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1.
《材料与设计》2015
ZnO hollow nanospheres were fabricated using polystyrene (PS) microspheres as templates were demonstrated in this paper. The structures and morphologies of obtained products were characterized by XRD, FESEM and TEM. The results revealed that ZnO hollow nanospheres possess a hexagonal wurtzite structure with a diameter around 450–500 nm. Ultraviolet–visible (UV–vis) analysis showed that ZnO hollow nanospheres had high absorption in the ultraviolet region and low absorption in the visible region. Room temperature photoluminescence (PL) spectrum showed a weak UV emission at 380 nm and a strong and broad yellow emission centered at 550 nm. The formation mechanism of hollow structure was also investigated. 相似文献
2.
ZnO hollow spherical structures have been synthesized by a facile template-free sonochemical process. The structures and morphologies of products have been characterized by XRD, FESEM and TEM. The results reveal that hollow spherical structures possess a hexagonal wurtzite structure with the in- and out-diameters of about 400 and 500 nm, respectively. The walls of the hollow structures are self-assembled by nanoparticles, partly composed of hexagonal nanoflakes with 40 nm in side lengths. Room temperature photoluminescence (PL) spectrum showed a UV emission at ∼ 384 nm and a broad green emission at the center of 535 nm. A possible formation mechanism was also proposed. 相似文献
3.
Ag/ZnO nanoparticles can be obtained via photocatalytic reduction of silver nitrate at ZnO nanorods when a solution of AgNO3 and nanorods ZnO suspended in ethyleneglycol is exposed to daylight. The mean size of the deposited sphere like Ag particles
is about 5 nm. However, some of the particles can be as large as 20 nm. The ZnO nanorods were pre-prepared by basic precipitation
from zinc acetate di-hydrate in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide. They are
about 50–300 nm in length and 10–50 nm in width. Transmission electron microscopy (TEM), energy-dispersive X-ray analysis
(EDS), X-ray powder diffraction (XRD), UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS), and photoluminescence
(PL) were used to characterize the resulting Ag/ZnO nanocomposites. 相似文献
4.
Cordt Zollfrank Carlos R. Rambo Miroslaw Batentschuk Peter Greil 《Journal of Materials Science》2007,42(15):6325-6330
ZnO tetrapods were prepared by Zn-vapour deposition at 740 °C in Argon and subsequent oxidation in air for 1–30 min. The photoluminescence
(PL) and cathodoluminescence (CL) spectra were measured from ZnO particles collected at various distances from the Zn source
representing decreasing dimensions. The ZnO tetrapods showed a green emission centred at 516 nm (2.40 eV) band and the exciton
emission at 387 nm (3.20 eV). The measured data suggested that the green emission is strongly increased for particle sizes
below 500 nm, whereas the exciton emission is dominant for particle size larger than 500 nm. Spatially resolved CL-measurement
on individual tetrapod legs showed, that the green emission increases with decreasing ZnO leg diameter. To our knowledge,
the local CL spectroscopic measurements were correlated with the dimensions of the individual ZnO tetrapods for the first
time. 相似文献
5.
ZnO tetrapods and Mn doped multipods have been prepared by a rapid thermal oxidation at 1220 °C during 6 min. Moreover, Mn doped ZnO nearly aligned nanostructures forming carpets over sintered pellets have been produced by the same method without the use of catalyst or gas flow. These rods show two different diameters, one of 500 nm and the other one of 300 nm, with lengths of 5 µm. XRD and Raman spectra demonstrate a good crystalline quality of the doped nanostructures. The room temperature photoluminescence shows a quenching of the intrinsic UV emission band on the ZnO tetrapods, due to an increase of material defects. 相似文献
6.
Huizhao Zhuang Jie Wang Junlin Li Peng Xu Feng Shi 《Journal of Materials Science: Materials in Electronics》2011,22(7):765-770
Well-crystallized ZnO nanowires have been successfully synthesized on NiCl2-coated Si substrates via a carbon thermal reduction deposition process. The pre-deposited Ni nanoparticles by dipping the
substrates into NiCl2 solution can promote the formation of ZnO nuclei. The as-synthesized nanowires were characterized by X-ray diffraction (XRD),
scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy
(HRTEM), X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) spectrum. The results demonstrate that the as-fabricated
nanowires with about 60 nm in diameter and several tens of micrometers in length are preferentially arranged along [0001]
direction with (0002) as the dominate surface. Room temperature PL spectrum illustrates that the ZnO nanowires exist a UV
emission peak and a green emission peak, and the peak centers locate at 387 and 510 nm. Finally, the growth mechanism of the
nanowires is briefly discussed. 相似文献
7.
