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1.
Fatemeh Mohandes Masoud Salavati-Niasari 《Journal of Physics and Chemistry of Solids》2010,71(12):1623-1628
The present work reports the synthesis of magnesium oxide (MgO) nanocrystals via a thermal decomposition route and the study of physicochemical properties of products. The MgO nanocrystals were prepared from magnesium oxalate powders as precursor. Transmission electron microscopy (TEM) analysis demonstrated MgO nanocrystals with an average diameter of about 20−25 nm. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electronic diffraction (SAED), and Fourier transform infrared (FT-IR) spectroscopy. Optical absorption and photoluminescence emission properties of MgO nanocrystals were investigated. 相似文献
2.
Large-scale cadmium sulfide (CdS) nanorods with high quality were successfully synthesized by solvothermal method using ethylenediamine
(en) aqueous as solvent. The as-obtained product was investigated by X-ray diffractometer (XRD), high-resolution transmission
electron microscopy (HRTEM), field emission scanning electron microscopy (FE-SEM), ultraviolet–visible (UV–Vis) spectrum and
photoluminescence (PL) spectrum. The length and width of the CdS nanorods were in the range of 1–2 μm, 30–40 nm, respectively.
XRD analysis revealed that the crystal structure of the product was hexagonal phase. Photoluminescence measurement showed
that the nanobelts have two main emission bands around 470 and 560 nm, which should come from the higher-level transition
and the intrinsic transition, respectively. 相似文献
3.
J. Q. Qi Y. Wang W. P. Chen L. T. Li H. L. W. Chan 《Journal of nanoparticle research》2006,8(6):959-963
Perovskite barium zirconate titanate nanoparticles (25–20 nm in diameter) were synthesized at low temperatures and under ambient pressure using titanium alkoxide, zirconium alkoxide and barium hydroxide as the starting materials. Microstructural analyses by X-ray diffraction and transmission electron microscopy indicated that the powders were nano-scaled, well crystallized, and had a perovskite phase. It is proposed that an acid–base neutralization reaction is the key mechanism behind the formation of such nanoparticles. 相似文献
4.
D. Kowalska P. Haro-González I. R. Martín J. M. Cáceres 《Applied Physics A: Materials Science & Processing》2010,99(4):771-776
This paper reports the results obtained in strontium barium niobate (SBN) nanocrystals in glasses doped with 1, 2.5 and 5 mol%
of Er3+ ions. The melt-quenching method was applied to fabricate the glasses with composition SrO–BaO–Nb2O5–B2O3 and further thermal treatment was used to obtain glass ceramic samples from the glass precursor. X-ray diffraction patterns
confirmed the formation of SBN nanocrystals with an average size of about 50 nm in diameter. Time-resolved fluorescence spectra
for the emission of Er3+ ions at 1550 nm have been analyzed in order to confirm the incorporation of the Er3+ ions into the nanocrystals. Green frequency upconversion emission under excitation at 975 nm coming from the ions in the
nanocrystals has been obtained. This intense upconversion is about a factor of 500 higher than that obtained from the ions
which reside in the glassy phase. Moreover, temporal evolution studies have been carried out with the purpose of determining
the involved upconversion mechanism and the importance of these processes as a source of losses for the optical amplification
at 1550 nm. 相似文献
5.
De Zhi Qin Xiao Ming Ma Lin Yang Li Zhang Zhong Jun Ma Jie Zhang 《Journal of nanoparticle research》2008,10(4):559-566
HgS nanocrystals conjugated with protein were synthesized in aqueous solution of Bovine Serum Albumin (BSA) at room temperature.
The obtained HgS nanoparticles with average diameter about 20–40 nm were characterized by powder X-ray diffraction (XRD),
transmission electron microscopy (TEM), selected-area electron diffraction (SAED) and high-resolution transmission electron
microscopy (HRTEM). The quantum-confined effect of the HgS nanoparticles is confirmed by the ultraviolet-visible (UV-vis)
and photoluminescence (PL) spectrum. The rescults indicate that the BSA not only induce the nucleation, but inhibit the further
growth of HgS nanoparticles. The effect of Hg2+ on BSA and the change of BSA conformation were studied through Fourier transform infrared (FTIR) spectroscopy and Circular
dichroism (CD) spectroscopy. The possible mechanism of HgS nanoparticles growth in the BSA solution was also discussed. 相似文献
6.
