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1.
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
2.
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
3.
In this present paper, we report the tunability of ZnO nanoparticles by ultrasonic irradiation. Different sized ZnO nanoparticles
viz. 2.58–2.97 nm have been synthesized with variation of ultrasonic irradiation time 75–270 min in presence of Histidine
as capping agent. UV and visible spectroscopy study revealed that as ultrasonic irradiation time increases, there is increase
in amount of formed ZnO nanoparticles and also there is red shift in absorption edge. This confirms the tunability of bandgap
of histidine capped ZnO nanoparticles with ultrasonic irradiation. Growth mechanism for controlling the size of ZnO nanoparticles
are also discussed. 相似文献
4.
Yue Zheng Chunsheng Shi Naiqin Zhao Xiwen Du Jiajun Li 《Journal of Materials Science》2010,45(24):6657-6660
SiC/ZnO nanocomposites were prepared by radio frequency alternate sputtering followed by annealing in N2 ambient. Well-crystallized ZnO matrix was obtained after annealed at 750 °C according to X-ray diffractometer patterns. Transmission
electron microscopy analyses indicated that the SiC thin layer aggregated to form SiC nanoclusters with the average size of
7.2 nm when the annealing temperature was 600 °C. When the annealing temperatures increased above 900 °C, some of the SiC
nanoclusters changed into SiC nanocrystals and surfacial atoms of the SiC nanoparticles were surrounded by a layer of SiO
x
(x ≤ 2) according to the Fourier transform infrared spectrums. The SiC/ZnO nanocomposites annealed at 750 °C exhibit strong
photoluminescence bands ranging from 250 to 600 nm. UV light originates from the near band edge emission of ZnO and the blue
emission peaked at around 465 nm (2.7 eV) may be due to the formation of emission centers caused by the defects in Si–O network,
while the green-emission peak at around 550 nm (2.3 eV) may be attributed to the deep level recombination luminescence caused
by the vacancies of oxygen and zinc. 相似文献
5.
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
6.
V. B. Patil S. G. Pawar S. L. Patil S. B. Krupanidhi 《Journal of Materials Science: Materials in Electronics》2010,21(4):355-359
The compositional, structural, microstructural, dc electrical conductivity and optical properties of undoped zinc oxide films
prepared by the sol–gel process using a spin-coating technique were investigated. The ZnO films were obtained by 5 cycle spin-coated
and dried zinc oxide films followed by annealing in air at 600 °C. The films deposited on the platinum coated silicon substrate
were crystallized in a hexagonal wurtzite form. The energy-dispersive X-ray (EDX) spectrometry shows Zn and O elements in
the products with an approximate molar ratio. TEM image of ZnO thin film shows that a grain of about 60–80 nm in size is really
an aggregate of many small crystallites of around 10–20 nm. Electron diffraction pattern shows that the ZnO films exhibited
hexagonal structure. The SEM micrograph showed that the films consist in nanocrystalline grains randomly distributed with
voids in different regions. The dc conductivity found in the range of 10−5–10−6 (Ω cm)−1. The optical study showed that the spectra for all samples give the transparency in the visible range. 相似文献
7.
J. H. Thorat K. G. Kanade L. K. Nikam P. D. Chaudhari B. B. Kale 《Journal of Materials Science: Materials in Electronics》2011,22(4):394-399
We report the solvothermal synthesis of nanostructured ZnO hexagons by hydrothermal method via intermediate zinc adipate.
The intermediate zinc adipate was obtained using precursors zinc acetate and adipic acid in aqueous and organic medium. Detailed
XRD analysis of the zinc adipate was studied for the first time. Thermal study of intermediate showed the formation of ZnO
at 400 °C. XRD study demonstrated the existence of wrutzite ZnO of high degree of crystallinity with crystallite size in the
range of 20–25 nm. Scanning Electron Microscopy (SEM) showed distinguished morphology in different medium. Transmission Electron
Microscopy (TEM) demonstrated nanostructured ZnO hexagons with average size 25–50 nm. The band gap for aqueous and organic
mediated ZnO was found to be 3.24 and 3.26 eV, respectively. The band gap obtained is higher than the bulk ZnO, which implies
nanocrystalline nature of the material. 相似文献
8.
