Zigzag Morphology Research Articles

Hierarchical hollow microspheres assembled from N-doped carbon coated Li4Ti5O12 nanosheets with enhanced lithium storage properties

Hierarchical hollow microspheres composed of N-doped carbon coated Li4Ti5O12 nanosheets (NC-LTO) have been synthesized on a large scale by a facile low-temperature solution-based approach combined with high temperature calcination. The primary Li4Ti5O12 nanosheets show zigzag morphology with a typical thickness of about 5.0 nm, which are uniformly coated with N-doped carbon layers. When evaluated for lithium storage capacity, the NC-LTO hollow microspheres display enhanced electrochemical energy storage performances compared to the pristine hollow microspheres composed of Li4Ti5O12 nanosheets (A-LTO), including high capacity (181.4 mA h g−1 at 0.5 C), excellent rate capability (140.8 mA h g−1 at 20 C), and good cyclic stability (92.8% capacity loss after 100 cycles at 20 C). The reasons for these improvements are explored in terms of the increased electronic conductivity and the facilitation of lithium ion transport arising from the introduction of N-doped carbon layers and the thin zigzag Li4Ti5O12 nanosheets.

Convenient synthesis of Ag nanowires with tunable length and morphology

Ag nanowires with zigzag and linear morphologies were fabricated using a one-pot polyol synthesis. The diameters of the nanowires were adjusted from 50 to 200nm by changing the concentration of PVP in reaction solutions. Quasi-cubic particles, linear nanowires, and zigzag nanowires were created through adjusting the reaction parameters. Cl− and O2 govern the morphology of resulting samples. Reaction time and temperature, as well as the kind of solvents affected the morphologies of the linear nanowires. The bending angles of the zigzag nanowires were varied with changing preparation parameters. These results indicate that twinned-crystal seeds play an important role for the growth of anisotropic Ag nanowires. The morphology of Ag nanostructures can be tuned by controlling the interplay between the population of the twinned-crystal seeds and the concentration of NaCl.

Study of Japanese sword from a viewpoint of steel strength

Abstract Two Japanese swords produced by 70 years ago and 600 years ago were investigated. Four-point bending test has been performed to estimate the strength of sharp edge of Japanese sword for the first time. The strength of sharp edge with fine lath martensite microstructure was evaluated, taking the specimen geometry of bending test into consideration. The strength of modern sword is estimated as high as approximately 4500 MPa (by four point bend test) and is considered to be a great value along with high hardness, which is comparable with the value of high performance tool steels. The fracture surface showed that the crack propagation behavior is smooth around sharp edge and ductile like the zigzag morphology from wavy pattern region into the core region.

Ordered Zigzag Stripes of Polymer Gel/Metal Nanoparticle Composites for Highly Stretchable Conductive Electrodes

Highly stretchable conductive composite lines with an ordered zigzag structure are prepared. The high stretchability arises from the interpenetrating network between the polymer gel and Ag nanoparticles, as well as the ordered zigzag morphology. Double transfer of the structures in a perpendicular configuration allows for the fabrication of 2D stretchable electrodes.

Aligned TiO2 nanocolumnar layers prepared by PVD-GLAD for transparent dye sensitized solar cells

Transparent thin film electrodes made of vertically aligned nanocolumns of TiO2 with well-controlled oblique angles were grown by physical vapor deposition at glancing incidence (PVD-GLAD). For an electrode thickness of 500 nm, we report a 40% variation on solar cell efficiency (from 0.6% to 1.04%) when the deposition angle was modified between 60° and 85°. Transparent thicker films with higher surface area deposited at the optimal angle of 70° were grown with a zigzag morphology which confers high mechanical strength to the thin films. Using this topology, the application of an electrode thickness of 3 µm in a DSC resulted in a power conversion efficiency of 2.78% maintaining electrode transparency.

Synthesis and Structural Characterization of Single Crystalline Zigzag SnO<SUB>2</SUB> Nanobelts

Freestanding single crystalline zigzag SnO2 nanobelts have been synthesized by a simple thermal evaporation on an iron cylindrical sharp substrate. The heating temperature and Ar gas flow rate are two key points to control the morphology of the nanobelts. The morphology and the microstructure of the nanobelts have been characterized with a number of microscopic techniques. Crystallographic analyses revealed that the zigzag morphology is formed with alternating growth directions between two energy-equal (101) and (101) planes. Moreover, structural and compositional characterization show that the nanobelts do not grow directly on the iron substrate but on the small crystalline grains deposited on the iron oxide columns, which are ascribed to the oxidation of the iron substrate.