Zuzanna A. Lewicka Angelo F. Benedetto Denise N. Benoit William W. Yu John D. Fortner Vicki L. Colvin 《Journal of nanoparticle research》2011,13(9):3607-3617
TiO2 and ZnO nanomaterials are widely used to block ultraviolet radiation in many skin care products, yet product labels do not
specify their dimensions, shape, or composition. The absence of this basic information creates a data gap for both researchers
and consumers alike. Here, we investigate the structural similarity of pigments derived from actual sunscreen products to
nanocrystals which have been the subject of intense scrutiny in the nanotoxicity literature. TiO2 and ZnO particles were isolated from eight out of nine commercial suncare products using three extraction methods. Their
dimension, shape, crystal phase, surface area, and elemental composition were examined using transmission and scanning electron
microscopy, X-ray diffraction, Brunauer–Emmett–Teller (BET) specific surface area analysis, energy dispersive X-ray and inductively
coupled plasma optical emission spectroscopy. TiO2 pigments were generally rutile nanocrystals (dimensions ~25 nm) with needle-like or near-spherical shapes. ZnO pigments were
wurtzite rods with a short axes less than 40 nm and longer dimensions often in excess of 100 nm. We identify two commercial
sources of TiO2 and ZnO nanocrystals whose physical and chemical features are similar to the pigments found in sunscreens. These particular
materials would be effective surrogates for the commercial product and could be used in studies of the health and environmental
impacts of engineered nanomaterials contained in sunscreens. 相似文献
7.
Growth and use of metal nanocrystal assemblies on high-density silicon nanowires formed by chemical vapor deposition 总被引:1,自引:0,他引:1
A.A. Yasseri S. Sharma T.I. Kamins Z. Li R. Stanley Williams 《Applied Physics A: Materials Science & Processing》2006,82(4):659-664
In this paper, we describe the growth and potential application of metal nanocrystal assemblies on metal-catalyzed, CVD-grown
silicon nanowires (SiNWs). The nanowires are decorated by chemical assembly of closely spaced (1–5 nm) Ag (30–100 nm diameter)
and Au (5–25 nm diameter) nanocrystals formed from solutions of AgNO3 and NaAuCl4·2H2O, respectively. The formation and growth of metal nanocrystals is believed to involve the galvanic reduction of metal ions
from solution and the subsequent oxidation of available Si-hydride sites on the surfaces of the nanowires. A native oxide
layer suppresses formation of metal nanocrystals; adding HF to the ionic solutions significantly increases the density of
nanocrystals on the surfaces of the nanowires. The nanocrystals coating the nanowires were characterized by X-ray photoelectron
spectroscopy, scanning electron microscopy, and X-ray diffraction. Ag nanocrystals on the nanowires afford sensitive detection
of Rhodamine 6G (R6G) molecules in the 100 picomolar–micromolar range by surface enhanced Raman spectroscopy. In addition,
Au nanocrystals formed on selected surfaces of a substrate of arbitrary shape can serve as effective nuclei for localized
nanowire growth.
PACS 81.07.b; 81.15.Gh 相似文献
8.
Jun Pan Baojuan Xi Jingfa Li Yan Yan Qianwen Li Yitai Qian 《Journal of nanoparticle research》2011,13(8):3535-3543
We report a new morphology of wurzite cadmium sulfide with nanoparticles decorated on rod-bundle structures, which were synthesized
via calcinations of an inorganic/organic composite at 400 °C in air. The composite was hydrothermally synthesized at 180 °C
using thioglycolic acid (TGA) and cadmium acetate as starting materials. The structure, composition, and morphology of the
prepared material were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscope,
FT-IR spectrometry, photoluminescence spectrometry, and UV–visible spectrometry. Results indicated that the composite could
be defined as CdS 0.65/Cd–TGA0.35. X-ray diffraction revealed that the annealed product is CdS with wurtizite phase. The diameter of the rod is about 150–400 nm
and the length from the top to the bottom of the decorated nanoparticle is about 100 nm. The composite showed high intensity
of photoluminescence with similar peak position, compared to that of wurtzite CdS, because of the structure defects. 相似文献
9.
