Search

A new molecular precursor Ca[SbO(SCH2COO)Cl H2O] was synthesized from the reaction of calcium thioacetate with SbCl3 in (1:1) ratio. The precursor was characterized by elemental analyses, infrared spectra (IR), and thermal analyses (TGA). IR spectra indicated that thioacetate chelates Sb in a binegative bidentate manner via thiol sulfur and carboxylate oxygen after deprotonation. TGA results indicated that the precursor decomposes in three steps. Calcium antimonate (CaSb2O6) was synthesized from the thermal decomposition of the molecular precursor at 250 °C in air. The calcination product was characterized by X-ray diffractions (XRD), scanning electron microscope (SEM), and transmittance electron microscope (TEM). The results of X-ray diffractions indicated the formation of calcium antimonate nanoparticles which crystallizes in hexagonal system. The crystallite size was found to be 32 nm. Electron microscopes (SEM and TEM) indicated the formation of aggregates of spherical nanoparticles that forms rod like shape. The optical band gap (Eg) measurements showed allowed direct electronic transition. The determined Eg value is 3.9 eV, which is larger than the bulk. [ABSTRACT FROM AUTHOR]

We performed cathodoluminescence (CL) spectroscopy and imaging in a high-resolution scanning electron microscope to locally and selectively excite and investigate the plasmonic properties of a multi-branched gold nanostar on a silicon substrate. This method allows us to map the local density of optical states from the nanostar with a spatial resolution down to a few nanometers. We resolve, both in the spatial and spectral domain, different plasmon modes associated with the nanostar. Finite-difference time-domain (FDTD) numerical simulations are performed to support the experimental observations. We investigate the effect of the substrate on the plasmonic properties of these complex-shaped nanostars. The powerful CL-FDTD combination helps us to understand the effect of the substrate on the plasmonic response of branched nanoparticles. [ABSTRACT FROM AUTHOR]

Inorganic nanoparticles of layered [two-dimensional (2D)] compounds with hollow polyhedral structure, known as fullerene-like nanoparticles (IF), were found to have excellent lubricating properties. This behavior can be explained by superposition of three main mechanisms: rolling, sliding, and exfoliation-material transfer (third body). In order to elucidate the tribological mechanism of individual nanoparticles in different regimes, in situ axial nanocompression and shearing forces were applied to individual nanoparticles using a high resolution scanning electron microscope. Gold nanoparticles deposited onto the IF nanoparticles surface served as markers, delineating the motion of individual IF nanoparticle. It can be concluded from these experiments that rolling is an important lubrication mechanism for IF-WS2 in the relatively low range of normal stress (0.96±0.38 GPa). Sliding is shown to be relevant under slightly higher normal stress, where the spacing between the two mating surfaces does not permit free rolling of the nanoparticles. Exfoliation of the IF nanoparticles becomes the dominant mechanism at the high end of normal stress; above 1.2 GPa and (slow) shear; i.e., boundary lubrication conditions. It is argued that the modus operandi of the nanoparticles depends on their degree of crystallinity (defects); sizes; shape, and their mechanical characteristics. This study suggests that the rolling mechanism, which leads to low friction and wear, could be attained by improving the sphericity of the IF nanoparticle, the dispersion (deagglomeration) of the nanoparticles, and the smoothness of the mating surfaces. [ABSTRACT FROM AUTHOR]

