共查询到20条相似文献,搜索用时 31 毫秒
1.
Yoshio Kobayashi Hidekazu Kakinuma Daisuke Nagao Yasuo Ando Terunobu Miyazaki Mikio Konno 《Journal of nanoparticle research》2009,11(7):1787-1794
This article describes a method for silica coating of Co–Pt alloy nanoparticles prepared in the presence of poly(vinylpyrrolidone)
(PVP) as a stabilizer. The Co–Pt nanoparticles were prepared in an aqueous solution at 25–80 °C from CoCl2 (3.0 × 10−4 M), H2PtCl6 (3.0 × 10−4 M), PVP (0–10 g/L), and NaBH4 (4.8 × 10−3–2.4 × 10−2 M). The silica coating was performed for the Co–Pt nanoparticle colloid containing the PVP ([Co] = [Pt] = 3.0 × 10−5 M) at 25 °C in (1/4) (v/v) water/ethanol solution with tetraethoxyorthosilicate (TEOS) (7.2 × 10−5–7.2 × 10−3 M) and ammonia (0.1–1.0 M). Silica particles, which had an average size of 43 nm and contained multiple cores of Co–Pt nanoparticles
with a size of ca. 8 nm, were produced at 1.4 × 10−3 M TEOS and 0.5 M ammonia after the preparation of Co–Pt nanoparticles at 80 °C, 5 g/L PVP, and 2.4 × 10−2 M NaBH4. Their core particles were fcc Co–Pt alloy crystallites. Their saturation magnetization was 2.0-emu/g sample, and their coercive
field was 12 Oe. 相似文献
2.
Sujittra Daengsakul Charusporn Mongkolkachit Chunpen Thomas Sineenat Siri Ian Thomas Vittaya Amornkitbamrung Santi Maensiri 《Applied Physics A: Materials Science & Processing》2009,96(3):691-699
This study reports the new and simple synthesis of magnetic La0.7Sr0.3MnO3 (LSMO) nanoparticles by thermal decomposition method using acetate salts of La, Sr and Mn as starting materials. To obtain
the LSMO nanoparticles, thermal decomposition of the precursor is carried out at the temperatures of 600, 700, 800, 900, and
1000°C for 6 hours. The synthesized LSMO nanoparticles were characterized by XRD, FT-IR, TEM and SEM. Structural characterization
shows that the prepared particles consisted of two phases of LaMnO3 (LMO) and LSMO with crystallite sizes ranging from 18 to 55 nm. All the prepared samples have a perovskite structure which
changes from cubic to rhombohedral with the increase in the thermal decomposition temperature. Basic magnetic characteristics
such as saturation magnetization (M
S) and coercive field (H
C) are evaluated by sample vibrating magnetometry at room temperature (20°C). The samples show soft ferromagnetic behavior
with M
S values of ∼9–55 emu/g and H
C values of ∼8–37 Oe, depending on the crystallite size and thermal decomposition temperature. The relationship between the
crystallite size and the magnetic properties is presented and discussed. The cytotoxicity of synthesized LSMO nanoparticles
was also evaluated with NIH 3T3 cells and the result showed that the synthesized nanoparticles were not toxic to the cells
as determined from cell viability in response to the liquid extraction of LSMO nanoparticles. 相似文献
3.
E. Veena Gopalan I. A. Al-Omari D. Sakthi Kumar Yasuhiko Yoshida P. A. Joy M. R. Anantharaman 《Applied Physics A: Materials Science & Processing》2010,99(2):497-503
The magnetocaloric properties of cobalt ferrite nanoparticles were investigated to evaluate the potential of these materials
as magnetic refrigerants. Nanosized cobalt ferrites were synthesized by the method of sol–gel combustion. The nanoparticles
were found to be spherical with an average crystallite size of 14 nm. The magnetic entropy change (ΔS
m) calculated indirectly from magnetization isotherms in the temperature region 170–320 K was found to be negative, signifying
an inverse magnetocaloric effect in the nanoparticles. The magnitudes of the ΔS
m values were found to be larger when compared to the reported values in the literature for the corresponding ferrite materials
in the nanoregime. 相似文献
4.
