Calit2

Ferromagnetic self-assembled r-MnAs quantum dots (QD) were grown epitaxially on metal catalyst-grown InAs nanowires (NW) by chemical vapor deposition. Magnetic force microscopy measurements demonstrated that the QDs are stable, single-domain ferromagnets with T c values of ∼310 K. Single QD switching was demonstrated at fields as low as 60 Oe. The hybrid ferromagnetic/semiconductor QD/NW properties provide a promising basis for the development of nanowire spin-valves and magnetic memory devices.

Ferromagnetic self-assembled r-MnAs quantum dots (QD) were grown epitaxially on metal catalyst-grown InAs nanowires (NW) by chemical vapor deposition. Magnetic force microscopy measurements demonstrated that the QDs are stable, single-domain ferromagnets with T c values of ∼310 K. Single QD switching was demonstrated at fields as low as 60 Oe. The hybrid ferromagnetic/semiconductor QD/NW properties provide a promising basis for the development of nanowire spin-valves and magnetic memory devices.

Catalyst-free growth of boron nanoribbons was observed by pyrolysis of diborane at 630−750°C and ∼200 mTorr in a quartz tube furnace. Nanodiffraction analysis indicates the nanoribbons are single crystal r-tetragonal boron. TEM images show the nanoribbon is covered by a 1−2 nm thick amorphous layer. Elemental analysis by EELS, EDX, and XPS shows the nanoribbons consist of boron with small amounts of oxygen and carbon. Infrared and Raman spectra are also reported.

Particle size is generally considered to be the primary factor in the design of nanocrystal photocatalysts, because the reduction of particle size increases the number of active sites. However, the benefit from the size reduction can be canceled by a higher electron-hole recombination rate due to the confined space in sphere-shaped nanoparticles. Here we report a mechanistic study on a novel nanobelt structure that overcomes the drawback of sphere-shaped nanoparticles. Single-crystalline anatase TiO 2 nanobelts with two dominant surfaces of (101) facet exhibit enhanced photocatalytic activity over the nanosphere counterparts with an identical crystal phase and similar specific surface area. The ab initio density functional theory (DFT) calculations show that the exposed (101) facet of the nanobelts yields an enhanced reactivity with molecular O 2 , facilitating the generation of superoxide radical. Moreover, the nanobelts exhibit a lower electron-hole recombination rate than the nanospheres due to the following three reasons: (i) greater charge mobility in the nanobelts, which is enabled along the longitudinal dimension of the crystals; (ii) fewer localized states near the band edges and in the bandgap due to fewer unpassivated surface states in the nanobelts; and (iii) enhanced charge separation due to trapping of photogenerated electrons by chemisorbed molecular O 2 on the (101) facet. Our results suggest that the photocatalysis efficiency of nanocrystals can be significantly improved by tailoring the shape and the surface structure of nanocrystals, which provides a new concept for rational design and development of high-performance photocatalysts.

Catalyst-assisted growth of single-crystal calcium hexaboride (CaB 6 ) nanowires was achieved by pyrolysis of diborane (B 2 H 6 ) over calcium oxide (CaO) powders at 860−900°C and ∼155 mTorr in a quartz tube furnace. TEM electron diffraction and Raman spectroscopy indicate that the nanowires are single-crystal CaB 6 and have a preferred [001] growth direction. Analysis of TEM/EDX/EELS data proves the nanowires consist of CaB 6 cores and thin (1−2 nm) amorphous oxide shell material. The CaB 6 nanowires have diameters of ∼15−40 nm, and lengths of ∼1−10 µm.

We show results on how the morphology of a ZnO layer can have a big impact on the random lasing threshold of the material. Plasma-enhanced chemical vapor deposition method is used to grow ZnO layers on sapphire substrates. The morphologies and structures of ZnO are observed to undergo transition when growth temperature decreases from 750 to 100°C: the deposited ZnO changes from crystalline films to nanocrystalline films with columnarshaped grains, then to well-aligned ZnO nanorods, and finally to randomly oriented irregularshaped grains. ZnO nucleation and surface diffusion rates, coalescence between crystal grains, and preferential growth along c-axis play important roles in this transition from continuous films to nanorods. Random lasing properties of our ZnO films and nanorods are studied. The scattering ability of ZnO is critical to control the lasing properties. The lowest lasing thresholds are observed for ZnO films grown between 500 and 600°C when the films have columnar-shaped grains and not at 750°C when the ZnO layer has a continuous crystalline film. Calculations based on quasi-2D random lasing are consistent with the experimental results of lasing threshold measurements. Figure 1. X-ray diffraction (a) θ-2θ scan and (b) φ scan on ZnO thin films grown on c-plane sapphire at 750°C.

Smart manufacturing is a framework for implementing smart technologies to optimize energy efficiency and productivity and to reduce waste, empowering workers and managers to improve decision-making. Research suggests that small and medium manufacturers (SMMs) face greater challenges to realize the potential of smart manufacturing than larger companies. However, little is known about how US SMMs view smart manufacturing and what their experiences have been with it, which is key to developing and implementing effective scaleddown solutions. The current paper presents survey findings for 54 owners and employees of US SMMs. Results show a limited level of readiness to adopt smart manufacturing, and that only 34% companies have begun implementing smart solutions and 26% would need to hire new employees. The top-most reported drivers of adoption were reducing costs (24%) and following a conscious strategy (15%), while the top-most barriers were the correlates: not having the time (26%) or...