Hengqiang Ye

Fabrication of ultrafine nanostructures with single-nanometre precision in a high-resolution transmission electron microscope

Highly ordered ultrafine nanostructures (feature size <10 nm) have been successfully fabricated with single-nanometre precision using a convergent electron beam (CEB) in a high-resolution transmission electron microscope (HRTEM). This approach can be widely applied to inorganic solid-state materials including insulators, semiconductors and metals. The feature size can be precisely controlled by the probe size and the irradiation time. The formation mechanism of nanostructures fabricated by CEB has been discussed in terms of knock-on damage and the beam heating effect. On the basis of the experimental results of electron energy-loss spectroscopy (EELS), finite element thermal analysis reveals that the heating effect of the high-energy electron beam is negligible in inorganic solid-state materials, and the sculpting of nanostructures is predominated by the knock-on damage or ionization of high-energy electrons.

In situ study of the growth of ZnO nanosheets using environmental scanning electron microscope

The authors demonstrated an investigation of the real-time growth of ZnO nanosheets via in situ observation in an environmental scanning electron microscope. It was found that ZnO nanosheets were grown in a two-stage process: [21¯1¯0]-oriented nanowires were grown first, and then ZnO nanosheets grew perpendicularly on the parent nanowires along the [0001] axis. The authors’ results revealed that the change of the ZnO growth direction from [21¯1¯0] (a axis) to [0001] (c axis) can be achieved by control of the growth temperature.The authors demonstrated an investigation of the real-time growth of ZnO nanosheets via in situ observation in an environmental scanning electron microscope. It was found that ZnO nanosheets were grown in a two-stage process: [21¯1¯0]-oriented nanowires were grown first, and then ZnO nanosheets grew perpendicularly on the parent nanowires along the [0001] axis. The authors’ results revealed that the change of the ZnO growth direction from [21¯1¯0] (a axis) to [0001] (c axis) can be achieved by control of the growth temperature.

STRUCTURAL AND ELECTRONIC PROPERTIES OF ONE DIMENSIONAL KxC60 CRYSTAL ENCAPSULATED IN CARBON NANOTUBE

The structural and electronic properties of potential one dimensional (1D) superconductor — KxC60 chain encapsulated inside a single-walled carbon nanotube is studied using first principles calculations. The stoichiometry of K to C60 of the 1D KxC60 crystal can reach 9, in contrast to a maximal stoichiometry of 6 found in the K doped bulk fullerides. The K 4s electrons are completely ionized, and fill chiefly the C60-derived bands in a nonrigid way. The density of states at the Fermi level of the encapsulated 1D KxC60 crystal is comparable to that in K doped bulk fullerides.