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The interface between vanadium and the basal plane of sapphire was studied by conventional and cross sectional high resolution electron microscopy (HREM) to clarify the atomic structure of the interface. A 50 nm thick vanadium film was deposited on the (0001) basal plane of sapphire by molecular beam epitaxy (MBE). The TEM observations of the interface were made from three directions: two cross-sectional views (parallel to [1 2 10]Al2O3 and [10 10 ]Al2O3) and plan view (parallel to [0001]Al2O3). From the SADP, the following orientation relationship was obtained: (111)V ‖(0001)Al2O3; [10 1 V ‖[1 2 10]Al2O3. Cross-sectional HREM observations showed the atomic configuration at the interface, and the existence of periodic arrays of geometrical misfit dislocations. Computer simulations show that sapphire is aluminum-terminated at the interface with vanadium.

High-resolution electron microscopy was performed on fine crystals with A-15 type structure prepared by vacuum-deposition of tungsten. The size distribution of the crystals with the A-15 type structure was ranged from 2 to 11 nm and was similar to that of the bcc type structure coexisting in the film, indicating that the nucleation of both structures generated at the same time in the initial stage of growth. The critical grain size of transformation from bcc to A-15 type structure was not observed in the nanometer-sized region. Coalescence of the nanometer-sized crystals with A-15 type structure was observed in the film. It was found that the crystals were connected by stacking faults with displacement vector of 1 2 〈100〉 and nanometer-sized tilt grain boundaries rotated by 30° around the 〈100〉 A-15 axis. It was also implied from the observation that the A-15 structure in the present film was stabilized by some kinds of lattice defects.

In a previous paper, we have shown that high resolution electron microscopy (HREM) is able to reveal nanometric domains in ferroelectric oxides, the existence of which cannot be proven by other means. However, this method cannot reveal all the domains. In this paper we calculate the limits of the HREM possibilities and expound a method to obtain some statistical information on the observed sample.

400 kV high-resolution electron microscopy is used to study the distribution of foreign atoms which are present in substitution in a Ni 3 Al intermetallic compound. The presence of elements heavier than Al can be detected in the images. It is shown that these elements are located on the Al sites. The contrast of atomic columns containing different elements is analysed by multislice calculation and image simulation. The contrast analysis combined with a statistical approach leads to an estimation of the overall composition which is in agreement with previous experimental results.

The morphology of supported Bi particles is studied using the technique of profile imaging at atomic resolution. These particles show a crystallized Bi core surrounded by an amorphous (or liquid) material. For small supported particles (diameter of the Bi core, about 6-9 nm) observed by high-resolution electron microscopy at room temperature, the lattice fringe orientation changes very rapidly during the observation. This fluctuating evolution is attributed to atomic rearrangements of the particle induced by the microscope electron beam. During this evolution, a decrease in the size of the crystallized Bi core is sometimes observed for the smaller particles.

By rotation of carbon nanotubes about their long axis and obtaining images by high-resolution electron microscopy, it is shown that carbon nanotubes do not have a perfectly cylindrical shape especially near the ends of the tubes.

Controlled intergrowths of cubic and hexagonal phases of faujasitic materials have been synthesized, using mixtures of crown ethers, and studied by HREM. The results reveal that the end-member materials are pure-phases, nearly free of defects and intergrowths such as those observed without the use of crown ethers. Mixed phases form intergrowths, rather than overgrowths, consisting of short blocks of up to 10 unit cells

An atomic arrangement of an Al-Pd-Mn decagonal quasicrystal with 1·2 nm periodicity has been proposed from high-resolution electron microscopy with the aid of computer simulation. A calculated image from the atomic model reproduced well the features of a high-resolution structure image taken from a thin sample.

The structure and the microstructure of the new high Tc superconductor Tl0.5Pb0.5Sr4 Cu2CO3O7 have been studied by high resolution electron microscopy. The experimental images fit well with the calculated ones based on a structure built up from the intergrowth of a 1201-type slice [Tl0.5Pb0.5Sr2CuCO5]1201~ with a [Sr2CuCO3O2]~ unit. The comparison of the calculated and experimental images with those of a 1223 structure, which exhibits similar cell parameters to those of Tl0.5Pb0.5Sr4Cu2CO3O7, shows that the oxycarbonate exhibits a characteristic contrast for some focus values which allows to differentiate the two structures. The investigation of numerous crystals attests of the high regularity of the stacking of the layers along c. One single type of defect was observed which suggests the possible existence of a new member [Tl0.5Pb0.5Sr2CuO5] [Sr2CuCO3O2]2 .

