共查询到20条相似文献,搜索用时 31 毫秒
1.
Panatarani Camellia Lenggoro I. Wuled Okuyama Kikuo 《Journal of nanoparticle research》2003,5(1-2):47-53
LiNO3 was used as a shield in the preparation of single crystalline ZnO particles by a spray pyrolysis process in order to prevent agglomeration and enhance the crystallinity of the ZnO. LiNO3 was added to a precursor solution of zinc acetate dihydrate prior to its atomization by means of an ultrasonic transducer. Agglomerate-free particles having a mean particle size of 26 nm were successfully obtained after washing the product. X-ray diffractometry, field-emission scanning electron micrograph and transmission electron micrograph data indicate that the size and morphology of ZnO were strongly influenced by the operating temperature used and the residence time of the particle in the reactor. 相似文献
2.
Seo Dae Jong Bin Park Seung Chan Kang Yun Leong Choy Kwang 《Journal of nanoparticle research》2003,5(3-4):199-210
Nanoparticles of ZnO, MgO and NiO were produced from droplets of aqueous salt solution in the flame spray pyrolysis reactor. Conventional spray pyrolysis, in which electrical furnace reactor is used, is reported to produce nanoparticles only from acetate precursor. If the reactor pressure is low (60torr), nitrate salt precursor is also known to produce nanoparticles. In this paper, we report that nanoparticles are produced from nitrate as well as acetate salt precursor solution when propane–oxygen diffusion flame is used to decompose aqueous aerosol droplets. At low flame temperature, however, nanoparticles are not formed and the particle morphology is similar to the morphology produced by the conventional spray pyrolysis. At high flame temperature, nanoparticles are formed, regardless of the salt type. Nanoparticles are formed at lower flame temperature from acetate salts than from nitrate salts. All nanoparticle prepared in this work were fully crystallized and the size measured from transmission electron microscopy images was 30nm. This size agreed well with the particle size calculated from X-ray diffraction and specific surface area data. 相似文献
3.
Harald Hagendorfer Christiane Lorenz Ralf Kaegi Brian Sinnet Robert Gehrig Natalie V. Goetz Martin Scheringer Christian Ludwig Andrea Ulrich 《Journal of nanoparticle research》2010,12(7):2481-2494
This study describes methods developed for reliable quantification of size- and element-specific release of engineered nanoparticles
(ENP) from consumer spray products. A modified glove box setup was designed to allow controlled spray experiments in a particle-minimized
environment. Time dependence of the particle size distribution in a size range of 10–500 nm and ENP release rates were studied
using a scanning mobility particle sizer (SMPS). In parallel, the aerosol was transferred to a size-calibrated electrostatic
TEM sampler. The deposited particles were investigated using electron microscopy techniques in combination with image processing
software. This approach enables the chemical and morphological characterization as well as quantification of released nanoparticles
from a spray product. The differentiation of solid ENP from the released nano-sized droplets was achieved by applying a thermo-desorbing
unit. After optimization, the setup was applied to investigate different spray situations using both pump and gas propellant
spray dispensers for a commercially available water-based nano-silver spray. The pump spray situation showed no measurable
nanoparticle release, whereas in the case of the gas spray, a significant release was observed. From the results it can be
assumed that the homogeneously distributed ENP from the original dispersion grow in size and change morphology during and
after the spray process but still exist as nanometer particles of size <100 nm. Furthermore, it seems that the release of
ENP correlates with the generated aerosol droplet size distribution produced by the spray vessel type used. This is the first
study presenting results concerning the release of ENP from spray products. 相似文献
4.
