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This work investigates defect formation and evolution associated with the deposition of GaP layers on precisely oriented Si(0 0 1) substrates. The GaP layers were grown with thicknesses ranging from ∼37 nm to ∼2 µm at a growth rate of 0.52 μm/hr using molecular beam epitaxy (MBE). The crystallinity of thin (37-nm) MBE-grown GaP layers was also compared with thin GaP layers grown by migration-enhanced epitaxy (MEE). The MBE growth procedure was shown to postpone relaxation of the epitaxial GaP layers up to a thickness of ∼250 nm. Detailed analysis of high-resolution X-ray diffraction patterns and comparison with cross-sectional transmission electron micrographs clarified the defect formation mechanism. Thin GaP layers showed very low defect densities except for anti-phase boundaries, whereas substantial threading defects predominated in the thicker, noticeably relaxed structures.

The order-disorder transition in Ni-Al alloys under irradiation represents an interplay between various reordering processes and disordering due to thermal spikes generated by incident high energy particles. Typically, ordering is enabled by diffusion of thermally generated vacancies, and can only take place at temperatures where they are mobile and in sufficiently high concentration. Here, in situ transmission electron micrographs reveal that the presence of He---usually considered to be a deleterious immiscible atom in this material---promotes reordering in ${\mathrm{Ni}}_{3}\mathrm{Al}$ at temperatures where vacancies are not effective ordering agents. A rate-theory model is presented, that quantitatively explains this behavior, based on parameters extracted from atomistic simulations. These calculations show that the ${\mathrm{V}}_{2}\mathrm{He}$ complex is an effective agent through its high stability and mobility. It is surmised that immiscible atoms may stabilize reordering agents in other materials undergoing driven processes, and preserve ordered phases at temperature where the driven processes would otherwise lead to disorder.

Junctions between carbon nanotubes and flat or curved graphene structures are fascinating for a number of reasons. It has been suggested that such junctions could be used in nanoelectronic devices, or as the basis of three-dimensional carbon materials, with many potential applications. However, there have been few detailed experimental analyses of nanotube-graphene connections. Here we describe junctions between nanotubes and graphene shells in a material produced by passing a current through graphite. Transmission electron micrographs show that the junction angles are not random but fall close to multiples of 30°. We show that connections with these angles are the only ones which are consistent with the symmetry of the hexagonal lattice, and molecular models show that a continuous lattice requires the presence of large carbon rings at the junction. Some of the configurations we propose have not been previously considered, and could be used to construct new kinds of three-dimensional carbon architecture. We also discuss the possible formation mechanism of the junctions.

The present study describes an environment-friendly biosynthesis of silver nanoparticles from marine red algae Spyridia filamentosa through the bio-reduction process. S. filamentosa have significantly high amounts of phytochemicals and secondary metabolites responsible for the formation of AgNPs. UV–Vis spectra results showed corresponding AgNPs peak at 420 nm. Transmission electron micrographs showed well dispersed spherical particles with the 20–30 nm in size. FT-IR and XRD results revealed the characteristics of AgNPs. Further, the AgNPs displayed potential antibacterial activity against Staphylococcus sp. (KC688883) and Klebsiella sp. (KC899845), and anticancer activity against MCF-7 cells.

We prepared a new size-stable UV-cured material by loading a radical scavenger, 4-methoxyphenol (MEHQ), into halloysite nanotubes (HNTs) to improve the size-stability of UV-cured products. Loading the MEHQ into halloysite nanotubes was intended to protect the curing reaction from the typical inhibitive influence of a radical scavenger. After the curing process, heating treatment was performed on the cured products to accelerate the release of MEHQ from the halloysite lumen. The Brunauer-Emmett-Teller tests and transmission electron micrographs showed that MEHQ was successfully loaded into the halloysite lumen. The photopolymerization kinetic curves of composites revealed that adding the MEHQ-loaded halloysite nanotubes (HNTs-M) into UV-cured materials enabled faster photopolymerization rate than adding a simple mixture of HNTs and MEHQ. With MEHQ loaded in HNTs, the inhibition influence of MEHQ could be reduced. The results of the size-stability test showed that composites with HNTs-M underwent lower deformation during daily use than neat cured materials. In particular, the volume shrinkage of the composites with 8 wt% HNTs-M in daily use was decreased by 51.3%. The results of the release experiment showed that the release rate of MEHQ could be increased through heating treatment. This method may be used to improve the size-stability of UV-curable materials in the future.

