Nanowires

Unusual corrugated nanowires of zinc oxide

A.M. Glushenkov, H. Zhang, J. Zou, G.Q. Lu and Y. Chen

Journal of Crystal Growth, 310 (2008) 3139-3143

Abstract: We report an unusual morphology of ZnO nanowires with a hexagonal cross-section and corrugated side walls.The formation of corrugated nanowires is attributed to the lateral growth activated by the high vapor supersaturation and the presence of stacking faults.

SEM and EELS of corrugated ZnO nanowires. (a) Low-magnified SEM image, (b) and (c) high-magnified SEM images showing an individual nanowire and wire tips, respectively. (d) EELS profile of a typical nanowire TEM of corrugated ZnO nanowires. (a)-(c) Bright-field images and corresponding SAED patterns for the same nanowire viewed along {11-00}, {45-10} and {12-10} directions, respectively 3D structural models for corrugated ZnO nanowires. (a) A basis structure of a diameter-modulated nanowire. (b) A modified model with side facets independent from each other and irregular surface features. The zigzag facets of [101-1 and [101-1-] families are shown in blue and red, respectively; the (0 0 01) plane is shown in yellow

Efficient production of ZnO nanowires by a ball milling and annealing method

A M Glushenkov, H Z Zhang, J Zou, G Q Lu and Y Chen

Nanotechnology 18 (2007) 175604 (6pp)

Abstract: ZnO powder was mechanically milled in a ball mill. This procedure was found to greatly increase its evaporation ability. The anomalous evaporation behaviour was caused by the disordered structure of the milled material and was not related to the increase in its surface area after milling. ZnO nanowires were synthesized by evaporation of this milled precursor. Nanowires with smooth and rough surfaces were present in the sample; the latter morphology was dominant. A green emission band centred at 510 nm was dominant in the cathodoluminescence spectrum of the nanowires.

SEM images of ZnO nanowires. (a) Low magnification image of a nanowire layer, (b) A typical nanowire, (c) Branches of nanowires $TEM images of ZnO nanowires. (a) Low resolution bright-field image, (b), (c) Nanowires with a smooth and rough surface, Respectively, (d) Low resolution image of a connection area between two nanowires, (e) High resolution image of the area marked with a square in (d), (f) Selected area diffraction pattern of the connection area of the nanowires shown in (d) and (e).$ Evaporation behaviour of unmilled (?) and milled (¦) powders

Pure Boron Nitride Nanowires Produced from Boron Triiodide

Yong Jun Chen, Hong Zhou Zhang, Ying Chen

Nanotechnology 17 (2006) 786-789

Abstract: A thick layer of pure boron nitride (BN) nanowires with a uniform diameter of 20 nm was synthesized using a CVD process with a new precursor BI3 for the first time via a new nitriding reaction between boron triiodide and ammonia at 1100ºC. Transmission electron microscopy revealed a nanocrystalline structure in BN nanowires and absence of any catalyst particle. Some BN nanowires self-assembled into long threads up to several hundred micrometers on top of the thick nanowire layer. The new nitriding reaction and lack of catalyst suggest new formation mechanism of BN nanowires.

SEM images of BN nanowires. (a) A large area of BN nanowire layer, (b) A high-magnification image of the nanowires showing a uniformed diameter, (c) Threads of BN nanowires formed on top of the layer indicated by black arrows, (d) A high-magnification image of a thread showing a large number of nanowires $TEM image of a large number of BN nanowires; the inset is the electron diffraction pattern taken from the nanowire cluster$

Fluoride-assisted synthesis of mullite (Al5.65Si0.35O9.175) nanowires

Yongjun Chen, Bo Chi, Qiuxiang Liu, Denise C. Mahond and Ying Chen

Chemical Communications, 2006, 2780-2782

Abstract: Novel silicon-deficient mullite (Al5.65Si0.35O9.175) single crystal nanowires were synthesized in large quantities on mica substrates assisted by the intermediate fluoride species. The nanowires have diameters in the range 50-100 nm and typical lengths of several mm. Aligned nanowires were observed at the substrate edge. The nanowires have strong photoluminescence (PL) emission bands at 310, 397, 452 and 468 nm.

(a) SEM images of the carpet-like nanowire film grown on the mica substrate, (b) Enlarged view of the nanowires. The inset shows the facet tip, smooth surface of the nanowires and diameter of approximately 50-100 nm, (c) and (d) SEM images of the aligned nanowires grown at the edge of the substrate, exhibiting similar diameters and lengths as those grown in the center of the substrate (a) Low magnification TEM image of a single nanowire. The inset is the SAED pattern of the nanowire, (b) The corresponding high resolution (HRTEM) image of the same nanowire. The top-right inset is the further magnified image, while the bottom-left inset is the EDX spectrum of the nanowire

Substitution Reactions of Carbon Nanotubes Template

Chi Pui Li,Ying Chen and John Fitz Gerald

APPLIED PHYSICS LETTERS 88, 223105 (2006)

Abstract: Substitution reactions between carbon nanotube (CNT) template and SiO produce carbon rich silicon oxide nanowires (SiO-C-NWs) which have been investigated using transmission electron microscopy (TEM) and X-ray energy dispersive spectroscopy (EDS). The reaction was carried out by thermal annealing at 1200 °C for 1 hour of a mixture of silicon monoxide (SiO) and iron (II) phthalocyanine, FeC32N8H16 (FePc) powders. Multiwalled CNTs were produced first via pyrolysis of FePc at a lower temperature (1000 °C). SiO vapors reacted with the CNTs at higher temperatures to produce amorphous SiO-C-NWs with a uniform diameter and a length in tens of micrometers. The special bamboo-like structure of the CNTs allows the reaction to start from the external surface of the tubes and transform each CNT into a solid nanowire section by section.

TEM images of transition process from a CNT to a SiO-C-NW: (a)low magnification image of a SiO-C-NW, (b) High magnification image taken from part B in (a) showing an external amorphous layer and an inner crystalline layer, (c) High magnification image taken from part C in (a) showing a completely amorphous structure, where the tube has been replaced Schematic diagrams showing a proposed growth mechanism of the SiO-C-NWs: (a) SiO vapors start to react with the terminated
graphite layers of CNT, (b) The transition of the top half in hollow crystalline graphitic tubular structure and the bottom half in a filled amorphous SiO-C-NW structure, (c) The completed SiO-C-NW