Weak-beam and high-resolution electron microscopy of dislocations in CoSi2 with the Cl structure, introduced at room temperature by pulverization, has shown that dislocations with the 〈100〉 Burgers vector and those with 1/2〈110〉 are dissociated into partial dislocations by the following reactions: 〈100〉 1/2〈100〉 + 1/2〈100〉 on {001} 1/2〈110〉 1/4〈111〉 + 1/4〈111〉 on {110} 1/2〈110〉 1/6〈211〉 + 1/6〈121〉 on {111} Stacking faults and micro-twins have also been observed by high resolution electron microscopy. Evidence that vacancies are mobile at room temperature has been obtained by observations of helical dislocations.

Within the last decade there have been major advances in the deployment of electron microscopy for the elucidation of solid catalysts. Some of these have been technical (instrumental), like the arrival of aberration-corrected lenses and of new kinds of in situ stages for solid-gas and solid-liquid studies. Others have been largely conceptual, such as precession electron diffraction, to provide diffraction intensities suitable for crystallographic studies, or like the revolutionary approach of Zewail and colleagues in using 4D electron microscopy which, with its abitity to reach picometer spatial resolution coupled with femtosecond time resolution, augurs well for future studies. Many major advances registered within the past few years are high-lighted in this article and along with their significance.

In the field of high-resolution transmission electron microscopy (HRTEM), the term “resolution” has come to hold a number of different meanings [M.A. O'Keefe and J.C.H. Spence, in: Proc. 49th Annual EMSA Meeting, p. 498]. The present work reviews the various definitions of HRTEM resolution, derives theoretical expressions for resolution, and suggests how high resolutions may be attained in practice.

High-resolution electron microscopy has been used to investigate the structure of coherent twin boundaries in ordered Cu 3 Au. Apart from confirming the previously established symmetric structure S and asymmetric structure A, the composition of atomic columns in the boundary has been examined. Evidence is presented for a new asymmetric structure which differs from structure A in the arrangement of Au and Cu atoms columns at the boundary

90° domain boundaries in BaTiO3 and PZT(52/48) have been studied with high-resolution electron microscopy. The high-resolution images with two-dimensional 4 A lattice fringes show that most 90° domain boundaries in BaTiO3 are parallel to (011) planes but can shift from one (011) plane to adjacent (011) planes. It is suggested that such shifts may occur on (01 1 ) or (001) planes. Across the domain boundary, lattice planes tilt about 0.5° in BaTiO3, which is close to the experimental value 0.6° from the selected-area diffraction pattern and the theoretical value 0.57°. In PZT(52/48), the tilt of lattice planes across the domain boundary in high-resolution images is only about 1°, which is smaller than the experimental value 2.8° from selected-area diffraction pattern and the value from theoretical calculation. The mismatch may indicate that in very thin films the lattice distortion and strain field can be relaxed. A diffuse dark contrast is found along 90° domain boundaries in both BaTiO3 and PZT(52/48) and is probably related to the lattice distortion or ionic displacement. The diffuse dark lines are about 4–10 unit cells wide around the domain boundary. Diffractograms from Fourier analysis of the regions in high-resolution images around the domain boundaries reveal the effects of the lattice distortion and strain field.

Using high resolution electron microscopy, the stage formation of the icosahedral phase during the process of mechanochemical treatment of the cubic Mg 3Z (Zn, Al) 49 crystals has been studied. It has been shown that in the initial stages the icosahedral phase forms locally owing to the formation of rotation defects and disorder of the crystal planes due to the action of plastic deformation. The size of the disordered regions in the icosahedral phase increases with increase in the time of mechanical treatment. An orientation correspondence has also been revealed between the initial cubic and icosahedral phases; this is apparently due to the similarity in the structural designs of the cubic and icosahedral phases.