S. Selladurai K. Muthukkumaran P. Kuppusami R. Divakar E. Mohandas V. S. Raghunathan 《Ionics》2007,13(2):87-92
Microstructural characterization of thin films of 5 mol% gadolinia-doped ceria films deposited by pulsed laser ablation in
the energy range 100–600 mJ/pulse has been investigated. As-deposited films were found to be nanocrystalline with preferred
orientation. X-ray diffraction (XRD) analysis revealed that the size of the nanocrystals of doped ceria does not vary significantly
with increasing laser energy, while transmission electron microscopy (TEM) study showed a uniform distribution of nanocrystals
of 8–10 nm for energies ≤200 mJ/pulse and nanocrystals embedded in a large crystalline matrix of doped ceria for energies
in the range 400–600 mJ/pulse. Though, the laser-ablated films were totally free from secondary phases, lattice imaging of
the large grained doped ceria showed growth-induced defects such as dislocations and ledges.
This artice was accidentally published twice. This is the second publication, please cite only the authoritative first one
which is available at . An additional erratum is available at .
An erratum to this article can be found at 相似文献
10.
Lead sulfide (PbS) nano-structured film has been grown on quartz substrates by the PLD technique. The deposited films were
characterized by X-ray diffraction (XRD), selected area electron diffraction (SAED), transmission electron microscopy (TEM)
and scanning electron microscopy (SEM). Formation of cubic phase of PbS nanocrystals is proven. The absorption and emission
spectra were measured for different thicknesses of the films. I–V characteristics and photoconductivity of the deposited film were also measured. The results indicate an efficient performance
of the deposited films as an optical detector. 相似文献
11.
The luminescence properties of zinc oxide (ZnO) nanocrystals grown from solution are reported. The ZnO nanocrystals were characterized by scanning electron microscopy, X-ray diffraction, cathodo- and photoluminescence (PL) spectroscopy. The ZnO nanocrystals have the same regular cone form with the average sizes of 100-500 nm. Apart from the near-band-edge emission around 381 nm and a weak yellow-orange band around 560-580 nm at 300 K, the PL spectra of the as-prepared ZnO nanocrystals under high-power laser excitation also showed a strong defect-induced violet emission peak in the range of 400 nm. The violet band intensity exhibits superlinear excitation power dependence while the UV emission intensity is saturated at high excitation laser power. With temperature raising the violet peak redshifts and its intensity increases displaying unconventional negative thermal quenching behavior, whereas intensity of the UV and yellow-orange bands decreases. The origin of the observed emission bands is discussed. 相似文献
12.
P. K. Khanna K. Srinivasa Rao K. R. Patil V. N. Singh B. R. Mehta 《Journal of nanoparticle research》2010,12(1):101-109
Surface-capped CdSe and CdTe nano-crystals (NCs) have been synthesized using cadmium acetate, oleic acid and respective tri-octylphosphine
chalcogenide (TOPE; E = Se/Te) in diphenyl ether (DPE). Well-dispersed CdSe particles showed two absorption bands at the region
of 431–34 and 458–60 nm in optical absorption study. A band-edge emission resulted at 515 nm with an excitation energy of
400 nm, in its photoluminescence (PL) spectrum. Similarly, UV–visible absorption study of CdTe revealed an absorption band
at <700 nm. The broadened X-ray diffraction (XRD) pattern showed that at higher reaction temperature cubic CdSe but hexagonal
CdTe can be obtained with crystallite size of <10 nm. Scanning electron microscopy (SEM) and transmission electron microscopy
(TEM) revealed that agglomerated particles are of spherical nature. The inter-planar spacing in CdTe was measured to be 0.406 nm,
a characteristic of (100) lattice plane in hexagonal CdTe. X-ray photoelectron spectroscopy (XPS) showed that CdSe NCs have
better air stability stable than CdTe. Presence of organic moiety around the semiconductor particles was confirmed by infra-red
(IR) spectroscopy. 相似文献
13.