Compositional images from a SEM (scanning electron microscope) are sometimes complemented by quantitative topographical data from devices such as an AFM (atomic force microscope) or WLI (white light interferometer). Indeed, even if a SEM could provide both kinds of information (composition and topography), the topographical data are incomplete because the SEM does not allow measuring the vertical dimension (i.e., perpendicular to the measurement plane). Thus these two kinds of information are usually measured using two different techniques, and at different locations on the sample. Mean values of surface composition are then linked to mean values of topography, and as a consequence this approach does not allow precisely linking a local topographical peak to its corresponding composition. The present work deals with a SEM/WLI combination methodology, based on the characterization, at the same location, of a nanocomposite (nanoparticles of AlCeO3 dispersed in a plasma-polymerized hexamethyldisiloxane ppHMDSO matrix and deposited by atmospheric plasma on a glass substrate) developed for improving anticorrosion properties. SEM images allow the supposition that the protuberances (peaks) observed on the surface of a specimen are linked to the nanoparticles dispersed in the polymer coating, but this link is not fully convincing. Thanks to a precise localization method, SEM compositional data and WLI topographical data are here measured at the same location. The recombination of both signals to form a 4D image (3D geometry and 1D composition) allows linking protuberances to nanoparticles aggregates without ambiguity. This composite image appears to be an interesting new tool (at the scale of observation, i.e., hundreds of micrometers) for the study of nanostructured coatings. [ABSTRACT FROM AUTHOR]

Preparation and characterization of silica nanoparticles via an economic route through sol-gel processing using the widely available and economic sodium silicate as a precursor were investigated. Through some experiments, the optimal synthesis conditions for the preparation of silica nanoparticles were obtained and the produced silica nanoparticles were characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), infrared specrra (IR) and thermogravimetric analysis (TG). The results indicated that the silica nanoparticles were successfully formed. The XRD analysis indicated the amorphous structure of the synthesized silica nanoparticles while the transmission electron microscope image exhibited monodispersed nanosized silica particles with a size ∼25nm. [ABSTRACT FROM AUTHOR]

Iron oxide nanoparticle of magnetite, one of well-known soft magnetic materials, has been investigated due to their various potential applications. In order to apply it as a magnetorheological (MR) material, composite of poly(vinyl butyral) and magnetite nanoparticles was prepared via solvent evaporation method using synthesized magnetite nanoparticles because of their proper magnetic characteristics and dispersion stability in a viscous medium. The magnetite nanoparticle was prepared via a co-precipitation method using ferrous and ferric ionic aqueous solutions. Surface and internal morphology of the composite particles were observed via scanning electron microscope and transmittance electron microscope. The MR fluid was prepared by suspending the composite particles in mineral oil. Its MR characteristics were examined via a rotational rheometer in a parallel plate geometry equipped with a magnetic field supplier. MR properties of the composite based MR fluid exhibit typical MR behavior with maximum yield stress of 800 Pa when 343 kA/m of magnetic field was applied. [ABSTRACT FROM AUTHOR]

Titanium oxide (TiO2) thin films can be prepared by controlled hydrolysis of a titanium tetrachloride (TiCl4) precursor in an aqueous solution at temperatures below 100°C. As part of an effort to understand the formation of such TiO2 films, the kinetics of the nucleation, growth, and aggregation of TiO2 nanoparticles in aqueous solutions of TiCl4 were studied using dynamic light scattering and a transmission electron microscope (TEM). A higher degree of supersaturation, produced by a higher solution temperature, a higher concentration of TiCl4, or a higher pH, results in a shorter nucleation induction time, a faster initial growth/aggregation rate, and a larger aggregate size. The interfacial energy of TiO2 nanoparticles was found to be 0.072 J/m2 from the homogeneous nucleation theory. Further investigations by a high-resolution scanning electron microscope (SEM) and TEM for the as-deposited films showed the structure hierarchy organized from nanocrystalline particles precipitated in the supersaturated solution. As a result, the effect of solution conditions on the nucleation, growth, and aggregation of TiO2 nanoparticles can provide useful guidance for tailoring of microstructures of the TiO2 films. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the precursor precipitates of Zinc oxide (ZnO) were obtained by a direct precipitation method via the reaction between Zinc nitrate (Zn(NO3)2) and Ammonium carbonate ((NH4)2CO3) in aqueous solutions with proper concentration. X-ray diffraction (XRD) analysis demonstrated that the precursor precipitates of ZnO were Zn4(CO3)(OH)6·H2O. Both the Differential thermal analysis (DTA) and the thermal gravimetric analysis (TGA) curves of the precursor precipitates show that no further weight loss and thermal effect were observed at a temperature of above 550°C. The precursor precipitates of ZnO were subjected to thermal calcinations and finally yielded the nano-sized ZnO powders. The calcined ZnO powders were characterized by XRD, Brunauer–Emmet–Teller analysis (BET), and scanning electron microscope (SEM), respectively. The XRD results indicated that the synthesized ZnO powders had a pure wurtzite structure and the average nano-particle sizes were about 35.2nm. However, the inconsistency of ZnO particle sizes derived from the BET methods and the XRD analysis indicated that a fraction of nano-sized ZnO powders were in the form of aggregates, which was also verified by SEM and TEM image. In addition, both the SEM image and the TEM photograph demonstrated that the nano-sized ZnO particles were of a pseudo-spherical shape. [Copyright &y& Elsevier]