This work described the rapid synthesis procedure for TiO2/MWCNT nanocatalyst using a modified microwave method. Transmission electron micrographs suggested TiO2 nanoparticles were strongly attached to the MWCNT. The surface area of the nanocatalysts determined by the Brunauer–Emmett–Teller method proved that the hybrid nanocatalyst have higher surface area (262.3 m2/g) than pristine TiO2 (172.3 m2/g). The photocatalytic activity of the nanocatalyst was investigated under visible light (VL) illumination by studying the degradation of methylene blue dye (MB) with concentration of 10 ppm in 100 mL H2O as a model compound. The results showed that the degradation efficiency obtained by using TiO2/MWCNTs is about 40% higher than bare TiO2. This signification enhancement was attributed to higher surface area and the ability of MWCNTs to act as a visible-light photosensitising agent revealing potential application in the treatment of wastewater.

BaSi2 epitaxial films were grown on Si(111) substrates by a two-step growth method including reactive deposition epitaxy (RDE) and molecular beam epitaxy (MBE). To enlarge the grain size of BaSi2, the Ba deposition rate and duration were varied from 0.25 to 1.0 nm/min and from 5 to 120 min during RDE, respectively. The effect of post-annealing was also investigated at 760 °C for 10 min. Plan-view transmission electron micrographs indicated that the grain size in the MBE-grown BaSi2 was significantly increased up to approximately 4.0 μm, which is much larger than 0.2 μm, reported previously.

Fe2O3–SnO2 nanocomposites (NCs) were prepared by hydrothermal and sonochemical methods. Transmission electron micrographs confirmed that the composites comprise nanoparticles. Energy-dispersive X-ray analyses revealed compositions of 25 at.% Sn and 22 at.% Fe for hydrothermally prepared NC (HNC) and 4 at.% Sn and 56 at.% Fe for sonochemically prepared NC (SNC). X-Ray diffractograms revealed rutile SnO2, γ-Fe2O3, and FeO(OH) as components of HNC, and rutile SnO2, γ-Fe2O3, β-Fe2O3 and FeO(OH) of SNC. Both NCs absorb visible light and display red emission. The solid-state impedance spectrum for HNC is a half-semicircular arc and SNC exhibits a quasi-linear relationship between Z′′ and Z′. Both NCs are ferromagnetic. The saturation magnetization of HNC is much less than that of the SNC, which in turn is far less than that of the γ-Fe2O3 precursor. Both NCs display visible light photocatalysis and HNC is a better photocatalyst than SNC. Furthermore, both NCs exhibit bactericidal activity.

This paper describes a comprehensive investigation of thick ZnTe epilayers (∼2.4 μm) grown under virtually identical conditions on GaSb, InAs, InP and GaAs (1 0 0) substrates using molecular beam epitaxy. Cross-section transmission electron micrographs of the different heterostructures showed greatly reduced defect densities away from the interface region. High-resolution electron micrographs revealed a highly coherent interface with isolated dislocations for the ZnTe/GaSb sample, and showed extensive areas with well-separated interfacial misfit dislocations for the ZnTe/InAs sample. Lomer edge dislocations with Burgers’ vector of (1/2) a 〈1 1 0〉, as well as perfect 60° dislocations, were identified at the interfaces of the ZnTe/InP and ZnTe/GaAs samples. Digital image processing based on lattice–fringe images was also used to analyze the spatial distribution of misfit dislocations at the hetero-interfaces, in particular to estimate the amount of residual strain.

This paper reports a new method to make crystal defects on the surface of multi-walled carbon nanotubes (MWCNTs) using the cobalt oxide as the oxidant for breaking carbon surface. The air oxidation of cobalt oxide (CoO) deposited on MWCNTs created various kinds of defects on their surface. Transmission Electron Micrograph (TEM) images showed clear defects such as broken crystal lines and asymmetric wall after air oxidation. X-ray powder diffraction (XRD) data showed that CoO on MWCNTs changed into Co3O4 after air oxidation. After removing Co3O4 from MWCNTs by acid, defective MWCNTs were obtained and showed defects of a clear trace where cobalt oxide had existed. This resulted from the reaction of air oxidation of CoO and carbon reduction of Co3O4, leading to the crystallinity defect of MWCNTs.

The microstructural evolution of commercial parity zirconium Zr702 with an initial grain size of ∼40 μm during equal channel angular pressing (ECAP) was investigated. ECAP was carried out at room temperature via route BC, in which the sample was rotated 90° in the same sense in each pass. After four ECAP passes, the microstructure of Zr702 revealed that the grain size decreased to ∼0.5 μm without fracture. Deformation twins were found in all the grains after the first pass of ECAP. Transmission electron micrographs of the ECAP-processed Zr702 revealed that the strain imposed during ECAP is accommodated mainly by { 1 1 2 ¯ 1 } deformation twinning.

Submicron Li 0.8 CoO 2 particles were prepared by sol–gel method, and then ball-mill grinding method was adopted to make nanosized Li 0.8 CoO 2 powders. The two kinds of powders were then examined by X-ray diffraction (XRD), ICP (inductively coupled plasma), the multi-point BET (Brunauer, Emmett and Teller) and transmission electron micrographs (TEM). It appeared that the Li 0.8 CoO 2 nanoparticles exhibited quite different electrochemical properties, such as higher open-circuit voltage and lower discharge capacity, compared to submicron Li 0.8 CoO 2 particles.

