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1.
Single-phase zinc aluminate (ZnAl 2O 4) nanoparticles with the spinel structure was successfully obtained by the sol–gel method. The nanoparticles are crystalline
with no impurities related to ZnO or Al 2O 3 residues. The microstructural environment of aluminum ions changes with heat treatment temperature, as observed by FT-IR
and also by 27Al solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) spectra. The photoluminescence spectra show that
the emission of pristine ZnAl 2O 4 may change depending on the calcining temperature due to the quantum size effect. 相似文献
2.
Microwave-induced combustion with glycine, CTAB-assisted hydrothermal process with NaOH and NH3, EDTA assisted-hydrothermal
methods have been applied to prepare NiFe 2O 4 nanoparticles for the first time. Structural and magnetic properties of the products were investigated by X-ray powder diffraction
(XRD), scanning electron microscopy (SEM), transmison electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR),
and electron spin resonance spectrometry (EPR). TEM measurements showed that morphology of the product depends on the synthesis
method employed. The average cystallite size of NiFe 2O 4 nanoparticles was in the range of 14–59 nm as measured by XRD. The uncoated sample (Method A) had an EPR linewidth of 1973
Oe, the coated samples reached lower values. The magnetic dipolar interactions existing among the Ni ferrite nanoparticles
are reduced by the coatings, which could cause the decrease in the linewidth of the EPR signals. Additionally, the linewidth
increases with an increase in the size and the size distribution of nanoparticles. 相似文献
3.
Zinc gallate (ZnGa 2O 4) nanopowders doped with Cr 3+ (1?mo%) were synthesized by the citric acid assisted sol–gel method. The influence of annealing temperature, structural, morphological, and optical properties of ZnGa 2O 4: Cr 3+ (1?mol%) nanosized particles were investigated. The X-ray diffraction (XRD) spectra indicated that the nanoparticles are cubic in structure and the annealing temperature did not influence any c in structure. The average crystallite size of ZnGa 2O 4: Cr 3+ nanoparticles were observed to increase from 11.85 to 30.88?nm as the annealing temperature increased from 600 to 1000?°C. The scanning electron microscopy (SEM) showed nearly spherical nanostructures that change in size with annealing temperature. The high resolution transmission electron microscope (HR-TEM) images show well resolved lattice fringes which is an indications of highly crystalline samples. Ultraviolet–visible (UV–Vis) measurement show decrease in reflectance in visible region and energy band gap was found to decrease with annealing temperature. The photoluminescence (PL) intensity was found to be maximum for sample annealed at high temperature (1000?°C) and least with sample annealed at low temperature (600?°C). An increase in annealing temperature leads significantly increment in PL intensity. The degree of crystallinity also increased with annealing temperature from XRD, SEM, and HR-TEM analysis. The photoluminescence lifetimes, particle size, and emission spectra are comparable with reports on bioimaging applications. 相似文献
4.
Eu, Dy co-doped strontium aluminate nanophosphors were prepared by the combustion synthesis method. Their structure and morphology were investigated by X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy. According to the XRD and the TEM analysis, the average crystallite size was found to be in the nanometer range. The phase structure of the prepared nanophosphor is consistent with a standard monoclinic phase with a space group P2 1. The prepared SrAl 2O 4:Eu 2+, Dy 3+ nanophosphor emitted green light with a peak at 510 nm showing blue shift, which is due to the reduction in the particle size. Two distinct peaks were observed in the ML intensity versus time curve. The two peaks in ML indicate the presence of charge transfer in an ML process. 相似文献
5.
