Synthesis and Characterization of Bowl-Like Single-Crystalline BaTiO3 Nanoparticles

Novel bowl-like single-crystalline BaTiO₃ nanoparticles were synthesized by a simple hydrothermal method using Ba(OH)₂·8H₂O and TiO₂ as precursors. The as-prepared products were characterized by XRD, Raman spectroscopy, SEM and TEM. The results show that the bowl-like BaTiO₃ nanoparticles are single-crystalline and have a size about 100–200 nm in diameter. Local piezoresponse force measurements indicate that the BaTiO₃ nanoparticles have switchable polarization at room temperature. The local effective piezoelectric coefficient d₃₃ ^* d_{33}^{ * } is approximately 28 pm/V.     

An organic/inorganic hybrid mesoporous silica membrane: preparation and characterization

An organic/inorganic hybrid mesoporous silica membrane composed of mesoporous silica materials inside the channels of polycarbonate filtration membrane (PC) was synthesized by using aspiration-induced infiltration method, and the surfactant in as-prepared membrane was removed by employing template-extraction method. The obtained materials were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD),transmission electron microscopy (TEM) and N₂ adsorption–desorption measurement. The SEM images and EDS elemental analyses show that as-synthesized materials in PC are one-dimensional silica rods estimated as 200 nm in diameter and 9 μm in length. Moreover, the results of XRD, TEM and N₂ adsorption–desorption analysis clearly demonstrate that such silica rods are mesoporous materials with two-dimensional hexagonal mesostructure and the average mesopore diameter is about 3.0 nm. In addition, the porosity of organic/inorganic hybrid mesoporous silica membrane was further examined by molecule permeation. It is found that small molecule, such as rhodamine B, can transport across the membrane, but relatively large molecule, such as horse radish peroxidase, can not transport across the membrane, indicating that it is size-selectivity of such a membrane for molecule permeation, which has the potential application in the molecule filters to separate bio-macromolecule from small molecule.     

Evolution of ZnS Nanoparticles via Facile CTAB Aqueous Micellar Solution Route: A Study on Controlling Parameters

Synthesis of semiconductor nanoparticles with new photophysical properties is an area of special interest. Here, we report synthesis of ZnS nanoparticles in aqueous micellar solution of Cetyltrimethylammonium bromide (CTAB). The size of ZnS nanodispersions in aqueous micellar solution has been calculated using UV-vis spectroscopy, XRD, SAXS, and TEM measurements. The nanoparticles are found to be polydispersed in the size range 6–15 nm. Surface passivation by surfactant molecules has been studied using FTIR and fluorescence spectroscopy. The nanoparticles have been better stabilized using CTAB concentration above 1 mM. Furthermore, room temperature absorption and fluorescence emission of powdered ZnS nanoparticles after redispersion in water have also been investigated and compared with that in aqueous micellar solution. Time-dependent absorption behavior reveals that the formation of ZnS nanoparticles depends on CTAB concentration and was complete within 25 min.     

Nafion-assisted deposition of microemulsion-synthesized platinum nanoparticles on BDD: Activation by electrogenerated OH radicals

Platinum nanoparticles have been synthesized by the water-in-oil (w/o) microemulsion technique and deposited onto boron-doped diamond (BDD) electrodes. Transmission electron microscopy (TEM) has shown that Pt particles size is limited to 2-5 nm range with narrow distribution. Anodic treatment at high overpotentials activates Pt deposit that is mechanically stabilized by a Nafion^® layer. Such activation results in enhancement of activity towards methanol electrooxidation, due to additional cleaning of the particles by oxidation of the residual surfactant by electrogenerated hydroxyl radicals.     

Low-temperature synthesis of Bi2Fe4O9 nanoparticles via a hydrothermal method

Bi₂Fe₄O₉ (BFO) nanoparticles were successfully synthesized by a hydrothermal method at a temperature as low as 100 °C. The as-prepared powders, characterized by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), transmission electron microscope (TEM) and physical property measurement system (PPMS), exhibited a pure BFO phase about 100 nm size with uniform sheet-like shape and exhibited an AF order at room temperature. It was found that high alkali concentration and alkali ion Na⁺ played a key role in the formation of BFO nanoparticles at a low temperature of 100 °C.     