Available online : 21 July 2005 This article has been retracted: please see Elsevier Policy on Article Withdrawal ( http://www.elsevier.com/locate/withdrawalpolicy ). This article has been retracted at the request of the Editor-in-Chief. Two papers published in the Journal of Crystal Growth are being retracted due to a case of misrepresentation and reuse of data. A reader of the Journal has brought to our attention the reuse of data within two published papers: 1. Growth behavior and microstructure evolution of ZnO nanorods grown on Si in aqueous solution, Sz-Chian Liou, Chi-Sheng Hsiao, San-Yuan Chen, Journal of Crystal Growth 274 (2005) 438–446. DOI: 10.1016/j.jcrysgro.2004.10.025 2. Nucleation and growth behavior of well-aligned ZnO nanorods on organic substrates in aqueous solutions, Chin-Ching Lin, San-Yuan Chen, and Syh-Yuh Cheng, Journal of Crystal Growth 283 (2005) 141–146. DOI: 10.1016/j.jcrysgro.2005.05.065 In these papers the same transmission electron micrograph was used to describe two different experimental situations and results bringing into question the content of these papers. The reuse of data without proper attribution is not acceptable within the scientific publishing community. In the present case, this is compounded by the attribution of the micrograph to a different experimental situation and drawing , as a result, new conclusions from data obtained from different samples. Such behavior undermines the integrity of the scientific publishing endeavor and is not acceptable. The authors are responsible for the content of their papers.

Fourier transform infrared spectroscopy (FTIR), combined with ultraviolet-visible spectroscopy (UV-Vis) and transmission electron micrograph (TEM), has been used to observe the interaction between fulvic acid (FA) and hematite. The FTIR data have shown that the interaction mechanism corresponds mainly to the ligand-exchange involving carboxylic functional groups of the FA and hematite surface sites. The general trends included an increase in the content of Fe(III)-humate complexes on hematite surfaces accompanied by a decrease in pH and an increasing in the ionic strength. Both UV-Vis spectroscopy and TEM images have shown that hematite can interplay with FA under acidic conditions. In particular, the TEM images have shown that the presence of FA can significantly alter the characteristics of the hematite surfaces. Photochemical experiments have shown that hematite promotes the phototransformation of lindane (γ-HCH), whereas the presence of FA adversely affects the phototransformation of the target pollutant. The hematite coated with FA displayed a somewhat better catalyzing capability compared to the hematite only.

In order to clarify the mechanism of the bainitic transformation, a new technique utilizing interference fringes in transmission electron micrographs was applied for observations of bainitic precipitates in copper alloys. Based on the theoretical consideration of image formation, the appearance of these fringes along the interface of a precipitate was taken to be evidence of the existence of a shear-type transformation strain. From the analysis on the spacing of interference fringes, the direction and magnitude of the shear strain were obtained. It was found that the shear strain associated with bainites has almost the same crystallographic direction and magnitude as the one associated with martensites in the same alloy. On the basis of these findings, a new model on the transformation mechanism is presented, in which the dislocation motion bringing about the lattice transformation is controlled by the atomic diffusion through a local concentration change. This model consistently explains both of existence of the transformation strain and the diffusion-control nature of the transformation.

Multilayer fullerene onions present an almost perfect round shape in transmission electron micrographs. On the other hand, single-layer fullerenes seem to become polyhedral with flat faces as the number of carbon atoms grows. We study geometries of fullerenes with symmetrically arranged defects. It is shown that these structures have a rounder shape, after energy minimization with a Tersoff-Brenner potential, than fullerenes with no defects.

La0.7Ca0.3MnO3(LCMO)/Gd0.7Ca0.3MnO3(GCMO) multilayers have been prepared by pulsed laser deposition. High-resolution transmission electron micrographs demonstrate that perfect hetero-epitaxial growth has been achieved in the LCMO/GCMO superlattices with strains. In the superlattices, the resistivity-peak temperature decreases with reducing the thickness of the LCMO layers. Large low field magnetoresistance (LFMR) of Delta rho/rho(H) = 278% is obtained at 78.5 K in a LCMO/CCMO superlattice when a magnetic field swept within +/- 3100 Oe. This result suggests that the interface strains between LCMO and GCMO layers may have influences on the magnetic transport properties and a suitable film structure could be used to increase the LFMR. (C) 2000 Published by Elsevier Science S.A. All rights reserved.