Magnetic Co 3O 4 nanoparticles were prepared by using microporous regenerated cellulose films as sacrificial scaffolds. The cellulose macromolecules
and the porous structure of the films made them used as spatially confined reacting sites where Co(OH) 2 nanoparticles could be synthesized in situ. When the cellulose matrix was removed by sintering at 500 °C, Co 3O 4 nanoparticles were obtained. XRD and XPS indicated that the prepared nanoparticles were pure Co 3O 4 without any impurity. TEM and SEM images revealed that the particle size of the nanoparticles was smaller than 100 nm. The
nanoparticles had weak ferromagnetic properties at 25 °C. Furthermore, the pronounced quantum confinement effects of the synthesized
nanoparticles have been observed, the optical bandgap energies determined were about 1.92 ~ 2.12 and 2.74 ~ 2.76 eV for O 2− → Co 3+ and O 2− → Co 2+ charge-transfer processes, respectively. Furthermore, the resulted Co 3O 4 nanoparticles behaved stable electrochemical performance with promising applications in the electrode for lithium ion battery. 相似文献
6.
Water-soluble Mn 3O 4 nanocrystals have been prepared through thermal decomposition in a high temperature boiling solvent, 2-pyrrolidone. The final
product was characterized with XRD, SEM, TEM, FTIR and Zeta Potential measurements. Average crystallite size was calculated
as ∼15 nm using XRD peak broadening. TEM analysis revealed spherical nanoparticles with an average diameter of 14±0.4 nm.
FTIR analysis indicated that 2-pyrrolidone coordinates with the Mn 3O 4 nanocrystals only via O from the carbonyl group, thus confining their growth and protecting their surfaces from interaction
with neighboring particles.
相似文献
7.
BaMoO 4 crystals were synthesized by a 900 W microwave induced plasma process (MIP) for 40, 60, 120 and 140 min. Phase, morphology, vibrational mode and energy gap were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy, Fourier transform infrared (FTIR) spectroscopy and UV-visible spectroscopy. In this research, the phase and morphology of product were influenced by microwave heating time. The sample processed for 140 min shows spherical particles tetragonal BaMoO 4 phase with size of 200–700 nm in diameter. BaMoO 4 with band gap of 3.35 eV shows a blue emission wavelength at 440 nm. 相似文献
8.
A new titanium complex [Ti(Me–Q) 2(Cl) 2] ( 1) is prepared by reacting titanium tetrachloride with 2-methyl-8-hydroxyquinoline in a fast and facile process. The complex is fully characterized based on its 1H and 13C NMR, IR, and UV spectra and elemental analysis. The prepared nanostructured compound is synthesized by the sonochemical method. This new nanostructure is characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), IR spectroscopy, and elemental analysis. Thermal stability of single crystalline and nanosize samples of the prepared compound is studied by thermal gravimetric (TG) and differential thermal analysis (DTA). The prepared complexes both bulk and nanosized are utilized as a precursor for the preparation of TiO 2 nanoparticles by direct thermal decomposition at 600°C in air. The morphology and size of TiO 2 nanoparticles are determined by SEM, powder XRD, and IR spectroscopy and the results show that the TiO 2 nanoparticle size depends on the initial particle size of 1. Photoluminescence (PL) properties of the nanostructured and crystalline bulk prepared complex and their TiO 2 nanoparticle cores are investigated. 相似文献
9.
Nickel ferrite nanoparticle is a soft magnetic material whose appealing properties as well as various technical applications have rendered it as one of the most attractive class of materials; its technical applications range from its utility as a sensor and catalyst to its utility in biomedical processes. The present paper focuses first on the synthesis of NiFe 2O 4 nanoparticles through co-precipitation method resulting in calcined nanoparticles that were achieved at different times and at a constant temperature (773 k). Afterward, they were dispersed in water that was mixed by chitosan. Chitosan was bonded on the surface of nanoparticles by controlling the pH of media. In order to assess the structural and magnetic properties of nanoparticles, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) analyses were conducted at room temperature. As per the results of XRD analysis, the pure NiFe 2O 4 was synthesized. Additionally, nanoparticles grew in size by extending the calcination process duration. TEM micrographs were used to determine the size and shape of particle; the obtained results indicate that the particle size was in a range of 17–30 nm and of a circular shape. The proper chitosan covering was also indicated by FTIR results. The VSM analysis also revealed that the saturated magnetization of NiFe 2O 4 nanoparticles stood in a range of 29 emu/g and 45 Q e. A stable maximum temperature ranging from 30 to 42 was successfully achieved within 10 min. Also, a specific absorption rate of up to 8.4 W/g was achieved. The study results revealed that the SAR parameter of the coated nickel ferrite nanoparticle is more than that of pure nickel ferrite or cobalt ferrite nanoparticles. 相似文献
10.
