Segmented tubular synthesis of monodispersed microsized copper oxalate

Monodispersed microsized copper oxalate particles were prepared in a segmented continuous flow tube reactor, and the effect of the main parameters such as organic additive agent, initial copper ions concentration, residence time, and segmented media on the final products were investigated experimentally. The obtained copper oxalate microsized particles were disc-like in the presence of citrate ligand,which was the shape inducer for the precipitated copper oxalate. Thermodynamic equilibrium diagrams of the Cu(Ⅱ)-oxalate-H_2O,Cu(Ⅱ)-oxalate-citrate-H_2O, and Cu(Ⅱ)-oxalate-EDTA-H_2O solution systems were drawn to estimate the possible copper species under the experimental conditions and to explain the formation mechanisms of copper oxalate particles in the segmented fluidic reactor. Both theoretical and experimental results indicated that the presence of chelating reagents such as citrate and EDTA had distinct effect on the evolution of particle shape. Air and kerosene were tested as media for the fluidic flow segmentation, and the latter was verified to better promote the growth of copper oxalate particles. The present study provides an easy method to prepare monodispersed copper oxalate microsized particles in a continuous scaling-up way, which can be utilized to prepare the precursor material for conductive inks.

CeO_(x)-supported monodispersed MoO_(3) clusters for high-efficiency electrochemical nitrogen reduction under ambient condition

Developing efficient and low-cost electrocatalysts is essential for the electroreduction of N_(2) to NH_(3).Here,highly monodispersed MoO_(3) clusters loaded on a coral-like CeO_(x)compound with abundant oxygen vacancies are successfully prepared by an impregnation-reduction method.The MoO_(3) clusters with small sizes of 2.6±0.5 nm are induced and anchored by the oxygen vacancies of CeO_(x),resulting in excellent nitrogen reduction reaction(NRR)performance.Additionally,the synergistic effects between MoO_(3) and CeO_(x)lead to a further improvement of the electrochemical performance.The as-prepared MoO_(3)-CeO_(x)catalyst shows an NH_(3) yield rate of 32.2 μg h^(-1) mg^(-1) cat and a faradaic efficiency of 7.04%at-0.75 V(vs.reversible hydrogen electrode)in 0.01 M Dulbecco’s Phosphate Buffered Saline.Moreover,it displays decent electrochemical stability over 30,000 s.Besides,the electrochemical NRR mechanism for MoO_(3)-CeO_(x)is investigated by in-situ Fourier transform infrared spectroscopy.N-H stretching,H-N-H bending,and N-N stretching are detected during the reaction,suggesting that an associative pathway is followed.This work provides an approach to designing and synthesizing potential electrocatalysts for NRR.

PREPARATION OF SPHERICAL， MONODISPERSED NANOMETER Eu_2O_3 PARTICLES

Spherical, monodispersed europium hydroxycarbonate particles wereobtained by homogeneous precipitation with urea in aqueous solution of Eu.(NO3)3at elevated temperature.The particles were readily converted to the uniformEu2O3 with average particle size of 50nm after calcined at 750℃.

Thermodynamic Stability of Ultrafine Monodispersed Colloidal Particles of Basic Yttrium Carbonate

A series of thermodynamic parameters in formation of ultrafine monodispersed colloidal particles of Y(OH)CO3 were measured, estimated and calculated. The thermodynamic stability of Y(OH)CO3 colloidal particles was studied and discussed by phenomenological model. It is suggested that ultrafine monodispersed colloidal particles of Y(OH)CO3 are stable only in a very narrow temporary supersaturation range ( 1<x<1 .08).

PREPARATIVE STUDIES ON MONODISPERSED POLYMERIC NICROPARTICLES AND LATEX-COATED PACKINGS IN ANION CHROMATOGRAPHY

Monodispersed potymeric microparticles were prepared by seed-poly- merization.High performance packings were obtained for anion chromatography by coating the surface-sutfonated partictes with quarternized latexes.

Surfactant-assisted synthesis and magnetic properties of monodispersed manganese ferrite nanocrystals

Monodispersed manganese ferrite （MnFe2O4） nanocrystals could be successfully synthesized in large quantities via a facile synthetic technique based on the pyrolysis of organometallic compound precursor, in which octadecene was used as solvent, and oleic acid and oleylamine were used as capping ligands. MnFe204 nanocrystals were obtained with size in a tunable range of 4- 15 nm and their morphologies could be tuned from spherical to triangle-shaped by varying the surfactants. The phase structure, morphology, and size of the products were characterized in detail by X-ray diffraction （XRD） and transmission electron microscopy （TEM）. Magnetic properties of MnFe2O4 nanocrystals with different morphologies were measured using a superconducting quantum interference device （SQUID）. Both monodisperse MnFe204 nanocrystals with spherical and triangle-shapes are superparamagnetic at room temperature while ferromagnetic at 2 K. The pyrolysis method may provide an effective route to synthesize other spinel ferrites or metal oxides nanocrystals.