The vertical ordering of GexSi1-x islands along the growth direction during low pressure chemical vapour deposition of GexSi1-x-Si bilayers on Si[001] is studied by transmission electron microscopy and analysed quantitatively using finite element method simulations. The calculation of local strain fields and the determination of an island correlation function allows one to describe the observed ordering behaviour in terms of a strain induced preferential nucleus formation above existing islands. In addition the compositions of the GexSi1-x layers are measured by a lattice fringe analysis of high-resolution transmission electron micrographs giving clear evidence for a substantial silicon germanium intermixing. The implications of these compositional modifications for the nucleation and ordering of islands are discussed indicating that islands are subjected to geometrical and compositional modifications during the growth process.

Lattice deformation in an island of Ge grown on a Si(001) surface is visualized by using Fourier transform mapping (FTM) of the transmission electron micrograph. The deformation images show not only strains normal to the Ge/Si interface but also strains parallel to the interface, as has been expected in Stranski–Krastanov growth. In addition, compression caused by the tilt of the lattice is found at the edges of the island. The compression is larger than the theoretical results calculated using a model that supposed the formation of a pure Ge island on Si substrate. This result suggests that interfacial mixing is caused by large stress at the island edges.

The geometric structure of grain boundaries in nanocrystalline Pd has been analysed in terms of power-law relationships. The power laws yielded exponents that were interpreted as fractal-like dimensions. The box-counting fractal dimension, , was computed for three images digitized from published transmission electron micrographs; the average result was . An average site occupation probability, p, was estimated for the lattices in the images, by determining the relationship between p and for pseudo-random fcc lattices. The results of further numerical simulations suggested that the grain boundaries had a box-counting fractal dimension of . The extent to which fractal theory is valid for nanocrystalline Pd is evaluated.

The authors have investigated the tunnel magnetoresistance (TMR) effect of magnetic tunnel junctions (MTJs) with Co2FeAl0.5Si0.5 full-Heusler electrodes and a MgO barrier in the thickness range of 1.5–2.5 nm. A cross-sectional transmission electron micrograph showed the epitaxial growth of both the upper and lower Co2FeAl0.5Si0.5 layers and a MgO barrier and some distortion in the MgO barrier after annealing above 400 °C. An exponential dependence of resistance × area product on MgO barrier thickness was observed. TMR ratio was strongly affected by MgO barrier thickness, exhibiting maxima of 220% at room temperature and 390% at 5 K. The latter corresponds to the spin polarization of 0.81. It was also found that the features of this MTJ include a small asymmetry voltage and weak temperature dependence of its TMR ratio.

The evolution of the microstructure of cold-deformed CuAu alloy is analyzed as a function of temperature and annealing time. Different temperature ranges were determined where the behavior of the microstructure formation during ordering of the alloy differs. The influence of the typical lamellar structure of CuAu on recrystallization was studied. Transmission electron micrographs suggest that a cooperative ‘tandem-mechanism’ involving ordering and dislocation resaturation operates and contributes to the formation of new grains. A comparison with other ordered alloys having the L1 0 , L1 2 or B2 superstructure is conducted in the paper. The role played by the immobilization of dislocation networks in retardation of recrystallization is also considered.

We studied in-plane transport of a two-dimensional hole gas in modulation-doped p-Si0.2Ge0.8 quantum wells (QWs) on Si0.5Ge0.5 relaxed buffer substrates with thicknesses L between 2.5 and 7 nm. We found that interface roughness scattering limits the low-temperature mobility μ of the samples with L between 2.5 and 4.5 nm. The interface roughness parameters were evaluated by fitting the experiment with the calculated μ limited by interface roughness scattering. We found that the obtained parameters were consistent with the values estimated from x-ray reflectivity and the transmission electron micrograph of the samples. When L is increased from 4.5 to 7 nm, μ increases only gradually and the highest μ of 0.44 m2/V s was observed for 7-nm-thick QWs. The scattering by defects, interface charge, and strain fluctuation are discussed as possible additional mobility-limiting mechanisms.

High-resolution transmission electron micrographs of {1101} interfacial twin dislocations in Ti thin films, previously published in this journal, are re-examined. Computer simulations of the experimental images have been obtained using atomic models deduced by Pond, Bacon and Serra in 1995. Two twin dislocations were analysed, with step heights of 4d(K1) and 2d(K1), where d(K1) is the spacing of the {1101) planes. Reasonable agreement with the predicted structures is obtained at about 0.17nm resolution.

The interfacial structure of [1011] twins obtained using atomic-scale computer simulation by Serra, Pond and Bacon in 1991 is shown to be qualitatively consistent with high-resolution transmission electron micrographs of such twins in Ti obtained by Kasukabe, Yamada, Peng and Bursil in 1993. In addition, images of two twinning dislocations are analysed using a circuit mapping method to determine their Burgers vectors and to demonstrate that they correspond to defects studied previously using computer simulation by Serra, Bacon and Pond in 1988 and by Serra, Pond and Bacon in 1991.