S. ZandiP. Kameli H. SalamatiH. Ahmadvand M. Hakimi 《Physica B: Condensed Matter》2011,406(17):3215-3218
In this investigation, ZnO nanoparticles were prepared by a simple and rapid method. This method is based on the short time solid state milling and calcinations of zinc acetate and citric acid powders. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, photoluminescence and UV-vis spectroscopy. It was shown that the calcination temperature significantly affected the particle size and optical properties of the synthesized ZnO nanoparticles. Calculation based on the XRD data shows that the average sizes of ZnO particles are in agreement with those from TEM images and the size of the particles increases on increasing the calcination temperature. Also the band gap of samples decreased from 3.29 to 3.23 eV on increasing the calcination temperature from 350 to 600 °C. Photoluminescence analyses show that many defects such as interstitial zinc, zinc vacancy and oxygen vacancy are responsible for the observed optical properties. 相似文献
5.
S. Iwan S. Bambang J.L. Zhao S.T. Tan H.M. Fan L. Sun S. Zhang H.H. Ryu X.W. Sun 《Physica B: Condensed Matter》2012,407(14):2721-2724
Erbium-doped ZnO (ZnO:Er) thin films with various doping concentrations were deposited on p-Si substrates by ultrasonic spray pyrolysis (USP). The n-ZnO:Er/p-Si heterojunctions were further employed to fabricate light-emitting diodes (LEDs). The devices showed diode-like rectifying current–voltage characteristics with a low reverse breakdown voltage, attributed to the avalanche breakdown. A distinct green electroluminescence peaking at 537 nm and 558 nm were observed at room temperature under reverse bias. The green electroluminescence originated from the electron impact excitation of Er3+ ions doped in ZnO films. 相似文献
6.
Wang Bin Zhao Yue Min Jiahua Sang Wenbin 《Applied Physics A: Materials Science & Processing》2009,94(4):715-718
P-type ZnO was realized by dual-doping with nitrogen and silver via electrostatic-enhanced ultrasonic spray pyrolysis. The
structural, electrical, and optical properties were explored by XRD, Hall-effect, and optical transmission spectra. The resistivity
of ZnO:(N,Ag) film was found to be 56 Ω cm−1 with the high mobility of 76.1 cm2/V s. Compared with ZnO:Ag film, ZnO:(N,Ag) film exhibited a higher and more stable optical transmittance. 相似文献
7.
Zinc oxide (ZnO) and Cu-doped ZnO (CZO) thin films were prepared on borosilicate glass substrates by spray pyrolysis technique.
The X-ray diffraction study revealed that Cu doping caused a reduction in crystallite size. AFM study showed an increase in
roughness with doping. This is attributed to the aggregation of particles to form clusters. From transmission electron microscopy
analysis, the particle size is measured to be in the range 30–65 nm (average particle size 48 nm) for undoped ZnO, whereas
it is in the range 24–56 nm (average particle size 40 nm) for CZO film. The electrical resistivity of the thin films was investigated
in the presence of air as well as N2 mixed air at different temperatures in the range 30–270 °C. The change in resistivity properties was explained on the basis
of conduction phenomena within the grain along with the grain boundaries as well as Cu- and N2-induced defect states. The thermal activation energy of ZnO was found to be in the range 0.04–0.7 eV and dependent on Cu
doping and N2 level in air. 相似文献
8.
Sharda 《Applied Surface Science》2010,256(8):2630-142
Free standing nanoparticles of ZnO doped with transition metal ion Mn have been prepared by solid state reaction method at 500 °C. X-ray diffraction (XRD) analysis confirmed high quality monophasic wurtzite hexagonal structure with particle size of 50 nm and no signature of dopant as separate phase. Incorporation of Mn has been confirmed with EDS. Bio-inorganic interface was created by capping the nanoparticles with heteromultifunctional organic stabilizer mercaptosuccinic acid (MSA). The surface morphological studies by scanning electron microscopy (SEM) showed formation of spherical particles and the nanoballs grow in size uniformly with MSA capping. MSA capping has been confirmed with thermo gravimetric analysis (TGA) and FTIR. Photoluminescence (PL) studies show that the ZnO:Mn2+ particles are excitable by blue light and emits in orange and red. Occurrence of room temperature ferromagnetism in Mn doped ZnO makes such biocompatible luminescent magnetic nanoparticles very promising material. 相似文献
9.
