Nanocrystals of binary metal tellurides, such as PbTe, Ni2Te3, and Cu7Te5, are synthesized by the polyol method under microwave radiation and studied using X-ray powder diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, and photoacoustic spectroscopy. Binary tellurides are formed only in the case when ethylene glycol is used as a reducing agent and only when the reaction is carried out under microwave radiation. No product is formed when the reactions are performed using a conventional technique of heating. The synthesis of the aforementioned metal tellurides is described, and the proposed mechanism of the reaction is discussed.

The microwave irradiation technique was used to prepare three Zintl phase compounds Na3SbTe3, NaSbTe2 and K3SbTe3. The as-prepared products were analyzed and characterized by XRD, EDX and SEM techniques. Higher microwave oven power and shorter irradiation time are required for the synthesis of Na3SbTe3, whereas lower oven power and longer irradiation time are needed for NaSbTe2. Moderate microwave irradiation conditions facilitate the formation of pure K3SbTe3. Pure phase of Na3SbTe3 are directly obtained by this technique for the first time. Compared with the traditional high-temperature solid-state synthesis, the microwave reaction required a considerable shortened reaction time for the preparation of the three Zintl compounds. The initial driving force for these reactions originates from the interaction of microwave electric field with alkali metals (Na and K) and Sb powders.

Porous nickel and cobalt oxides were prepared using NiSO4·6H2O and anhydrous Co(CH3COO)2, a precursor other than alkoxides and cetyltrimethylammonium bromide as organic surfactant. The sonication method has been used for such synthesis. The surfactants were removed by calcination, as well as by solvent extraction and it is extent was examined by IR spectroscopy. The trend of removal of surfactant was followed by TGA studies and the change in phases by DSC. The products were identified by XRD. Peak in low angle XRD indicates the porous nature of the oxides. The morphology of the pores was studied by transmission electron microscopy. The pores were found less ordered, having an average size of 4–6 nm. The Brunauer–Emmet–Teller surface areas of the as-prepared, as well as the treated samples are reported having H2 and H4 type hysteresis for Ni and Co, respectively.

A novel synthetic strategy has been developed for the fabrication of mesostructured titanosilicate with very high titanium content. By the combination of ultrasound radiation and a separate hydrolysis procedure, highly ordered MCM-41 titanosilicates can be synthesized within 3 h from gels with Ti/Si ratios up to 1. The physicochemical properties of the materials were characterized by means of XRD, TEM, FT-IR, UV-Vis DRS, 2 9 Si MAS NMR, and liquid nitrogen adsorption-desorption measurements. The results suggested that during crystallization, sonication re-dispersed and accelerated the condensation of inorganic species, and resulted in more condensed pore walls compared to those synthesized with the conventional methods. The presence of silica and ultrasound radiation remarkably suppressed the aggregation of titanium species, thus, at the medium titanium level, a relatively homogeneous dispersion of titanium within the MCM-41 framework was attained.

Two types of intermetallic lithium alloys, Li21Si5 and Li17Sn4 (previously Li22Si5 and Li22Sn5), were prepared for the first time using microwave-assisted solid-state reaction. The optimum oven power for their preparation is 80-60%, and the irradiation times are 5 min for Li21Si5 or 10 min for Li17Sn4. A cheap alumina crucible was found to be the most suitable container in quick (less than 10 min) microwave reactions for Li-containing alloys. The synthesized compounds were characterized by PXRD. Mossbauer spectroscopy was used to characterize Li17Sn4 under different conditions. The hyperfine interaction parameters of Sn-119 in Li17Sn4 show a typical Li-Sn alloy Sn isomer shift (1.88 mm/s). The oxidization processes of the two intermetallic lithium alloys in air were investigated. The microwave method was found to be simple, fast and efficient, with high selectivity for the preparation of these compounds. (C) 2004 Elsevier Inc. All rights reserved.

Highly ordered ZnO crystals of 0.15 μm width and 0.5 μm length were grown on silicon wafers coated with a monolayer of SiCl3(CH2)11−O−C6H5 molecules. Various techniques (contact angle measurements, ellipsometry, ATR-FTIR) were employed for determining the quality of the monolayer coating. In addition, the bare and silane-coated Si wafers were studied by X-ray reflectivity (XR) and grazing-incidence diffraction (GID) using synchrotron radiation. The results obtained point to a possible relationship between the organization of the self-assembled monolayer (SAM) coating, the dipole moment of the headgroup, and the orientation of the ZnO crystals.