In this article, nanocrystalline silicon carbide (nc-SiC) and composite have been synthesized at an annealing temperature
as low as 750 °C through the thermal reaction of Si/C/Si multilayers deposited on the Si(100) substrate by ultra-high-vacuum
ion beam sputtering (UHV IBS) compared with the conventional thermal formation of crystalline SiC (c-SiC) nanostructures above
1,000 °C. The evolution of microstructure and reaction between C and Si was examined by Raman spectroscopy, Fourier transform
infrared spectrometer (FTIR), high-resolution field emission scanning electron microscope (HR-FESEM), and high-resolution
transmission electron microscopy. The c-SiC nanoparticles (np-SiC) of around 20–120 nm in diameter appeared on the top and
bottom of the three-layer film with a particle density of around 2.63 × 1010 cm−2 after 750 °C annealing. The composite of nc-SiC and Si nanocrystals (nc-Si) size below 5 nm embedded in an amorphous SiC
(a-SiC) matrix appeared at the interface between the Si and C layers. Efficient thermal energy is the driving force for the
formation of nc-SiC and composite through interdiffusion between C and Si. The broad visible photoluminescence (PL) spectrum
of 350–750 nm can be obtained from the annealed composite Si/C/Si multilayer and deconvoluted into four bands of blue (~430 nm),
green (~500 nm), green–yellow (~550 nm), and orange (~640 nm) emission, corresponding to the emission origins from nc-SiC,
sp2 carbon clusters, np-SiC, and nc-Si, respectively. 相似文献
14.
S. Selladurai K. Muthukkumaran P. Kuppusami R. Divakar E. Mohandas V. S. Raghunathan 《Ionics》2006,12(6):365-370
Microstructural characterization of thin films of 5 mol% gadolinia doped ceria films deposited by pulsed laser ablation in
the energy range 100–600 mJ/pulse has been investigated, as deposited films were found to be nanocrystalline with preferred
orientation. X-ray diffraction analysis revealed that the size of the nanocrystals of doped ceria does not vary significantly
with increasing laser energy, whereas transmission electron microscopy study showed a uniform distribution of nanocrystal
of 8–10 nm for energies ≤200 mJ/pulse and nanocrystals embedded in a large crystalline matrix of doped ceria for energies
in the range 400–600 mJ/pulse. Although the laser-ablated films were totally free from secondary phases, lattice imaging of
the large grained doped ceria showed growth-induced defects, such as dislocations and ledges. 相似文献
15.
ZnO–CuO core–shell nanorods and CuO-nanoparticle–ZnO-nanorod integrated structures were synthesized for the first time by
a two-stage solution process. Scanning electron microscopy and high-resolution transmission electron microscopy show that
the diameter and the length of the nanorods are around 60 and 800 nm, respectively. The morphologies of outer CuO could be
varied from nanoparticles to nanoshells by adjusting the solvent and dipping processes of copper (II) nitrate solution. The
CuO nanoparticles are single-crystalline or highly textured structures with size of around 30 nm. The CuO shell with thickness
of around 10 nm is constructed of nanocrystals with sizes in the range of 3–10 nm embedded in an amorphous matrix. Room-temperature
cathodoluminescence measurements of the CuO–ZnO nanocomposites exhibit relatively sharp ultraviolet emissions at 380 nm as
well as broad green and yellow emissions at 500 and 585 nm. The p-CuO/n-ZnO one-dimensional nanocomposites are promising for
optoelectronic nanodevice applications. 相似文献
16.
Tantalum nitride (TaN) nanocrystals have been successfully synthesized at 650 °C through a solid-state reaction in an autoclave. The X-ray powder diffraction pattern indicates that the product is a mixture of hexagonal and metastable cubic TaN. Transmission electron microscopy images and selected area electron diffraction patterns show that the hexagonal TaN crystallites consist of nanorod with a typical size of about 50×1000 nm and the cubic TaN crystallites are composed of uniform particles with an average size of about 30 nm. 相似文献
17.