Conventional methods of interpretation of HREM images rely on structure modeling followed by image simulation. These methods are inapplicable to the interpretation of micrographs of amorphous materials because the atomic structure is unknown a-priori. Previous experimental work by the present authors had indicated that the cross-correlation of intensity fields of different regions of an HREM micrograph can identify regions of structural order in an apparently random matrix. The present paper confirms this initial result by reporting results of cross-correlations on computer-simulated HREM images. The images were generated from a “multislice” calculation of electron-wavefront propagation through a composite material consisting of a Si crystallite affixed to a relatively thick amorphous Si substrate. The cross-correlation technique is shown to be capable of retrieving the c-Si region where the simulated HREM images reveal to evidence of the crystallite. There is an optimum microscope defocus for which retrieval of the ordered structure is most efficacious. The cross-correlation technique is found to be superior to conventional Fourier filtering for identifying regions of atomic order.

The technique of high-resolution electron microscopy represents a powerful method for characterizing the microstructure of thin films and surfaces. We demonstrate its usefulness by reference to some recent studies of metals, semiconductors, and oxides, in particular, showing that it can be used to follow physical and chemical changes inducedin situ by the electron beam orex situ as a result of annealing or chemical treatment.

High-resolution electron microscopy has been utilized to elucidate the structural nature of oxygen-containing planar inversion domain boundaries in aluminum nitride. A model for this defect is proposed which incorporates the necessary structural elements needed to describe the entire AlN-Al 2 O 3 system. Image simulations of the proposed defect structure, for a range of imaging conditions, are in excellent agreement with experimental micrographs and provide substantial evidence for the validity of the proposed model.

Recent grain boundary modeling studies in fcc metals have revealed global correlations between GB energy and (i) the rigid-body translation normal to the grain boundary (the so-called volume expansion) and (ii) the degree of deviation of the local atomic coordination across the interface relative to the ideal lattice. This communication describes an approach towards evaluation of such parameters by analyzing images obtained by axial high-resolution electron microscopy, utilizing digital image-processing techniques. Observations on several 〈1 1 0〉 tilt GB's in Au are presented.

BaTiO3 ceramics are investigated by high-resolution electron microscopy with the aid of image simulation. Ferroelectric 180° domain walls parallel to the {110}p-plane (p: pseudo-cubic lattice), and dislocation loops or oxygen vacancy walls are observed in multi-beam lattice images. BaTiO3-Keramik wird mittels hochauflosender Elektronenmikroskopie und Bildsimulation untersucht. Ferroelektrische 180°-Domanenwande parallel zur {110}p-Ebene (p: pseudokubisches Gitter) und Versetzungsschleifen oder Sauerstoffleerstellenwande werden in den Mehrstrahl-Gitterdiagrammen beobachtet.

Various types of G. P. zones and θ'-phase are formed by aging in Al-1.6 at%Cu crystals. Formation processes of these structures have been investigated by high resolution electron microscopy with the following results: (a) Three-dimensional Cu-atom clusters are formed at the beginning of aging at both 373 and 423 K, respectively. (b) In 373 K aging, these clusters change to G.P.-1 zones and/or G.P.-2(3) zones whose Cu-rich planes are separated with three Al-rich planes. Multi-layered G.P.-2(3) zones and sometimes multi-layered G.P.-2(2) zones whose Cu-rich planes are separated with two Al-rich planes are formed by further aging at 373 K

Metal nano-clusters have catalytic properties related to their size, their shape and crystalline structure. The most important advances for catalysis in electron microscopy, was the possibility to insert gas in the microscope during observations with the aim to close simultaneously the material and the pressure gap in catalysis [1–3].

New methods for both qualitative and quantitative analysis of the GaAs/AlGaAs interface by high-resolution electron microscopy at 400 kV in

By making good use of the excellent properties of the imaging plate (IP), i.e., high sensitivity, a wide dynamic range and good linearity for electron intensity, high-resolution electron microscope (HREM) images were quantitatively analyzed. In W 8 Ta 2 O 29 , contrast changes due to the dynamical diffraction effect were quantitatively evaluated and compared with the simulated images. In Pb ( Ba , Sr ) 2 ( Eu , Ce ) 2 Cu 3 O y , which is related to high- T c superconductors, atomic columns containing heavy elements such as Pb were clearly distinguished from those of relatively light elements such as Cu. Furthermore, quantitatively evaluated contour maps revealed vacant oxygen positions, which are important in characterization of both the structure and the electrical properties of the high- T c superconductors. These results demonstrate that the IP is effective and indispensable for the quantitative analysis of HREM images as well as for electron diffraction patterns.