Abstract: Dispersion degree strongly influences the rheological properties of nanosized particles containing suspension and, as a consequence, the quality of the deposited film. Furthermore, their applications will be rigorously restricted if the bad dispersion cannot be solved effectively. In this investigation, two physical dispersal processes, mechanical mixing with a three-roller mill and sonication, are used to disperse the nanosized silver particles in ethylene glycol and their effectiveness in dispersion are compared. The particle size distributions after dispersion with various procedures are observed by field emission scanning electron microscope (FE-SEM) and measured by image analysis technique. The measurement results show that mixing with a three-roll mill is an effective tool to break the agglomerates of silver nanoparticles in solvent, resulting in a better dispersion. The dispersion degree effect on the rheological properties and thixotropic characteristics of these suspensions are also elucidated. In addition, the film deposited from suspension with Ag nanoparticles mixed by three-roller mill has the lowest resistivity of approximately 3.64×102 μΩcm. [Copyright &y& Elsevier]

Abstract: Antiferromagnetic Co3O4 nanoparticles with diameter around 30nm have been synthesized by a solution-based method. The phase identification by the wide-angle X-ray powder diffraction indicates that the Co3O4 nanoparticle has a cubic spinel structure with a lattice constant of 0.80843(2)nm. The image of field emission scanning electron microscope shows that the nanoparticles are assembled together to form nanorods. The magnetic properties of Co3O4 fine particles have been measured by a superconducting quantum interference device magnetometer. A deviation of the Néel temperature from the bulk is observed, which can be well described by the theory of finite-size scaling. An enhanced coercivity as well as a loop shift are observed in the field-cooled hysteresis loop. The exchange bias field decreases with increasing temperature and diminishes at the Néel temperature. The training effect and the opening of the loop reveal the existence of the spin-glass-like surface spins. [Copyright &y& Elsevier]

Different amounts of La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM) nanoparticles were dispersed in a silver thin-film cathode using the radio frequency magnetron sputtering method. The nanostructure of the Ag-LSGM composite thin-film cathode was observed using a field-emission scanning electron microscope, and the area specific resistance of the Ag-LSGM composite thin-film cathodes was measured by the three-probe ac impedance method. The silver grains became smaller as the amount of the LSGM nanoparticles increased after annealing at 600°C in air for 100 h. The non-charge-transfer resistance decreased and became constant with an increase in the amount of LSGM nanoparticles dispersed in the Ag-LSGM composite thin-film cathode. It was suggested that oxygen atoms diffuse faster on the silver grain boundary than in the silver grain bulk. [ABSTRACT FROM AUTHOR]

Abstract: Nanoparticles of cadmium sulfide (nano-CdS) have been successfully prepared from an aqueous solution of cadmium chloride and sodium sulfide by a novel sonochemical method. Through adding polyvinylpyrrolidone K30 (PVP) as the dispersant, a yellow translucent colloidal solution of cadmium sulfide which was considerably stable within at least one month was obtained. The characterizations of nanoparticles by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM) and FT-IR spectroscopy showed good properties of small size, high surface area and crystal structure. The size of the prepared nanoparticles was about 3–5nm according to XRD spectra and TEM images. Poly(diallyldimethylammonium chloride) (PDDA) has been employed to fabricate multilayer films on quartz wafer and indium tin oxide (ITO) electrode in a layer-by-layer manner. Atomic force microscopy (AFM) displayed the dense coverage of the substrate surface by the nanoparticles. UV–vis absorption spectroscopy confirmed the consecutive growth of PDDA/nanoparticles layer pairs. The photoelectrochemical and the electrochemical behaviors of the prepared CdS particle were examined as well. [Copyright &y& Elsevier]