A study of the lithium intercalation into nanoparticles of LiCoO<Subscript>2</Subscript> from an aqueous solution

Nanoparticles of lithium cobalt oxide (LiCoO₂) were synthesized by means of a citrate sol–gel combustion route. The particles were characterized by scanning and transmission electron microscopies (SEM and TEM), energy-dispersive X-ray spectroscopy, and X-ray diffraction (XRD) measurements. Near spherical nanoparticles of around 100 nm were observed in SEM and TEM micrographs. XRD data indicated that the as-prepared nanoparticles presented pure phase of LiCoO₂ with R-3m symmetry. The kinetics of electrochemical intercalation of lithium into the nanoparticles were investigated by means of cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS) with special emphasis on the application potential as cathode material for aqueous rechargeable lithium batteries. CV studies of the nanoparticles at slow scan rate of 0.1 mV s⁻¹ between 600 and 820 mV versus Ag/AgCl, demonstrated that the nanoparticles represented well-defined reversible peaks. The non-linear chemical diffusion of lithium into the nanoparticles was explored by EIS. In this regards, the results were discussed based on an equivalent circuit, distinguishing the kinetic properties of lithium intercalation. The kinetic parameters of lithium intercalation were obtained using the equivalent circuit, which were in good agreement with the experimental results. The changes of kinetic parameters of lithium intercalation with potential were also discussed in detail.     

Magnetic and Cytotoxicity Properties of La1−x Sr x MnO3 (0 ≤ x ≤ 0.5) Nanoparticles Prepared by a Simple Thermal Hydro-Decomposition

This study reports the magnetic and cytotoxicity properties of magnetic nanoparticles of La_1−x Sr _x MnO₃ (LSMO) with x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5 by a simple thermal decomposition method by using acetate salts of La, Sr, and Mn as starting materials in aqueous solution. To obtain the LSMO nanoparticles, thermal decomposition of the precursor was carried out at the temperatures of 600, 700, 800, and 900 °C for 6 h. The synthesized LSMO nanoparticles were characterized by XRD, FT-IR, TEM, and SEM. Structural characterization shows that the prepared particles consist of two phases of LaMnO₃ (LMO) and LSMO with crystallite sizes ranging from 20 nm to 87 nm. All the prepared samples have a perovskite structure with transformation from cubic to rhombohedral at thermal decomposition temperature higher than 900 °C in LSMO samples of x ≤ 0.3. Basic magnetic characteristics such as saturated magnetization (M _S) and coercive field (H _C) were evaluated by vibrating sample magnetometry at room temperature (20 °C). The samples show paramagnetic behavior for all the samples with x = 0 or LMO, and a superparamagnetic behavior for the other samples having M _S values of ~20–47 emu/g and the H _C values of ~10–40 Oe, depending on the crystallite size and thermal decomposition temperature. Cytotoxicity of the synthesized LSMO nanoparticles was also evaluated with NIH 3T3 cells and the result shows that the synthesized nanoparticles were not toxic to the cells as determined from cell viability in response to the liquid extract of LSMO nanoparticles.     

Morphology and Photoluminescence of HfO2 Obtained by Microwave-Hydrothermal

In this letter, we report on the obtention of hafnium oxide (HfO₂) nanostructures by the microwave-hydrothermal method. These nanostructures were analyzed by X-ray diffraction (XRD), field-emission gum scanning electron microscopy (FEG-SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectrometry (EDXS), ultraviolet–visible (UV–vis) spectroscopy, and photoluminescence (PL) measurements. XRD patterns confirmed that this material crystallizes in a monoclinic structure. FEG-SEM and TEM micrographs indicated that the rice-like morphologies were formed due to an increase in the effective collisions between the nanoparticles during the MH processing. The EDXS spectrum was used to verify the chemical compositional of this oxide. UV–vis spectrum revealed that this material have an indirect optical band gap. When excited with 488 nm wavelength at room temperature, the HfO₂ nanostructures exhibited only one broad PL band with a maximum at around 548 nm (green emission).     