Polymorphic ZnO has been prepared by a solution method at low temperature (40–90 °C) and the product has been characterized
by transmission electron microscopy, UV–vis absorption, and photoluminescence spectroscopy. It is found that the morphology
and microstructure of ZnO can be tuned by varying the growth temperature and crystallization condition. The as-synthesized
product exhibits narrowed band gap and strong orange luminescence at 620 nm, which may arise from the interstitial oxygen
ion defect introduced into ZnO in the solution growth process. 相似文献
9.
Aidin Lak Abdolreza Simchi Ziarat Ali Nemati 《Journal of Materials Science: Materials in Electronics》2012,23(2):361-369
Using a combined hydrothermal and sol–gel route, TiO2
-capped ZnO nanoparticles with an average size of 60 nm were prepared. The titania shell was amorphous with a thickness of
~10 nm. Formation of Zn2TiO4 phase at higher calcination temperature was noticed. Effects of Ti/Zn molar ratio and coating time on the thickness of TiO2 shell and the photoactivity of the particles for decolorization of Methylene Blue (MB) under UV lamp irradiation (3 mW/cm2) were investigated. The nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, fourier-transform
infrared spectrometry (FTIR), diffuse reflectance spectroscopy (DLS), and atomic absorption spectroscopy. Analysis of the
photoactivity results according to Langmuir–Hinshelwood model revealed a two-step decolorization process with a high kinetics
rate at the early stage followed by a slower step. The capped nanoparticles synthesized under specific conditions exhibited
higher photodecolorization yield and faster kinetics in comparison to the uncoated ZnO and P25-Degussa TiO2 nanoparticles. 相似文献
10.
Zinc oxide nanomaterials with an average particle size of 20–30 nm are readily synthesized by the reaction of zinc acetate
and oxalic acid under hydrothermal conditions. The samples are characterized by XRD, SEM, TEM, UV and photoluminescence (PL)
studies. The average crystal size of the as prepared ZnO nanopowder is determined by XRD and the values are in good agreement
with the TEM analysis. UV absorption spectra revealed the absorption at wavelength < 370 nm indicating the smaller size of
ZnO nanoparticles. The quality and purity of ZnO nanomaterial crystalline samples are confirmed by photoluminescence spectra. 相似文献
11.
Haiming Zhang Yujie Li Guofeng Hu Bo Gao Yanjun Zhu 《Journal of Materials Science: Materials in Electronics》2010,21(11):1164-1167
Large-scale ZnO tetrapods have been fabricated on silicon substrate by a simple thermal evaporation method at 700 °C without
vapor transportation and characterized by FESEM, XRD, Micro-Raman, and PL, respectively. FESEM images indicate that the length
of tetrapod arm is about 3–4 μm, and the diameter of the tip is about 50 nm. XRD and Raman spectrum reveal that ZnO tetrapods
are highly pure hexagonal wurtzite structure. The PL spectrum indicates that the ZnO tetrapods have strong green emission
at 510 nm. 相似文献
12.
Sanjaya Brahma Kalya Jagannatha Rao Srinivasarao Shivashankar 《Bulletin of Materials Science》2010,33(2):89-95
Large quantities of single-crystalline ZnO nanorods and nanotubes have been prepared by the microwave irradiation of a metalorganic
complex of zinc, in the presence of a surfactant. The method is simple, fast, and inexpensive (as it uses a domestic microwave
oven), and yields pure nanostructures of the hexagonal würtzite phase of ZnO in min, and requires no conventional templating.
The ZnO nanotubes formed have a hollow core with inner diameter varying from 140–160 nm and a wall of thickness, 40–50 nm.
The length of nanorods and nanotubes varies in the narrow range of 500–600 nm. These nanostructures have been characterized
by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area
electron diffraction (SAED). The ZnO nanorods and nanotubes are found by SAED to be single-crystalline. The growth process
of ZnO nanorods and nanotubes has been investigated by varying the surfactant concentration and microwave irradiation time.