V. G. Slutskii E. S. Severin L. A. Polenov 《Russian Journal of Physical Chemistry B, Focus on Physics》2010,4(3):515-516
Boron-containing (C2B4H2)
n
nanoparticles with size 6.7, 7.8, and 10.8 nm inert at room temperature were synthesized. The synthesis was performed by
the pyrolysis of gaseous carborane C2B4H6 at 1200–1280 K and the initial carborane pressure (5–25) × 10−3 MPa. An analytic dependence relating the size of nanoparticles to the temperature and initial carborane pressure was obtained. 相似文献
5.
Ruslan Sergiienko Sunghoon Kim Etsuro Shibata Takashi Nakamura 《Journal of nanoparticle research》2010,12(2):481-491
For the first time Fe–Pt alloy included carbon nanocapsules were synthesized by an electric plasma discharge in an ultrasonic
cavitation field of liquid ethanol. This contrasts the extensively used chemical synthesis methods which produce uncoated
Fe–Pt alloy nanoparticles. We proposed that the as-synthesized Fe–Pt alloy included carbon nanocapsules are potentially useful
in biomedical applications. Thereby an aim of this work was to coat the Fe–Pt alloy nanoparticles by graphite shells using
plasma discharge in liquid ethanol and to study the structure and magnetic properties of the carbon encapsulated Fe–Pt alloy
nanoparticles. The core–shell structured nanoparticles were characterized by transmission electron microscopy and X-ray diffraction.
These methods revealed the presence of a disordered face-centered cubic (fcc) structure (γFe, Pt) in the cores of the as-synthesized carbon nanocapsules. The as-synthesized carbon nanocapsules showed the soft magnetic
character at room temperature. These carbon nanocapsules may provide a new approach in the transport and delivery of anticancer
drugs. 相似文献
6.
Xinqi Ma Caixia Feng Zhensheng Jin Xinyong Guo Jianjun Yang Zhijun Zhang 《Journal of nanoparticle research》2005,7(6):681-683
A new method for preparing PtO x -inserted sodium titanate nanotube was reported. By suction of H2PtCl6 ethanol solution into the nanotubes first and annealed at 653 K for 3 h afterwards, Pt nanoparticles formed in the nanotubes. The size of Pt nanoparticles is controlled by the dimensions of nanotubes. Some of them are spherical, some are nanorods. XPS and XRD results revealed that during annealing the following complex reaction happened:
相似文献
$Na_1.1H_0.9Ti_2O_4(OH)_2 + H_2PtCl_6+ O_2 \rightarrow TiO_2(anatase) + PtO_x(x=1,2)+NaCl+ HCl\!\uparrow\!\!.$
7.
Adrián?M.?T.?Silva Bruno?F.?Machado Helder?T.?Gomes José?L.?Figueiredo Goran?Dra?i? Joaquim?L.?Faria 《Journal of nanoparticle research》2010,12(1):121-133
Ce–Ti–O supports with different Ce/Ti molar ratios were synthesized by the solvothermal method using hexadecyltrimethylammonium
bromide. Pt nanoparticles were then supported by photochemical deposition. The shape, size, and structure of these materials
were analyzed by high-resolution transmission electron microscopy. The single CeO2 support was also prepared, consisting of agglomerated cubic particles ranging from ~3 to 8 nm. When titania was combined
with ceria, a nanostructured architecture was produced, evidencing the strong influence of Ti in the support structure. Photodeposition
of Pt nanoparticles is more efficient on Ce–Ti–O supports than in pristine CeO2. Crystalline Pt nanoparticles (mainly of ~2 to 4 nm) were detected. The catalytic properties of the materials were tested
in the selective hydrogenation of cinnamaldehyde to cinnamyl alcohol. It was observed that Pt supported on Ce–Ti–O is more
active and selective than Pt on CeO2 or TiO2 separately. The catalyst with 40 mol% Ce leads to total conversion of cinnamaldehyde in a few minutes; however, higher selectivity
toward the desired product (cinnamyl alcohol) was obtained with higher amounts of Ce (50 mol%). 相似文献
8.
