Q. Fu

Wuhan University, Wu-han-shih, Hubei, China

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Publications (17)34.91 Total impact

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    ABSTRACT: ZnO hexagonal pyramids have been synthesized on silicon (100) substrates by thermal evaporation of metal Zn powder at a low temperature of 467°C without a metal catalyst. Scanning electron microscopy and transmission microscopy observations show that the growth of hexagonal pyramids is initiated by the preferred nucleation ZnO grain or nanorod on Si substrate, followed by growth of hexagonal pyramids via vapor–solid growth process. The photoluminescence spectrum of the hexagonal pyramids shows two emission bands located at 380 and 503nm. Because of their characteristic pyramid shape with a nanotip, hexagonal ZnO pyramids may be expected to be suitable for electronic and optoelectronic devices such as field emitters, atomic force microscopy probes, optoelectronic devices for medical diagnosis.
    Physica E Low-dimensional Systems and Nanostructures 11/2010; 43(1):410-414. · 1.86 Impact Factor
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    ABSTRACT: The structural and optical properties of ZnO hollow spheres with club-shaped nanorods grown on the outer and inner surfaces were investigated by using Zn powder as precursor at . SEM, XRD, TEM and HRTEM were used to characterize the morphology and crystalline structure of the samples. Thus to realize the controlling of surface morphology, it is most essential to grow ZnO hollow spheres at different experimental conditions. Therefore, the effect of the growth temperature on surface morphology of ZnO hollow spheres should be scrutinized in detail. We grew ZnO hollow spheres by thermal evaporation at various temperatures in the range of 465–. We found that the increase in growth temperature transformed surface morphology from nanowires to club-shaped nanorods and nanograins. In addition, the increased growth temperature caused changes of optical qualities of the products.
    Physica E Low-dimensional Systems and Nanostructures 01/2009; · 1.86 Impact Factor
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    ABSTRACT: We present a novel approach to investigate the relationship between the ordered domains of nanopores in an anodic aluminum oxide (AAO) template and the underlying substrate grain boundary structure, by simultaneously analyzing the ordering of the concaves remnant on the surface of the aluminum and its grain boundary structure using Electron Backscatter Diffraction (EBSD). These observations show that the ordered domains of the AAO template can extend across the substrate grain boundaries and the mechanism is discussed.
    Solid State Communications 11/2008; 148(s 7–8):286–288. · 1.53 Impact Factor
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    ABSTRACT: CdO nanotubes (NTs) with a mean diameter of 50 nm have been fabricated by the simple thermal evaporation of Cd powder without using any catalyst or template. The growth mechanism of CdO NTs is discussed. It is suggested that the CdO NTs are formed by the sublimation of the Cd cores of the Cd/CdO core/shell nanocables. The direct and indirect band gaps of the CdO NTs are determined to be 2.85 eV and 2.05 eV, respectively. This type of high surface area structural CdO NTs could find promising applications in catalysis, gas sensors, nano-optics, and active material encapsulation.
    Materials Letters 09/2008; 62(24):3928-3930. · 2.27 Impact Factor
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    ABSTRACT: A newly developed solid–gas chemical reaction route has been demonstrated to fabricate MgO nanotube arrays by using prefabricated ZnO nanorods as templates. The formation process involves the Kirkendall effect, in which the out-diffusion of the ZnO core material through the MgO shells is faster than the in-diffusion of the vapor-phase Mg atoms, resulting in the formation of Kirkendall voids, which eventually induces hollow MgO nanotubes. The dimensions and sizes of the obtained MgO nanotubes can be controlled by employing suitable ZnO templates. Other types of complex hollow MgO architectures with different aspect ratios can be further manipulated and fabricated by this method, depending on the morphologies of the starting ZnO nanostructures used as templates. These hollow MgO architectures with high surface-to-volume ratios may have promising applications in catalysis, drug delivery, nano-optics, nanoreactors, and active material encapsulation.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
    Berichte der deutschen chemischen Gesellschaft 05/2008; 2008(17):2727 - 2732. · 2.94 Impact Factor
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    ABSTRACT: A low-cost and catalyst-free two-step approach has been developed to produce ZnO nanotubes (ZNTs) by simple thermal oxidation of Zn nanowires under 20 Pa at a low temperature of 400 °C. The growth mechanism of ZNTs is discussed in detail. The formation of these tubular structures is closely linked to the oxidation pressure and temperature, which involves a process consisting of the deposition of Zn nanowires, cracking of the Zn nanowires and sublimation of the Zn cores, and subsequent oxidation to ZNTs. The optical properties were studied by using Raman and photoluminescence spectra, where a strong green emission related to the single ionized oxygen vacancy appears. The photocatalytic activity measurement indicates an enhanced photocatalytic activity of the prepared ZNTs due to their high surface-to-volume ratios and abundant oxygen vacancies near the surfaces of the ZNTs. This type of high surface area structural ZNTs could find promising potential for optoelectronic and environmental applications.