R. Baghdad B. Kharroubi A. Abdiche M. Bousmaha M.A. Bezzerrouk A. Zeinert M. El Marssi K. Zellama 《Superlattices and Microstructures》2012
Mn-doped ZnO thin films with different percentage of Mn content (0, 1, 3 and 5 at.%) and substrate temperature of 350 °C, were deposited by a simple ultrasonic spray pyrolysis method under atmospheric pressure. We have studied the structural and optical properties by using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and ultra-violet visible near infrared (UV–Vis-NIR) spectroscopy. The lattice parameters calculated for the Mn-doped ZnO from XRD pattern were found to be slightly larger than those of the undoped ZnO, which indicate substitution of Mn in ZnO lattice. Compared with the Raman spectra for ZnO pure films, the Mn-doping effect on the spectra is revealed by the presence of additional peak around 524 cm−1 due to Mn incorporation. With increasing Mn doping the optical band gap increases indicating the Burstein–Moss effect. 相似文献
10.
A simple spray pyrolysis setup is used to grow multi-walled carbon nanotubes (MWCNTs), from a ferrocene solution in benzene
as precursor. The effects of process variables such as growth temperature, position of the aerosol generator and position
in the reactor where the sample was formed were investigated. These variables have a strong influence on the graphitization
degree, homogeneity, diameter and alignment of the nanotubes, as observed by TEM, SEM, XRD and Raman spectroscopy. Vertically
aligned MWCNT arrays with high density were obtained in large areas (10 × 10 mm2), with high yield (2.1 mg cm−2) and at a growth rate at 1.43 μm min−1, by a suitable choice of the experimental conditions. 相似文献
11.
Yanping Zhang Xiaowei Sun Likun Pan Haibo Li Zhuo Sun Changqing Sun Beng Kang Tay 《Solid State Ionics》2009,180(32-35):1525-1528
Carbon nanotube (CNT)–zinc oxide (ZnO) nanocomposite and gel poly(vinyl alcohol)–phosphomolybdic acid were employed as the electrode and electrolyte of the experimental supercapacitor cell, respectively. The ZnO nanodots were deposited onto CNT films by ultrasonic spray pyrolysis in different times. The results of electrochemical measurements showed that the electrode with ZnO deposited in 5 min had the optimal capacitive properties among the experimental series, with a lowest interfacial electron transfer resistance, a very high capacitance of 323.9 F/g and good reversibility in the repetitive charge/discharge cycling test. 相似文献
12.
Camellia Panatarani 《Journal of Physics and Chemistry of Solids》2004,65(11):1843-1847
A europium doped ZnO (ZnO:Eu) particle was directly synthesized by the spray pyrolysis method. The crystal structure of samples was designated by the europium ion and the synthesis temperature. We identified the coexistence of Eu2+ and Eu3+ ions in the as prepared ZnO, which was strongly influenced by the doping concentration and the synthesis temperature. With addition of a 0.5 mol% concentration of europium ions, only the Eu2+ ion existed in particles, while both Eu2+ and Eu3+ ions existed in sample using 1 mol% or higher concentration of europium ions. Changing the wavelength of the excitation source, we also found that both the blue and red luminescence can be obtained. 相似文献
13.