Sayoko Shironita 《Applied Surface Science》2008,254(23):7604-7607
Pt particles in a uniform dispersion were successfully synthesized on single-site photocatalyst (Ti-containing mesoporous silica (Ti-HMS)) under UV-light irradiation by a photo-assisted deposition (PAD) method. Using an aqueous solution of H2PtCl6 as a precursor, the nano-sized Pt metal particles were deposited directly on the photo-excited tetrahedrally coordinated titanium oxide moieties within the framework of mesoporous silica (PAD-Pt/Ti-HMS). The Pt catalysts were characterized by means of XRD, Pt LIII-edge XAFS, CO adsorption, and TEM analysis. It was demonstrated that Pt particles had mean diameter of 4 nm in a narrow size distribution. Meanwhile, Pt particles loaded by a conventional impregnation method (imp-Pt/Ti-HMS) showed a wide size distribution ranging from 2 to 30 nm. The PAD-Pt/Ti-HMS catalyst was more active in the CO oxidation than the conventional impregnated imp-Pt/Ti-HMS catalyst. It is suggested that the PAD method using single-site photocatalyst is a useful and unique technique to prepare fine and uniform Pt nanoparticles. 相似文献
9.
Rhodium nanoparticles were synthesized by the reduction of Rh3+ ion in ethanol solvent with use of the polyvinylpyrrolidone (PVP) of various molecular weights and the solvent of different volume ratios of water to ethanol. The formed Rh(PVP) nanoparticles have been characterized by transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and near edge X-ray absorption fine structure (NEXAFS) techniques. The TEM and AFM results show that the Rh(PVP) nanoparticles are monodispersed and do not agglomerate with each other. The particle size can be controlled by the molecular weight of PVP and/or the water/ethanol ratio of the solvent. The XPS and NEXAFS results indicate that the chlorine derived from RhCl3(3H2O) remains in the obtained nanoparticles but can be removed by heating. 相似文献
10.
Hui Shun Chin Kuan Yew Cheong Khairunisak Abdul Razak 《Journal of nanoparticle research》2011,13(7):2807-2818
Antimony trioxide (Sb2O3) nanoparticles with particle size range from 2 to 12 nm were successfully synthesized by chemical reducing method. Antimony trichloride was reduced by hydrazine with the presence of sodium hydroxide (NaOH) as catalyst in ethylene glycol at 120 °C for 1 h. Effects of hydrazine concentration ([N2H5OH]/[Sb3+] = 0.75, 5, 10, 20, and 30, when concentration of NaOH was fixed [NaOH]/[Sb3+] = 3) and NaOH concentration ([NaOH]/[Sb3+] = 0, 1, 3, and 5, when concentration of hydrazine was fixed [N2H5OH]/[Sb3+] = 10) on the particle size and shape of the Sb2O3 nanoparticles were investigated. Transmission electron microscope, selected area electron diffraction pattern, and high resolution electron microscope were employed to study the morphology and crystallinity of the nanoparticles. It was observed that the particle size decreased and remained constant when [N2H5OH]/[Sb3+]) ≥ 10 and [NaOH]/[Sb3+] = 3. Further study on the crystallinity and phase of the nanoparticles was assisted by X-ray diffractometer (XRD). XRD revealed a cubic phase of Sb2O3 (ICDD file no. 00-043-1071) with preferred plane of (622) and lattice spacing of 1.68 Å. Correlation between UV–visible absorption wavelengths of the nanoparticles and their sizes was established. 相似文献
11.
O. Kaman P. Veverka Z. Jirák M. Maryško K. Knížek M. Veverka P. Kašpar M. Burian V. Šepelák E. Pollert 《Journal of nanoparticle research》2011,13(3):1237-1252
The magnetic nanoparticles of La0.75Sr0.25MnO3 perovskite manganite with a controlled size were prepared via sol–gel procedure, followed by thermal treatment and subsequent
mechanical processing of the resulting raw product. The prepared materials were structurally studied by the XRD and TEM methods
and probed by DC magnetic measurements. The nanoparticles of the mean crystallite sizes 11–40 nm exhibit T
C in the range of ≈310–347 K and the sample possessing 20-nm crystallites was identified as the most suitable for hyperthermia
experiments. In order to obtain a colloidally stable suspension and prevent toxic effects, the selected magnetic cores were
further encapsulated into silica shell using tetraethoxysilane. The detailed magnetic studies were focused on the comparison
of the raw product, the bare nanoparticles after mechanical processing and the silica-coated nanoparticles, dealing also with
effects of size distribution and magnetic interactions. The heating experiments were carried out in an AC field of frequencies
100 kHz–1 MHz and amplitude 3.0–8.9 kA m−1 on water dispersions of the samples, and the generated heat was deduced from their warming rate taking into account experimentally
determined thermal losses into surroundings. The experiments demonstrate that the heating efficiency of the coated nanoparticles
is generally higher than that of the bare magnetic cores. It is also shown that the aggregation of the bare nanoparticles
increases heating efficiency at least in a certain concentration range. 相似文献
12.
