Powder of BaCe_{0.54}Zr_{0.36}Y_{0.1}O_{2.95} (BCZY) ceramics compound was synthesized by a modified sol-gel method using triethylenetetraamine, TETA as a chelating agent. The samples were dried and calcined at 325°C and 1100°C, respectively. The resulting powder properties were characterized using Particle Size Analyzer (PSA), Scanning Electron Microscope (SEM), X-Ray Fluorescence Spectroscopy (XRF) and Energy Dispersive X-Ray (EDX). At calcination temperature of 1100°C, the sample shows particles with high purity, spherical shape and a single particle size distribution in the range of 342-396 nm. XRF and EDX analysis revealed that the elemental composition of Ba, Ce, Zr and Y present in the sample is almost the same as the nominal stoichiometric composition of BCZY compound. Thus, TETA is one of the potential chelating agents that can be used to synthesize high purity and homogeneous spherically grained cerate-zirconate powders.
The aim of the present work is to compare two methods of synthesis of nanocrystallline zinc oxide doped with iron oxide. The synthesis was carried out using microwave asssisted hydrothermal synthesis and traditional wet chemistry method followed by calcination. The phase composition of the samples was determined using X-ray diffraction measurements. Depending on the chemical composition of the samples, hexagonal ZnO, and/or cubic ZnFe_{2}O_{4} were identified. The morphology of the received materials was characterized using scanning electron microscopy. Two different structures of agglomerates were observed: a hexagonal structure (corresponding to zinc oxide) and spherical (corresponding to spinel phase). The effect of the iron oxide concentration on specific surface area and density of the samples was determined.
Mesoporous maghemite (γ -Fe₂O₃), obtained by thermal decomposition of iron citrate xerogel hydrate, was investigated by X-ray diffraction, scanning electron microscopy, the Mössbauer and impedance spectroscopies and low temperature nitrogen adsorption. The influence of precursor molar concentration on the material morphology, crystalline and magnetic microstructures and electric conductivity was studied. Obtained results open up the possibility for synthesis of ultrafine γ -Fe₂O₃ with controlled structural and morphological characteristics.
This work reports the results of an experimental investigation on physical and mechanical properties of Algerian date palm tree residues in order to optimize their performances when used as reinforcement. The results have shown that all the samples are characterized by porous and fibrous structure with irregular surface, which contains a large number of uncompleted grown fibers (expected to be residual lignin). Concerning the mechanical properties of date palm fibers (DPF), the results show that they are comparable to those reported for coir and are lower than those reported for other natural fibers. However with regard to the specific mechanical properties, date palm fibers show higher values than those of other natural fibers. This is due to the low values of bulk density of date palm wood, especially of that of Petiole.
In this study, Fe and Pt nanoparticles are first synthesized by decomposition of iron(II) chloride tetrahydrate and reduction of platinum(II) acetylacetonate. Then, FePt nanoparticles are similarly fabricated by adding LiBEt3H to the phenyl ether solution in the presence of oleic acid, oleylamine surfactant at 100°C, followed by refluxing at 255°C. The samples were characterized by transmission electron microscopy and energy dispersive spectroscopy analyses after heat treatments. Transmission electron microscopy images show that self-assembled 8 nm Fe nanoparticles are formed as polygon shape, whereas Pt nanoparticles have broad size distribution. On the other hand, 4.5 nm FePt nanoparticles have standard division about 9%. The results of energy dispersive spectroscopy analysis reveal that the composition of Pt, Fe and FePt nanoparticles gives Fe_{56}Pt_{44} stoichiometry.
In this study, lanthanum and Co-, Ni-based oxides at different compositions were prepared by the sol-gel citrate method. Ammonium carbonate and citric acid were used as complexing agent and solvent. The oxides were characterized by scanning electron microscopy-energy-dispersive spectroscopy, X-ray diffraction, and the Brunauer-Emmett-Teller method. Surface area analysis was carried out and the effects of substitution of cobalt and nickel on the physical properties of the synthesized oxides were investigated.
Track etched membranes are porous systems consisting of a thin polymer foil with channels from surface to surface. Latent ion tracks are the result of the passage of swift ions through solid matter and they can be etched selectively. As a result, conical, cylindrical or other shape channels can be obtained. The increasing interest in the polymer track etched membranes with nanochannels is connected with development and creation of nanoporous materials of unique properties. The template synthesis method based on deposition of materials inside well-defined uniform pores of membranes offers unique possibilities of formation of one-dimensional, high aspect ratio (length to diameter) cylindrical species having form of rods, wires, tubules, multiwall tubules and multilayer rods, practically from any solid material. Metal-organic frameworks are a class of hybrid materials comprising metal ion-based vertices and organic ligands (linkers) which serve to connect the vertices into one-, two- or three-dimensional periodic structures. A specific property of porous structures is their intrinsic porosity, which renders them potentially useful for gas storage, separation and catalysis. The possibility of obtaining a new composite material: polymeric track etched membrane with pores filled with hybrid porous material has been demonstrated.
An aqueous solution method has been developed for synthesizing size-controlled Mn^{2+} doped CdS nanocrystals with a relatively narrow size distribution. The nanocrystal samples were characterized by UV-Vis absorption spectra and photoluminescence spectra. We prepared narrow size distribution particles under different synthesis conditions. The effect of manganese concentration on the photoluminescence properties was investigated. Luminescence intensity in different excitation wavelength correlates with different size of CdS:Mn nanocrystals on luminescence spectra. We found that by narrowing the size distribution and doping concentration, CdS samples can be prepared with high luminescence intensity.