An incoherent {112} twin boundary in aluminium has been observed by high resolution electron microscopy. No rigid body translation parallel to the boundary plane has been found. The experimental structure is in agreement with one of the calculated models. The junction of the {112} segment with a coherent {111} boundary is also studied.

High Resolution Electron Microscopy is performed on (Fe 3 4 Cu 1 4 )Sr 2 (Ce 2 3 Y 1 3 ) 3 Cu 2 O 11 to determine the defects occurring in this material. Only planar defects are observed, which are all related to the number of CeO 2 layers. The defects can be described with (Fe,Cu)Sr 2 (Ce,Y) n Cu 2 O 5+2 n , n being 1,2, …, 5. The n =0 member is also observed where an extra CuO 2 layer is missing.

The structure of 3:2 mullites is investigated by high-resolution electron microscopy. Attention is paid to the identification of isolated defects, i.e., oxygen vacancies in pure 3:2 mullite and chromium interstitials in chromium-doped mullite. Models for such defects, including lattice reconstruction effects, are analyzed with the help of image simulations.

ErBa 2 Cu 4 O 8 has been studied with High Resolution Electron Microscopy to determine whether ErBa 2 Cu 5 O 9 can be formed locally by the intercalation of Cu and O, in samples heated in the temperature range 100–250°C. Prior to the formation of planar defects, a 2 a,b,c superstructure is formed upon heating, occurring only near the surface. The 2 a period is present only in the (CuO) 2 double layer. Upon heating, several types of planar defects are formed: (1) a set of defects showing an increase in the c lattice parameter of 0.15–0.30 nm; the defects seem to be obtained by insertion of a more or less amorphous layer between the CuO layers of the (CuO) 2 double layers; (2) a new group of structures in which extra layers are intercalated between the CuO layers, each layer having a width of 0.28(2) nm. The latter group of structures and the 2 a,b,c superstructure can be explained with the presence of CO 3 groups in the lattice. Continuous heating above 150°C leads to amorphization, progressing from the surface. No evidence is obtained which would indicate that ErBa 2 Cu 5 O 9 can be formed under these conditions.

A preliminary HREM study of indialite (hexagonal α-cordierite Mg 2 Al 4 Si 5 O 18 ) is reported. Conditions under which the structure of this compound can be optimally imaged in the a and c projections are discussed for the case of a 400 kV microscope, with a Scherzer resolution of 0.17 nm. Both numerical simulations and experimental multi-beam micrographs demonstrate that the whole cation sublattice is imaged in the [0001] orientation, while only Al + Si atoms contribute directly to the image in the [2110] orientation.

In the 〈110〉{001} slip system in L12 ordered alloys, both screw and edge dislocations may become locked by dissociating into nonplanar structures. In this paper the structure of edge dislocations in the [110](001) primary cube system in Ni3Ga and Ni3(Al, Ti) single crystals has been observed with weak-beam and lattice-imaging microscopy. Near 600°C the edge superdislocations are locked in the double Lomer—Cottrell lock; near 700°C the edge dislocations are locked in nonplanar structures formed by climb dissociations. Both structures have been observed directly by high-resolution electron microscopy. The implications of the locking of the edge dislocations on the operation of 〈110〉{001} and 〈110〉{111} slip systems are discussed.

The principle of image deconvolution in HREM by means of maximum entropy (ME) is introduced. The ME image deconvolution was performed in terms of a single image taken at an arbitrary defocus condition or in terms of the combination of an image with the corresponding electron diffraction pattern. The weighted ME method is introduced for crystals thicker than a weak phase object. The test results on simulated images of chlorinated-copper phthalocyanine for various defocus values are shown. The method is also efficient for crystals consisting of atoms with great differences in atomic weight and for very noisy images.