    Nanotechnology 01/2008; 19(4):045605. · 3.84 Impact Factor
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    ABSTRACT: ZnO nanorods and microrods are synthesized on an Si (100) substrate by hydrothermal treatment (HTT). The influence of electric field on the hydrothermal growth process of ZnO was investigated, which has not been reported previously. By applying a dc electric field, ZnO nanorods are found to disappear, and a new shape of amorphous ZnO nanostructures is observed. The ion exchange mechanism is used to explain the growth of ZnO rods. After postgrowth annealing in air, the morphologies and structures of the ZnO rods changes, and the length to diameter ratio of ZnO nanorods decreases.
    Physica E Low-dimensional Systems and Nanostructures 01/2008; 40(4):852-858. · 1.86 Impact Factor
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    ABSTRACT: Catalyst-free, low-temperature (430 °C), high-density, well-aligned, single-crystalline zinc oxide (ZnO) microprism (ZMP) arrays have been synthesized over the entire c-ZnO/poly-Zn-coated Si substrates by simple thermal evaporation of Zn powder. Specially, the microprisms obtained possess hexagonal umbrella-like tips on which vertical thin ZnO nanowires grow. The growth mechanism of a three-stage thermodynamic process was discussed. Photoluminescence spectra show a strong ultraviolet (UV) emission enhancement of the ZMPs after H+ (hydrogen ions) implantation. This kind of special ZnO microstructure may find potential applications in field emission, UV laser emission devices, multifunctional microdevices and highly integrated multichannel nano-optoelectronic devices.
    Physica E: Low-dimensional Systems and Nanostructures. 01/2008;
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    ABSTRACT: Elastic strain fields at the interface of the epilayer and buffer layer of the InGaAsP/InP heterostructure were characterized by electron backscatter diffraction (EBSD) technology based on scanning electron microscopy. The InGaAsP/InP heterostructure which contained lattice misfit was under a dislocation-free condition. Image quality (IQ) was used as the strain sensitive parameter. From the image quality map and image quality curve, we observed directly the distribution of the elastic strain fields at the interface along the direction perpendicular to the interface as well as the interface structure between the epilayer and buffer layer by transmission electron microscopy and high resolution transmission microscopy.
    Journal of Physics D Applied Physics 11/2007; 40(23):7302. · 2.53 Impact Factor
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    ABSTRACT: Ag ions with four kinds of energies were implanted into silica to doses of 5×1016 and 1×1017ions/cm2, respectively. Hollow Ag nanoclusters were observed in the 1×1017Ag+ions/cm2 implanted samples with energies of 150 and 200keV. The evolution of hollow nanoclusters during annealing was carried out by in situ transmission electron microscopy observation. The energy dependence for the formation of hollow nanoclusters is studied. A potential mechanism for the formation of irradiation-induced nanovoids in nanoclusters is discussed.
    Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms 09/2007; 262(2):201-204. · 1.19 Impact Factor
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    ABSTRACT: Novel hollow ZnO microstructures and ZnO microberets (ZMBs) with nanowires grown vertically on both the inner and outer surfaces of beret shells were synthesized on Si(100) substrates by simple thermal evaporation of pure zinc powder without any catalyst or template material at a relative low temperature of 490 degrees C. XRD, SAED, and HRTEM patterns show that the nanowires and shells of ZMBs are single-crystalline wurtzite structures. The growth mechanism of ZMBs is discussed in detail. The formation of these hollow microstructures depends on the optimum starting time of air introduction. It is a good way to grow well-aligned nanowires by using a nanoscale rough ZnO surface to realize a "self-catalyzed" vapor-liquid-solid process. The photoluminescence spectrum reveals a strong green emission related to the high surface-to-volume ratio of ZMBs. These types of special hollow high surface area structural ZMBs may find potential applications in functional architectural composite materials, solar cell photoanodes, and nanooptoelectronic devices.
    The Journal of Physical Chemistry B 12/2006; 110(46):23211-4. · 3.61 Impact Factor
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    ABSTRACT: ZnO quantum dots (QDs) were fabricated on Si (001) substrates by pulsed laser deposition (PLD) and subsequent thermal annealing. X-ray diffraction and transmission electron microscopy analyses revealed that the ZnO QDs had polycrystalline hexagonal wurtzite structure. The size and density of ZnO QDs were investigated by atomic force microscopy. It has been found that the density decreased while the size increased with increasing annealing temperature. The analysis of size distribution of the dots shows an obvious bimodal mode according to scaling theory. The Raman spectrum shows a typical resonant multi-phonon form for the ZnO QDs. The collapse from the top of the dots was observed firstly after the samples were exposed in air for 30 days.
