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Several different synthetic methods have been developed to fabricate tungsten oxide (WO3) nanostructures, but most of them require exotic reagents or are unsuitable for mass production. In this paper, we present a systematic investigation demonstrating that arc discharge is a fast and inexpensive synthesis method which can be used to produce high quality tungsten oxide nanostructures for NO2 gas sensing measurements. The as-synthesized WO3 nanostructures are characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), finger-print Raman spectroscopy and proton induced x-ray emission (PIXE). The analysis shows that spheroidal-shaped monoclinic WO3 crystal nanostructures were produced with an average diameter of 30 nm (range 10-100 nm) at an arc discharge current of 110 A and 300 Torr oxygen partial pressure. It is found that the morphology is controlled by the arc discharge parameters of current and oxygen partial pressure, e.g. a high arc discharge current combined with a low oxygen partial pressure results in small WO3 nanostructures with improved conductivity. Sensors produced from the WO3 nanostructures show a strong response to NO2 gas at 325 degC. The ability to tune the morphology of the WO3 nanostructures makes this method ideal for the fabrication of gas sensing materials. [ABSTRACT FROM AUTHOR]

We have developed a novel technique based on the selective desorption of an oxide film in order to grow ordered arrays of silicon carbide nanocrystals on a silicon surface. These nanocrystals form as a byproduct of void nucleation in the oxide during the high-temperature vacuum annealing of silicon, a process which normally produces a random distribution of nanocrystals across the silicon surface after its oxide layer has been fully desorbed. By the pre-deposition of a thin layer of excess silicon on the oxide surface through a patterned lithography mask, site-specific nucleation of voids in the silicon oxide can instead be achieved during the annealing step, leading to the growth of silicon carbide nanocrystals in regular patterns over the silicon surface. [ABSTRACT FROM AUTHOR]

Several different synthetic methods have been developed to fabricate tungsten oxide (WO(3)) nanostructures, but most of them require exotic reagents or are unsuitable for mass production. In this paper, we present a systematic investigation demonstrating that arc discharge is a fast and inexpensive synthesis method which can be used to produce high quality tungsten oxide nanostructures for NO(2) gas sensing measurements. The as-synthesized WO(3) nanostructures are characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), finger-print Raman spectroscopy and proton induced x-ray emission (PIXE). The analysis shows that spheroidal-shaped monoclinic WO(3) crystal nanostructures were produced with an average diameter of 30 nm (range 10-100 nm) at an arc discharge current of 110 A and 300 Torr oxygen partial pressure. It is found that the morphology is controlled by the arc discharge parameters of current and oxygen partial pressure, e.g. a high arc discharge current combined with a low oxygen partial pressure results in small WO(3) nanostructures with improved conductivity. Sensors produced from the WO(3) nanostructures show a strong response to NO(2) gas at 325 °C. The ability to tune the morphology of the WO(3) nanostructures makes this method ideal for the fabrication of gas sensing materials.

We have developed a novel technique based on the selective desorption of an oxide film in order to grow ordered arrays of silicon carbide nanocrystals on a silicon surface. These nanocrystals form as a byproduct of void nucleation in the oxide during the high-temperature vacuum annealing of silicon, a process which normally produces a random distribution of nanocrystals across the silicon surface after its oxide layer has been fully desorbed. By the pre-deposition of a thin layer of excess silicon on the oxide surface through a patterned lithography mask, site-specific nucleation of voids in the silicon oxide can instead be achieved during the annealing step, leading to the growth of silicon carbide nanocrystals in regular patterns over the silicon surface.