A Ti–7·5Mn–0·5B alloy has been prepared by consolidation of the rapidly solidified alloy fibres. Examination of the microstructure of the as consolidated alloy, using transmission electron microscopy, shows that the β phase has undergone the initial stage of β→ω transformation, as indicated by the circular diffused streaking in the selected area diffraction patterns from the β phase. At this stage, the bright field image of the β phase shows a mottled contrast, but it is not possible to observe the w phase using either bright or dark field transmission electron micrographs. After aging at room temperature for about six months, the advanced stage of the β→ω transformation has been observed in the β phase. This is evidenced by the discrete spots detected in the ω phase reflections in the selected area diffraction patterns and the centred dark field image taken from the β phase in the aged specimens. The thermodynamic conditions for the β→ω transformation at room temperature and its implications for ...

A long chain compound, calcium stearate ((CH 3 (CH 2 ) 16 CO 2 ) 2 Ca), was vacuum-deposited onto an amorphous carbon film kept at 0°C to form plate-like crystals, in which molecules arranged normal to the surface. After deposition, the small crystals on the substrate were annealed at 25–80°C for 5–60 min. They coalesced with each other and grew larger with increasing the temperature of the substrate and the elapsing period. The size of the crystals and the number of them in unit area were estimated by using transmission electron micrographs to confirm the mechanism of crystal growth and surface migration of long chain molecules.

YBa2Cu3O7−x (YBCO) films with BaGeO3 (BGeO), BaSiO3 (BSiO) second phase additions were processed by pulsed laser deposition. Sectored targets with BGO or BSiO wedges as well as pre‐mixed targets of YBCO, BGeO or BSiO with appropriate compositions were used to deposit YBCO+BGeO and YBCO+BSiO films on (100) single crystal LaAlO3 substrates. The cross‐sectional transmission electron micrographs showed the presence of 20 nm diameter nanocolumns in the YBCO films of both the compositions. However, the critical transition temperature (Tc) of the films was found to significantly decrease. As a result, the critical current density (Jc) in applied magnetic fields was suppressed. The YBCO+BGeO and YBCO+BSiO films made with lower concentrations of additions showed slight improvement in Tc indicating that the substitution of Ge and Si in the lattice is possibly responsible for the Tc depression. This study shows that in addition to the ability to form nanocolumns, the chemical compatibility of BaSnO3 (BSO) and BaZrO3 (BZO) as observed in YBCO+BSO and YBCO+BZO is critical to process high Jc YBCO films.YBa2Cu3O7−x (YBCO) films with BaGeO3 (BGeO), BaSiO3 (BSiO) second phase additions were processed by pulsed laser deposition. Sectored targets with BGO or BSiO wedges as well as pre‐mixed targets of YBCO, BGeO or BSiO with appropriate compositions were used to deposit YBCO+BGeO and YBCO+BSiO films on (100) single crystal LaAlO3 substrates. The cross‐sectional transmission electron micrographs showed the presence of 20 nm diameter nanocolumns in the YBCO films of both the compositions. However, the critical transition temperature (Tc) of the films was found to significantly decrease. As a result, the critical current density (Jc) in applied magnetic fields was suppressed. The YBCO+BGeO and YBCO+BSiO films made with lower concentrations of additions showed slight improvement in Tc indicating that the substitution of Ge and Si in the lattice is possibly responsible for the Tc depression. This study shows that in addition to the ability to form nanocolumns, the chemical compatibility of BaSnO3 (BSO) and BaZrO3...

A new method for recording multiple dark-field transmission electron micrographs using a scanning transmission electron microscope fitted with a quadrant detector is described. Simultaneous multiple recording is particularly advantageous when studying electron beamsensitive polymers and images of crystals of poly(butylene terephthalate) are presented by way of example. Resolution levels of ca. 10 nm are demonstrated.

We report on the antiphase boundaries network of ${\mathrm{Fe}}_{3}{\mathrm{O}}_{4}(111)$ thin films. $5\text{\ensuremath{-}}\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}50\text{\ensuremath{-}}\mathrm{nm}$-thick samples were epitaxially grown by molecular beam epitaxy onto $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Al}}_{2}{\mathrm{O}}_{3}(0001)$ substrates. The magnetic properties of the samples have been interpreted within the framework of a one-dimensional model of antiphase boundary (APB), which predicts that the magnetization is given by ${M}_{\ensuremath{\infty}}(1\ensuremath{-}b∕\sqrt{H})$ in the approach to saturation regime. Transmission electron micrographs of several samples were used to extract the statistical parameters of the APB network, particular emphasis being put on the relevance and statistical significance of the studied parameters. The mean antiphase domain size $\overline{D}$, as the antiphase boundaries characteristic length ${l}_{0}$ extracted from a fractal analysis, vary as the square root of film thickness/deposition time and are within the $10\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ range. The APB density was found to vary as $1∕{l}_{0}$ as expected from the fractal dimensions of the network. The dependency of the $b$ parameter of the magnetic model on the APB density is finally analyzed in the light of micromagnetic simulations of chains including finite size antiphase domains and two APBs.