Based on the various results obtained, a tentative and plausible mechanism for the formation of ZnO nanostructures is proposed. 相似文献
13.
ZnO nanorods with diameters ranging from 25 to 88 nm and with length up to 1 μm were obtained via citric acid-assisted annealing
route. The sample was characterized by X-ray diffraction, field-emission scanning electron microscopy (FE-SEM), Raman spectrometer,
FTIR spectrophotometer, ultraviolet visible (UV–VIS) spectroscopy, and photoluminescence (PL) spectroscopy. It demonstrates
that the sample is composed of ZnO with hexagonal structure and the ZnO nanorods are of excellent optical quality. 相似文献
14.
Vidhika Sharma Pushpendra Kumar Jaya Shrivastava Anjana Solanki V. R. Satsangi Sahab Dass Rohit Shrivastav 《Journal of Materials Science》2011,46(11):3792-3801
Cu-incorporated nanocrystalline ZnO thin films were deposited on glass substrate by sol–gel. To a solution of zinc acetate
2-hydrate in dimethyl formamide, calculated quantities of copper acetate were added. The clear solution, obtained after 2 h
of continuous stirring, was coated on ITO plates. Pre-annealing at 250 °C was followed by sintering at 400, 500, and 600 °C.
XRD analysis revealed dominant evolution of hexagonal ZnO with a possible simultaneous growth of meta-stable cubic ZnO. AFM
and SEM analysis indicated preferential growth of nanocrystallites along c-axis. Optical characterization led to two prominent absorption thresholds in the UV region; one matching with the band gap
of bulk ZnO and the second at slightly higher energy, suggesting quantum confinement effect in nanocrystallites. Cu incorporation
influenced the two band gap energies differently. Photoelectrochemical splitting of water using 1% at. Cu–ZnO film sintered
at 600 °C resulted in 141% gain in photocurrent at zero bias. 相似文献
15.
Shr-Nan Bai 《Journal of Materials Science: Materials in Electronics》2012,23(2):398-402
Hexagonal ZnO nanowires were synthesized on pre-seeded silicon (100) substrates by a simple hydrothermal method at a relatively
low temperature of 95 °C without any catalyst or template. The pre-seeded layer was produced using the sol–gel spin coating
technique with 1 M zinc acetate in ethanol and ethanolamine. The structural properties of the nanowires were characterized
by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD pattern indicated that the as-grown ZnO nanowires
had the single-phase wurtzite structure, formed along the c-axis. SEM revealed that the nanostructure thin film had wire textures
and the synthesis processes importantly influence the final size and shape of the ZnO nanowires. High-resolution transmission
electron microscopy (HRTEM) provided further insight into the structure of ZnO nanostructures. The obtained HRTEM image was
of the tip of an individual nanowire. The ZnO nanowires highly preferentially grew in the (002) crystal plane. The lattice
spacing between adjacent (002) lattice planes was calculated to be 0.52 nm. The optical characteristics of the nanowires were
determined from cathodoluminescence (CL) spectra. The CL revealed a fairly high surface state density of ZnO nanowires that
grew at reaction concentrations of 0.01–0.25 M. 相似文献
16.
S. Mridha M. Dutta Durga Basak 《Journal of Materials Science: Materials in Electronics》2009,20(Z1):376-379
A series of n-ZnO/p-Si thin film heterojunctions have been fabricated by a low cost sol–gel technique for different ZnO film thicknesses and
the dark as well as photo current–voltage (I–V) characteristics have been investigated in details. The heterojunction with ZnO thickness of 0.46 μm shows the best diode
characteristics in terms of rectification ratio, I
F/I
R = 5.7 × 103 at 5 V and reverse leakage current density, J
R = 7.6 × 10−5 A cm−2 at −5 V. From the photo I–V curves and wavelength dependent photocurrent of the heterojunctions, it is found that the junction with 0.46 μm ZnO thickness
shows the highest sensitivity towards both UV and visible lights. 相似文献
17.
