The long-term aim of our research is to detect and image dislocations in the SEM with EBSD. We will apply it first to the characterization of threading dislocations in Si/Si-Ge structures. As an initial step, we set out to detect the shift of the Kikuchi bands in EBSD patterns to sub-pixel precision.

In the standard analysis of EBSD patterns, to find the positions of Kikuchi bands, it is usual to use the Hough transform. This transform displays the intensity along all lines in the EBSD pattern, as a function of the position and the angle of the line. Thus linear features in the pattern (Figure 1) appears as peaks in the transform (Figure 2a). in normal EBSD analysis, the aim is to determine the orientation of the grain to a precision of perhaps a degree or two. Therefore, many simplifications are made in the software with the aim of gaining speed.

An accuracy of better than 1% is needed to measure the changes in charge density due to bonding. Here we report an accuracy up to 0.025% (random error) obtained in rutile crystal structure factors measurement by QCBED. This error is the standard deviation in the mean value obtained from ten data sets. Systematic errors may be present. Figure 1 gives an example of the (200) refinement results. Table 1 lists several low order structure factor refinement results. The accuracy of the measured electron structure factors was 0.1-0.2% but after conversion to x-ray structure factors, the accuracy for low orders improved due to the Mott formula [1] For (110) and (101) reflections, the accuracy in x-ray structure factors became 0.025% and 0.048% respectively. This accuracy is equivalent to that of the X-ray single crystal Pendellosung method on silicon crystals [2].

The experiments were done on a Leo 912 Omega TEM.

A study of the initial stage of AIN growth on SiC substrate by the sublimation re-condensation technique was undertaken to understand the origin of crystal defects in bulk AIN crystals. When SiC was used as a seed crystal the AIN crystals did not completely coalesce, and individual grains were observed. Such crystal growth features were determined by the initial nucleation of the crystals. in this study, the nucleation of AIN on 6H-SiC(0001) was investigated by Scanning Electronic Microscopy (SEM), S-4700 Hitachi, and Electron Backscattered Diffraction (EBSD), Thermo Noran Phase ID.

At high temperatures (>1800°C) in the presence of AIN, the surface of the SiC substrate first decomposed along remnant polishing scratches[l], ultimately leaving hexagonal hillocks; simultaneously, the AIN nucleated on these SiC hillocks. Surprisingly, the AIN nuclei appeared out of alignment with the underlying SiC hillocks. By measuring several points from the SEM image (figure 1), this misorientation is in the range of 15° to 30°.

A free computer program was introduced recently to process electron diffraction ring patterns. The program (called ProcessDiffraction) produces XDR-like output from the digitized version of the measured diffraction patterns. The enhanced functionality of V1.2 is summarized in the present paper.

1. 1. The program starts with a hint-window giving suggestions what can be done next. Hints change permanently as processing progresses. The hint-window can be switched off optionally. It is a complement to the Windows-style Help-system.

2. 2. The center of the rings is found by manually shifting the measured pattern until it overlaps with a generated reference circle. The computer can further refine the position of the center.

3. 3. Elliptical distortion of the measured pattern (NOT of the display, which is irrelevant) is corrected by adjusting the eccentricity and axis direction of the reference ellipse (distorted from the reference circle) until visually coincide with the measured ring.

Electron backscatter diffraction (EBSD) is a powerful tool used for the characterization of deformed microstructures and has been successfully applied to determine the microtexture of specific regions of bulk samples. The work presented here is a continuation of previous analyses investigating the microstructural response of 6xxx aluminum extrudates to complex die designs. Specifically, the grain orientations across longitudinal welds produced from porthole dies is being studied.

Previous work examined the cross section of a sample that was extruded using a specially designed die that would position the weld in the center of the part. This specimen, shown in Figure 1, is a simple, solid, rectangular shape produced under controlled conditions. The other sample being studied, seen in Figure 2, was part of an actual extrusion run, conducted with typical industrial parameters. This sample is part of a complex shape that uses a porthole die to produce hollow sections.