The sanidic polyamide [NM-Ph(CO 2 R) 3 (CO 2 Me)-NMCO-Ph(OR) 2 CO] n (R=C 12 H 25 ) is studied. It is shown that this polymer has a biaxial structure with quasi 2-D long range translational correlations. The correlations in one direction are limited by the length of the molecule. The oriented regions are separated by regions in which the molecules are less oriented

Microtwin sequences in the NiAl 3R martensite phase are investigated at different compositions using conventional and high resolution electron microscopy and electron diffraction. The results show, upon increasing the Ni content, an increase of the c/a ratio, an increase of the c and a decrease of the a parameter of the fct lattice and a decrease of the twin density. The various compositions were obtained by annealing samples with the same bulk composition at different decomposition temperatures.

The commensurate and incommensurate structural configurations underlying the diffuse scattering from athermal {omega} found in the as-quenched {beta} phase of Ti with 8 and 15 at. % Mo have been investigated by high-resolution electron microscopy. Image interperetations were based on a simulation code developed via observed images of the commensurate {omega} phase formed by annealing Ti-8 at. % Mo. Athermal {omega} is observed as linear structural arrays or strings'' of

Oxygen arrangement on Hg0.5Tl0.5Ba2CuOx (100) surface was studied by high-resolution electron microscopy. The {100} planes were found to be stable and to have preferred atomic surface. A surface structure model of Hg0.5Tl0.5Ba2CuOx was proposed and compared to the image calculations, which indicated the surface consists of Ba layers and oxygen atoms on the (Hg, Tl) layers. The present work indicates that the stable {100} planes of Hg-1201-type superconducting oxides would be suitable for the future device application.

Spin-valve microstructure has been studied by means of high-resolution electron microscopy. The investigation has focused on the waviness of the interfaces between the nonmagnetic and adjacent ferromagnetic layers in order to estimate the magnetostatic coupling termed the `orange peel’ effect. Numerical analysis of the high-resolution electron micrographs has enabled quantitative data on the interface waviness and thus on the magnetostatic coupling to be obtained.

The fine structure of unhydrated cement clinker Ca4Al6SO16 (C4A3S) and its four superstructures have been studied by means of electron diffraction and high resolution electron microscopy (HREM). The match between experimental images and simulated ones verifies the result of X-ray structural analysis: C4A3S having a cubic lattice with space group l43m,Z = 2. The frequent apperance of forbidden reflections such as 1/2, −1/2, 0 along the 〈110〉* directions of C4A3S imply the presence of superstructures which may be due to an orderly inverse occupation of Ca2+ ions. Various structure models based upon the observed structural images have been proposed for these four superstructures. A new cubic phase witha′ = 1.5 nm is also found by selected area electron diffraction (SAED).

Niobium films were grown by molecular beam epitaxy on sapphire substrates of different orientations. A unique three-dimensional orientation relationship was determined between the Al 2 O 3 substrate and the niobium film independent of substrate orientation: (0001) S ‖(111) Nb and [2 11 0] S ‖[1 1 0] Nb . This observation is in contrast with topotaxial relationships obtained between Al 2 O 3 particles formed by internal oxidation of Nb Al alloys where close-packed planes are parallel: (0001) S ‖(110) Nb . The atomistic structure of the interface was identified by high resolution electron microscopy. Regions of good matching alternate with regions which contain localized misfit dislocations. These observations will be discussed and compared with results published in the literature.

Defects present in thin films of syndiotactic polystyrene are studied by high resolution electron microscopy and microdiffraction. Small domains are observed and are interpreted an a new superstructure (sPs 8″ ) by analogy with a recent model (sPs 8' ) proposed for the rest of the crystal. The two superstructures result from ordering between enantiomorphous pairs of molecular clusters

The atomic structures of heterophase interfaces with large misfits (>14% in Ag/Ni and Au/Ni) and with small misfits (∼2% in Ag/NiO and Au/NiO) have been studied by high-resolution electron microscopy (HREM). It is found that all interfaces are strongly faceted on (111) planes. This indicates that (111) interfaces have the lowest interfacial energy in both metal/metal and metal/metal-oxide systems. For the metal interfaces, this also agrees with determinations of interfacial energies by lattice statics calculations. The large misfit of Ag/Ni and Au/Ni interfaces is accommodated by misfit dislocations. Observations of misfit localization by HREM are in good agreement with images derived from computer simulation, based on relaxed structures, obtained in embedded atom calculations. All misfit dislocations at the Ag/Ni and Au/Ni interfaces lie exactly in the plane of the interfaces, while the dislocations at Ag/NiO and Au/NiO interfaces reside at a stand-off distance, 3 to 4 (111)Ag or (111)Au interplanar spacings from the interfaces.