Amit Kumar S. M. Yusuf J. V. Yakhmi 《Applied Physics A: Materials Science & Processing》2010,99(1):79-83
We have synthesized nanoparticles of Cu1.5[Cr(CN)6]⋅6.5H2O of varying size by using poly(vinylpyrrolidone) (PVP) as a protecting polymer. The particle size variation has been achieved
by varying the amount of the PVP surfactant with the reactants. The prepared nanoparticles have been investigated by using
X-ray diffraction, transmission electron microscopy, and direct-current magnetization techniques. The nanoparticles crystallize
in a face centred cubic structure (space group: Fm3m). The approximate particle sizes for the three samples are 18, 9, and
5 nm, respectively. Non-PVP nanoparticles (18 nm) show a magnetic ordering temperature of 65 K. A decrease in the magnetic
ordering temperature was observed with decreasing particle size. These nanoparticles are magnetically very soft, showing negligibly
small values of the coercivity and remanent magnetization. The maximum magnetization and spontaneous magnetization values
at 5 K are found to decrease with decreasing particle size. The observed magnetization behaviour of the nanoparticles has
been attributed to the increasing surface spin disorder with decreasing particle size. 相似文献
13.
A method to prepare a core–shell structure consisting of a Pt metal core coated with a silica shell (Pt(in)SiO2) is described herein. A silica shell was grown on poly(vinylpyrrolidone) (PVP)-stabilized Pt nanoparticles 2–3 nm in size through hydrolysis and condensation reactions of tetraethyl orthosilicate (TEOS) in a water/ethanol mixture with ammonia as a catalyst. This process requires precise control of the reaction conditions to avoid the formation of silica particles containing multiple Pt cores and core-free silica. The length of PVP molecules, water content, concentration of ammonia and Pt nanoparticles in solution were found to significantly influence the core–shell structure. By optimizing these parameters, it was possible to prepare core–shell particles each containing a single Pt nanoparticle with a silica layer coating approximately 10 nm thick. 相似文献
14.
Photochemical synthesis of copper nanoparticles incorporated in poly(vinyl pyrrolidone) 总被引:1,自引:0,他引:1
Salvatore Giuffrida Lucia L. Costanzo Giorgio Ventimiglia Corrado Bongiorno 《Journal of nanoparticle research》2008,10(7):1183-1192
The effect of the presence of poly(vinyl pyrrolidone) (PVP) on the copper nanoparticle formation, obtained by UV irradiation
of ethanol solution of Cu(acac)2 (acac = 2,4-pentanedionato), was investigated. At 254 nm, in conditions of light completely absorbed by complex, the PVP
exhibited protective and stabilizing effects, as shown by the formation of a colloidal copper solution and by a block of the
heterogeneous process, which leads to thin film formation on the quartz walls. The colloidal solution was tested for several
months by plasmon position and it was found that it remained unaltered in inert atmosphere, but returned to the starting complex
on contact with air. The PVP ability to control the particle size was investigated by carrying out photoreduction sensitized
by Hacac at 254 and 300 nm, in the presence of PVP concentration varying from 0 to 0.2 M. In this range it was possible to
obtain copper nanoparticles of dimensions decreasing from 30 to 4 nm. Besides this, the PVP (0.005–0.05 M) role as sensitizer
was investigated by irradiating solutions of Cu(acac)2 at 300 nm which is an inactive wavelength for copper reduction by direct light absorption. It was found that the PVP was
an efficient sensitizer of the copper photoreduction. The nanoparticles were characterized by plasmon band, Trasmission Electron
Microscope (TEM) as well as Dynamic Light Scattering (DSL) analysis. The overall results evidence the advantages of the PVP
use in the nanoparticle copper formation through the photochemical technique such as the exclusive formation of colloidal
copper, their size control, stable colloidal solution and complete return to the starting complex. 相似文献
15.