Elastically-filtered transmission electron diffraction patterns of La0.5Ca0.5MnO3-δ have been obtained between 105K to 288K using the Leo 912 Omega. On heating La0.5Ca0.5MnO3 undergoes a transition from antiferromagnetic insulator to ferromagnetic metal (TN ∼ 150K) and then to paramagnetic insulator (Tc ∼ 230K) . The q modulation wave vector along the b-axis direction arises from charge ordering of Mn3+ and Mn4+, and orbital ordering of dz22 orbitals associated with Jahn-Teller distortions in the Mn3+O6 octahedra at low temperature. Both the intensity and the position of superlattice peaks change as a function of temperature during heating. The large incommensurability we see between 105K to 260K differs from that seen previously and proposed model. Figure 1 a) shows the lattice constants a, b, c related to the simple perovskite lattice parameters ap (ap ∼ 3.9Å) by a≈b≈ap and c≈2ap, and indicates the octahedral coordination.

In our initial studies of the phase identification analysis of individual particles by EBSD, we observed that the quality of the EBSD patterns obtained from particles less than 1 micrometer in size decreased with decreasing particle size, density, and atomic number. This effect is shown in FIG. 1 by comparison of an EBSD pattern from a 12 um Al2O3 particle (FIG. la) and a 200 nm Al2O3 particle FIG. lb. Both particles were mounted on 2 mm thick carbon substrates. The Kikuchi bands from the larger particle are clearly visible while the bands from the smaller particle are not. This decrease in image quality is believed to be the result of a combination of 2 factors related to the electron scattering associated with these very small particles. First, as particle size decreases below about 1 micrometer, an increasing number of electrons are transmitted through the bottom of the particles.

Electron backscatter diffraction (EBSD) in the SEM has become a widely used technique for both automated orientation mapping and the identification of unknown crystalline phases. Despite the rapidly growing use of this technique for the above applications, there has been relatively little fundamental research concerned with determining the thickness of the surface layer that generates the EBSD pattern. EBSD patterns are related through reciprocity to electron channeling patterns. Based on this assumption the thickness of the surface layer that an EBSD pattern is generated in is 2 or 3 extinction distances. Extinction distances at low SEM voltages (10-20 kV) are quite short. Thus, EBSD patterns are generated in very thin surface layers. This paper will discuss the results of a study of the information depth of EBSD in the SEM.

Previous research has attempted to determine the information depth of EBSD by obtaining patterns from samples that have had layers of other crystalline or microcrystalline material deposited on the surface.

In a landmark paper Henderson compared X-ray, neutrons and electrons for protein structure determination. He showed that electron microscopy should be superior to X-ray or neutron diffraction in terms of dose for a given resolution. in addition he presented a theoretical analysis to determine the smallest size molecule whose structure could be determined by phase contrast microscopy. Although he qualitatively considered amplitude contrast mechanisms and concluded they were inferior to phase contrast, no explicit numerical analysis was performed. It has been implicitly assumed that bright field phase contrast imaging is the optimal technique for imaging small biological molecules. Protein specimens are usually embedded in some medium such as ice or glucose. Since they must give a very low contrast it seems reasonable to expect that bright field techniques for these weakly scattering objects would be inferior, given that a weak signal is sitting on large background.

The structure and composition of low angle grain boundaries produced in sapphire by a liquid phase sintering process were investigated by conventional and high resolution transmission electron microscopy (CTEM and HRTEM, respectively). Considering the current emphasis on producing ceramics with textured microstructures for various applications, the question of grain boundary wetting vs. dewetting has become a relevant issue to determining the microstructure development and the properties of these liquid phase sintered materials. Accordingly, the present study was designed to cover a wide range of tilt misorientations, twist misorientations, and boundary orientations.

The boundaries were formed by the directed growth of two sapphire plates, both having nominal <0001>, , or surface orientations through an alumina tape-cast containing an anorthite composition glass phase. After an initial hot-pressing stage, followed by an anneal at 1600° C for 200 hours, the samples typically contained a single boundary delineated by isolated pockets of entrapped glass, Fig. 1.

Silica and titania based ceramics and their analogs are some of the most fundamental in crystal chemistry and ceramic science Our interests include applications of nanostructures and chemical composites of the ceramics in nanoelectronics, chemical processes and as scaffolds in biotechnologies. Finely divided titania is used in a vast array of products including paper, paint, food and clothing. Novel microscopy methods including dynamic environmental-high resolution transmission EM (EHREM) at the atomic level, FESEM and cathodoluminescence are leading to striking progress in the development of the ceramic nanotechnologies.