Studies on Monodispersed Microspheres of Zinc Sulfide Doped with Mn^(2+)

In this paper, zinc acetate, manganese acetate and thiacetamide are used as raw materials to successfully synthesize monodispersed ZnS：Mn^2＋ microspheres by using hydrothermal method and taking P123 surfactant as a template. The products were characterized by XRD, STEM, FT-IR and N2 adsorption-desorption. And the results show that the diameter of this microsphere is 1.0 μm or so, which is larger than that of ZnS microsphere without Mn^2＋ doping, and it has monodispersion, smooth surface and uniform size, The doping of Mn^2＋ does not obviously change the structure of monodispersed ZnS microsphere. The photoluminescence peak lies in a wide band ranging from 450 to 650 nm, and the microspheres emit orange light; with the increase of Mn^2＋ concentration, fluorescence intensity of ZnS：Mn^2＋ microsphere changes, and when the mole ratio of Mn^2＋：Zn^2＋ is 0.3：1, the fluorescence intensity is the strongest.

Preparation and Characterization of Monodispersed Co_2O_3 Ultrafine Particle Sol

The present, paper contains a new composite material Co;O;UFP sol prepared by using W/O microemulsion method, and its size distribution, interracial and optical nonlincar properties are discussed. The method for the preparation of UFP sol is as follows: at first, CoCl;and DBS so-

Synthesis of 3-D ordered macroporous silicate using the template formed from monodispersed polystyrene latex

Based on the template formed from monodispersed polystyrene (PS) latex, a modified fast sol-gel process was employed to synthesize a three-dimensional ( 3-D ) ordered macroporous silica material after removing the template by calcination at high temperature. It was indicated that there existed highly ordered packed pores within the whole silica material by SEM morphology observation. It was also found that the pores were interconnected. The pore size could be controlled mainly by varying the particle size of the latex ranging from 101 to 102 nm. The formation process of the ordered pores was also preliminarily discussed.

Preparation of Monodispersed Copper Nanoparticles by an Environmentally Friendly Chemical Reduction

In this paper, highly dispersive nanosized copper particles with a mean particle size of less than 6 nm are prepared by an environmentally friendly chemical reduction method. Non-toxic L-ascorbic acid acts as both reducing agent and antioxidant in ethylene glycol in the absence of any other capping agent. Transmission electron microscopy （TEM） is used to characterize the size and morphology of Cu nanoparticles. The results of UV-Vis spectroscopy （UV-Vis）, energy dispersive spectroscopy （EDS） and high resolution TEM （HRTEM） illustrate that the resultant product is pure Cu nanocrystals. The size of Cu nanoparticles is remarkably impacted by the order of reagent addition, and the investigation reveals the reaction procedure of Cu^2＋ ions and L-ascorbic acid.

Preparation and characterization of monodispersed spherical Fe_2O_3@SiO_2 reddish pigments with core-shell structure

The α-Fe_2 O_3@SiO_2 reddish pigments with core-shell structure were successfully prepared by hydrothermal and Stober methods. The structure, morphology, and chromaticity of the synthesized pigments were characterized by XRD, SEM, TEM, FTIR, XPS, and colorimetry. The results indicated that the as-prepared pigments have the characteristics of narrow particle size distribution, high dispersion,and good sphericity. The α-Fe_2 O_3@SiO_2 reddish pigments were uniform and well dispersed in solution. In addition, the pigments with different shell thickness were also prepared, and the effect of shell thickness on the color performance of the pigments was discussed.

X-ray Diffraction Study on the Superconducting Thin Films YBCO in a Monodispersed System

The preparations of superconducting thin films by DC, RF sputtering, laser evaporation and the MOCVD method have been reported. In order to extend the applications of high Tc superconducting thin films in industry, a homogeneous sol with monodispersed particles Y2O3, BaO and CuO in size of nanocrystalline 50—200 nm

Studies on monodispersed colloidal particles of doped yttrium compounds

Monodispersed particles of doped yttrium basic carbonates were prepared at aging at elevated temperature corresponding salts solutions in the presence of urea. Coprecipitation in mixed solutions of yttrium, lanthanum and neodymium salts under similar experimental conditions yielded composite particles of basic carbonates. The content of the three metals in the solids followed closely the initial composition of the reacting solutions. On calcination all prepared solids converted to their corresponding oxides while retaining their particle morphology. The so-prepared powders were characterized by various techniques.