Co-doped ZnAl2O4 nanoparticles were prepared by hydrothermal method. The samples were characterized by XRD, HRTEM, EDX, FT-IR, XPS, PL, and UV–Vis, and the effects of cobalt doping on the microstructure and optical property of the samples were studied. The experimental results showed that Co-doped ZnAl2O4 nanoparticles synthesized by this method are single phase with cubic crystal structure, no other impurity phases were observed. Furthermore, with increasing the Co2+ concentration, the average crystallite size of the Co-doped samples became smaller. The absorption bands in FT-IR spectra are broadened in the low frequency region, the PL spectra had the red-shift and the UV–Vis peaks intensity gradually enhanced. 相似文献
11.
Super paramagnetic ZnFe 2O 4 nanoparticles were prepared by a surfactant assisted (ethylamine) hydrothermal method along with heat treatment. The nanoparticles were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, high resolution scanning electron microscopy, Transmission electron microscopy, vibrating sample magnetometer and diffuse reflectance spectra technique. From the analyses, influence of calcination temperature on the structural, vibrational, morphological, magnetic and optical properties of ZnFe 2O 4 nanoparticles were investigated. The ZnFe 2O 4 nanoparticles with an average particle size of 17 nm showed high photocatalytic activity in the degradation of methylene blue (90 %). This work demonstrates that ZnFe 2O4 can be used as a potential monocomponent in visible-light photocatalysis for the degradation of organic pollutants. Furthermore, the products were super paramagnetic and could be conveniently separated within 15 min and recycled by using simple magnet, which is very beneficial for the degradation of organic pollutants. 相似文献
12.
Li 2ZnTi 3O 8/C nanocomposite has been synthesized using phenolic resin as carbon source in this work. The structure, morphology, and electrochemical properties of the as-prepared Li 2ZnTi 3O 8 samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), Raman spectroscopy (RS), galvanostatic charge–discharge, and AC impedance spectroscopy. SEM images show that Li 2ZnTi 3O 8/C was agglomerated with a primary particle size of ca. 40 nm. TEM images reveal that a homogeneous carbon layer (ca. 5 nm) formed on the surface of Li 2ZnTi 3O 8 particles which is favorable to improve the electronic conductivity and inhibit the growth of Li 2ZnTi 3O 8 during annealing process. The as-prepared Li 2ZnTi 3O 8/C composite with 6.0 wt.% carbon exhibited a high initial discharge capacity of 425 and 159 mAh g ?1 at 0.05 and 5 A g ?1, respectively. At a high current density of 1 A g ?1, 95.5 % of its initial value is obtained after 100 cycles. 相似文献
13.
In the paper cesium tungstate nanofibers for the first time have been fabricated successfully by a simple electrospinning technique followed by heat treatment. The cesium tungstate nanofibers have been characterized by XRD, SEM, and FTIR techniques. The results indicated the morphology and quality of the annealed electrospun samples are strongly dependent on the citric acid content within electrospinning solution. It is found with increasing the citric acid content from 7 to 22% the samples morphology changed from a particle structure to a fibrous structure. The average diameter of nanofibers was ~350 nm. XRD analysis reveals that all of the samples have good crystallinity with the same diffraction peaks that can be indexed to the tetragonal phase of Cs 2W 3O 10. Furthermore, the photocatalyst properties of cesium tungstate has not been reported to date. In the work the synthesized Cs 2W 3O 10 nanofibers were found to exhibit photocatalytic performance in the photodegradation of RhB aqueous solution used as a pollutant model. 相似文献
14.