Phase transformations in the cristobalite form of silica, from the tetragonal a phase (low or room temperature form) to the cubic β phase (high temperature, (270°C) form) result in discontinuous thermal expansion and are not conducive to nanotechnology. Here we report fundamental in situatomic resolution studies of the phase transformations using EHREM and have used the results to design a number of stable, single-phase structures at room temperature (RT).

Nanoparticles are increasingly being heralded as the next-generation building blocks for modern materials design. Coating of semiconductor, metal, or metal oxide nanoparticles with a thin layer of a compatible material makes possible the control of interparticle and particle-matrix interactions, thereby further improving functional properties of devices and expanding the range of potential applications . The core-shell geometry has previously allowed for the enhancement of luminescence of semiconductor nanoparticles, charging of metal cores, chemical and colloidal stability, and optimization of magnetic properties of nanoparticles.

The work reported here uses new approaches to synthesize metal-coated nanoparticles characterized with high-resolution electron microscopy (HRTEM), micro-diffraction, and electron energy dispersive X-ray (EDX). Colloidal uniform composite nanoparticles of SiO2/TiO2 were synthesized using the sol-gel process. Fig. l-(a) shows a TEM micrograph of a group of particles coated with an outer layer.

One objective of the present work is to study the processes of assembly/self assembly of diamond clusters into nanostructures such as dots, wires,and filmsunder the influence of high electric fields. Diamond nanoparticles (∼2-5 nm in size) in a suspension of ethyl alcohol were deposited by pulsed electrophoresis onto sharp metal needles, such as those employed for field electron emission applications [1,2]. A custom designed sample holder has been constructed for a JEOL 2010 F, which allows for the convenient transfer of the sharp metal wires for analysis at high resolution, and then for removal (e.g. for re-deposition). These procedures allow us to precisely control the deposition thickness and morphology. They are capable of building a variety of deposition structures, even an isolated nanodiamond particle. The geometry of the deposits depends upon the applied voltage, the concentration of the suspension, the pulse duration, and the local electric field (which in turn depends on tip geometry, e.g. see Fig. 1).

Microindentation using a hard indentor is a very useful tool to probe the local mechanical properties (plastic flow, fracture, toughness, creep, etc.) of hard solids. We have used a depth sensitive indentation (DSI) version of this technique to study the shell of the conch Strombus gigas.In particular, we prepared polished sections in which the third order lamellae, the basic building block of the structure, could be indented along the three orthogonal directions; the indentation behavior along these three directions is quite different. Besides the normal information such as the hardness H from some typical dimension (typically the diameter of a pyramid-shaped indentation produced by a so-called Vickers diamond indenter) after indenting with a given load, the DSI technique also provides much additional information available from the loading and unloading curves. As can be seen from Fig. 1, the loading and unloading curves for the three orientations are quite different, as is the depth of the residual impression.

New analytical methods have been implemented with novel instrumentation designed to extend, to explore and to exploit an expanded performance envelop for high resolution imaging, EDX chemical microanalysis and chemical imaging with robust and representative bulk samples in a scanning electron microscope (SEM). A key contribution is the integrated and innovative design of the in-lens electron optics, sample holders, detectors including for EDX, specimen chamber and vacuum system. Each component has been improved individually over previous practice and they have been made to work together much better, especially with respect to combining advanced electron imaging at low voltages with efficient x-ray analysis and mapping.

Compared to a conventional out-of-lens/semi-in-lens FESEM the secondary electron image (SEI) resolution at the widely used low voltage of 1 kV is improved by a factor of almost 2x to <1.5nm and this facilitates low voltage imaging at primary magnifications of 250,000x (Fig.1) or more.

The preparation of frozen amorphous nano-meter thin films of solutions containing particles, and imaging with cryo- TEM, opens for the first time the possibility to study cluster assembles interacting with liquids. The method is here used to show evidence for assembly of ordered 3-dimensional aggregates of ligand stabilized 5-nm gold clusters in a long chain alcohol solution. The use of the plunge-freezing method allows freezing of solutions at a cooling rate that does not allow re-organization of the clusters. The stability of the amorphous solid solutions under the electron beam make it possible to record several pictures of the same aggregate at different angles and clearly identify the super-structure.