MoTea4-Mediated Polarized Growth Is Essential for Proper Asexual Development and Pathogenesis in Magnaporthe oryzae

Polarized growth is essential for cellular development and function and requires coordinated organization of the cytoskeletal elements. Tea4, an important polarity determinant, regulates localized F-actin assembly and bipolar growth in fission yeast and directional mycelial growth in Aspergillus. Here, we characterize Tea4 in the rice blast fungus Magnaporthe oryzae (MoTea4). Similar to its orthologs, MoTea4-green fluorescent protein (MoTea4-GFP) showed punctate distribution confined to growth zones, particularly in the mycelial tips, aerial hyphae, conidiophores, conidia, and infection structures (appressoria) in Magnaporthe. MoTea4 was dispensable for vegetative growth in Magnaporthe. However, loss of MoTea4 led to a zigzag morphology in the aerial hyphae and a huge reduction in conidiation. The majority of the tea4Delta conidia were two celled, as opposed to the tricellular conidia in the wild type. Structure-function analysis indicated that the SH3 and coiled-coil domains of MoTea4 are necessary for proper conidiation in Magnaporthe. The tea4Delta conidia failed to produce proper appressoria and consequently failed to infect the host plants. The tea4Delta conidia and germ tubes showed disorganized F-actin structures with significantly reduced numbers of cortical actin patches. Compared to the wild-type conidia, the tea4Delta conidia showed aberrant germination, poor cytoplasmic streaming, and persistent accumulation of lipid droplets, likely due to the impaired F-actin cytoskeleton. Latrunculin A treatment of germinating wild-type conidia showed that an intact F-actin cytoskeleton is indeed essential for appressorial development in Magnaporthe. We show that MoTea4 plays an important role in organizing the F-actin cytoskeleton and is essentially required for polarized growth and morphogenesis during asexual and pathogenic development in Magnaporthe.

Effects of Chlorinated Trans-1,4-polyisoprene on Cure, Morphology, and Mechanical Properties of Neoprene Blends and Their Vulcanizates

Chlorinated trans-1,4-polyisoprene (CTPI) was synthesized by a water phase suspension method. The crystalline morphology of nascent CTPI was characterized by polarizing optical microscopy (POM). The effect of CTPI on the curing characteristics, mechanical properties, and fracture surface of neoprene/trans-1,4-polyisoprene (CR/TPI) blend vulcanizates were investigated. The experimental results showed that the scorch time and the optimum time of CR/TPI/CTPI compounds were shortened with the incorporation of CTPI into the compounds. At the same time, the dispersibility of carbon black in the compounds was improved. With the incorporation of CTPI into the CR/TPI compounds, the fatigue failure surface of CR/TPI/CTPI vulcanizate was quiet different from that of CR compounds. The flexing resistance of CR/TPI/CTPI vulcanizates obviously improved, and the fatigue failure surface showed zigzag morphology. Dynamic mechanical analysis (DMA) revealed that the compatibility between CR and TPI was improved with the incorporation of CTPI into CR/TPI blends.

Effects of twin and surface facet on strain-rate sensitivity of gold nanowires at different temperatures

We use classical molecular-dynamics simulations to examine the strain-rate sensitivity of single-crystalline and twinned Au nanowires (NWs) with a diameter of 12.3 nm deformed in tension at temperatures between 10 K and 450 K. It is found that the strain-rate sensitivity above 100 K is significantly smaller in twinned Au NWs with perfectly circular cross-section than in similar NWs without twins, while the activation volume remains in the same range of $1{b}^{3}--15{b}^{3}$ with $b$ the magnitude of Burgers vector. This behavior is markedly different from that generally observed in bulk face-centered cubic metals where addition of nanoscale twins increases both strength and strain-rate sensitivity. Furthermore, our simulations show a threefold decrease in strain-rate sensitivity in twinned Au NWs with zigzag morphology constructed by assembly of {111} surface facets in comparison to the different types of circular Au NWs. The rate-controlling deformation mechanisms related to surface dislocation emission and twin-slip interaction, and their dependence on temperature and surface morphology are analyzed in detail. The combination of ultrahigh strength and decreased sensitivity to strain-rate predicted above 100 K in twinned Au NWs with faceted surface morphology holds great promise for creating metallic nanostructures with increased failure resistance to extreme loading conditions.

Three-dimensional analysis of microstructures in titanium

Samples of Ti–4.3Fe–6.7Mo–1.5Al were isothermally annealed in the temperature range of 730–780 °C for various times to study the β–α transformation. Serial sectioning in conjunction with both optical and EBSD analyses was applied to determine the three-dimensional (3-D) morphologies of primary α phase. The 3-D analysis proved to be essential for characterization of the complex morphologies of α grains and consequently for the identification of growth behavior. It showed that nucleation of α grains takes place at β–β grain boundaries and significant branching takes place after initial growth of α grains along β–β grain boundaries. Some branches grow inside the β grain interior. The branching behavior is shown to interact with β–β grain boundaries, leading to a zig-zag morphology. The presented 3-D analysis of α grains and their influence on β–β grain boundaries clearly show that 2-D observations of the microstructural morphologies are not sufficient to adequately represent the transformation characteristics.

