Biomedical subjects
Publications and source records attributed to Yunyi Fu.
We report the gate-controlled rectification behavior in C(70)@SWNT networks at room temperature in air. The electrical transport characteristics can be fitted well with the conventional Schottky diode model. The origin of the rectifying behavior in fullerene peapod networks device is qualitatively discussed. This paper demonstrates a strategy for diode fabrication based on peapod networks.
Bicrystalline nanowires of hematite (alpha-Fe(2)O(3)) have been successfully synthesized by the oxidation of pure iron. The product was characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM in combination with focal series reconstruction, energy-dispersive X-ray spectroscopy, and electron energy-loss spectroscopy. The bicrystalline nanowires have diameters of 20-80 nm and lengths up to 20 microm. All of the investigated materials are found to be alpha-Fe(2)O(3) with a rhombohedral crystal structure. Investigations indicate that most of the bicrystalline nanowires are nanotwins with ellipsoidal heads. The orientation relationship between the nanotwins can be described as (110)(M)//(110)(T), [110](M)//[0](T). An energy-filtered TEM investigation indicates that the ellipsoidal head is iron-rich. The growth mechanism of such unique nanostructures is considered to be a solid-phase growth via surface and internal diffusions of molecules from base to tip.
By using scanning near-field optical microscopy (SNOM), we have observed the polarization phenomena of carbon nanotubes (CNTs), which were synthesized by pyrolysis of a metal phthalocyanine method. Using SNOM, an area of about 100 nm in the thin part of the honeycomblike aligned CNT can be investigated, where the CNTs are nearly parallel or cross aligned with only a few layers. Transmission intensity of the light absorption with constant height scan identified the thickness of the nanotube layers. By changing the linear polarization of the incident light, the dependence of transmission versus polarization angle was recorded. The observed different polarization cannot be explained by using the model of optical absorption of continuum medium. We have proposed a model of discrete polarization absorption, which can be used to identify the number of layers of CNTs and their relative orientations. The combination of SNOM technique and our model can be used for optical polarization of carbon nanotubes of discrete medium.