    Solid State Communications 01/2006; 137(10):561-565. · 1.53 Impact Factor
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    ABSTRACT: In this paper, we report an approach to prepare a new type of field emitter made up of ZnO nanowires coated with an amorphous carbon (a-C) or carbon nitride film (a-CNx). The coated ZnO nanowires form coaxial nanocables. The best field emission properties, which showed a very low turn-on electric field of 1.5 V µm−1 and an emission current density of 1 mA cm−2 (enough to produce a luminance of 300 cd m−2 from a VGA FED with a typical high-voltage phosphor screen efficacy of 9 lm W−1) under the field of only 2.5 V µm−1, have been obtained from the a-CNx coated ZnO nanowire field emitter among three kinds of emitters: a-C coated ZnO nanowires, a-CNx coated ZnO nanowires and uncoated ZnO nanowires. Microstructures and crystal configuration were investigated by scanning electron microscopy, x-ray diffraction and transmission electron microscopy. Band edge transition without any significant photoluminescence peak relating to intrinsic defects has been observed by photoluminescence measurement. The superior properties of the field emission are attributed to the low work function of the coated carbon nitride film and good electron transport property of the ZnO nanowires with an extremely sharp tip.
    Nanotechnology 05/2005; 16(6):985. · 3.84 Impact Factor
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    ABSTRACT: We report the syntheses of self-catalyst-grown and self-assembled ZnO nanoscrews (ZNS). The morphology and microstructures were characterized by using scanning electron microscopy, transmission electron microscopy and x-ray diffraction. The results reveal that the aligned ZNS are single crystalline grown along the c axis, with 18 sides on their tops but six sides on their stems, while the whole exhibits sixfold symmetry. The formation of such a special-shaped ZNS that may have potential applications in fabrication of nanodevices, is related to the increase of the oxygen supply during the growth followed by a rapidly cooling down process. The growth kinetics of the ZNS is discussed. The field-emission studies show a good stability of the emission current and a low turn-on electrical field.
    Applied Physics Letters 03/2005; · 3.52 Impact Factor
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    ABSTRACT: The zinc oxide (ZnO) nanowires with different morphology and diameter were synthesized on silicon (100) substrates by heating pure zinc powder at low temperatures of 450 °C and 480 °C. Scanning electron microscopy (SEM) was used to analyze the morphology and diameter of samples. The electron field emission properties between different morphology of ZnO nanowires samples were compared. A low turn-on field at 3.6 V/μm was observed from nanorods due to better alignment, and a strong emission current density of 3.6 mA/cm2 at electronic field 9.0V/μm was obtained from needle-like nanowires sample. The emission stability of ZnO samples is also presented.
    Materials Letters - MATER LETT. 01/2005; 59(19):2465-2467.
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    ABSTRACT: 1D-nanostructural zinc oxide (ZnO) with different shapes have been synthesized on p-type Si(1 0 0) and glass substrates via vapor phase growth by heating pure zinc powder at temperatures between 480 and 570 °C. The different ZnO nanostructures depend on the substrates and the growth temperatures. Scanning electron microscopy and X-ray diffraction revealed that a well-aligned nanowires array, which are vertical to the substrate of Si(1 0 0) with 18 sides on their heads, but six sides on their stems, has been formed at 480 °C. Raman study on the ZnO nanostructures shows that the coupling strength between electron and phonon determined by the ratio of the second- to the first-order Raman scattering cross-sections declines with decreasing diameter of the nanowires. However, a little changes of the coupling strength in terms of the width of the nanobelts have been observed.
    Applied Surface Science 01/2005; · 2.54 Impact Factor
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    ABSTRACT: ZnO nanostructures have been grown on p-type Si(1 0 0) and glass substrates by thermal evaporating pure zinc powder without any metal catalysts at 450 or 480 °C. The microstructures of the samples under SEM show nanowires, nanorods and feathers-like morphologies. XRD reveals a preferred orientation of the well-aligned nanorods grown on silicon substrates at 480 °C. And all kinds of grown nanostructural samples are hexagonal ZnO crystal. The growth mechanism of synthesized nanostructures is discussed. Temperature and substrate are critical experimental parameters for the formation of different morphologies of ZnO nanostructures. Room-temperature photoluminescence spectrum of the well-aligned nanorods shows a blue emission band at 420 and 444 nm. The blue luminescence is due to the electrons transition from the shallow donor levels of oxygen vacancies to the valence band.
    Materials Science and Engineering: B. 01/2005; 121:77-80.