This study presents using zeolitic imidazolate framework-8 (ZIF-8) as porous filler dispersed phase and polyurethane (PU) as continuous phase to synthesis mixed matrix membranes (MMMs). ZIF-8 nanoparticles were synthesized using centrifugal method. The synthesized nanoparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA). In order to investigate the effect of ZIF-8 loading on the membrane performance in CO 2/CH 4 separation, different membranes were prepared with various amounts of ZIF-8 (0–50 wt%). Membranes properties were characterized by SEM, XRD, TGA, differential scanning calorimetry (DSC), and tensile analysis. SEM images exhibit that the ZIF-8 is dispersed uniformly in cross section of membrane. Thermal stability of membranes increases with addition of the ZIF-8 nanoparticles into the polymer matrix. Both tensile strength and strain at break in the MMMs increase with the ZIF-8 loading. To study the effect of feed pressure on CO 2 and CH 4 transport properties of the membranes, single gas experiments were conducted at 4, 8, and 12 bar feed pressures. Incorporation of ZIF-8 crystals into continuous PU matrix resulted in high-performance gas separation membranes. Increasing feed pressure, significantly, increased separation performances in all the membranes. 相似文献
15.
The comparative study of the role of binary oxide support on catalyst physico-chemical properties and performance in methanol
synthesis were undertaken and the spinel like type structures (ZnAl 2O 4, FeAlO 3, CrAl 3O 6) were prepared and used as the supports for 5% metal (Cu, Ag, Au, Ru) dispersed catalysts. The monometallic 5% Cu/support
and bimetallic 1% Au (or 1% Ru)-5% Cu/support (Al 2O 3, ZnAl 2O 4, FeAlO 3, CrAl 3O 6) catalysts were investigated by BET, XRD and TPR methods. Activity tests in methanol synthesis of CO and CO 2 mixture hydrogenation were carried out. The order of Cu/support catalysts activity in methanol synthesis: CrAl 3O{ia6} > FeAlO 3 > ZnAl 2O 4 is conditioned by their reducibility in hydrogen at low temperature. Gold appeared more efficient than ruthenium in promotion
of Cu/support catalysts.
Published in Russian in Kinetika i Kataliz, 2009, Vol. 50, No. 2, pp. 242–248.
The article is published in the original. 相似文献
16.
We report a simple and inexpensive synthesis route of TiO 2 nanoparticles using electrical arc discharge between titanium electrodes in oxygen bubbled deionized (DI) water followed
by heat treatment. The resulting nanoparticles were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy
(XPS), dynamic light scattering (DLS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD
patterns demonstrate formation of TiO 2 phase in oxygen bubbled water after heat treatment and dominance of rutile to anatase phase. The size and morphology of TiO 2 nanoparticles were studied using different arc currents as a crucial parameter in properties of final product. Microscopic
studies reveal nanosize spherical particles. DLS results indicate that at 20 A arc current, the size of the particles is about
37 nm and increases to 59 nm by increasing the arc current up to 40 A. Photodegradation of Rhodamine B (Rh. B) as a standard
pollution shows that heat treated samples in oxygen bubbled water for 2 h at 500 °C, have more photocatalytic activity due
to enhancement in crystallinity. 相似文献
17.
Layered LiNi 1/3Co 1/3Mn 1/3O 2 nanoparticles were prepared by modified Pechini method and used as cathode materials for Li-ion batteries. The pyrolytic
behaviors of the foamed precursors were analyzed by use of simultaneous thermogravimetric and differential thermal analysis
(TG-DTA). Structure, morphology and electrochemical performance characterization of the samples were investigated by X-ray
diffraction (XRD), field emission scanning electron macroscopy(SEM), Brunauer-Emmett-Teller (BET) specific surface area and
charge–discharge tests. The results showed that the samples prepared by modified Pechini method caclined at 900 °C for 10 h
were indexed to pure LiNi 1/3Co 1/3Mn 1/3O 2 with well hexagonal structure. The particle size was in a range of 100–300 nm. The specific surface area was larger than
that of the as-obtained sample by Pechini method. Initial discharge capacity of 163.8 mAh/g in the range 2.8–4.4 V (vs. Li/Li +) and at 0.1C for LiNi 1/3Co 1/3Mn 1/3O 2 prepared by modified Pechini method was obtained, higher than that of the sample prepared by Pechini method (143.5 mAh/g).