K. Sambath M. Saroja M. Venkatachalam K. Rajendran N. Muthukumarasamy 《Journal of Materials Science: Materials in Electronics》2012,23(2):431-436
ZnO nanostructures have been synthesized in a controlled manner by varying the pH of the precursor solution using hydrothermal
technique. The morphological changes of the prepared ZnO nanostructures have been investigated in the range of pH 5–10. Radial
hexagonal rod-like shape is formed at lower pH values of 5 and 6 whereas, flower-like shape is obtained for higher pH values
of 9 and 10. Flake-like structure is observed at moderate pH of 8. The prepared ZnO nanostructures have been characterized
using X-ray diffraction technique (XRD), energy dispersive X-ray analysis, scanning electron microscope and FTIR spectroscopy.
XRD results show that the prepared ZnO nanostructures exhibit hexagonal wurtzite structure. The growth mechanism suggests
that the supersaturation of the precursor results in various nucleation habits, which induce the formation of ZnO nanostructures
with different morphologies. UV–Vis spectroscopy and photoluminescence were applied to study the optical properties. The photoluminescence
spectrum demonstrated two emission bands, a near band edge emission in the UV region and a strong deep band emission in the
visible region. The change in pH from 5 to 10 results in band gap variations of 3.47–3.97 eV and blue-shift in the peak emission
of visible PL from 560 to 460 nm. 相似文献
8.
Study of structural and optical properties of Ge doped ZnO films 总被引:1,自引:0,他引:1
The Ge doped ZnO films were deposited on quartz substrates by radio frequency magnetron sputtering. The effects of doping and substrate temperature on the structural and optical properties of the Ge doped ZnO films were investigated by means of X-ray diffraction (XRD), UV-visible transmission spectra, X-ray photoelectron spectroscopy and photoluminescence (PL) spectra. The XRD patterns showed that Zn2GeO4 phases were formed in the films. With the increase of substrate temperature the crystallization of Zn2GeO4 was improved, and that of ZnO phases turned worse, and no diffraction peak of ZnO was observed when the substrate temperature was 700 °C. Obvious ultraviolet (UV) light emission was found due to ZnO grains, and it was much stronger than that of un-doped ZnO films. The enhancement of UV light emission at about 380 nm may be caused by excitons which were formed at the interface between Zn2GeO4 and ZnO grains. In the visible region of the PL spectra, the green light emission peak of samples at about 512 nm was associated with defects in ZnO. A red shift of the green light emission peak was observed which can be explained by the fact that there is a luminescence center at about 548 nm taking the place of the defect emission of ZnO with the increase of substrate temperature. The red shift of the green light emission peak and the 548 nm green light emission peaks of the PL spectrum show that some Ge2+ should replace the Zn2+ positions during the Zn2GeO4 grains growth and form the Ge2+ luminescence centers in Zn2GeO4 grains. 相似文献
9.
In the paper, a simple microwave-assisted decomposing reaction in the presence of PEG400 has been successfully developed to synthesize ZnO nanorods with 10-25 nm of diameter and 60-200 nm of length. The product was analyzed and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and HRTEM. Ultraviolet-visible (UV-vis) absorption peak of ZnO nanorods shows a distinct blue shift from that of the bulk and the Photoluminescence (PL) spectrum exhibits a strong near-band-edge emission at 385 nm. Further experiments have also been designed, and the results show that microwave radiation and surfactant PEG400 all played an important role on the formation of ZnO nanorods. 相似文献
10.
11.
L.Z. Pei H.S. Zhao W. Tan H.Y. Yu Y.W. Chen Qian-Feng Zhang 《Materials Characterization》2009,60(9):1063-1067
Single crystalline ZnO nanorods with wurtzite structure have been prepared by a simple hydrothermal process. The microstructure and composition of the products were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM, energy dispersive X-ray spectrum (EDS) and Raman spectrum. The nanorods have diameters ranging from 100 nm to 800 nm and length of longer than 10 µm. Raman peak at 437.8 cm− 1 displays the characteristic peak of wurtzite ZnO. Photoluminescence (PL) spectrum shows a blue light emission at 441 nm, which is related to radiative recombination of photo-generated holes with singularly ionized oxygen vacancies. 相似文献
12.