Water Denitration over a Pd–Sn/Al2O3 Catalyst

Bimetallic Pd–Sn catalysts were synthesized by incipient-wetness impregnation of the metals on alumina and employed for the reduction of nitrates from aqueous solutions. The catalysts were characterized by FTIR spectroscopy of adsorbed CO, X-ray diffraction (XRD), transmission electron microscopy (TEM), and H₂ chemisorption. The influence of the metal ratio was evaluated in reaction measurements. The bimetallic Pd–Sn catalysts exhibited high selectivity for nitrate removal forming less NO₂⁻ and NH₄⁺ than the Pd–Cu catalysts.     

Synthesis and Characterization of Core-shell ZrO2/PAAEM/PS Nanoparticles

This work demonstrates the synthesis of core-shell ZrO₂/PAAEM/PS nanoparticles through a combination of sol–gel method and emulsifier-free emulsion polymerizaiton. By this method, the modified nanometer ZrO₂ cores were prepared by chemical modification at a molecular level of zirconium propoxide with monomer of acetoacetoxyethylmethacrylate (AAEM), and then copolymerized with vinyl monomer to form uniform-size hybrid nanoparticles with diameter of around 250 nm. The morphology, composition, and thermal stability of the core-shell particles were characterized by various techniques including transmission electron microscopy (TEM), X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and thermal-gravimetry analyzer (TGA). The results indicate that the inorganic–organic nanocomposites exhibit good thermal stability with the maximum decomposition temperature of ~447 °C. This approach would be useful for the synthesis of other inorganic–organic nanocomposites with desired functionalities.     

Influence of Cobalt Doping on the Physical Properties of Zn<Subscript>0.9</Subscript>Cd<Subscript>0.1</Subscript>S Nanoparticles

Zn_0.9Cd_0.1S nanoparticles doped with 0.005–0.24 M cobalt have been prepared by co-precipitation technique in ice bath at 280 K. For the cobalt concentration >0.18 M, XRD pattern shows unidentified phases along with Zn_0.9Cd_0.1S sphalerite phase. For low cobalt concentration (≤0.05 M) particle size, d _XRD is ~3.5 nm, while for high cobalt concentration (>0.05 M) particle size decreases abruptly (~2 nm) as detected by XRD. However, TEM analysis shows the similar particle size (~3.5 nm) irrespective of the cobalt concentration. Local strain in the alloyed nanoparticles with cobalt concentration of 0.18 M increases ~46% in comparison to that of 0.05 M. Direct to indirect energy band-gap transition is obtained when cobalt concentration goes beyond 0.05 M. A red shift in energy band gap is also observed for both the cases. Nanoparticles with low cobalt concentrations were found to have paramagnetic nature with no antiferromagnetic coupling. A negative Curie–Weiss temperature of −75 K with antiferromagnetic coupling was obtained for the high cobalt concentration.     

Preparation of spherical nanoparticles of LaAlO3 via the reverse microemulsion process

Spherical LaAlO₃ nanoparticles in a reverse microemulsion consisting of solution (water phase), Tween-80 and Span-80 (surfactant), n-butanol (cosurfactant, and cyclohexane (oil phase) were prepared. Precursor powders and calcined powders were characterized by differential thermal analysis (DTA), thermogravimetry analysis (TG), X-ray diffraction (XRD) and transmission electron microscopy (TEM). A pure perovskite LaAlO₃ formed when the precursor hydroxides calcined at 800 °C for 2 h. The particle size was about 50 nm and the shape of the monodisperse particles is spherical. The reverse microemulsion process can dramatically lower the crystallization temperature of LaAlO₃ about 700 °C than the classical solid-state reaction method.     

Synthesis of TiO<Subscript>2</Subscript> Nanoparticles by Microemulsion/Heat Treated Method and Photodegradation of Methylene Blue