Hexagonal CdSe and hexagonal CdS nanoparticles have been prepared using Cd(Ac)2 and less hazardous elemental Se or S as precursors, respectively, with the aid of ultrasound irradiation under an atmosphere of H2/Ar (5/95, V/V). The products consist of 7–10nm nanocrystallites which aggregated in the form of polydispersive nanoclusters with sizes in the range 30–40nm in the case of CdSe, and near monodispersive nanoclusters with a mean size of about 40nm in the case of CdS. X-ray diffraction, high-resolution TEM and SAED patterns (selected area electron diffraction patterns) show that the as-prepared particles are well crystallized. X-ray photoelectron spectroscopy (XPS) measurements further confirm the formation of CdSe and CdS. Diffuse reflection spectra indicate that both the CdSe and the CdS nanocryslallites are direct band-gap semiconductors with band-gap values of about 1.83 and 2.62eV, respectively. Control experiments demonstrate that the hydrogen is the reducing agent, and the extreme high temperature induced by the collapse of the bubble accelerates the reduction of elemental Se or S by hydrogen. An ultrasound assisted in situ reduction/combination mechanism is proposed.

Li3Bi and Li3Sb are two types of intermetallic lithium alloys, which were prepared for the first time by a microwave-assisted solid-state reaction. They were characterized by PXRD and SEM techniques. Pure phases of Li3Bi and Li3Sb were obtained after only 2 min and 1 min irradiation at 80% microwave power, respectively. The microwave method was found to be simple, fast and efficient for the preparation of these compounds. The oxidization processes of the two intermetallic lithium alloys in air were investigated. After exposure of the two intermetallic compounds to air for 5 hours only the corresponding Bi and Sb were detected by XRD analyses, the Li metal having been converted to amorphous Li2O. SEM observations show that the products are homogeneous, meaning that Bi and Sb are homogeneously dispersed in the amorphous products. The oxidized products may be potential composite anode materials for Li ion batteries.

In this work, we studied the impact of some factors on the behavior of practical electrodes of Li-ion batteries. These included elevated temperatures (45–80°C), prolonged storage of Li-ion cells, and additives in the electrolyte solution. The Li-ion battery systems studied included negative electrodes (anodes) comprising of mesocarbon microbeads (MCMB) and mesocarbon fibers (MCF), and LixCoO2 positive electrodes (cathodes) in an ethylene carbonate (EC)/ethyl-methyl carbonate (EMC) (1:2)/LiPF6 1M solution. Vinylene carbonate (VC) and a Li-organo-borate complex (Li-OBC) were tested as additives. It is shown that the electrochemical response of Li–C negative electrodes depends on the structure of the surface films controlling their behavior, which change upon storage, temperature, and cycling. We established that impedance of these electrodes increased with storage time due to the enrichment of the surface films by LiF and other fluorine-containing species. The capacity fading of the LixCoO2 electrodes in cycling/storage processes at elevated temperatures relates mostly to surface phenomena, whereas the bulk structural characteristics of the electrodes do not change.

Synthesis of a composite mesoporous iron-titanium oxide by ultrasound irradiation is here reported. Iron(III) etboxide and titanium(IV) isopropoxide were used as precursors, and dodecylamine was used as the templating agent. The synthesis was completed in 6 h in one stage. The product was characterized by XRD, TEM, DSC, TGA, XPS, EDX, and BET methods. Magnetic properties were studied by magnetization and Mossbauer spectroscopy. Short-range ordered structure of the product was demonstrated by low-angle XRD measurements. After heat treatment, this structure collapsed and crystalline phases of gamma-Fe2O3 oxide and anatase of TiO2 were observed. The calcinated material showed slight magnetic properties corresponding to the amount of iron oxide. The removal of the surfactant by extraction with diluted nitric acid resulted in the increase of surface area to 650 m(2)/g and the pore volume to 0.45 mL/g. The catalytic properties of the material were examined in the oxidation of cyclohexane under mild conditions, and a high conversion of the substrate to cyclohexanol and cyclohexanone was obtained.

La1−xSrxMnO3 (x=0.3) (LSM) nanoparticles were prepared by a sonication-assisted coprecipitation method. The coprecipitation reaction is carried out with ultrasound radiation. Lower sintering temperatures are required for the sonication-assisted product. Fully crystallized LSM with an average particle size 24nm is obtained after the as-prepared mixture is annealed at 900°C for 2h. Magnetic properties indicate that the transition temperature from the paramagnetic to ferromagnetic state of the sample is quite sharp and occurs at 366K for samples annealed for 2h at 900 and 1100°C.