Self-assembly of end-tethered nanorods in a neat system and role of block fractions and aspect ratio

We report a computational study of the self-assembly of end-tethered nanorods in a neat system (no solvent). We present morphological phase diagrams for low and moderate aspect ratio rods as a function of inverse temperature vs. relative tether fraction. Our simulations predict that the end-tethered rods self-assemble into hexagonally arranged chiral cylinders, hexagonally perforated lamellae, monolayer and bilayer arrowhead structures and wavy lamellae. For high aspect ratio tethered nanorods and small tether fractions, we observe that the tethered nanorods self-assemble into smectic and zig-zag lamellar morphologies.

Zn-Doped Gallium Nitride Nanotubes with Zigzag Morphology

Zn-doped gallium nitride (GaN) nanotubes with zigzag morphology have been synthesized by a chemical vapor deposition method. A single-crystalline zigzag nanotube consists of two building blocks with equivalent growth directions, hexagonal cross sections, and about 10 nm wall thicknesses. The formation of the nanotube is attributed to the reduction of electrostatic interaction energy caused by the polar side surfaces of GaN. A room temperature photoluminescence spectrum of Zn-doped GaN nanotubes with zigzag morphology shows two peaks at 2.97 and 2.16 eV, respectively.

Bicrystal AlN Zigzag Nanowires

Bicrystal AlN zigzag nanowires have been synthesized by directly nitriding aluminum powders using Fe(NO3)3 as a catalyst. The structural characterizations reveal that there are three types of grain boundaries between the two single crystals. The lattice mismatches along these boundaries cause asymmetrical residual stresses, which tilt these boundaries to different directions, leading to the formation of a zigzag morphology. The transitions between these boundaries offset these lattice mismatch stresses and stabilize the structure.

Synthesis and characterization of silver nanowires with zigzag morphology in N, N-dimethylformamide

Zigzag silver nanowires with a uniform diameter of 20±5 nm were prepared by reducing silver nitrate (AgNO 3) with N, N-dimethylformamide (DMF) in the presence of tetrabutyl titanate (TBT) and acetylacetone (AcAc) at 373 K for 18 h. X-ray and selected area electron diffraction (XRD and SAED) patterns reveal that the prepared product is made of pure silver with face centered cubic structure. Transmission electron microscopy (TEM) investigations suggest that the amount of silver nanowires is enhanced with increase in reaction time, and the end-to-end assemblies of silver nanorods are observed during the reaction process. After 18 h reaction, silver nanowires with zigzag morphology are obtained. In this paper, a possible growth process of silver nanowires with this interesting shape is described. Silver nanoparticles with small sizes were obtained by reducing Ag + ions with DMF, providing seeds for homogeneous growth of silver nanorods. With the extending reaction time, the synthesized silver nanorods were connected in an end-to-end manner, and the interface between the connections of two nanorods gradually disappeared. The final product shows zigzag morphology with various angles. The angles between two connecting straight parts of zigzag nanowires exhibit an alterable range of 74–151°. These silver nanowires show tremendous potential applications in future nanoscale electronic circuits.

The atomic-scale studies of the behavior of the crystal dissolution in a molten metal

The early atomic-scale dissolution behavior of Cu in a molten pure Sn was studied by transmission electron microscope (TEM). The innermost region adjacent to the Cu lattice is an amorphous Cu–Sn diffusion zone that contains dispersed ε-Cu 3Sn nanocrystalline cells. The zigzag morphology reveal between Cu lattice and amorphous Cu–Sn diffusion zone. The height of step is about 0.2–1.1 nm on the terrace. The formation of zigzag morphology is initiated by preferential removal of Cu atoms from the kink sites on the crystal surface. The dissolved atoms form an amorphous Cu–Sn diffusion zone. This diffusion zone is a non-saturated state prior to further formation of crystalline cell.

Preparation and Characterization of Straight and Zigzag AlN Nanowires

Hexagonal single-crystal AlN nanowires with straight or zigzag morphologies were successfully synthesized by the reaction of aluminum alloy in an ammonia/nitrogen atmosphere at 1100 degrees C. It is found that the crystal tropism of the nanowires is along [0001], whereas the growth directions of the zigzag nanowires shift between [2111] and [2111].