The sample preparation uses a modified controlled-environment vitrification system built in glass. Solidification of the liquid phase was achieved by plunging the solution, suspended in the holes of a lacy carbon on a copper grid, into liquid ethane (-174 °C) or in some cases liquid nitrogen.

Carbon nanotubes have many unique properties, including a tensile strength greater than that of steel and current-carrying capacity greater than any known metal or superconductor. Many applications have been identified, including field-emission displays and ultra-small transistors. At present, the main barrier to such applications is the ability to synthesize the nanotubes in a large scale with controlled properties'.

The work reported here is an effort for growing carbon nanotubes on porous silicon with a designed pattern. Experimental procedures include (1) a liquid catalyst was prepared by mixing AlCl3.6H2O, SiCl4, FeCl3.6H2O, MoO2Cl2,P-123 chemical components; (2) a flat piece of polydimethylsiloxane (PDMS) elastomer stamp containing a designed pattern was etched in the oxygen plasma, followed by spin coating the catalyst on the patterned stamp;(3) the inked stamp was printed onto a porous silicon substrate. This substrate was then heated in air at 70°C for 10 minutes to stabilize the catalytic pattern on the surface of porous silicon.

Yttria-stabilized zirconia (YSZ) has been the subject of many experimental and theoretical studies, due to the commercial applications of zirconia-based ceramics in solid state oxide fuel cells. Since the grain boundaries usually dominate the overall macroscopic performance of the bulk material, it is essential to develop a fundamental understanding of their structure-property relationships. Previous research has been performed on the atomic structure of grain boundaries in YSZ, but no precise atomic scale compositional and chemistry characterization has been carried out. Here we report a detailed analytical study of an [001] symmetric 24° bicrystal tilt grain boundary in YSZ prepared with ∼10 mol % Y2O3 by Shinkosha Co., Ltd by the combination of Z-contrast imaging and electron energy loss spectroscopy (EELS).

The experimental analysis of the YSZ sample was carried out on a 200kV Schottky field emission JEOL 201 OF STEM/TEM4.

The crystal structures of high temperature superconducting cuprates consist of alternative stacking of charge-reservoir (CR) block and conduction block. in case of YBa2Cu3Oy, (YBCO), CR block contains one-dimensional Cu(I)-O chain and BaO layers, and conduction block contains two-dimensional Cu(II)O2 planes and Y layers. YSr2Cu3Oy (YSCO), where Ba-sites of the YBCO are replaced by Sr completely can be obtained only by high-pressure synthesis. However, by replacing Cu(I) partly by Cr, YSr2Cu3-xCrxOy can be obtained even under ambientpressure conditions. The compound YSr2Cu2.8Cr0.2Oy (x=0.2) is non-superconductive, but, superconductivity is induced by partial replacement of Sr-sites with Ba; the compounds with YSr2-xBaxCu2.8Cr0.2Oy (x≤0.5) is non-superconductive, but the compound with x≥1.0 is superconductive. in order to obtain the structural information about the transition to superconducting phases, the effect of the Ba substitution is investigated by transmission electron microscopy (TEM).In the present study, the compounds with YSr2-xBaxCu2.8Cr0.2Oy (x=0-1.5) are examined by high resolution TEM (HRTEM) and electron energy-loss spectroscopy (EELS) to elucidate structural and electrical modification induced by Ba-substitution.

Since the superior properties of multi-wall carbon nanotubes (MWCNT) could improve numerous devices such as electronics and sensors, many efforts have been made in investigating the growth mechanism of MWCNT to synthesize high quality MWCNT. Chemical vapor deposition (CVD) is widely used for MWCNT synthesis, and scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) are useful methods for analyzing the structure, morphology and composition of MWCNT.

Temperature and pressure are two important growth parameters for fabricating carbon nanotubes. in MWCNT growth by CVD, the plasma assisted method is normally used for low temperature growth. However, a high temperature environment is required for thermal CVD. A systematic study of temperature and pressure-dependence is very helpful to understanding MWCNT growth. Transition metal particles are commonly used as catalysts in carbon nanotube growth. It is also interesting to know the how temperature and pressure affect the interface of carbon species and catalyst particles.