In this work, TiO₂ nanoparticles were prepared by microemulsion (ME)/heat treated method and its photodecomposition property of methylene blue. Microemulsion (ME) consisted of water, cyclohexane and an anionic surfactant such as bis (2-ethylhexyl) sodium sulfosuccinate (AOT). Titanium tetraisopropoxide (TTIP) was dropped into the ME solution and then then TiO₂ nanoparticles were formed by the hydrolysis reaction between TTIP in the organic solvent and the water in the core of ME. The smallest diameter of the particles was 20 nm in the system of cyclohexane with surfactant when the molar ratio of water to surfactant was 2. The effect of the process parameters (water/surfactant ratio, different temperatures) on the final characteristics has been investigated, in terms of structural phase and particle size. The TiO₂ nanoparticles were characterized by means of X-ray diffraction, Transmission and scanning electron microscopy, Fourier-Transformed infrared and differential thermal analysis. TiO₂ nanoparticles prepared in this condition were collected as amorphous powder, and converted to anatase phase at less than 350 °C, which is lower than the ordinal phase transition temperature. The crystallite size and crystallinity increase with an increase of heat treated s temperature. The particles are shown to have a spherical shape and have a uniform size distribution. The size of nanoparticles raises with an increase of water/surfactant ratio. In the photocatalytic decomposition of methylene blue, the photocatalytic activity is mainly determined by the crystallinity of TiO₂. In addition, the TiO₂ heat treated at 350 °C shows the highest activity on the photocatalytic decomposition of methylene blue (k = 1.7 × 10⁻² min⁻¹).     

Synthesis,Morphology and Viscoelastic Properties of Epoxy/Polyhedral Oligomeric Silsesquioxane (POSS) and Epoxy/Cyanate Ester/POSS Nanocomposites

TriSilanolPhenyl-polyhedral oligomeric silsesquioxane (POSS-1) (C₄₂H₃₈O₁₂Si₇), 1–15 wt%, was incorporated into aliphatic epoxy resin (Clearstrem Products, Inc.) with aliphatic diamine curing agents and cured. This epoxy resin was also blended with an equal weight (50/50 w/w) of aromatic cyanate ester resin, Lonza’s PT-15, and 1–15 wt% of POSS-1 and cured. These composites were characterized by FT-IR, X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (X-EDS), dynamic mechanical thermal analysis (DMTA) and three-point bending flexural tests. XRD and X-EDS measurements were consistant with partial molecular dispersion of the POSS units in the continuous matrix phase, together with POSS aggregates. TEM and SEM show that POSS-1-enriched nanoparticles are present in the matrix resins of both the epoxy/POSS and epoxy/cyanate ester/POSS-1 composites. The storage bending moduli, E′, in the rubbery region and the glass transition temperatures, T_g, of epoxy and epoxy/cyanate ester 1-5% POSS-1 composites are higher than those of the reference resins. Small amounts (≤5 wt%) of POSS-1 improved E′ and T_g of both systems and raised flexural strengths and moduli.     

Hydrothermal synthesis of amorphous MoS2 nanofiber bundles via acidification of ammonium heptamolybdate tetrahydrate

MoS₂ nanofiber bundles have been prepared by hydrothermal method using ammonium molybdate with sulfur source in acidic medium and maintained at 180 °C for several hours. The obtained black crystalline products are characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectrometer (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The PXRD pattern of the sample can be readily indexed as hexagonal 2H-MoS₂. FTIR spectrum of the MoS₂ shows the band at 480 cm⁻¹ corresponds to the γ_as(Mo-S). SEM/TEM images of the samples exhibit that the MoS₂ nanofiber exist in bundles of 120–300 nm in diameter and 20–25 μm in length. The effects of temperature, duration and other experimental parameters on the morphology of the products are investigated.     

Hydrodechlorination of CCl<Subscript>4</Subscript> on Pt–Au/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Catalysts

A series of Pt/Al₂O₃ catalysts were prepared by the impregnation method and were characterized by TEM, XRD, H₂ and CO chemisorptions, and investigated in the hydrodechlorination of tetrachloromethane. Three Pt-rich, Pt–Au/Al₂O₃ catalysts (Pt₁₀₀, Pt₉₅Au₅ and Pt₉₀Au₁₀) showed a similar metal particle size (~2.5–2.7 nm), so observed changes in the catalytic behavior are ascribed to alloying effect, especially because a considerable degree of Pt–Au mixing was achieved in the bimetallic samples. It appeared that by introducing very small amount of gold (10 at.%) to platinum, the catalytic activity is increased. It is argued that the occurrence of this moderate synergistic effect is associated with a decreased tendency of surface chloriding when platinum is alloyed with gold. Zbigniew Kowalczyk—deceased.     