The cover shows transmission electron micrographs of typical microstructures in as-deposited copper samples. More about recent developments in nanostructured materials research can be found in the review paper by C. Suryanarayana on page 983. Nanostructured materials with extremely fine grain sizes, typically less than 100 nm, have been shown to exhibit extremely high strength and hardness, increased diffusivity, useful sintering characteristics, and other unusual properties. Significant developments have taken place in recent years in trying to achieve high strength and ductility at the same time. New and potential applications are also being sought after. Several commercial ventures have also started (estimated to be around 1000 in different parts of the world). This overview will present the recent developments in our understanding of the mechanical behavior and molecular dynamics simulation studies, highlight the present unresolved issues, and discuss some of the promising applications for these novel and exciting materials.

Results are presented of complementary measurements that probe the electronic structure and charge-density wave (CDW) modulation in the quasi-two-dimensional compounds $\mathrm{La}{\mathrm{Te}}_{1.95}$ and $\mathrm{Ce}{\mathrm{Te}}_{2}$. Transmission electron micrographs show that the modulation wave vectors associated with the CDW are different for the two materials, and in both cases are incommensurate with the underlying lattice. These wave vectors are shown to correspond to nesting features of a simplified model of the Fermi surface. Angle-resolved photoemission spectroscopy is used to reveal the electronic structure and Fermi-surface topology in the CDW state. The data indicate a large CDW gap that varies in magnitude around the Fermi surface somewhat differently for the two compounds. Differences in the volume of the original Fermi surface are related to the doping effect of Te vacancies. Heat-capacity measurements at low temperatures indicate a very small electronic density of states, consistent with the electrical resistivity, which appears to be semiconducting or semimetallic.

In Pd/Si multilayers grown by sputtering Pd and Si alternatively, Pd 2 Si is formed during sputtering when the sublayer thickness of Pd is less than 2 nm, and no silicide is found when Pd sublayer is thicker. The transmission electron micrographs and electron diffraction patterns of Pd and Si single layers with various thicknesses show that thin Pd films 0.9–1.4 nm thick are island-like and all the Si films are homogeneous and amorphous. It is suggested that the sputtered Si particles carrying high energy can result in a big local temperature rise of the Pd islands and promote Pd and Si atoms to interdiffuse and react with each other to form Pd 2 Si.

Anomalous misfit strain relaxation was found in the large lattice-mismatched YBa2Cu3O7-δ /MgO heterostructure system. No breakdown of the lattice coherency along the growth direction was found in X-ray diffraction independently of the critical layer thickness hc (~12A). Transmission electron micrographs clearly revealed that the large misfit was relaxed within 1 unit lattice of YBa2Cu3O7−δ at the heterointerface.

This paper reports a robust approach for jet-processing viscous media in both the single- and multi-phase. The multi-phase medium (a nanosuspension) has nanosized SiO2 (5 nm) particulate material at a loading of ∼10 wt% in suspension. Aerodynamically assisted jetting has previously not been applied to the processing of particulate-based high viscosity nanosuspensions. Our investigations demonstrate that it is possible to generate jets, from which droplets are initiated by jet fragmentation, to the drawing of continuous threads in the micrometer range from the processing of particulate suspensions. The study presents an operational guide of applied pressure–flow rate; demarcations identify regions within the map where droplets and threads are generated, together with their respective operational parameters. The effect of applied pressure and flow rate on the jetting process to the generation of droplets to threads together with transmission electron micrographs of the droplet residues forms the discussion in this paper. These investigations into this jetting approach both elucidate and welcome aerodynamically assisted jetting into the micro- and nano-fabrication arena.

The two‐ (2D) to three‐dimensional (3D) growth mode transition during the initial stages of growth of highly strained InxGa1−xAs on GaAs is used to obtain quantum dot structures. Transmission electron micrographs (TEM) reveal that when the growth of InxGa1−xAs is interrupted exactly at the onset of this 2D–3D transition, dislocation‐free islands (dots) of InGaAs result. Size distribution measurements from TEM images indicate that these dots are less than 300 A in diameter and remarkably uniform. A phase diagram is constructed, showing the growth conditions under which these strained coherent uniform dots form. Photoluminescence from layers containing these dots is observed and correlated with growth conditions and with structural data obtained from TEM images. We observe that the photoluminescence emitted from the dots and an underlying reference quantum well are nearly equal, indicating a high quantum efficiency for these quantum dots.