With increasing interest in nanometer scale studies, a common research issue is the need to use different analytical systems with a universal substrate to relocate objects on the nanometer scale. Our paper addresses this need. Using the delicate milling capability of a focused ion beam (FIB) system, a region of interest (ROI) on a sample is labelled via a milled reference grid. FIB technology allows for milling and deposition of material at the sub 20-nm level, in a similar user environment as a standard scanning electron microscope (SEM). Presently commercially available transmission electron microscope (TEM) grids have spacings on the order 100 μm on average; this technique can extend this dimension down to the submicrometre level. With a grid on the order of a few micrometres optical, FIBs, TEMs, scanning electron microscopes (SEMs), and atomic force microscopes (AFM) are able to image the ROI, without special chemical processes or conductive coatings required. To demonstrate, Au nanoparticles of ∼ 25 nm in size were placed on a commercial Formvar®- and carbon-coated TEM grid and later milled with a grid pattern. Demonstration of this technique is also extended to bulk glass substrates for the purpose of sample location. This process is explained and demonstrated using all of the aforementioned analytical techniques. [ABSTRACT FROM AUTHOR]

Abstract  Single-phase LiCoPO4 nanoparticles were synthesized by solid-state reaction method and subsequent high-energy ball milling. The electrochemical properties of LiCoPO4/Li batteries were analyzed by ac impedance experiments, cyclic voltammetry (CV), and charge/discharge tests. The structural and morphological performance of LiCoPO4 nanoparticles was investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). The XRD result demonstrated that LiCoPO4 nanoparticles had an orthorhombic olivine-type structure with a space group of Pmnb. Different conductive additives including acetylene black and carbon black (SP270) were used to fabricate electrodes. The morphologies of the electrodes and different conductive additives were observed by field emission-scanning electron microscopy (FE-SEM). LiCoPO4/Li battery with acetylene black showed the best electrochemical properties, and exhibited a discharge plateau at around 4.7 V with an initial discharge capacity of 110 mAh g−1 at a discharge current density of 0.05 mA cm−2 at 25 �C. [ABSTRACT FROM AUTHOR]

Ag nanoparticle deposition on the surface of spherical SiO2 nanoparticles was studied to achieve hybrid structure of Ag–SiO2 nanocomposite. SiO2 nanoparticles were served as seeds for continuous Ag metal deposition. The ratio of elements and morphology was studied with scanning electron microscope energy dispersive X-ray and transmission electron microscope. The antibacterial properties of Ag–SiO2 nanocomposite were examined. The homogeneously formed Ag nanoparticles on the surface of SiO2 nanoparticles without aggregation of Ag nanoparticles showed excellent antibacterial abilities. [ABSTRACT FROM AUTHOR]

This article focuses on the nanoparticle electrocatalytical action on electrodeposition of nickel and the chemical combination state between nanoparticles and matrix metal in composite coating. The electrochemical behavior, from common and composite brush electroplating solution, is investigated by cyclic voltammetry. The interaction between nanoparticles and matrix metal nickel is researched by X-Ray Photoelectron Spectrometry (XPS). The microstructure and morphology of coating are observed with Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM). The results show that nanoparticles not only can obviously induce the increasing of the current efficiency and decreasing of overpotential, but also can distinctly refine the metal crystal grains of composite coating. The experimental results demonstrate that nanoparticles take part in the electrode reaction and can evidently catalyze nickel electrodeposition. Part of the unsaturated oxygen atoms on nanoparticles surface can combine with some of the absorbed nickel atoms and form nickel-oxygen chemical bonds. There is chemical binding interaction at the interface between nanoparticles’ surface and matrix metal nickel. [ABSTRACT FROM AUTHOR]