Yuan Li Qing Li Huijie Wu Jin Zhang Hua Lin Ming Nie Yu Zhang 《Materials Science and Engineering: B》2013,178(2):135-141
High yield ZnS nanospheres were generated conveniently in aqueous solution with the assistance of surfactant polyvinyl pyrrolidone (PVP). The products were characterized by XRD, EDX, XPS, FESEM, TEM and HRTEM. The as-prepared ZnS nanospheres were uniform with an average diameter of 80 nm. The role of PVP in the forming of ZnS nanospheres was investigated. The results indicated that surfactant PVP plays a crucial role on the morphology and size of the products. Moreover, a tentative explanation for the growth mechanism of ZnS nanospheres was proposed. UV–vis and PL absorption spectrum were used to investigate the optical properties of ZnS nanospheres. The UV–vis spectrum indicated that the sample exhibits a dramatic blue-shift. PL spectrum reveals that ZnS nanospheres have a strong visible emission peak centered at 516 nm with excitation light of 400 nm. 相似文献
13.
Mahuya Chakrabarti S. Das Keka R. Chakrabarti D. Sanyal A. Chakrabarti 《Materials Characterization》2009,60(9):1014-1019
Defect induced room temperature ferromagnetic properties of polyvinylpyrrolidone (PVP) capped nanocrystalline ZnO samples have been studied. Crystal phase and the lattice parameter of the synthesized nanocrystalline samples have been determined from X-ray diffraction spectra (XRD) and high-resolution transmission electron micrographs (HR-TEM). Room temperature photoluminescence (PL) spectrum for the bare ZnO sample shows a strong band at ~ 379 nm and another band at ~ 525 nm. The PL spectra also revealed that the number of oxygen vacancies in the uncapped sample is more than the PVP capped sample. Both sample exhibit ferromagnetic property at room temperature when annealed at 500 °C for 3 h, due to the formation of adequate oxygen vacancy related defects. The saturation magnetization for the annealed PVP capped sample is found to be larger compared to that for the uncapped sample. 相似文献
14.
ZnO/TiO2 thin films were fabricated on quartz glass substrates by E-beam evaporation. The structural and optical properties were investigated by X-ray diffraction (XRD), Raman spectra, optical transmittance and photoluminescence. XRD analysis indicates that the TiO2 buffer layer can increase the preferential orientation along the (002) plane of the ZnO film. PL measurements suggest that co-emission of strong UV peak at 378 nm, violet peak at 423 nm and weak green luminescence at 544 nm is observed in the ZnO/TiO2 thin film. The violet luminescence emission at 423 nm is attributed to the interface trap in the ZnO film grain boundaries. 相似文献
15.
Lingling Miao Haiming Zhang Yanjun Zhu Yan Yang Qin Li Jing Li 《Journal of Materials Science: Materials in Electronics》2012,23(10):1887-1890
In this paper, we report a new ZnO nanofibers-nanorods structure which was successfully prepared by the electrospun ZnO nanofibers as seed to guide hydrothermal epitaxial growth of the ZnO nanorods. The structure was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL). The XRD results indicate that ZnO nanofibers obtained at 600° have high crystallinity with a typical hexagonal wurtzite structure. Furthermore compared with the strongest diffraction of ZnO nanofibers in (101) plane, the diffraction from (002) plane of ZnO nanofibers-nanorods becomes the strongest. The SEM shows that the diameters of epitaxial-grown ZnO nanorods on ZnO nanofibers were approximately 100–200?nm. The PL spectrum shows that the ZnO nanofibers-nanorods have a broad green-yellow emission around 537?nm, in contrast to that of ZnO nanofibers, the peak had obvious redshift about 24?nm and the luminous intensity weakened. 相似文献
16.
Changzhen Liu Xiuling Wu Yongqian Wang Zhengjie Zhang 《Materials Research Bulletin》2011,46(9):1414-1416
Sheet-like ZnO with regular hexagon shape and uniform diameter has been successfully synthesized through a two-step method without any metal catalyst. First, the sheet-like ZnO precursor was synthesized in a weak alkaline carbamide environment with stirring in a constant temperature water-bath by the homogeneous precipitation method, then sheet-like ZnO was obtained by calcining at 600 °C for 2 h. The structures and optical properties of sheet-like ZnO have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), photoluminescence (PL) and UV-vis-NIR spectrophotometer. The results reveal that the product is highly crystalline with hexagonal wurtzite phase and has appearance of hexagon at (0 0 0 1) plane. The HRTEM images confirm that the individual sheet-like ZnO is single crystal. The PL spectrum exhibits a narrow ultraviolet emission at 397 nm and a broad visible emission centering at 502 nm. The band gap of sheet-like ZnO is about 3.15 eV. 相似文献
17.