We propose a position space renormalization group approach based on Kadanoff's block method, for the calculation of an effective dielectric function of cermet type films (3D) or island films (2D). The results obtained on simulated lattices account for both the resonant absorption and the optical cross-over corresponding to the metal-nonmetal transition. The effective dielectric function is found to obey scaling laws with critical exponents s 3D = 0.75 and s 2D = 1.35 for polarization terms and t 3D = 2.2, t 2D = 1.52 for the conduction, very close to the theoretical estimates. These models have also been applied to digitized transmission electron micrographs of 2D and 3D systems, and we obtain a very good agreement with most of the experimental data.

Amorphous Ni sub chi Nb sub chi-1 powders were prepared by mechanical alloying for 0.2 smaller than chi smaller than 0.8. The structural refinement during milling was studied by optical and electron microscopic examinations. The data are in good agreement with Benjamin's model. Transmission electron micrographs give the first direct evidence that the mechanisms of amorphization by mechanical alloying is governed by a solid state interdiffusion reaction. (IFAM)

Films of sphalerite structure CdTe grown on (100) faces of Ge were annealed in vacuum for 6 to 9 h at 400 °C. This greatly reduced the number of planar defects in the films and eliminated the streaks from their diffraction patterns. Similar annealing of the (0001) wurtzite-structure films of CdTe grown on (111) surfaces of Ge had no effect on the structure of the CdTe films. Moire fringes with a 15 A spacing were seen in transmission electron micrographs of as-grown CdTe (111) Ge heterojunctions in regions in which equal thicknesses of CdTe and Ge overlapped. Instead of Moire fringes, lines with a 160 A spacing were seen in these heterojunctions after annealing. This can be interpreted as a consequence of interdiffusion of the CdTe and Ge across the interface to form a graded heterojunction. Co-evaporation of CdTe and 5 wt% of excess To produced a new type of planar {111} defect in the films grown on (100) Ge. The likelihood of structurla changes therefore must be taken into account when considering the effects of annealing on the electrical or optical properties of II–VI compounds, and of II–VI heterojunctions. CdTe-Schichten mit Sphaleritstruktur auf (100)-Flachen von Ge wurden 6 bis 9 Stunden im Vakuum bei 400 °C getempert. Dabei wurde die Anzahl der ebenen Defekte in den Schichten stark vermindert und die Streifen von ihren Beugungsbildern eliminiert. Eine ahnliche Temperung von (0001)-CdTe-Schichten auf (111)-Oberflachen von Ge hat keinen Einflus auf die Struktur der CdTe-Schichten. Moirestreifen mit 15 A Abstand werden in den Transmissionselektronendiagrammen von ursprunglichen CdTe (111) Ge-Heteroubergangen in Bereichen beobachtet, in denen sich gleiche Dicken von CdTe und Ge uberlappen. Anstelle von Moirestreifen werden Linien mit 160 A Abstand in diesen Heteroubergangen nach Temperung beobachtet. Dies last sich als Folge einer Interdiffusion des CdTe und Ge uber die Grenzflache deuten, wobei ein graduierter Heteroubergang gebildet wird. Gleichzeitige Verdampfung von CdTe und 5 Gew% Uberschus-Te produziert einen neuen Typ von ebenen {111}-Defekten in auf (100)-Ge gewachsenen Schichten. Die Wahrscheinlichkeit von strukturellen Anderungen mus deshalb in Betracht gezogen werden, wenn die Temperungseinflusse auf elektrische oder optische Eigenschaften von II–VI-Verbindungen und von II–VI-Heteroubergangen untersucht werden.

Direct lattice imaging techniques are used to study the syntaxy between β and β″ structures in aluminum/sodium oxide and gallium/sodium oxide. An imaging code for the β and β″ type compounds enables direct recognition, from the transmission electron micrographs, of the variations of stacking sequences between the two phases. The syntaxial plane which is obersevd is of {00l} type. Les techniques de visualisation de reseau sont appliquees a l'etude de la syntaxie entre les structures de type β et β″ dans les aluminates et gallates de sodium. Elles permettent une observation directe, a partir de micrographies electroniques par transmission, des variations de sequences d'empilement entre les composes de type β et β″. Le plan de syntaxie observe est du type {00l}.

Grain boundary structure and energy have an influence on the formation of the annealing texture as well as the material ability to continue the steady state deformation at high temperatures. Texture measurements together with the statistical distribution of grain boundary rotation parameters show changes during high temperature deformation. Annealed structure contains grain boundaries having rotation parameters in certain favoured groups. Such groups do not necessarily belong to any low indexed coincidence orientation relationship, even though periodic contrast of grain boundary dislocations in numerous boundaries is resolved in the transmission electron micrographs. The texture becomes stronger during the high temperature deformation with increasing strain compared with the annealed texture. The rotation parameters of grain boundaries in deformed structure include often few degrees rotations from certain coincidence orientation relationship, but they do not, however, show such a grouping of rotation parameters as in the annealed structure. Furthermore, rotation angles of small angle boundaries were found to increase with increasing deformation strain at high temperature. Several mechanisms of grain boundary sliding are interpreted based on the structural observations. Finally, based on the existence of orientation relationship groups, estimates for low energy grain boundaries are presented.