Abstract: One-dimensional (1D) rod-like structure of znic oxide constructed by nanoparticles was synthesized by the thermal treatment of zinc oxalate sub-micron rods, which were obtained via alcohol thermal process. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and photoluminescence (PL) spectrum. SEM and TEM show that the morphology of zinc oxalate dihydrate precursor is rod-like, about 400nm in average diameter and 3μm in average length. The zinc oxide obtained by annealing zinc oxalate exhibits 1D rod-like structure constructed by ZnO nanoparticles in original direction of the precursor. The room-temperature photoluminescence spectrum of as-prepared ZnO shows UV emission around 398nm and a diverse visible emission peaks indicating that there are deep level defects in ZnO nanoparticles. [Copyright &y& Elsevier]

The effect of mechanical stirring on the morphology of hexagonal layer-structure birnessite nanoparticles produced from decomposition of KMnO4 in dilute aqueous H2SO4 is investigated, with characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA), and N2 adsorption (BET).Mechanical stirring during an initial stage of synthesis is shown to produce black birnessite containing nanofibers, whereas granular particulates of brown birnessite are produced without stirring. This is the first reduction synthesis of black birnessite nanoparticles with dendritic morphology without any use of organic reductant, and suggests that a particular morphology can arise from structural preferences of Mn in acidic conditions rather than particular organic reactants. These results enlighten the possibility of synthesizing nanoparticles with controlled size and morphology. [ABSTRACT FROM AUTHOR]

Abstract: Nanosized PbFe12O19 hexaferrite particles have been synthesized by citrate precursor decomposition method and the crystal structure, morphology and particle size, and magnetic properties of as-synthesized particles were characterized by X-ray diffraction, field emission scanning electron microscope, infrared spectroscopy, Raman spectroscopy and vibrating sample magnetometer, respectively. X-ray diffraction shows that the ratio between the reactants has a significant effect on the purity of obtained PbFe12O19 particles and an optimal ratio to synthesize pure lead ferrite was found. Infrared and Raman spectra show the evidence of existence of γ-Fe2O3 and α-Fe2O3 phase in the formation process of PbM. With the increase of calcination temperature, saturation magnetization and coercivity show dependence on particle size. A maximum coercivity of 3.8kOe and maximum saturation magnetization of 49.0emu/g are obtained from the sample decomposed at 800°C. [Copyright &y& Elsevier]

Abstract: Nickel (Ni) always accumulates on multi-walled carbon nanotubes (MWCNT) by direct electrodeposition. In this paper, nickel nanoparticles were electro crystallized on 4-nitroaniline (NA) radical monolayer-grafted on MWCNT through molecular level design. The structure and nature of the Ni/NA/MWCNT were characterized by field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), the results show that Ni nanoparticles were homogeneously electrodeposited on the surfaces of MWCNT. This complex catalyst showed excellent electro-catalytic activity for oxidation of ethanol in alkaline solution. [Copyright &y& Elsevier]

Abstract: Hydrophobic BaSO4 nanoparticles were successfully produced via a one-step process through precipitation reaction in aqueous solution of BaCl2 and (NH4)2SO4 with octadecyl dihydrogen phosphate (n-C18H37OPO3H2, ODP) as a modifying agent. The ODP was used to control the BaSO4 particle size and to modify the surface property of the particles produced from the precipitation. Measurements of relative contact angle and active ratio indicated that BaSO4 samples were hydrophobic. The samples were characterized by using field emission scanning electron microscope, transmission electron microscopy, X-ray diffraction, infrared analysis, thermogravimetric analysis and energy dispersive X-ray analysis. The results suggested that the hydrophobic property was attributed to presence of a thin layer of barium alkyl phosphates, which was formed and coated onto the surface of BaSO4 particles during the reaction process. The thin films at the surface of the BaSO4 modified the surface property and control the particle size and morphology. [Copyright &y& Elsevier]