Haiyun Yu Xinyu Song Zhilei Yin Weiliu Fan Xuejie Tan Chunhua Fan Sixiu Sun 《Journal of nanoparticle research》2007,9(2):301-308
The single-crystalline β-FeOOH hollow nanorods with a diameter ranging from 20∼30 nm and length in the range of 70–110 nm
have been successfully synthesized through a two-step route in the solution. The phase transformation and the morphologies
of the hollow β-FeOOH nanorods were investigated with X-ray powdered diffraction (XRD), scanning electron microscopy (SEM),
transmission electron microscopy (TEM), selected area electric diffraction (SAED), high-resolution transmission electron microscopy
(HRTEM), infrared spectrum (IR) and thermo-gravimetric analysis (TGA). These studies indicate that the first step is an incomplete-reaction
course. Furthermore, The formation mechanism of the hollow nanorods has been discussed. It is found that the mixed system
including chitosan and n-propanol is essential for the final formation of the hollow β-FeOOH nanorods. 相似文献
18.
Saeid Zanganeh Amir Kajbafvala Navid Zanganeh Matin Sadat Mohajerani Aidin Lak M. R. Bayati H. R. Zargar S. K. Sadrnezhaad 《Applied Physics A: Materials Science & Processing》2010,99(1):317-321
A flower-like boehmite nanostructure was prepared through a template-free chemical route by the self-assembly process of nanosize
petals 800–1000 nm long, 200–250 nm wide, 20–50 nm thick and having an average crystallite size of about 2.21 nm. X-ray diffraction
analysis (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), DTA/TGA analyses and Brunauer–Emmet–Teller
(BET-N2) analyses were used in order to characterize the product obtained. XRD results exhibited that the obtained nanostructures
composed of pure orthorhombic AlOOH phase. The effects of Cl− ions and TEA on the growth of boehmite three-dimensional nanoarchitectures in the presence of
NO3-\mathrm{NO}_{3}^{-}
ions were investigated. BET analyses of as-prepared material demonstrate that this nanostructure material has a high specific
surface area, as high as 123 m2 g−1. 相似文献
19.
Ashish Tiwari S. A. Khan R. S. Kher S. J. Dhoble 《Journal of Applied Spectroscopy》2011,78(5):680-685
ZnS:Cu nanocrystals capped with different capping molecules have been successfully synthesized by a simple aqueous method.
The prepared nanocrystals were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive
analysis by X-rays (EDAX). The surface characterization of the nanocrystals was done by FTIR spectroscopy. The effect of capping
agents on absorption and photoluminescence (PL) spectra of the ZnS:Cu nanocrystals was studied. A blue shift of the absorption
peaks was observed and attributed to a quantum confinement effect, which increases the band gap energy. The photoluminescence
spectra of the capped ZnS:Cu nanocrystals showed a broad peak in the range of 460–480 nm. The intensity of the PL spectra
strongly depended on the capping agents. 相似文献
20.
Shin Horiuchi Takeshi Hanada Noriya Izu Ichiro Matsubara 《Journal of nanoparticle research》2012,14(3):734
The microstructures and the organization mechanism of cerium oxide (ceria) nanospheres were investigated by transmission electron
microscopy. The ceria nanospheres with the diameter of 50–150 nm were produced by the polyol synthesis method with cerium
nitrate precursor and with polyvinylpyrrolidone (PVP) used as a protecting agent. Dose-limited observations performed by energy-filtering
transmission electron microscopy revealed that the ceria nanospheres were the aggregated products consisting of ceria nanocrystallites
~3 nm in size and PVP-derived polymer products. It was found that the ceria nanocrystallites were oriented within the nanospheres
by high-resolution transmission electron microscopy and selected-area electron diffraction. Selective adsorption of PVP on
the crystal facets of the ceria nanocrystallites was suggested, and the aggregation of the PVP-adsorbed ceria through cross-linking
reaction of PVP causes the crystal orientation. 相似文献