We have measured the response of WC/C multilayers to x-ray fluxes on the order of 200 MW/cm2 using laser-generated plasmas and found that these multilayers will maintain near peak reflectivity for at least 1 ns but are eventually destroyed. A description of the experiments and data analysis methods is given. Transmission electron micrographs of WC/C multilayers before and after irradiation show melting to be the dominant damage mechanism. The results of the experiments will be compared with simulations.

The tribological failure sequence of polytetrafluoroethylene (PTFE) and carbon-fiber-reinforced PTFE was investigated by means of microstructural observation and wear rate measurement under air and water lubricants. A morphological model of the detailed wear processes involved is presented to explain the observed scanning and transmission electron micrographs and the model is correlated with the measured wear rate data.

In small areas InP has epitaxially been grown by organometallic vapour phase epitaxy on synthetically grown lattice-adapted garnet substrate. Two one-dimensional lattice-matching relations have to be fulfilled. A high-resolution transmission electron micrograph shows that a somewhat inclined (001) InP surface is grown on a ( 1 11) garnet substrate in agreement with the matching relations.

A new method is proposed for the analysis (vacancy or interstital) of dislocation loops by means of the so-called inside-outside contrast. A simple and straightforward recipe is developed which is applicable in the same manner to loops of edge and of non-edge type irrespective of the loop orientation within the transmission foil; in particular, there is no reason for a subdivision of the loop orientations into “safe” and “unsafe” orientations as required when applying the method of Maher and Eyre. Es wird eine neue Method vorgeschlagen, um anhand des sogenannten “inside-outside” Kontrastes von Versetzungsringen deren Natur (Leerstellen-bzw. Zwischengitteratom-Typ) zu bestimmen. Es ergibt sich eine einfache und einheitliche Verfahrensvorschrift, die in gleicher Weise auf Versetzungsringe mit und ohne Scherkomponente angewandt werden kann, unabhangig von der Ringorientierung in der Durchstrahlungsprobe. Insbesondere bedingt diese Vorschrift keine Aufteilung der Ringorientierungen in „sichere” und „unsichere” Orientierungen, wie dies bei Anwendung der Methode von Maher und Eyre erforderlich ist.

Direct lattice imaging techniques are applied to study stacking sequences and sequence faults in hexagonal ferrites of the M n S-type. A similar imaging code as deduced for the M 2 Y n -type compounds enables direct recognition of the stacking sequences from the high resolution transmission electron micrographs. Hexagonal ferrite crystals with stacking sequences of the type M, MS, M 2 S and M 4 S have been investigated.

Cu-Cr alloys which were given various aging and reversion treatments were investigated in terms of electrical resistivity and hardness. Transmission electron microscopy was one technique employed. Some results obtained are as follows: the increment of electrical resistivity after the reversion at a constant temperature decreases as the aging temperature rises. In a constant aging condition, the increment of electrical resistivity after the reversion increases, and the time required for a maximum reversion becomes shorter as the reversion temperature rises. The reversion phenomena can be repeated, but its amount decreases rapidly by repetition. At first, the amount of reversion increases with aging time and reaches its maximum, and then tends to decrease again. Hardness changes by the reversion are very small, but the hardness tends to soften slightly. Any changes in transmission electron micrographs by the reversion treatment cannot be detected.

Copper single crystals oriented for single glide were deformed in tension at 78 °K to various resolved shear stresses and were then neutron-irradiated at 4 to 20 °K before stress-removal in order to pin the dislocations in the stress-applied state. A comparison of transmission electron micrographs obtained from the centre and the surface regions shows that, from early stage II onwards, the dislocation arrangement in the surface region corresponds to a lower stress than that in the centre. At the same time the dislocation density is distinctly lower in the surface region than in the interior. Furthermore, X-ray investigations show that during deformation the primary glide plane is bent characteristically near the surface in the direction of the slip vector. Details of these results, which are in good qualitative agreement with flow stress measurements and electron microscope work of Fourie, are discussed and compared with the literature.

Theories of dispersion-phase-strengthening are briefly discussed and then critically examined in the light of experimental evidence obtained with nickel containing a fine dispersion of thoria. The results are in close agreement with Orowan's theory. The work-hardening theory of Fisher, Hart, and Pry, though in qualitative agreement with the experimental results, postulates the formation of concentric dislocation loops around particles of the dispersed phase. Transmission electron micrographs of the nickel-thoria indicate that the formation of prismatic loops near to particles is a more likely process, and this is borne out by analysis of the experimental results.