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Vertically aligned, untangled planarized arrays of multiwall carbon nanotubes (MWNTs) with Ohmic back contacts were grown in nanopore templates on arbitrary substrates. The templates were prepared by sputter depositing Nd-doped Al films onto W-coated substrates, followed by anodization to form an aluminum oxide nanopore array. The W underlayer helps eliminate the aluminum oxide barrier that typically occurs at the nanopore bottoms by instead forming a thin WO3 layer. The WO3 can be selectively etched to enable electrodeposition of Co catalysts with control over the Co site density. This led to control of the site density of MWNTs grown by thermal chemical vapor deposition, with W also serving as a back electrical contact. Ohmic contact to MWNTs was confirmed, even following ultrasonic cutting of the entire array to a uniform height.

We investigate the structure of 1/3 <0[bar.1]11> dislocations observed in [Bi.sub.2][Te.sub.3] nanowires. This particular type of dislocation is interesting because it has a large Burgers vector (b = 1.048 nm) with a component normal to the basal planes equal to the thickness of one full [Bi.sub.2][Te.sub.3] quintuple unit (i.e., c/3). Atomic-resolution high-angle annular dark-field scanning transmission electron microscopy observations show that the dislocations form with a complex dissociated core structure. This structure consists of two partial dislocations that separate a defected region consisting of a seven-plane-thick septuple unit, consistent with a local patch of [Bi.sub.3][Te.sub.4], rather than the normal [Bi.sub.2][Te.sub.3] quintuple layer structure. As we discuss, details of the core structure can be understood from an analysis of the crystallographic parameters of the observed partial dislocations. This analysis suggests a mechanism to accommodate the loss of tellurium through the heterogeneous nucleation and growth of seven-layer defects at 1/3 <0[bar.1]11>--type dislocations.

Chemical solution deposition (CSD) is used to grow high-quality (100)-oriented films of SrTiO3 (STO) on CSD Ba0.2 Ca0.8TiO3(100) (BCT) templates on textured W-doped Ni(100) (Ni:W) tape substrates. The BCT template films form a thin layer or “skin” that bridges its significant porosity. STO films grown at 1000 °C appear optimized for heteroepitaxial orientation, surface coverage, and film smoothness. Both interfaces in the STO(100)/BCT(100)/Ni:W(100) stack demonstrate excellent atomic registry and compositional abruptness. Doping STO with a few atomic percent of Nb reduces oxygen diffusion into the film by an order of magnitude and provides greater protection to the Ni interfacial surface from oxidation during the growth of additional functional oxides requiring relatively higher p(O2) high-temperature processing, such as superconducting YBa2Cu3O7−δ. CSD growth of BCT and STO also planarizes pre-existing grooves in the Ni:W(100) tapes while maintaining a high degree of orientation by forming facets at the interfaces.

Free-standing aligned carbon nanotubes have previously been grown above 700°C on mesoporous silica embedded with iron nanoparticles. Here, carbon nanotubes aligned over areas up to several square centimeters were grown on nickel-coated glass below 666°C by plasma-enhanced hot filament chemical vapor deposition. Acetylene gas was used as the carbon source and ammonia gas was used as a catalyst and dilution gas. Nanotubes with controllable diameters from 20 to 400 nanometers and lengths from 0.1 to 50 micrometers were obtained. Using this method, large panels of aligned carbon nanotubes can be made under conditions that are suitable for device fabrication.

We review the synthesis methods and properties of single crystal, powder, and thin film TlBaCaCuO high-temperature superconducting (Tl-HTS) materials. With transition temperatures ≥ 100 K for several compounds, Tl-HTS materials present real opportunities for applications above 77 K. Experiments using (1) single crystals: determined precise structural parameters and identified the complex Tl1+–Tl3+ equilibrium model; (2) powders: studied the complex thermodynamic phase diagram; and (3) epitaxial films: studied fundamental properties such as electron pair symmetry and the effect of controlled extrinsic defects on flux pinning strength, as well as providing the large-area surfaces required for device applications.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

Chemical solution deposition (CSD) is used to grow high-quality (100)-oriented films of SrTiO 3 (STO) on CSD Ba 0.2 Ca 0.8 TiO 3 (100) (BCT) templates on textured W-doped Ni(100) (Ni:W) tape substrates. The BCT template films form a thin layer or “skin” that bridges its significant porosity. STO films grown at 1000 °C appear optimized for heteroepitaxial orientation, surface coverage, and film smoothness. Both interfaces in the STO(100)/BCT(100)/Ni:W(100) stack demonstrate excellent atomic registry and compositional abruptness. Doping STO with a few atomic percent of Nb reduces oxygen diffusion into the film by an order of magnitude and provides greater protection to the Ni interfacial surface from oxidation during the growth of additional functional oxides requiring relatively higher p(O 2 ) high-temperature processing, such as superconducting YBa 2 Cu 3 O 7−δ . CSD growth of BCT and STO also planarizes pre-existing grooves in the Ni:W(100) tapes while maintaining a high degree of orientation by forming facets at the interfaces.