Moreover, the comparison of electrochemical results at different current rates indicated that the sample prepared by modified
Pechini method exhibited improved rate capability. 相似文献
18.
The nanosized xerogel of titanium dioxide (TiO 2) and manganese oxides (MnO 2, Mn 2O 3, Mn 3O 4) was prepared by the sol-gel method using manganese chloride (MnCl 2·4H 2O) and titanium isopropoxide (Ti(O-iPr) 4) as precursors in cetyltrimethylammonium bromide (CTAB)/ ethanol/H 2O/HCl micelle solutions, following the calcinations of the produced powders at difference temperatures. The nanostructure
and phase composition of these nanoparticles were characterized with X-ray powder diffraction (XRD), transmission electron
microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The spectroscopic
characterizations of these nanoparticles were also done with UV-Vis spectroscopy and laser Raman spectroscopy (LRS). XRD patterns
show that the pyrophanite MnTiO 3 phase was formed at the calcinations temperature of 900°C. The TEM images show that the nanoparticles are almost spherical
or slight ellipose and the sizes are 50 nm on average. The UV-Vis spectra show that the nanosized MnTiO 3 have significant absorption bands in the visible region. There are new absorption peaks of MnTiO 3 nanoparticles in LRS compared with the pure TiO 2 powder. 相似文献
19.
Mn 3O 4 powders have been produced from Electrolytic Manganese Residue (EMR). After leaching of EMR in sulfuric acid, MnSO 4 solution containing various ions was obtained. Purifying the solution obtained and then adding aqueous alkali to the purified
MnSO 4 solution, Mn(OH) 2 was prepared. Two methods were employed to produce Mn 3O 4. One way was oxidation of Mn(OH) 2 in aqueous phase under atmosphere pressure to obtain Mn 3O 4. The other way was roasting Mn(OH) 2 precursors in the range of 500°C to 700°C. The prepared samples were investigated by using several techniques including X-ray
powder diffraction (XRD), Fourier Transformation Infra-Red (FTIR) spectra, and Brunauer-Emmett-Teller (BET) specific surface
area instrument. Particle distribution and magnetic measurements were carried out on laser particle size analyzer, vibrating
sample magnetometer (VSM). Through XRD, FTIR and determination of total Mn content (TMC), the products prepared were confirmed
to be a single phase Mn 3O 4. BET specific surface areas can reach to 32 m 2 g −1. The results indicated that products synthesized by aqueous solution oxidation method had higher specific surface areas and
smaller particle size than those prepared by means of roasting. However the products prepared using the above two methods
showed no obvious differences in magnetic property.
相似文献
20.
The effect of heat-treatment on 10 wt% CuO-ZnAl 2O 4 catalytic activity in methylation of phenol and the degree of interaction of CuO active phase with support spinel phase were investigated. The CuO-ZnAl 2O 4 sample was subjected to heat-treatment up to 1000°C. The thermal products were characterized by X-ray diffraction (XRD) analysis, nitrogen adsorption-desorption at -196°C and temperature-programmed desorption (TPD-MS) of CO 2. Additionally, the reducibility of copper phases was investigated by temperature-programmed reduction (TPR). XRD patterns of the fresh catalyst sample (calcined at 600°C) indicated the presence of a mixture of poorly crystallized CuO and ZnAl 2O 4 spinel phase. The presence of two reducible copper species has been found on fresh CuO-ZnAl 2O 4 catalyst by TPR analysis. After subsequent calcinations in air at elevated temperatures some CuO disappeared with appearance of CuAl 2O 4 phase. The catalytic results revealed that the CuO addition to ZnAl 2O 4 increases the activity in ortho-methylation of phenol. Subsequent heat-treatment up to 900°C causes partial deactivation of copper centers, which is the result of transformation of CuO to the inactive CuAl 2O 4 phase. 相似文献
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