Manoranjan Ghosh Ritwik Bhattacharyya A. K. Raychaudhuri 《Bulletin of Materials Science》2008,31(3):283-289
We report the synthesis and optical properties of compact and aligned ZnO nanorod arrays (dia, ∼ 50–200 nm) grown on a glass
substrate with varying seed particle density. The suspension of ZnO nanoparticles (size, ∼ 15 nm) of various concentrations
are used as seed layer for the growth of nanorod arrays via selfassembly of ZnO from solution. We studied the effect of various
growth parameters (such as seeding density, microstructure of the seed layer) as well as the growth time on the growth and
alignment of the nanorods. We find that the growth, areal density and alignment of the nanorods depend on the density of seed
particles which can be controlled. It is observed that there is a critical density of the seed particles at which nanorod
arrays show maximum preferred orientation along [002] direction. The minimum and maximum radius of the aligned nanorods synthesized
by this method lie in the range 50–220 nm which depend on the seeding density and time of growth. These nanorods have a bandgap
of 3.3 eV as in the case of bulk crystals and show emission in the UV region of the spectrum (∼ 400 nm) due to excitonic recombination
and defect related emission in the visible region. 相似文献
18.
Shao-Hwa Hu Yi-Chuan Chen Chyi-Ching Hwang Cheng-Hsiung Peng Dah-Chuan Gong 《Journal of Materials Science》2010,45(19):5309-5317
Nanocrystalline ZnO particles were synthesized from an aqueous solution composed of zinc acetate dihydrate (Zn(CH3COO)2·2H2O) and urea (H2NCONH2). A precipitating precursor, basic zinc carbonate (Zn5(CO3)2(OH)6), was first formed by hydrothermally treating the solution at 120 °C for 2–4 h. Nanocrystalline ZnO particles were then obtained
by calcining the precursors at 350–650 °C for 0.5–2 h. The synthesis products were characterized using thermogravimetry–differential
scanning calorimetry–mass spectrometry, X-ray diffraction, scanning electron microscopy, transmission electron microscopy
and photoluminescence techniques. Based on the experimental results, a possible reaction mechanism for the ZnO formation was
proposed. The effects of experimental parameters (namely, the hydrothermal treatment time, the calcination time, and the calcination
temperature) on the characteristics of the resulting ZnO products (i.e., the crystalline size and the photoluminescence properties)
were analyzed by the Taguchi method to attain the optimum synthesis conditions. By using the appropriate parameters derived
from this method, we verified that the optimized synthesis provided a yield of ~70% and that the resulting ZnO particles possessed
the characteristics of a ~25 nm crystalline size and a satisfactory photoluminescence property. 相似文献
19.
Wang H Wingett D Engelhard MH Feris K Reddy KM Turner P Layne J Hanley C Bell J Tenne D Wang C Punnoose A 《Journal of materials science. Materials in medicine》2009,20(1):11-22
Fluorescein isothiocyanate (FITC)-encapsulated SiO2 core-shell particles with a nanoscale ZnO finishing layer have been synthesized for the first time as multifunctional “smart”
nanostructures. Detailed characterization studies confirmed the formation of an outer ZnO layer on the SiO2–FITC core. These ~200 nm sized particles showed promise toward cell imaging and cellular uptake studies using the bacterium
Escherichia coli and Jurkat cancer cells, respectively. The FITC encapsulated ZnO particles demonstrated excellent selectivity in preferentially
killing Jurkat cancer cells with minimal toxicity to normal primary immune cells (18% and 75% viability remaining, respectively,
after exposure to 60 μg/ml) and inhibited the growth of both gram-positive and gram-negative bacteria at concentrations ≥250–500 μg/ml
(for Staphylococcus aureus and Escherichia coli, respectively). These results indicate that the novel FITC encapsulated multifunctional particles with nanoscale ZnO surface
layer can be used as smart nanostructures for particle tracking, cell imaging, antibacterial treatments and cancer therapy. 相似文献
20.
《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