A comprehensive understanding of the relation between structure and properties in nano-materials calls for an extensive knowledge of the adhesion between nanoparticles. Electron diffraction contrast from the stress field caused by adhesion between contacting particles yields a detailed information on surface energy, grain boundary energy, dislocation and interphase formation mechanisms. However, the image interpretation is hindered by the scarcity of defined image condition data to fit the theoretical simulations due to the non-trivial TEM experimental situation on such a nanometric scale.

In our contribution, we challenge the above characterization complications by initiating CBED, HREM, and EELS on contacting nanoparticles with a CM200 FEG TEM. The main objective of our investigation is a quantitative simulation of the contacting stress field images from contacting nanoparticles and a quantitative characterization of the adhesion properties. In our approach, we started with cobalt particles which were coherently precipitated in a Cu-Co0.2wt% alloy, and then extracted using the carbon evaporation replica technique.

Bilayer thin films have been utilized in superconducting transition-edge sensors (TES) for photodetector development. A TES is formed with a normal metal conductor film and a superconductor film, so called bilayer, deposited on a subtract. In its,transition temperature region, the resistance of the superconductor film is extremely sensitive to the temperature. When an incident radiation ray arrives, the temperature of the bilayer increases, leading the resistance increases tremendously. A superconducting quantum interference device measures the current variation for read-out. By varying the relative thickness of the normal metal conductor layer and the superconductor layer, one can adjust the transition temperature of the bilayer to a desired range according to the proximity effect. TES bilayers are fabricated on Si-based substrates for the development of infrared, ultra-violet, and x-ray detectors.

Various normal and superconducting metal combinations are considered as bilayer candidates. When two metals are brought together, the concerns usually rise to those materials issues that may affect TES performance.

Chromium films are commonly used as a metal “glue” layer because of good adhesion to glass. It is believed that an intermediate oxide layer is formed during deposition, since Cr has a very strong affinity for oxygen. For example, a graded Cu/Cr/CrOx/SiO2 structure ensures excellent adhesion of Cu to glass, whereas Cu exhibits poor adhesion to most dielectrics. In our recent study, however, a diffusion layer, Cr2O3+SiOy, was observed between CrOx and SiO2 (glass) substrate. It is quite likely that this diffusion layer is responsible for the good adhesion of Cr film to glass.

The relative compositions of the major components across the interface are shown in Fig 1. A Cr film was evaporated on Corning Code 1737 glass (Al2O3-B2O3-SiO2 with ˜67at.% Si02) substrate at room temperature (RT) and subsequently covered with about lOnm Cu. A 5nm'wide diffusion layer is seen. The corresponding regions are also indicated in Fig 2, an Annular Dark Field (ADF) image whose contrast is approximately proportional to the density if the thickness is assumed uniform.

The TEM thickness fringe method [1] was developed as a potential routine technique to determine compositional profiles in quantum well systems. This technique has the advantages that a) TEM sample preparation is simple and the experiment is easy to set up and b) thickness fringe profiles show fine structure which is sensitive to chemistry [2]. In this paper, we demonstrate the ability of the method to measure the chemical abruptness at the interface between two layers of different composition.

90° wedge AlGaAs/GaAs TEM samples were prepared by the cleavage method, where the samples were cleaved along two orthogonal {110} planes. The samples were mounted on Cu grids and were investigated in a Philips EM430 TEM. Samples were orientated to the [100] direction precisely and bright-field images were acquired digitally using a CCD camera. Fig 1 shows an enlarged image of thickness fringes.

Since the edges of samples are 90° wedges, the thickness at any point can be accurately determined and the fringe profile can be compared with fringe profiles calculated for a range of Al compositions.

Owing to its unique and outstanding physical-chemical properties, diamond is considered to be one of the most important potential materials for applications such as in mechanical, optical, thermal, and electronic devices. Among them, the most attractive application of diamond would be a semiconductor for high temperature and high power electronic devices. To realize such novel devices, a high quality of defect-free single-crystal diamond film is required. Recently, continuous diamond films are found to be able to grow on Pt(lll) substrate. Since the diamond film synthesized on Pt shows a high degree of epitaxy, this approach has drawn the attention of reseafchers in this field and some research results have been reported. However, the heteroepitaxial mechanism is still to be elucidated; in particular, why does diamond grow heteroepitaxially on the Pt substrate and how do the atoms align in the interface between diamond and the Pt substrate? In order to solve those problems, it is very necessary to study the diamond growth mechanism on an atomic scale.