Abstract: The prodrug 5′-octanoyl-CPA (Oct-CPA) of the antiischemic N 6-cyclopentyladenosine (CPA) has been encapsulated by nanoprecipitation in poly(lactic acid) nanoparticles, which have been recovered by gel-filtration, ultra-centrifugation or dialysis. We have analysed how different surfactants and purification methods can influence the nanoparticle characteristics. The particle sizes have been obtained by scanning electron microscope, whereas a SdFFF system was employed to detect their distributions. The Oct-CPA release from nanoparticles and stabilities in human blood of free and encapsulated prodrug have been analysed by HPLC techniques. The effects of nanoparticles on CPA interaction toward adenosine A1 receptor (its action site) have been analysed using radiolabelled drugs. The smallest nanoparticles and the best degree of homogeneity have been obtained using sodium cholate; the best recovery has been achieved by dialysis, whereas gel-filtration and ultra-centrifugation have induced the greatest removal of surfactants. The release of Oct-CPA was better controlled from the nanoparticles obtained using Pluronic F68 and purified by gel-filtration or ultra-centrifugation. Similarly, these nanoparticles better increased the stability of the prodrug in human blood. In particular, the nanoparticles purified by ultra-centrifugation induced a strong stability to a fraction of the encapsulated Oct-CPA. Any interference by unloaded nanoparticles has been registered for CPA-adenosine A1 receptor interaction. [Copyright &y& Elsevier]

The deposition of remaining nanoparticles in the Caribbean Sea generates the formation of potentially dangerous elements, which influence at the imbalance of ecosystems. The detection of nanoparticles is not simple and the use of conventional methods is difficult application, which is why we highlight the immediacy and importance of this research for the areas of marine biology, urbanism, engineering and geosciences, applied in the Caribbean Sea. The general objective of this study is to evaluate the use of advanced methods for the determination of toxic nanoparticles, which can directly affect the development of marine organisms in the aquatic ecosystem in waters of the Caribbean Sea, favoring the construction of future international public policies with the elaboration of projects capable of mitigating these levels of contamination. The morphology and structure of nanoparticles were analyzed by emission scanning electron microscope with a high-resolution electron microscope. The nanoparticles smaller than 97 nm were identified in different proportions. The morphological analyses indicated nanoparticles' presence in the form of nanotubes, nanospheres, and nanofibers, which were shown in an agglomerated form. The presence of potentially hazardous elements, such as As, Cd, Pb, Mg, Ni and V were verified. In addition, the presence of asbestos in the form of minerals was confirmed, and that of titanium dioxide was found in large quantities. The results provide new data and emphasize the possible consequences to the in the Caribbean Sea, with the identification of dangerous elements (As, Cb, Pb, Hg, Ni and V), harmful to the marine ecosystem. Therefore, there is a need for strict control to reduce contamination of the Caribbean Sea and avoid risks to the ecosystem and public health, through suggestions of international public policies, through constant monitoring and the application of environmental recovery projects in this marine estuary. [Display omitted] • The diverse sources of nanoparticles increasingly induce their exposure in the waters of the Caribbean Sea. • The nanoparticles caused the formation of potentially hazardous elements. • The identification of nanoparticles is of paramount importance due to being more reactive. • As, Cd, Pb, Mg, Ni, and V were detected used advanced characterizations. • The results expound useful information in assessing the environmental risks and for public health. [ABSTRACT FROM AUTHOR]

The article discusses a study on the synthesis of tri-n-octylphosphine oxide (TOPO)-coated CdSe/ZnS microparticles. The study used an optical microscope and a scanning electron microscope in characterizing the microparticles. It found more than 100 particles to ensure a statistically representative size. It also examined the effect of organic solvents on the microparticles.