Multiple Sharp Bendings of Carbon Nanotubes during Growth to Produce Zigzag Morphology

Carbon nanotubes have been grown with a sharply defined zigzag structure by introducing changes in the direction of applied electric field during dc plasma enhanced chemical vapor deposition (PECVD). The nanotubes maintain the same diameter before and after each bend while preserving the catalyst particle at the tip of growing nanotubes. The bends have very sharp radii of curvature of only ∼25 nm. As a simple inclined field direction cannot produce such a zigzag growth due to the tendency of field lines intersecting perpendicular to the local surface, the bending has been introduced primarily by dramatically manipulating the electric field lines through controlled movement of field-concentrating conductor plates.

Effect of oxygen adsorption on the structure and spin-reorientation transition of Fe films on Cu(1 1 25)

The morphology, structure, and magnetism of Fe films on an oxygen-precovered, stepped Cu(1 1 25) surface are investigated by scanning tunneling microscopy, low-energy electron diffraction, and magneto-optical Kerr effect analysis. After exposure of Cu(1 1 25) to about 600 L of oxygen at 493 K, a well-ordered (2√×√)R45° superstructure is formed. The O-induced structure has a zig-zag morphology, showing a high density of facets and is very stable during subsequent Fe deposition. Fcc Fe can be stabilized up to 20 monolayer (ML) thickness, while the magnetization of the films reorients from perpendicular to in-plane at 15 ML. From 24 ML, the linear extrapolation line of the thickness dependence of the Kerr intensity of the transformed bcc Fe films does not go along with the pure fully magnetized bcc Fe films. We conclude that oxygen adsorption strongly affects the structure and spin-reorientation transition of Fe films.

Morphology of zigzag carbon nanofibers prepared by catalytic pyrolysis of acetylene using Fe-group containing alloy catalysts

The morphologies of the two-dimensional (2D) zigzag carbon nanofibers obtained by the catalytic pyrolysis of acetylene using the Fe-containing catalysts are examined in detail, and the growth mechanism is also discussed. Using the alloy catalyst of Fe-38Cr-4Mn-4Mo at the reaction temperature 750–790 °C, the zigzag carbon nanofibers were formed at a higher content (20–50%) in deposits together with the twisted carbon nanocoils. The morphology of the zigzag carbon nanofibers mainly depended on the catalysts, and carbon nanofibers with various zigzag morphologies were obtained. The growth of large amounts of regular zigzag carbon fibers was observed in the presence of the high Fe-containing alloy catalyst, suggesting that the Fe element plays an important role in the formation of the regular zigzag carbon nanofibers. There is some possibility of masking or deactivating of one crystal face among the three catalyst crystal faces by the Fe element, and thus only two crystal faces are involved in the growth of the 2D-zigzag fibers while the three dimensional-helical/spiral structure of the carbon nanocoils is formed from three crystal faces.

EBSD and TEM study of self-accommodating martensites in Cu 75.7Al 15.4Mn 8.9 shape memory alloy

Morphologies and orientation relationships of martensites in Cu 75.7Al 15.4Mn 8.9 shape memory alloy were studied for the first time by means of electron backscatter diffraction (EBSD) technique, transmission electron microscopy (TEM) and phenomenological calculation. The martensite was identified to be an 18R 1 type monoclinic one with its β angle very close to 90°. Each plate group of martensite variants consists of four variants A, B, C and D showing characteristic spear- and fork-like morphologies. Variants A and C (and equivalently B and D) are twin-related with respect to the ( 1 ̄ 2 ̄ 8) 18 R plane of the 18R 1 martensite, which is transformed from, and nearly parallel to (with an error of only 0.60°), a (0 1 1) P plane of the parent phase. Variant-pair A–D (and equivalently B–C) is twin related with respect nearly to the (2 0 20) 18 R plane, which is transformed from a ( 1 ̄ 0 0) P parent plane. However, the discrepancy between these two planes, (2 0 20) 18 R and ( 1 ̄ 0 0) P , is 2.01°, larger than that (0.60°) between ( 1 ̄ 2 ̄ 8) 18 R and (0 1 1) P . Therefore, this twin boundary prefers to consist microscopically of several low index planes, forming a zigzag morphology, as observed by TEM. Phenomenological calculation of the cubic D0 3 parent phase to monoclinic M18R 1 martensite transformation revealed that although the magnitude of the shape strain produced by the martensitic transformation is calculated to be rather large ( m=0.2005), the average shape deformation of each self-accommodating plate group is rather small. And the total average shape deformation for six plate groups becomes nearly zero, except for a small volume contraction. The angles between the basal plane of the 18R 1 martensite and the twin planes of different variant-pairs in a plate group, determined from EBSD and TEM experiments, are consistent with phenomenological calculations.