Grain boundaries and related planar defects in crystalline materials are often characterized by relaxations from geometric lattice constructions in order to lower the interfacial energy. Grain boundaries may relax by local reconstructions of the atomic structure along the interface and/or rigid-body lattice translations that perturb the relative positions of the grains far from the interface. Rigid-body lattice translations can by studied using α-fringe contrast along planar interfaces in strong-beam transmission electron microscopy (TEM) images.[l-3] Oscillatory fringe contrast may appear along an interface between two grains which are related by a translation vector, R, when the interface lies inclined to the incident electron beam and imaged with a diffraction vector, gc, common to both grains.[4] The fringe contrast is due to an interference between the direct and scattered electron beams when the diffracted electron beams undergo a phase shift propagating across the interface. The phase shift, α, is proportional to the projection of R onto gc (i.e. α = Rgc) and the fringe contrast is known as α-fringe.

Quantum confinement effects in opto-electronic materials have typically been limited to onedimensional confinement due to the constraints of epitaxial growth techniques. One method of forming higher degrees of confinement is the spontaneous lateral modulation seen in InAlAs shortperiod superlattices (SPS) grown on InP(00l). Here, a small number of monolayers (0.5 ˜ 2) of InAs and AlAs is alternately deposited by MBE to build a layer that exhibits lateral modulation on the 10 ˜ 25 nm scale. These materials show strong polarization and a large red shift (˜500meV) of the photo-emission spectra.

A key to understanding and predicting the properties of these films is determining their composition distribution. Using an HB-501 STEM, we have investigated the detailed composition distribution within a strongly modulated sample. The sample was grown in slight tension with respect to the InP substrate, a condition in which lateral modulation is known to be strong. Figure 1 shows a highangle annular dark-field (HAADF) image together with an intensity line scan from the image.

In the copper metallization adopted for better speed and reliability in microelectronic devices, the choice of underlayer is one of the major concerns. Its requirements include low electrical resistance, adhesion to Cu and adjacent dielectric materials, confinement of Cu from drifting, and nucleation and texture enhancement of the overlying Cu film. Metallic tantalum is a very promising candidate. In this paper, the thermal stability of Cu/Ta interfaces is investigated to estimate the reliability of such a Ta underlayer.

Thin Cu and Ta films were consecutively deposited without breaking vacuum using a dc sputtering method to simulate the seed layer and underlayer in a Cu metallization structure. All the synthesized Ta films were the metastable tetragonal structure rather than the stable body-centered cubic (bcc) phase.

We have shown that (111) Cu grows epitaxially on top of (002) tetragonal Ta even though the Cu and Ta have hexagonal and tetragonal atomic arrangement on those planes, respectively. Using electron diffraction in cross-sectional and plan-view samples, an unexpected atomic matching at the interface was discovered as shown in Figure 1(b).

Quantitative evaluation of coherency strains in Ni-12 at.% Al alloys has been performed by means of high resolution electron microscopy (HREM) and convergent beam electron diffraction (CBED) techniques. The alloy Ni-12 at.%Al is composed of two phases, the disordered fee Ni-Al solid solution and the coherent Ni3Al (γ') particles with an LI2 structure. The presence of γ' particles can impart excellent mechanical properties to these alloys. However these particles coarsen if subject to high temperature with an important reduction of mechanical properties. Coarsening of coherent particles in solid alloys is driven by the decrease of surface and elastic energies. The effect of surface energy is well understood but that of the elastic energy still requires experimental investigation. The source of elastic interaction between particles is the lattice parameter mismatch between particles and matrix. Evaluation of the elastic strain fields around particles can give some insight into the elastic interaction between particles and thus into the coarsening mechanism from an experimental viewpoint.

The mechanical properties of Al-Cu-Mg alloys depend on a dispersion of Al2CuMg phase precipitates which form as laths along <100>A1, with {012}A1 as the habit plane. Despite extensive study, the crystal structure, morphology and interface structure between the Al2CuMg intermetallic phase and the Al matrix are still not well understood. Since the mechanical behavior of Al alloys strengthened by the S-phase cannot be controlled without a clear understanding of its crystallography and interface structure, the goal of this investigation was to characterize the crystal structure, evolution and interface structure of the S-phase using quantitative electron beam characterization techniques. Several models have been proposed for the crystal structure of Al2CuMg. A widely accepted model of the S-phase was given by Perlitz and Westgren (PW) [1], shown in Fig. 1. The unit cell of the PW model is orthorhombic with unit cell dimensions a = 0.4 nm, b = 0.923 nm, and c = 0.714 nm, space group Cmcm, containing 16 atoms in the ratio Al:Cu:Mg = 2:1:1.

