The mechanical resonance of a single ZnO nanobelt, induced by an alternative electric field, was studied by in situ transmission electron microscopy. Due to the rectangular cross section of the nanobelt, two fundamental resonance modes have been observed corresponding to two orthogonal transverse vibration directions, showing the versatile applications of nanobelts as nanocantilevers and nanoresonators. The bending modulus of the ZnO nanobelts was measured to be ∼52 GPa and the damping time constant of the resonance in a vacuum of 5×10−8 Torr was ∼1.2 ms and quality factor Q=500.

Recent interest in the growth of aligned carbon nanotube films using transition metal catalysts has led to questions concerning the growth mechanism involved. In our experiment carbon tubules grown using Ni catalysts exhibit a preferred orientation relative to the catalytically active surfaces of Ni. The axial directions of the tubular structure are mainly parallel to the ͗110͘ and ͗042͘ directions of Ni. The faceted shape of the Ni particles determines the intrinsic structure of the tubules. A mechanism involving spiral growth is proposed to explain the nucleation and growth of such tubules.

Nanocrystalline diamond films were grown by microwave plasma assisted chemical vapor deposition using N2 and CH4 as precursors . The microstructure of the films such as the diamond grain size, graphite content, and N incorporation, was controlled by introducing a small amount of hydrogen gas (0-10 sccm) in the growth. Effects of the growth parameters on the film microstructure were investigated using transmission electron microscopy, x-ray diffraction, Raman spectroscopy, and secondary ion mass spectroscopy. A surface stabilizing model is suggested to explain the formation mechanism of the uniformly grain size-controlled nanocrystalline diamond. A systematic investigation on the film microstructure and their field electron emission (FEE) property is presented for varoius films of different diamond grain sizes and graphite contents. It was found that the FEE property highly depended on the diamond/graphite mixed phase structure. Novel field emission properties (1 V/mum emission threshold an 10mA/cm² emission current) are obtained by optimizing the growth parameters. A transport-tunneling mechanism is applied to explain the experimental observations. Our results showed that nanocrystalline diamond film can be a very promising cold cathode material for field emission applications

Nanotechnology V 1505Synthesis and Electrical Transport of Single-Crystal NH 4 V 3 O 8 Nanobelts. -Monoclinic single-crystalline nanobelts of the title compound with widths of 80-180 nm, thicknesses of 50-100 nm, and lengths up to tens of micrometers are synthesized at large scale from an aqueous solution of NH4VO3 containing HCl (autoclave, pH 1.5, 180°C, 36 h). The samples are characterized by XRD, FTIR spectroscopy, SEM, and TEM. The nanobelts exhibit nonlinear, symmetric current/voltage characteristics, with a conductivity of 0.1-1 S/cm at room temperature and a dielectric constant of about 130. It is anticipated that the novel nanobelts may have unique applications as nanoelectrodes or nanosensors. -(MAI, L. Q.; LAO, C. S.; HU, B.; ZHOU, J.; QI, Y. Y.; CHEN, W.; GU, E. D.; WANG*