Optically transparent liquid marbles were made from water and glycerol drops embedded in surface-treated fumed silica nanoparticles. The mechanical robustness of such liquid marbles is shown to be greater than similar marbles made from microparticulate poly(tetrafluoroethylene), both under compressive and tensile loading conditions. Using liquid evaporation data and environmental scanning electron microscope images, we demonstrate that their robustness may be attributed to a nanoparticulate elastic thin film that self-assembles on the liquid-vapor interface. [ABSTRACT FROM AUTHOR]

Abstract: Without the use of any extra surfactant or template, hexagonal phase ZnO crystallites consisting of individual nanorods or nanorod assemblies were synthesized simply by solvothermal treatment of several nanometer ZnO2 nanoparticles in three different solvents (including ethanol, 80 wt.% hydrazine hydrate aqueous solution and ethylenediamine) at 150 °C for 24 h. The structures and optical properties of the resultant products were characterized by means of X-ray powder diffraction (XRD), scanning electron microscope (SEM), and room temperature photoluminescence (RTPL) spectra. The RTPL spectra of the resultant products all showed a much stronger ultraviolet bandgap emission peaking at around 387 nm and a weaker emission associated with the defect level. The as-synthesized ZnO crystallites are promising materials for the optoelectronic devices due to their excellent UV emission properties. [Copyright &y& Elsevier]

Hollow BiFeO3 nanoparticles were synthesized by an electrospray route for the first time. The phase purity and structure have been investigated by x-ray diffraction and Raman spectroscopy. Transmission and scanning electron microscope investigations revealed that the as-obtained BiFeO3 hollow spheres were polycrystalline, with a shell thickness of 35 nm. The formation mechanism can be possibly explained by Ostwald ripening. Raman spectra have verified decreased vibrational frequencies in BiFeO3 nanoparticles. These hollow and core-shell multiferroic nanoparticles exhibit significantly enhanced ferromagnetism from 5 to 600 K due to a broken spiral spin structure. The ferroelectricity of hollow BiFeO3 particles exhibits a lower switching electric field, which is confirmed by Kelvin probe force microscopy. [ABSTRACT FROM AUTHOR]

This study report on the synthesis of spinel CuFe2O4 nanostructures by surfactant-assisted method. The catalysts were characterized by X-ray diffraction (XRD), laser Raman, transition electron microscope (TEM), scanning electron microscope (SEM), energy dispersive X-ray (EDX), hydrogen temperature programmed reduction (H2-TPR), and Brunauer-Teller-Emmett-Teller (BET) surface area techniques. CuFe2O4 was active for pinene oxidation using tertiary butyl hydroperoxide (TBHP) to pinene oxide, verbenol, and verbenone aroma oxygenates. Under optimized reaction conditions, the spinel CuFe2O4 catalyst could afford 80% pinene conversion at a combined verbenol/verbenone selectivity of 76% within the reaction time of 20 h. The changes in catalyst synthesis solvent composition ratios induced significantly varying redox, phases, and textural structure features, which resulted in various catalytic enhancement effect. Characterization results showed the spinel CuFe2O4 catalyst possessing less than 5 wt% impurity phases, Cu(OH)2, and CuO to afford the best catalytic performance. The CuFe2O4 catalyst was recyclable to up to five reaction cycles without loss of its activity. The recyclability of the bimetal CuFe2O4 oxide catalyst was simply rendered by use of an external magnet to separate it from the liquid solution. [ABSTRACT FROM AUTHOR]

An activated-carbon (AC) assisted route is developed to synthesize a ZnO nanoparticle network. The route involves simple addition of AC to the solution containing the zinc salt and finally removing them by burning at higher temperature to form a sponge-like porous ZnO nanoparticles. The surface area measurements show that AC-assisted ZnO nanoparticles (AC-ZnO) have a higher surface area than those synthesized without AC (B-ZnO), which is further confirmed by the field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM) images. Ultraviolet (UV) absorbance results show that the optical quality remains almost unchanged for both types of nanoparticles. Enhanced and faster UV photosensitivity has been observed for the AC-ZnO. The change in the UV photosensing properties demonstrated here provides a new approach to synthesizing other high surface area materials for novel physical and chemical properties. [ABSTRACT FROM AUTHOR]