Superstructure phenomena in the barium diphosphate tungsten bronzes with hexagonal tunnels, Ba (P2O4)2 (WO3)2m , are characterized by electron diffraction and high resolution electron microscopy. A model of superstructure is deduced from the observations and used to perform image calculations. The comparison of experimental and calculated images allows to associate the superstructure phenomena to orderings of the barium cations in the hexagonal tunnels.

By using immersion calorimetry with liquids of various molecular dimensions, the distributions of the micropore sizes have been obtained for a number of active carbons, for the range 0.3 to 0.75 nm. These carbons have also been examined by high-resolution electron microscopy, the results from both techniques being displayed in the form of histograms. The agreement between the two methods appears to be good and provides possible evidence of the reduced interaction radius of adsorbed molecules and of exfoliation.

The present article is a brief introduction to structure determination of meso- and microporous materials (zeolites) by electron crystallography. The used approaches are illustrated by several examples.

The crystal structures of thermoelectric (TE) compounds Bi1.91Sr2.0Rh1.77Ox and Bi 2.12Ba2.00Rh1.95Ox are investigated by means of electron diffraction measurements and high-resolution electron microscopy. These compounds have layered structures and consist of two interpenetrating subsystems exhibiting incommensurated periodicities along b-axis. Both subsystems, CdI2 -type RhO2 sheets and a distorted four-layered rock-salt (RS)-type (Bi,(Sr,Ba))O blocks, have common a-, c-axes and beta;-angles. On the other hand, the ratios of two axis lengths, i.e., b 1 (RhO2 sheet) / b2 (RS-type block), are irrational. Based on the cation ratio and b1/b2 value, the structural formulae are expressed as [(Bi1-x>Rhx)2(Sr1-yBi y)2O4+delta]0.63RhO2 with x = 0.077, y = 0.016 and delta = 0.46 for the Sr-system and [(Bi1-x>Rhx)2(Sr1-yBi y)2O4+delta]0.56RhO2 with x = 0.037, y = 0.047 and delta = 0.39 for the Ba-system, respectively. Based on the electron diffraction measurements, it is found that these compounds have irrational modulation vectors, q1 = -a* + 0.63b1* and q2 = 0.17b1* + c for Bi-Sr-Rh-O, and q1 = -a* + 0.56b1* and q 2 = 0.11b1* + 0.35c* for Bi-Ba-Rh-O, respectively, being the indications of (3+2) dimensional structures. High-resolution images taken with the incident electron beam parallel to the a- and c-axes clearly exhibit modulated atomic arrangements. These compounds are characterized by the displacement modulations in both RhO2 layers and the RS-type blocks

We introduce a simple preparation method for ultrathin carbon support films that is especially useful for high-resolution electron microscopy (HREM) of nanoparticles. Oxidized iron nanoparticles were used as a test sample in a demonstration of this method. The film qualities are discussed on the basis of electron-energy-loss spectroscopy (EELS) and image analysis techniques such as thickness maps and histograms. We carried out a comparison between the homemade and commercial film qualities. The relative thickness of the homemade support films was 0.6 times less than that of the commercial films, which was calculated from the EELS analysis, whereas the thicknesses of both carbon support films varied within about 3%. The percentage of the observable area was about 67 ± 7.6% of the support film. This was about twice as large as the commercial film (32 ± 9.3%). The HREM image of the sample prepared with our support film improved 9% in brightness and 15% in contrast compared with images obtained with the commercial support.

The structures of light emitting porous and nanocrystalline silicon films have been investigated using high resolution electron microscopy. A pseudo-ordered structure has been found from the Fourier transformation of the high resolution images after digital processing of the images. The structure description was distinguished from common amorphous and nanocrystalline silicon films. The formation mechanism of the pseudo-ordered structure is described in the letter.