The design and a description of a very simple and inexpensive air-tight cell for powder x-ray diffraction analysis are discussed. The cell is designed for the Bruker AXS powder diffractometer. It is easily manipulated inside a glove box and reduces the sample preparation time to a fraction of the time required for other hermetic cells or environmental chambers.

Nanoparticles of the CuInTe(2) (CIT) and CuInSe(2) (CIS) alloys have been prepared using the microwave-assisted polyol method. In this simple and quick reaction the polyol is both the solvent and the reducing agent. XRD studies show that nanoparticles of CIT and CIS are formed in the body-centered tetragonal structure and their average diameters are approximately 94 and approximately 83 nm, respectively. Electron microscopy studies show that these formed particles are poorly aggregated with a mean diameter of 100 and 85 nm, respectively. The products have been characterized by different analytical techniques, and the electronic properties have been measured using photoacoustic spectroscopy (PAS).

Nanospherical Ag2S/PVA and nanoneedles of CuS/PVA composite have been prepared by sonochemical irradiation of a 10% ethylenediamine–water solution of elemental sulfur, silver nitrate, or copper acetate in the presence of polyvinyl alcohol. The particle sizes are 25 and 225 nm for Ag2S/PVA and CuS/PVA nanocomposites, respectively. These nanocomposite materials are characterized using analytical techniques such as X-ray diffraction, transmission electron microscopy, thermo-gravimetric analysis, and diffuse reflection spectroscopy. A band gap of 1.05 and 2.08 eV are estimated for Ag2S/PVA and CuS/PVA nanocomposites, respectively.

Nanocrystals of Ag2E (E = Se, Te) were prepared using the polyol reduction method under sonochemical irradiation. Particles were characterized using TEM, HRTEM, SEM, and XRD. The optical properties of the products were studied using photoacoustic spectroscopy (PAS). The differences between the as-prepared samples and single crystals and method of the nanoparticle formation are discussed.

Europium oxide nanorods have been prepared by the sonication of an aqueous solution of europium nitrate in the presence of ammonia. The properties of the Eu2O3 nanorods were characterized by X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, Mossbauer spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, high-resolution scanning electron microscopy, and X-ray photoelectron spectroscopy. The particle sizes measured from transmission electron micrographs and HRSEM are about 50 x 500 nm (W x L). A possible sonochemical mechanism for formation of the cut-opium oxide nanorods is discussed.

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

Silver nanoparticles with an average size of ∼5 nm were deposited on the surface of preformed silica submicrospheres with the aid of power ultrasound. Ultrasound irradiation of a slurry of silica submicrospheres, silver nitrate, and ammonia in an aqueous medium for 90 min under an atmosphere of argon to hydrogen (95:5) yielded a silver−silica nanocomposite. By controlling the atmospheric and reaction conditions, we could achieve the deposition of metallic silver on the surface of the silica spheres. The resulting silver-deposited silica submicrosphere samples were characterized with X-ray diffraction, transmission electron microscopy, differential scanning calorimetry, energy-dispersive X-ray analysis, high-resolution transmission electron microscopy, high-resolution scanning electron microscopy, photoacoustic spectroscopy, and Fourier transform infrared, UV−visible, and X-ray photoelectron spectroscopy.

alpha-CuSe crystals of different sizes and shapes have been synthesized by a sonochemical method using the less hazardous elemental Se and Cu(Ac)(2) as precursors under an atmosphere of H-2/Ar (5 : 95 v/v). X-ray diffraction (XRD), energy-dispersive analytical X-ray (EDAX) and inductively coupled plasma (ICP) have been applied to characterize the products. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) results show that they are crystallized nanoparticles of tens of nanometers or flakes of 1 mm, depending on the irradiation time. Thermogravimetric analysis (TGA) indicates that the products are stable up to about 480 degreesC. Diffusion reflection spectra (DRS) reveal that both of them show an indirect band gap with a similar value of about 1.31 eV. Photoacoustic spectra results show that the nanoparticles and the flakes have direct band gaps of about 2.39 eV and 2.21 eV, respectively. This is the first report of the optical properties of alpha-CuSe. We propose an in situ reduction/reaction mechanism to explain the formation of CuSe. The influence of ultrasound on the shape and the size of the product is discussed. The chelating role of the DMSO solvent in the reaction has also been studied.