Pure and 10 mol% Fe^{3+} doped CeO_2 nanocrystals were synthesized by hydrothermal method using two different basic solutions (NH_4OH and NaOH). All the samples were calcinated at 140°C and 200°C. The characterization of crystalline structure, vibrational and optical properties was performed using X-ray diffraction, Raman spectroscopy and spectroscopic ellipsometry. The obtained results showed that the Fe-doped samples are solid solutions with different size of nanocrystals, very dependent on the synthesis temperature and type of basic solution. The Raman measurements demonstrated electron molecular vibrational coupling and increase of oxygen vacancy concentration whereas doping provokes a small decrease of optical absorption edge in comparison with pure ceria.
Thick films of zinc oxide (ZnO) nanopowders have been prepared by high energy ball-milling for various spans of mill time (3-18 h). The morphology and crystal structure of the prepared ZnO powder were characterized by scanning electron microscope and X-ray diffraction. The ZnO thick films were then used to construct a gas sensor for O,O-dimethyl dithiophosphate of diethyl mercaptosuccinate (malathion) at different operating temperatures. The sensor response at 100 ppm of malathion was found to reach a maximum as large as 80 at 6 h of high energy ball-milling, four times larger than that found for ethanol. Scanning electron microscope observation of the granular state and pore size distribution analyses indicated that increasing high energy ball-milling time gave rise especially to an increase in the volume of pores in the pore size range of 6-35 nm. It is suggested that such a change in nanostructure is responsible for the marked promotion of the response to malathion.
Magnetic nanostructured materials have been found to be very efficient in wastewater decontamination. Among the various synthesis methods, co-precipitation is a rapid and cost-effective technique for the manufacturing of magnetic nanoparticles; moreover, using green chemistry for their stabilization with natural non-toxic capping agents in aqueous solution, such materials become potential candidates as nanocatalytic formulations for water remediation, topic which represents the aim of the present study. Thus, three types of environment-friendly magnetic fluids were synthesized using the chemical precipitation route, the resulted samples being further characterized by various analytical techniques, in order to assess their microstructural features. The results revealed excellent stability in suspension of all samples, the magnetite nanoparticles exhibiting sizes in the nanoscale range with a relatively spherical shape and suitable magnetic properties. Such nanoparticle based products could be the right choice for magnetic responsive and recyclable materials used in the degradation of emerging pollutants from wastewaters.
Gold nanoparticles have a great number of applications, among others in material sciences, biology and medicine. A method for the synthesis of gold nanoparticles in solution with the use of gemini surfactant was proposed and the nanoparticles obtained were subjected to thorough characterisation. The method proposed is a modification of the Turkevich method, based on reduction of tetrachloroauric acid in the presence of trisodium citrate and a dicationic (gemini) surfactant - 1,1'-(1,4-butan)bis(3-dodecyloxymethylimidazolium) di-propionate. Morphology and size distribution of gold nanoparticles obtained were examined by the transmission electron microscopy (TEM), UV-Vis spectroscopy and small angle scattering of synchrotron radiation (SAXS). The plasmon resonance of the nanoparticles obtained was observed in the wavelength range corresponding to the presence of gold nanoparticles with sizes ranging from 5 to 100 nm. TEM images confirmed that the spherical shape of nanoparticles was dominated in reference solutions prepared of sodium citrate and tetrachloroauric acid. In the solutions prepared with addition of gemini surfactant, the gold nanoparticles of triangular morphology were observed.
The purification and functionalization of commercial multiwall carbon nanotubes was investigated. Carbon nanotubes (CNT CO., Ltd, Korea) were treated with boiling concentrated HNO_3 under a reflux condenser for about 50 h at 120°C in order to purify and oxidize the raw material. The oxidized multiwall carbon nanotubes were rinsed with deionized water until stabilization of the filtrate pH. Measurement techniques included elemental analysis (CHN), scanning electron microscopy with energy dispersive X-ray spectrometer, inductively coupled plasma mass spectrometry, Fourier transform infrared spectroscopy and thermal analysis. With the measurement techniques used the following information was obtained: CHN analysis provided information about the quantitative composition of the following elements carbon, hydrogen, nitrogen, scanning electron microscopy imaging provided information on shape, thickness and length of the nanotubes, energy dispersive X-ray spectrometry analysis of information about surface atomic composition of the quantitative analysis, inductively coupled plasma mass spectrometry quantitative analysis of the atomic composition (metals, especially Fe, Al), the Fourier transform infrared studies provided information about qualitative analysis of surface functional groups C_{x}O_{y}H_{z} (COOH, OH, COO) and thermal gravimetric-differential thermal analysis - quantitative analysis of thermal decomposition products. It was found that oxidation leads to the removal of amorphous carbon and forms mainly carboxylic functional groups linked to the nanotubes. The Fourier transform infrared spectra indicate the presence of some other structures, like ketone (quinone), acid anhydride, ether and epoxy groups. Nitric acid treatment also effectively removes aluminum oxide catalyst and iron catalyst from commercial multiwall carbon nanotubes.
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