Field nanoemitter: one-dimension Al4C3 ceramics

MWCNT-Reinforced AA7075 Composites: Effect of Reinforcement Percentage on Mechanical Properties

Metal–matrix composites (MMC) of aluminium alloy 7075 (AA7075) containing 1 wt.% and 0.5 wt.% multiwall carbon nanotubes (MWCNTs) were developed by powder metallurgy, using a high energy ball milling (HEBM) process for dispersion of the MWCNTs. The powder of the AA7075-MWCNT obtained was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The microstructural changes produced during the milling process, such as the modification of the crystallite size, as well as the micro-deformation of the matrix crystal lattice, were determined using the Scherrer formula. After consolidation into a strip shape using the hot powder extrusion (HPE) process at 500 °C, no porosity was detected and a fine homogeneous dispersion of the reinforcement into the matrix was obtained. After performing a 0.2 HV test and tensile tests in the extruded profiles of both composites, a better combination of properties was found in samples of AA7075-0.5 wt.% MWCNT, with the increase in measured ductility being especially remarkable.

Anisotropic electrical transport of flexible tungsten carbide nanostructures: towards nanoscale interconnects and electron emitters

Due to the coexistence of metal- and ionic-bonds in a hexagonal tungsten carbide (WC) lattice, disparate electron behaviors were found in the basal plane and along the c-axial direction, which may create an interesting anisotropic mechanical and electrical performance. To demonstrate this, low-dimensional nanostructures such as nanowires and nanosheets are suitable for investigation because they usually grow in single crystals with special orientations. Herein, we report the experimental research regarding the anisotropic conductivity of [0001] grown WC nanowires and basal plane-expanded nanosheets, which resulted in a conductivity of 7.86 × 10³ Ω^-1 · m^-1 and 7.68 × 10⁴ Ω^-1 · m^-1 respectively. This conforms to the fact that the highly localized W d state aligns along the c direction, while there is little intraplanar directional bonding in the W planes. With advanced micro-manipulation technology, the conductivity of a nanowire was tested to be approximately constant, even under a considerable bending state. Moreover, the field electron emission of WC was evaluated based on large area emission and single nanowire (nanosheet) emission. A single nanowire exhibits a stable electron emission performance, which can output emission currents >3 uA before fusing. These results provide useful references to assess low-dimensional WC nanostructures as electronic materials in flexible devices, such as nanoscale interconnects and electron emitters.

2D free-standing Ge-doped ZnO: excellent electron-emitter and excitation-power-dependent photoluminescence redshift

Ge-Doped ZnO 2D nanostructures show large current-emission capabilities (>35 mA cm⁻²) and an excitation power-dependent PL redshift.

Triple phase boundary induced self-catalyzed growth of Ge–graphite core–shell nanowires: field electron emission and surface wettability

Ge–graphite core–shell nanowires with good field electron emission capability and surface superhydrophobicity were synthesized by triple phase boundary-induced self-catalyzed growth.

Optimized performances of tetrapod-like ZnO nanostructures for a triode structure field emission planar light source

Tetrapod-like ZnO (T-ZnO) nanostructures were synthesized by a simple vapor phase oxidation method without any catalysts or additives. We optimized the performances of T-ZnO nanostructures by adjusting the partial pressure of Zn vapour in the total pressure of the quartz chamber and obtained T-ZnO nanostructure materials of high purity, uniform morphology and size and high aspect ratio with a low turn-on electric field of 2.75 V μm(-1), a large field enhancement factor of 3410 and good field emission stability for more than 70 hour continuous emission. Besides, based on the optimized T-ZnO, we developed metal grid mask-assisted water-based electrostatic spraying technology, and fabricated a large-scale, pollution-free, hole-shaped array T-ZnO nanostructure cathode used in a triode structure field emission planar light source. The controllable performances of the triode device were intensively investigated and the results showed that the triode device uniformly illuminated with a luminous intensity as high as 8000 cd m(-2) under the conditions of 200 V grid voltage and 3300 V anode voltage. The research in this paper will benefit the development of a high performance planar light source based on T-ZnO nanostructures.

β-Sialon nanowires, nanobelts and hierarchical nanostructures: morphology control, growth mechanism and cathodoluminescence properties

Morphology control of one dimension (1D) nanomaterials is a pivotal issue in the field of nanoscience research to exploit their novel properties. Herein, we report the morphology controlled synthesis of 1D β-Sialon nanowires, nanobelts and hierarchical nanostructures via a thermal-chemical vapour deposition process using an appropriately selected catalyst and optimized temperature schedule. Vapour-solid (VS), a combination of vapour-liquid-solid (VLS)-based and VS-tip, and a combination of VS for one-generation nanowires with nucleation, growth and coalescence of two-generation nanobranches (NGCB) are used to explain the growth of β-Sialon nanowires, nanobelts and hierarchical nanostructures, respectively. Cathodoluminescence measurements show that the individual β-Sialon 1D nanostructures with different morphologies have different luminescent properties. All nanostructures exhibit two distinct emission peaks, the violet/blue emission centered at ~390 nm (3.18 eV), attributable to the near band edge (NBE) emission, and the red emission centered at ~728 nm (1.70 eV), assigned to the deep level (DL) emission. However, the DL emission is the ruling emission in the case of an individual β-Sialon nanowire, whereas the NBE emission becomes dominant in the case of an individual nanobelt as well as a hierarchical nanostructure due to the size and surface effects. The as-synthesized β-Sialon with controlled nanostructures and various morphologies can find potential applications in future nanodevices with tailorable or tunable photoelectric properties.

Step-edge induced ordered growth: targeting to assemble super long horizontal nanowire alignment in large-scale

Nowadays, the development of nano-synthesis has turned to controllable design for specific demands in micro-nano device application, to be integrated into functional units more conveniently with low-cost and efficiency principles. In this case, an appropriate approach for directly obtaining horizontally aligned nanowires in a large scale would be of great significance in future micro-nano device integration. Here, on the HOPG surface, we managed to achieve this. The approach is versatile to various kinds of materials. Horizontally aligned nanowires of Al-C based materials, such as Al4C3 and Al4O4C, were achieved. All of the nanowires exhibit a high degree ordered alignments and possess super aspect ratios with uniform widths of about 100 nm and lengths on the millimeter level. We believe the assembly mechanism lies in a step-edge induced ordered growth process, through which quaternary Al-Si-O-C nanoball alignment could also be obtained. It is expected that this method could be beneficial to adjust many useful materials for micro device integration in the future.

One-Dimensional Al4O4C Ceramics: A New Type of Blue Light Emitter

Ceramic Al₄O₄C, which has few active functions, has been used as an additive in carbon-containing refractory materials to improve their oxidation resistance and thermal properties. Herein, the crystal and electronic structures of this novel material were systematically investigated for opto-electrical applications, which revealed interesting fluorescence features via photoluminescence (PL) and cathode luminescence (CL). When a 325 nm laser was focused on one end of a single Al₄O₄C needle, the entire needle was illuminated by the blue emission, which implies that this material exhibits excellent waveguide properties. Interestingly, the thin end exhibited the highest light intensity even though the excited region was located at the thick end. We believe the reason for this observed behaviour is related to the excellent waveguide behaviour as well as to the needle shape, which induces this intriguing blue-light convergence effect. Ab initio calculations demonstrated that the emission light emanates from the interband transition.