One-step and low-temperature synthesis of monetite nanoparticles in an all-in-one system (reactant,solvent, and template) based on calcium chloride-choline chloride deep eutectic medium

Monetite nanoparticles were synthesized via a facile and sustainable method using deep eutectic medium based on CaCl₂·6H₂O-choline chloride to act as solvent, reactant and template. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR). Analysis data revealed the formation of CaHPO₄ nanoparticles crystalized in anorthic structure with spherical morphology, mean particle size of 65 nm, and high elemental-structural purity. The results suggested the ternary role of the eutectic system in synthesis of monetite nanoparticles providing the synthesis medium, calcium-active reaction sites, and electrosteric stabilization by which the deep eutectic system can control the particle growth and agglomeration of monetite.     

Simplified synthesis of isomorphously nickel substituted ZSM-5

Isomorphously nickel-substituted nano-crystalline ZSM-5 is synthesized in the absence of acidic aqueous fluoride medium incorporating simple and low-cost metal inorganic salt precursor NiCl₂.6H₂O instead of large organic cationic salt like bis (tetraethyl ammonium) tetrachloronickelate (II) with less water quantity to minimize the synthesis waste. PXRD, FT-IR, TG/DTG, XPS, UV–Vis DRS, SEM, TEM, ICP and N₂ adsorption-desorption techniques were used to confirm the presence of nano-crystalline material having a MFI structure and heteroatom substitution. The unit cell dimensions increase with increasing levels of nickel substitution. The crystallite size of as synthesized samples was in the range of 60–75 nm, which increased to 60–160 nm after calcination at 550°C. Percentage crystallinity and crystallite size increases with increasing nickel substitution level up to 0.17 mol and beyond that the material becomes amorphous.     

Nanofiltration membranes prepared by direct microemulsion copolymerization using poly(ethylene oxide) macromonomer as a polymerizable surfactant

A novel polymer membrane with nanosized pore structures has been prepared from the direct copolymerization of acrylonitrile (AN) with a polymerizable nonionic surfactant in water‐in‐oil (w/o) or bicontinuous microemulsions. This polymerizable surfactant is ω‐methoxy poly(ethylene oxide)₄₀ undecyl‐α‐methacrylate macromonomer [CH₃O (CH₂CH₂O)₄₀ (CH₂)₁₁ OCO(CH₃)CCH₂, abbreviated: C₁‐PEO‐C₁₁‐MA‐40]. Besides PEO macromonomer, AN, and crosslinker ethyleneglycol dimethacrylate, the microemulsion system contained varying amount of water that formed w/o microemulsions having water droplet structures and bicontinuous microemulsions consisting of interconnected water channel. The polymerized membranes prepared in this study have pore radii ranging from 0.38 to 2.4 nm as evaluated by PEG filtration. The pore size appears to vary linearly with water content in precursor microemulsions. But a sharp change in the gradient of the linear relationship is observed around 25 wt % water content. Membranes made from bicontinuous (>25 wt % water) microemulsion polymerization have a larger and interconnected (open‐cell) nanostructures. In contrast, much smaller closed‐cell (disinterconnected) nanostructures were obtained from w/o (<25 wt % water) microemulsion polymerization and the membrane exhibited a permselectivity toward water in pervaporation separation of high ethanol (>50 wt %) aqueous solutions. The separation factor (α) for 95% ethanol aqueous solution by the membrane derived from the microemulsion containing 10 wt % water is about 20. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2785–2794, 2000     

Preparation and Properties of ε-Fe3N-Based Magnetic Fluid

In this work, ε-Fe₃N nanoparticles and ε-Fe₃N-based magnetic fluid were synthesized by chemical reaction of iron carbonyl and ammonia gas. The size of ε-Fe₃N nanoparticles was tested by TEM and XRD. Stable ε-Fe₃N-based magnetic fluid was prepared by controlling the proper ratio of carrier liquid and surfactant. The saturation magnetization of stable ε-Fe₃N-based magnetic fluid was calculated according to the volume fraction of the particles in the fluid. The result shows that both the calculated and measured magnetizations increase by increasing the particle concentration. With the increasing concentration of the ε-Fe₃N particles, the measured value of the magnetic fluid magnetization gradually departs from the calculated magnetization, which was caused by agglomeration affects due to large volume fraction and large particle size.