth is normally not possible inside a MOCVD reactor, especially the nucleation phase and subsequent deposition of a continuous film. The environmental scanning electron microscope (ESEM) operates at a pressure range of 133-666 Pa (1-5 Torr) which is similar to the growth condition normally used for oxide film MOCVD on microhotplates. Our results show that microhotplate MOCVD can be monitored in situby secondary electron and backscattered electron imaging in the ESEM.

The microhotplate chemical sensor devices employed in this work are mounted in conventional 40 pin packages which provide separate electrical connections to each of the four micromachined heater and contact structures.