It is well documented that the pulsed laser vaporization of graphite produces both carbon nanotubes and C60 in the presence of certain metallic catalysts. In nanotube production most of the Ceo is removed along with other residual contaminants during succeeding purification and annealing steps. The possibility of C60 becoming trapped inside a nanotube during this elaborate sequence has been considered but not previously detected.

Nanotubes are observed with high resolution transmission electron microscopy under conditions chosen to minimize both exposure time and irradiation damage. Since a nanotube satisfies the weak phase object approximation, its image is a projection of the specimen -potential in the direction of the electron beam. The image has maximum contrast where the beam encounters the most carbon atoms, which occurs where it is tangent to the tube’s walls. Thus, the image consists of two dark parallel lines whose separation is equal to the tube diameter, 1.4 nm.

The noble metal (Me = Au, Pd, Rh, and Pt) polynuclear coordination compounds of Chini’s type eventually serve as a remarkable bridge between molecular clusters and metal colloids. The sizes of the metal cores of the cluster compounds are close to lower sizes of colloidal metal particles. However, chemically stabilized nanoclusters have a distinct ligand environment with a definite stoichiometry inherent to molecular clusters. Interest in structures of the cluster compounds has increased in recent years in view of their unique selective catalytic properties under mild conditions, which, in principle, open a way to the development of a new branch of catalysis by metal clusters, quantum-size effects in the thermodynamic properties, and applications as nano-sized electronic devices (quantum dots). A key feature in structural characterization of such species (they are amorphous solids usually unsuitable for x-ray diffraction analysis) is to understand the relations between the atomic arrangement, electronic structure and chemical reactivity.

Three-dimensional structure studies provide important information about the organization of macromolecules, often revealing biological mechanisms and protein structure-function relationships. 400 KV electron cryo-microscopy is an emerging technology that is proving to be a powerful tool for studying the structures of large macromolecular assemblies that are often not tractable using other techniques. Its large depth of field makes it well-suited for imaging large objects to high resolution. In addition, a high accelerating voltage minimizes chromatic aberration yielding images of higher contrast. Recently a 400 KV electron cryo-microscope has been used to image periodic arrays of tubulin to 3.5 Å and single particles at somewhat lower resolutions (13 Å) providing practical demonstrations of its usefulness in modern structural biology. In this paper we present high resolution image data of two large icosahedral viruses: herpes simplex virus IB nucleocapsid (HSV IB) and rice dwarf virus (RDV). Human herpes virus (HSV) is associated with a spectrum of diseases ranging from cold sores to more severe clinical manifestations such as mental retardation.

Various techniques have been developed to infer the 3D relationship of reciprocal lattice vectors from electron diffraction patterns taken at different specimen orientations. Such relationship is subsequently applied in crystallographic analyses. Due to the transmitted nature of the electron beam, TEM images present 3D information averaged throughout the thickness of the specimen on each micrograph. Techniques for acquiring 3D information from such images include stereomicroscopy for characterizing irregular dislocation networks, and 3D reconstruction of nonperiodic macromolecular assemblies. Prospects for finding the 3D lattice parameters of nanocrystals from HREM images taken at different specimen orientations have been discussed. Here we apply this stereo lattice imaging to a 7 nm crystal, and discuss its application to compact fee and bec lattices in general. Results on other lattice types will be published separately.

Generally 3 non-coplanar lattice vectors seen along 2 different zone axes are sufficient for inferring a subset of the 3D reciprocal lattice of a single crystal.

Aluminum Nitride (AIN) has arised as a promising synthetic material, valued for its high thermal conductivity coupled with high electrical resistivity. These properties, associated with the fact that AIN is nontoxic and has thermal expansion characteristics which closely match those of silicon, makes it an excellent material for electronic packaging. Currently two commercial processes are primaly used for the manufacture of AIN powder, the direct nitridation of the metal, and the carbothermic reduction of the alumina in the presence of nitrogem.

In this work, nanosized aluminum nitride particles were synthesized from the phase using ammonia and aluminum chloride vapor as reactants. This system consists of a vaporization system, ammonia (NH3) distributor, tubular synthesis reactor and powder collection system. The aluminum chloride (AlCl3) vapor starts to react with ammonia injected in the synthesis reactor inlet position (mixing zone). The aluminum nitride nucleates and grows along the reactor length. The aluminum nitride powder produced was collected and chemically and physically characterized.

