Nanorods
Air-assisted Growth of Tin Dioxide Nanoribbons
Tao Tao, Alexey M. Glushenkov, Qi Y. Chen, Ying Chen
Journal of Nanoscience and Nanotechnology, 10 (2010) 5015-5019
Abstract: SnO2 nanoribbons have been synthesized by annealing of a milled SnO2 powder that has a metastable structure created by ball milling treatment. When the milled powder was annealed in an assembly of two combustion boats, SnO2 nanoribbons formed. The nanoribbons tend to grow along the [101] crystallographic direction and their side surfaces are represented by ± (010) and ± (101 ) facets. The oxygen plays an important role in enhancing their formation.
A novel approach for real mass transformation from V2O5 particles to nanorods
Alexey M. Glushenkov, Vladimir I. Stukachev, Mohd Faiz Hassan, Gennady G. Kuvshinov, Hua Kun Liu, and Ying Chen
Crystal Growth & Design, 8(10) (2008) 3661-5
Abstract: A solid-state, mass-quantity transformation from V2O5 powders to nanorods has been realized via a two-step approach. The nanorods were formed through a controlled nanoscale growth from the nanocrystalline V2O5 phase created by a ball milling treatment. The nanorods grow along the [010] direction and are dominated by {001} surfaces. Surface energy minimization and surface diffusion play important roles in their growth mechanism. Real large quantity production can be achieved when the annealing process is conducted in a fluidized bed which can treat large quantities of the milled materials at once. The crystal orientation of nanorods provides an improved cycling stability for lithium intercalation.
Growth and structure of prismatic boron nitride nanorods
H.Z. Zhang, J. D. Fitz Gerald, L. T. Chadderton, J. Yu, Y. Chen
Physical Review B 74(1)(2006) 045407
Abstract: Growth takes place by rapid surface diffusion of BN molecules, and follows heterogeneous nucleation at catalytic particles of an Fe/Si alloy. Lattice imaging transmission electron microscopy studies reveal a central axial row of rather small truncated pyramidal nanovoids on eachnanorod, surrounded by three basal planar BN domains which, with successive deposition of epitaxial layers adapt to the void geometry by crystallographic faceting. The bulk strain in the nanorods is taken up by the presence of what appear to be simple nanostacking faults in the external, near-surface domains which, like the nanovoids are regularly repetitive along the nanorod length. Growth terminates with a clear cuneiform tip for each nanorod. Lateral nanorod dimensions are essentially determined by the size of the catalytic particle, which remains as a foundation essentially responsible for base growth. Growth, structure, and dominating facets are shown to be consistent with a system which seek slowest bulk and surface energies according to the well-known thermodynamics of the capillarity of solids.
(a) Lattice images of the nanorods (b) Corresponding electron diffraction pattern (c) the distribution of the apex angles (d) the composition of the nanorods: B and N only
PatternedGrowth and cathodoluminescence of conical boron nitride nanorods
H.Z. Zhang, M. Phillips, J. Fitz Gerald, J. Yu, Y. Chen
Appl. Phys. Lett. 88 (2006) 093117
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Cathodoluminescence (CL) spectra of the nanorods show two broad emission bands centered at 3.75 and 1.85 eV. Panchromatic CL images reveal clear patterned structure. ©2006 American Institute of Physics
Conical boron nitride nanorods synthesized via the ball-milling and annealing method
H.Z. Zhang, J. Fitz Gerald, J. Yu, Y. Chen
Journal of the American Ceramic Society 89 (2006) 675-679
Abstract: Nanorods: A boron nitride (BN) nanostructure, conical BN nanorod, has been synthesized in a large quantity on Si substrates for the first time via the ball-milling and annealing method. Nitridation of milled boron carbide (B4C) powders was performed in nitrogen gas at 1300°C on the surface of the substrates to form the BN nanorods. The highly crystallized nanorods consist of conical BN basal layers stacked along the nanorod axis. Ball milling of the B4C powders can significantly enhance the nitridation of the powders and thus facilitate the formation of nanorods during the annealing process.(2) Patterned growth: A catalyst layer of Fe(NO3)3 was patterned on a silicon substrate by using a copper grid as a mask. The nanorods were grown via annealing milled boron carbide powders at 1300°C in a flow of nitrogen gas. The as-grown nanorods exhibit uniform morphology and the catalyst pattern precisely defines the position of nanorod deposition.
1.Milling-effect:
(a) XRD pattern shows the milled B4C powder having smallcrystallite sizes; (b) Enhanced nitridation of the milled B4C powder
2.Morphology:
(a) The BN nanorods are grown on the silicon substrate on a large scale. The nanorods have (b) conical tips and (c) bulbous attachment (catalyst particles)
Field emission characteristics of conical boron nitride nanorods
H.Z.Zhang, Q. Zhao, J. Yu, D. P. Yu, and Y. Chen
J. Phys. D: Appl. Phys.(2006), Accepted
Abstract: The emission current of the BN nanorods can be up to ˜60 µA at an applied voltage of ˜3 kV. Two distinct slopes are evident in the Fowler-Nordheim (FN) plot. The field-emission characteristics can be explained using a site-related tunneling-controlled mechanism. The occurrence of two FN slopes is attributed to the switchover from tip emission to side emission, which results from the differences in interface barrier, geometry, as well as total emission area of the two emission interfaces.