Thomas Rudin Karsten Wegner Sotiris E. Pratsinis 《Journal of nanoparticle research》2011,13(7):2715-2725
A new flame-assisted spray pyrolysis (FASP) reactor design is presented, which allows the use of inexpensive precursors and
solvents (e.g., ethanol) for synthesis of nanoparticles (10–20 nm) with uniform characteristics. In this reactor design, a
gas-assisted atomizer generates the precursor solution spray that is mixed and combusted with externally fed inexpensive fuel
gases (acetylene or methane) at a defined height above the atomizing nozzle. The gaseous fuel feed can be varied to control
the combustion enthalpy content of the flame and onset of particle formation. This way, the enthalpy density of the flame
is decoupled from the precursor solution composition. Low enthalpy content precursor solutions are prone to synthesis of non-uniform
particles (e.g., bimodal particle size distribution) by standard flame spray pyrolysis (FSP) processes. For example, metal
nitrates in ethanol typically produce nanosized particles by gas-to-particle conversion along with larger particles by droplet-to-particle
conversion. The present FASP design facilitates the use of such low enthalpy precursor solutions for synthesis of homogeneous
nanopowders by increasing the combustion enthalpy density of the flame with low-cost, gaseous fuels. The effect of flame enthalpy
density on product properties in the FASP configuration is explored by the example of Bi2O3 nanoparticles produced from bismuth nitrate in ethanol. Product powders were characterized by nitrogen adsorption, X-ray
diffraction, X-ray disk centrifuge, and transmission electron microscopy. Homogeneous Bi2O3 nanopowders were produced both by increasing the gaseous fuel content and, most notably, by cutting the air entrainment prior
to ignition of the spray. 相似文献
14.
Homogeneous ZnO Nanoparticles by Flame Spray Pyrolysis 总被引:2,自引:0,他引:2
Zinc oxide (ZnO) nanoparticles were made by flame spray pyrolysis (FSP) of zinc acrylate–methanol–acetic acid solution. The effect of solution feed rate on particle specific surface area (SSA) and crystalline size was examined. The average primary particle diameter can be controlled from 10 to 20nm by the solution feed rate. All powders were crystalline zincite. The primary particle diameter observed by transmission electron microscopy (TEM) was in agreement with the equivalent average primary particle diameter calculated from the SSA as well as with the crystalline size calculated from the X-ray diffraction (XRD) patterns for all powders, indicating that the primary particles were rather uniform in diameter and single crystals. Increasing the solution feed rate increases the flame height, and therefore coalescence and/or surface growth was enhanced, resulting in larger primary particles. Compared with ZnO nanoparticles made by other processes, the FSP-made powder exhibits some of the smallest and most homogeneous primary particles. Furthermore, the FSP-made powder has comparable BET equivalent primary particle diameter with but higher crystallinity than sol–gel derived ZnO powders. 相似文献
15.
To resolve the problem of p-type doping in ZnO, nitrogen and aluminum (N-Al) codoped ZnO films were prepared by the ultrasonic spray pyrolysis (USP) technique. The structural and electrical properties of N-Al codoped ZnO films were investigated. The results demonstrate that the undoped ZnO films exhibit the preferential orientation of (002) plane, while ZnO films show high orientation of (101) plane after codoping with N and Al. The N-Al codoped ZnO films under optimum conditions show p-type conduction, with a low resistivity of 1.7×10−2Ω cm, carrier concentration of 5.09×1018 cm−3 and high Hall mobility of 73.6 cm2 V−1 s−1. A conversion from p-type conduction to n-type was observed during the increase of measurement temperature. 相似文献
16.
Takao Tani Lutz Mdler SotirisE. Pratsinis 《Particle & Particle Systems Characterization》2002,19(5):354-358
Composite ZnO/SiO2 nanoparticles were made by flame spray pyrolysis (FSP). Characteristics of the product powder and its crystallization behavior on post‐calcination were evaluated. Polyhedral aggregates of nano‐sized primary particles consisting of ZnO nano‐crystals 1–3 nm in size and amorphous SiO2 were obtained by FSP. A short residence time in the flame can result in the co‐existence of the ZnO and SiO2 clusters without substitution or reaction hindering each other's grain growth. There was almost no change in the XRD pattern by calcination at 600 °C for 2 h, suggesting a high thermal stability of the ZnO nano‐crystals in the composite particles. A pure α‐willemite phase was obtained at 900 °C. At this calcination temperature, dC and dBET of the powder were 63 and 44 nm, respectively. The nano‐composite structure of the FSP‐made particles can suppress crystalline growth of ZnO during calcination to maintain a high reactivity of ZnO with SiO2, obtaining pure α‐willemite with high specific surface area at low calcination temperatures. 相似文献
17.
