[Show abstract][Hide abstract] ABSTRACT: Ga-filled MgO and silica nanotubes were fabricated by a simple one-step method. The height of the gallium column in both two kinds of nanotube varies linearly and reproducibly to the temperature change when in situ heating and cooling in transmission electron microscope, make them ideal nanothermometers for use in a wide variety of microenvironments. The Ga-filled MgO nanothermometer has a rather high sensitivity of 6.02 nm/degrees C in the measuring range of 30-450 degrees C, which is one of the most sensitive nanothermometer. In comparison, the Ga-filled silica nanothermometer has a moderate sensitivity of 1.15 nm/degrees C in a wide temperature range of 30-900 degrees.
Full-text · Article · Aug 2012 · Journal of Nanoscience and Nanotechnology
[Show abstract][Hide abstract] ABSTRACT: Fe- and Fe3C-filled carbon nanostructures were synthesised by simply catalytically pyrolysing ferrocene and acetonitrile. The novel hybrid structures fabricated were thoroughly characterised by X-ray diffraction, scanning and transmission electron microscopy, electron energy loss spectroscopy, Raman spectroscopy and magnetic measurement. Aligned arrays of Fe- and Fe3C-filled carbon nanotubes (CNTs) and flower-like Fe3C-filled N-doped multi-branched CNTs clusters were revealed. High coercivity of 670 Oe for the flower-like nanostructures was observed, and the possible mechanism for coercivity enhancement was discussed.
[Show abstract][Hide abstract] ABSTRACT: Electrically driven gallium movement in carbon nanotubes is discussed. A higher current (~15 mA) makes the gallium migrate sharply toward the anode, which increases its mass transport speed with time in the range of 0 to more than 10.345 fg s(-1). In contrast, a lower current (~2 mA) only drives gallium to contact the anode, which decreases the resistance of the nanocomposite sharply, from 2.564 kΩ to 0.4 Ω. These results are valuable for designing electrically driven nanomass delivery and nanoswitches, respectively.
[Show abstract][Hide abstract] ABSTRACT: We report on the synthesis, field electron emission and electric transport properties of a novel nanomaterial: ordered arrays of crystallized silicon multi-branch nanostructures. A decent field electron emission with relatively low turn-on field of 3.16 V µm⁻¹ and high field-enhancement factor of 1252 was received for the silicon nanobranches. The relevancies between field-emission current-voltage characteristic, turn-on field, threshold field and sample-anode distance have been thoroughly analyzed. In addition, electrical transport measurements revealed a small electrical resistance of 0.51 MΩ for as-prepared silicon nanobranches. In contrast, by improving the silicon nanobranch-electrode contact, vacuum annealing dramatically reduced the electrical resistance, by a factor approaching two, while thermal oxidation resulted in a much higher resistance due to the amorphous oxide coating of the silicon nanobranches, both of the current versus voltage curves became more linear and symmetrical, and the transport stability was obviously improved.
[Show abstract][Hide abstract] ABSTRACT: A variety of silicon based multilevel branched submicrometer/ nanostructures, such as branched nanowheat-heads, big branched nanowheat-heads, and branched nanowires, have been rationally synthesized via a simple one-step, inexpensive, and catalyst-free fabrication technique. High-resolution transmission electron microscopy studies suggested that the main stem of wheat head and the nanotips of silicon branched nanowheat-heads are single crystals with the preferential growth direction along the [1̅12] and [11̅2] and orientation, respectively. Compared with big branched nanowheat-heads and branched nanowires, the room-temperature Raman frequency of branched nanowheat-heads is blue-shifted and its full width at half-maximum broadens. A moderately strong photoluminescence emission at 550 nm was suggested to be induced by defects, such as stacking faults or the SiOx surface in the branched nanowheat-heads, suggesting potential applications in light-emitting nanodevices. These studies shed light on new opportunities for fabricating different 3-dimensional nanostructures based on their property investigation.
Full-text · Article · Nov 2009 · The Journal of Physical Chemistry C