R. Elilarassi G. Chandrasekaran 《Journal of Materials Science: Materials in Electronics》2011,22(7):751-756
Nanocrystalline Zn1−x
Ni
x
O (x = 0.00, 0.02, 0.04, 0.06, 0.08) powders were synthesized by a simple sol–gel autocombustion method using metal nitrates of
zinc, nickel and glycine. Structural and optical properties of the Ni-doped ZnO samples annealed at 800 °C are characterized
using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis using X-rays (EDAX), UV–visible
spectroscopy and photoluminescence (PL). X-ray diffraction analysis reveals that the Ni-doped ZnO crystallizes in a hexagonal
wurtzite structure and secondary phase (NiO) was observed with the sensitivity of XRD measurement with the increasing nickel
concentration (x ≥ 0.04). The lattice constants of Ni-doped ZnO nanoparticles increase slightly when Ni2+ is doped into ZnO lattice. The optical absorption band edge of the nickel doped samples was observed above 387 nm (3.20 eV)
along with well-defined absorbance peaks at around 439 (2.82 eV), 615(2.01 eV) and 655 nm (1.89 eV). PL measurements of Ni-doped
samples illustrated the strong UV emission band at ~3.02 eV, weak blue emission bands at 2.82 and 2.75 eV, and a strong green
emission band at 2.26 eV. The observed red shift in the band gap from UV–visible analysis and near band edge UV emission with
Ni doping may be considered to be related to the incorporation of Ni ions into the Zn site of the ZnO lattice. 相似文献
18.
Tiangui YouJunfeng Yan Zhiyong Zhang Jun LiJiangxiao Tian Jiangni YunWu Zhao 《Materials Letters》2012,66(1):246-249
A simple low temperature hydrothermal process was employed to fabricate the needle-like ZnO array in the diluted butyl amine. The microstructure, morphology and the photoluminescence property of the as-prepared products were characterized by x-ray diffraction (XRD), transmission electron microscope (TEM), field emission environment scanning electron microscope (SEM) and photoluminescence spectrum (PL). The results show that the needle-like ZnO crystals are hexagonal wurtzite monocrystal with slender figure and smooth surface. A possible growth mechanism of the needle-like ZnO array related to the diluted butyl amine is proposed. The PL spectrum of the needle-like ZnO array shows a strong blue light emission at 437 nm and a relatively low ultraviolet emission at 377 nm. 相似文献
19.
Flower-like ZnO nano/microstructures have been synthesized by thermal treatment of Zn(NH3)42+ precursor in aqueous solvent, using ammonia as the structure directing agent. A number of techniques, including X-ray diffraction (XRD), field emission scan electron microscopy (FESEM), transmission electron microscopy (TEM), thermal analysis, and photoluminescence (PL) were used to characterize the obtained ZnO structures. The photoluminescence (PL) measurements indicated that the as-synthesized ZnO structures showed UV (∼375 nm), blue (∼465 nm), and yellow (∼585 nm) emission bands when they were excited by a He-Gd laser using 320 nm as the excitation source. Furthermore, it has been interestingly found that the intensity of light emission at ∼585 nm remarkably decreased when the obtained ZnO nanocrystals were annealed at 600 °C for 3 h in air. The reason might be the possible oxygen vacancies and interstitials in the sample decreased at high temperature. 相似文献
20.
We synthesized vertically aligned ZnO nanowires on SiO2 wafer <100> using the Au, ZnO and Au/ZnO seed layers through the physical vapor deposition process. The growth direction of ZnO nanowire was controlled by using the three different seed layers. From the XRD results, we observed the highest intensity of the (002) peak on the Au/ZnO seed layer among the three seed layers. The SEM images show that all of the ZnO nanowires have an average diameter of about 100 ~ 200 nm and a length of about 5 μm, and the nanowires grown on the Au/ZnO seed layer are oriented the most perpendicularly to the substrate surface. From the PL analysis, we observed that the intensity of broad emissions at 400-600 nm relating the green emission for the ZnO nanowires on the Au/ZnO seed layer was much weaker than that for the ZnO nanowires on the ZnO seed layer. The experiment results indicate that the selection of seed layers is important to grow nanowires vertically for the application of nanoscale devices. 相似文献