《Current Applied Physics》2010,10(5):1249-1254
This paper reports on a simple and inexpensive ultrasonic spray pyrolysis method to synthesize agglomerate-free nanosized SnO2 particles with a size smaller than 10 nm. Scanning electron microscopy, transmission electron microscopy and high resolution X-ray diffraction studies were used to characterize the morphology, crystallinity, and structure of the SnO2 particles. Under the optimized experimental conditions, the prepared SnO2 sensor shows the high response (S = 491) towards 100 ppm ethanol gas at 300 °C, linearity in the range of 100–500 ppm, quick response time (2 s), recovery time (60 s) and selectivity against other gases. The response of the sensor was monitored in a 250–450 °C temperature range. The seven fold enhancement in gas response and selective detection of C2H5OH in the presence of other gases such as CH3OH and CH3CHOHCH3 are the significant points in this investigation. These results demonstrate that pure nanocrystalline SnO2 thin film can be used as the sensing material for fabricating high performance ethanol sensors. 相似文献
18.
ShaoMin Zhou RuiJian Yuan ShiYun Lou YongQiang Wang HongLei Yuan GongYu Zhu LiSheng Liu YaoMing Hao Ning Li 《Journal of nanoparticle research》2011,13(10):4511-4518
Large-scale amorphous wire-like ZnO nanostructures were prepared by ultrasonic spray pyrolysis Zn(CO)5 without involvement of any template or patterned catalyst. The as-obtained amorphous ZnO nanowires were characterized using
scanning/transmission electron microscopy, X-ray diffraction/photoelectron spectroscopy, energy-dispersed X-ray spectrometry,
selected area electronic diffraction, and high-resolution transmission electron microscopy. The results reveal the as-made
noncrystalline samples are about 30–60 nm in diameter and several tens of microns in length and the growth mechanism is tentatively
proposed as the self-assembly soft template mechanism. The photoluminescence spectra in all of the as-studied specimens exhibit
one wide visible emission peak in about 508 nm. The corresponding PL intensity greatly increased with an annealing temperature,
which has an application for a high efficiency vacuum fluorescent displays and a low-voltage phosphor. 相似文献
19.
ZnO nanoparticles were synthesized by the continuous spray pyrolysis technique (CoSP) and the effect of applied voltage across the spray nozzle and an annular ground electrode during spray has been studied. X-ray diffraction and transmission electron microscopy studies showed that the product has (hexagonal) wurtzite structure with the average particle size decreasing from 18.5?nm to 12.9?nm in the presence of a high DC voltage (1?kV). The higher value of the absorption peak for the nanoparticles synthesized without voltage is supportive of this behavior. The films deposited by spin coating using these nanoparticles can be used for a variety of applications, particularly as photoelectrodes for dye-sensitized solar cells. 相似文献
20.
Surface modification with EDTA molecule: A feasible method to enhance the adsorption property of ZnO
Chong Sun Xuanwei WuHao Meng Xinxin XuJunli Xu Xia Zhang 《Journal of Physics and Chemistry of Solids》2014
Surface-functionalized zinc oxide (ZnO) nanoparticles were synthesized with ethylene diamine tetraacetic acid (EDTA) as a modification agent, which were used as adsorbents in the adsorption of Cu2+ at certain conditions. The transmission electron microscopy (TEM) results show that the average size of ZnO particles is about 45 nm, and it exhibits hexagonal wurtzite structure. Fourier transform infrared (FTIR) spectra reveal that the EDTA species are chemically bonded on the surface of ZnO. Compared with bare ZnO particles, the functionalized ZnO nanoparticles have a better activity in the Cu2+ adsorption. The maximum adsorption capacity of functionalized ZnO nanoparticles is 20.97 mg/g, while it is 17.93 mg/g for the bare ZnO. The adsorption isotherm of bare ZnO particles is in accordance with the Freundlich model, and the chemical adsorption is in a dominant position in the adsorption process of Cu2+ on functionalized ZnO particles. 相似文献