Steven Yueh-Hsiu Wu Ching-Li Tseng Feng-Huei Lin 《Journal of nanoparticle research》2010,12(4):1173-1185
In this study, a magnetic iron-doped calcium sulfide (Fe–CaS) nanoparticle was newly developed and studied for the purpose
of hyperthermia due to its promising magnetic property, adequate biodegradation rate, and relatively good biocompatibility.
Fe–CaS nanoparticles were synthesized by a wet chemical co-precipitation process with heat treatment in a N2 atmosphere, and were subsequently cooled in N2 and exposed to air at a low temperature. The crystal structure of the Fe–CaS nanoparticles was similar to that of the CaS,
which was identified by an X-ray diffractometer (XRD). The particle size was less than 40 nm based on a Debye–Scherrer equation
and transmission electron microscope (TEM) examination. Magnetic properties obtained from the SQUID magnetometer demonstrated
that the synthesized CaS was a diamagnetic property. Once the Fe ions were doped, the synthesized Fe–CaS converted into paramagnetism
which showed no hysteresis loop. Having been heated above 600 °C in N2, the Fe–CaS showed a promising magnetic property to produce enough energy to increase the temperature for hyperthermia. 10 mg/ml
of the Fe–CaS was able to generate heat to elevate the media temperature over 42.5 °C within 6 min. The area of the hysteresis
loop increased with the increasing of the treated temperature, especially at 800 °C for 1 h. This is because more Fe ions
replaced Ca ions in the lattice at the higher heat treatment temperature. The heat production was also increasing with the
increasing of heat treatment temperature, which resulted in an adequate specific absorption ratio (SAR) value, which was found
to be 45.47 W/g at 37 °C under an alternative magnetic field of f = 750 KHz, H = 10 Oe. The in vitro biocompatibility test of the synthesized Fe–CaS nanoparticles examined by the LDH assay showed no cytotoxicity
to 3T3 fibroblast. The result of in vitro cell hyperthermia shows that under magnetic field the Fe–CaS nanoparticles were
able to generate heat and kill the CT-26 cancer cells significantly. We believe that the developed Fe–CaS nanoparticles have
great potential as thermo-seeds for cancer hyperthermia in the near future. 相似文献
16.
S. Sambasivam D. Paul Joseph Jung Hyun Jeong Byung Chun Choi Kwon Taek Lim Sang Su Kim Tae Kwon Song 《Journal of nanoparticle research》2011,13(10):4623-4630
Diluted magnetic semiconductor (DMS) nanoparticles of Sn1−x
Er
x
O2 (x = 0.0, 0.02, 0.04, and 0.1) were prepared by sol–gel method. The X-ray diffraction patterns showed SnO2 rutile structure for all samples with no impurity peaks. The decrease in crystallite size with Er concentration was confirmed
from TEM measurements (from 12 to 4 nm). The UV–Visible absorption spectra of Er-doped SnO2 nanoparticles showed blue shift in band gap compared to undoped SnO2. The electron spin resonance analysis of Er-doped SnO2 nanoparticles indicate Er3+ in a rutile lattice and also decrease in intensity with Er concentration above x = 0.02. Temperature-dependent magnetization studies and the inverse susceptibility curves indicated increased antiferromagnetic
interaction with Er concentration. 相似文献
17.
Ken-ichi Mimura Kosuke Hiramatsu Makoto Moriya Wataru Sakamoto Satoshi Kawado Yoshiaki Uesu Toshinobu Yogo 《Journal of nanoparticle research》2010,12(5):1933-1943
A transparent BaTiO3 particle/polymer hybrid was synthesized from a Ba–Ti double alkoxide modified with an organic ligand and its refractive index
and second harmonic generation were studied. BaTiO3 particles modified with 2-vinyloxyethanol (ethylene glycol monovinyl ether, EGMVE) were polymerized with methyl methacrylate
(MMA) yielding the transparent BaTiO3 particle/poly MMA hybrid. X-ray photoelectron spectra indicated that the formation of chemical bonds between BaTiO3 nanoparticles and the organic matrix. The refractive indexes of the hybrid films depended on the crystallite size of BaTiO3 nanoparticles and the volume fractions of BaTiO3 and polymer phases. The hybrid film synthesized at BaTiO3/8EGMVE/30H2O/PMMA revealed a refractive index of 1.65 at 589 nm with an Abbe number of 54. The hybrid film exhibited a second harmonic
wave of 532 nm on irradiation with a fundamental wave of 1,064 nm. 相似文献
18.