Though quasicrystals were discovered more than a decade ago, the fundamental questions of why and how quasicrystals form are still unanswered. Knowledge of atomic positions, for all species present, is the most important factor in trying to answer this question, and we have therefore applied Z-contrast imaging to this problem. The quasicrystalline structure, a state with long-range order, but no periodic translation symmetry, has been commonly described by the Penrose tiling model, in which two types of tile are connected according to strict matching rules. However, such a mathematical description does not provide any physical insight into how and why quasicrystals arise. An alternative description of the ideal quasicrystal has been given by Gummelt, who showed that the ideal quasicrystalline arrangement can be obtained with a single type of tile which is allowed to overlap so as to cover the surface. The equivalence of these two descriptions was proved by Steinhardt and Jeong.

Ordered self-assembly of nanocrystals is scientifically interesting due to not only the unique properties of the nanocrystals, but also the collective properties of the assembly. Compared to lithography method, self-assembly is limited by a lack of control over the sizes of the ordered arrays, resulting in difficulties in characterizing their physical and chemical properties. New techniques are needed to manipulate the self-assembling process and the nanostructures formed.

In this work, polystyrene (PS) spheres were used as the template to form large bulk ordered anatase nanostructure with cobalt doping. The ordered PS template was infiltrated with absolute alcohol solution of titanium butoxide. After the precursor was dried, it was treated at 160°C for 5 hours and then at 450°C for another 5 hours. To dope cobalt into the structure, the porous titania host was immersed in a heptane solution with cobalt carbonyl. After drying in vacuum at room temperature, it was treated at 160°C.

Since the discovery of high temperature superconducting (HTS) ceramics there has been a great deal of discussion about theories of superconductivity. In a recent theory it has been proposed that the Tc's in these new materials are related in some way to a subtle phase separation in the structure. HTS ceramics have been studied quite intensively by high resolution transmission electron microscopy (HRTEM) and by electron diffraction (ED). In such studies the major focus invariably has been on the periodic structure of the object. However, early HRTEM work on Yba2cu3O7-x by Barry found that in addition to the crystalline order, the Yba2cu3O7-x HTS has a non-periodic structural modulation. In this work we have used an image processing method to look for subtle structural changes in Yba2cu3O7-x by measuring the bending of lattice fringes at twin planes. The image processing method is similar to the method used by Hetherington to study rigid body displacements at gold grain boundaries.

Xe inclusions can be formed in an Al matrix by ion implantation. The inclusion size and state (solid, liquid or vapor) can be controlled by changing the total ion dose and implantation temperature. Inclusions below about 10nm in size have been reported to be solid with a face centered cubic structure and a lattice parameter of about 0.6nm. Small solid inclusions have cuboctahedral shapes bounded by {111} and to a lesser extent by {100} facet planes. Larger liquid inclusions maintain their facets on the {111} planes of Al but the {100} facets become rounded . It is found that high resolution images of these liquid Xe inclusions exhibit an unusual contrast effect similar to that previously observed for liquid Pb inclusions in Al. This contrast is limited to the {111} facets and could indicate the presence of a thin solid layer of Xe. In this work we investigate the origin of this contrast effect by HRTEM observation and image simulation.

Nanosized Xe precipitates were formed in an Al matrix by ion implantation with 35 keV Xe at 474K to a dose 5×1015 ions/cm2. Through focus series of high resolution electron micrographs in the <110> zone axis orientation were taken on the Berkeley ARM-1000 at an accelerating voltage of 800kV.

The technique of high resolution imaging is important for characterizing the structure of small metal particle catalysts and nanophase materials. For bimetallic systems, it is possible to use local lattice parameter measurements to identify alloy compositions in ensembles of nanometer sized metal particles [1]. However, determining alloy composition is challenging because changes in lattice parameters of only a few percent must be reliably detected. We have performed measurements of the apparent d(111) fringe spacing on both simulated and experimental HREM images from Pt particles in the size range 15 - 35 Å. A series of initial image simulations of Pt cubeoctahedrons with 17 Å (201 atoms) and 34 Å (1289 atoms) in diameter have been studied in order to understand the effect of different parameters on the accuracy of lattice spacing. The clusters were built using the Rhodius program developed by Botana et al [2]. Starting with a bulk crystal we create cubeoctahedra by applying successive cuts along either the (111) or (100) direction. A supercell size of 50Å was selected and the particles were oriented at or close to the [110]. Images were calculated by the multi-slice techniques using both the CERIUS and EMS applications. The supercell was divided into 20 slices and the following parameters were used in the calculation Eo = 400 kV, Cs = 1mm, Δf= -320 Å, focal spread = 80 Å, convergence = 0.5 mrad and atomic vibration = 0.35Å.