M. Maaza B. D. Ngom S. Khamlich J. B. Kana Kana P. Sibuyi D. Hamidi S. Ekambaram 《Journal of nanoparticle research》2012,14(2):714
The possibility of synthesizing binary oxides nanoparticles in a nano-scaled form by laser liquid solid interaction using
a NdYAG “1.064 μm” as an irradiating laser source is reported. The case of MoO3−δ is emphasized. Furthermore, it is demonstrated that the Mo–O electronic valence can be controlled through the coupling effects
of oxygen enriched nature of the used coating liquid layer, namely pure H2O or H2O2 and the laser beam fluence. Dark blue hydrated molybdic pentoxide Mo2O5·xH2O and yellow molybdenum trioxide MoO3 nano-suspensions were reproducibly synthesized with hydrogen peroxide and water, respectively, at a relatively high ablation
rate. The average size of the molybdenum trioxide nanoparticles was about <ϕ>~8 nm, slightly larger than the molybdic pentoxide
ones “<ϕ>~6.2 nm”. 相似文献
19.
J.W. Yoon T. Sasaki N. Koshizaki 《Applied Physics A: Materials Science & Processing》2003,76(4):641-643
Nanocrystalline thin films of complex oxides such as BaTiO3 and LaFeO3 were prepared by pulsed laser ablation without substrate heating. Targets under various Ar pressures were irradiated using
an ArF excimer laser. The off-axis configuration of targets and substrates was used to synthesize the films. The crystallinity
and chemical composition of the deposited films were strongly dependent on the processing Ar gas pressure. In case of BaTiO3, the film deposited at 10 Pa was a single phase of BaTiO3 with a crystallite size around 7.2 nm. With increasing Ar pressure to 200 Pa, XRD peaks of BaTiO3 as well as BaCO3 were observed. The by-products could be due to reaction with carbon dioxide in air after taking the sample out of the chamber.
For LaFeO3, the films deposited under 50 to 200 Pa had a single phase with a crystallite size below 10 nm. When the Ar pressure exceeded
100 Pa, the crystallite size tended to decrease for both BaTiO3 and LaFeO3, which could be due to formation of aggregated nanoparticles. Below 10 Pa, oxygen deficiency was observed. Over 50 Pa, the
atomic concentration of all the constituent elements was almost constant, especially the [Ba]/[Ti] and [La]/[Fe] ratios, which
were nearly unity.
Received: 19 June 2002 / Accepted: 24 June 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +81-298/61-6355, E-mail: yoon-jw@aist.go.jp 相似文献
20.
To synthesize low-cost, highly conductive metal nanoparticles for inkjet printing materials, we synthesized Sn–Ag bimetallic
nanoparticles using a polyol process with poly(vinyl pyrrolidone). Because a surface oxidation layer forms on Sn nanoparticles,
various compositions of Sn–xAg [x = 0, 20, 40, 60, 80, 100 (wt%)] nanoparticles were synthesized and characterized for the purpose of removing the β-Sn phase.
The results of XPS, TEM, and XRD analyses confirm that the formation of a bimetallic phase, such as Ag4Sn or Ag3Sn, hinders the β-Sn phase and, consequently, leads to the removal of the surface oxidation layer. To measure the sheet resistance
of various compositions of Sn–Ag nanoparticles, we made the ink that contains Sn–Ag by dispersing 10 wt% of Sn–Ag nanoparticles
in methanol. The sheet resistance is decreased by the conductive Sn–Ag phases, such as the fcc, Ag4Sn, and Ag3Sn phases, but sharply increased by the low-conductive Sn nanoparticles and the surface oxidation layer on the Sn nanoparticles.
The sheet resistance results confirm that 80Ag20Sn and 60Ag40Sn bimetallic nanoparticles are suitable candidates for inkjet
printing materials. 相似文献