Synthesis of monodispersed nanosized CeO_2 by hydrolysis of the cerium complex precursor

A cerium-triethanolamine complex was obtained by the reaction of cerium(III) nitrate and triethanolamine in ethanol solution. Spontaneous oxidation of cerium(III) to cerium(IV) by oxygen occurred during the reaction. The complex was crystalline and soluble in water. Nanosized ceria (CeO2) particles could be prepared via hydrolysis of the complex in aqueous solution, and the extent of agglomeration of particles increased with the increase in temperature for hydrolysis. Under the low temperature of 25 oC, mon...

Synthesis of monodispersed Fe3O4@C core/shell nanoparticles

We report a facile method to synthesize dispersed Fe304@C nanoparticles （NPs）. Fe304 NPs were firstly prepared via the high temperature diol thermal decomposition method. Fe304@C NPs were fabricated using glucose as a carbon source by hydro- thermal process. The obtained products were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, vibrating sample magnetometer （VSM） and Raman spectra. The results indicate that the original shapes and magnetic property of Fe304 NPs can be well preserved. The magnetic particles are well dispersed in the carbon matrix. This strategy would provide an efficient approach for existing applications in Li-ion batteries and drug delivery. Meanwhile, it offers the raw materials to assemble future functional nanometer and micrometer superstructures.

Facile Preparation and Formation Mechanism of Uniform Silver Nanoparticles Using OP-10 as Emulsifier in Reverse Microemulsion

Using the polymerizable hydrophobic styrene monomer as the dispersion medium and the traditional nonionic surfactant OP-10 as emulsifier, stable silver nanoparticles of narrow size distribution were prepared by a reverse （w/o） microemulsion method. The powder X-ray diffraction （XRD） pattern indicated that the obtained silver nanoparticles were of face-centered cubic structure. The results of the transmission electron microscopy （TEM） show that the final silver nanoparticles are of spherical structure with an average diameter of 15.2 nm and of a Gaussian distribution. The internal high-ordered structure of silver nanoparticles was characterized by the field-emission high-resolution transmission electron microscopy （FEHRTEM）, indicating that the silver is monocrystalline and it has only one nucleation site during the formation process of a nanoparticle. The time-resolved UV-visible absorption spectra was used to monitor the process of the reaction in situ. The results show that the concentration of silver nanoparticles increases but the size changes little and the morphology transforms from obvious ellipsoidal shape to nearly spherical shape during the process. The experimental results indicate that the droplets’ dynamic exchange which is closely related to the nature of surfactant film is the control factor of the kinetics. The dynamic exchange mechanism of silver nanoparticle formation is proposed to involve continual encounter of two separate droplets forming transient fused dimer in which the chemical reaction occurs followed by re-separation without combination. Attributed to the dual role of surfactant in the nanoparticle formation, tailored nanoparticles can be successfully synthesized in control in the premise of a certain stability of reverse microemulsion.

STABILITY OF EMULSIFIER-FREE EMULSION COPOLYMERIZATION OF METHYL METHACRYLATE/BUTYL ACRYLATE/SODIUM MONO(ETHYL POLYOXYETHYLENE)MALEATE

A series of new water-soluble bifunctional comonomers having both carboxyl and alkyl polyoxyethylene groups, such as sodium mono(ethyl polyoxyethylene) maleate (ZE series) with various molecular weights of polyoxyethylene ethyl ether, were synthesized and characterized. The effects of the structural factor, the amount and feeding mode of the comonomers, the initiator concentration and polymerization temperature on the stability of emulsifier-free emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA) in the presence of a small amount of ZE with potassium persulfate as initiator were investigated. Stable, almost monodispersed MMA/BA/ZE emulsifier-free latex particles were prepared.

Ultrasonic-Assisted Synthesis of Monodisperse Ag Nanoparticles and Their Applications in Surface Enhanced Raman Scattering and Fluorescence Enhancement

Monodisperse Ag nanoparticles with diameters of about 3.4 nm were synthesized by a facile ultrasonic synthetic route at room temperature with the reduction of borane-tert-butylamine in the presence of oleylamine （OAm） and oleic acid （OA）. The reaction parameters of time, the molar ratios of OAm to OA were studied, and it was found that these parameters played important roles in the morphology and size of the products. Meanwhile, surface enhanced Raman spectrum （SERS） property suggested the Ag nanoparticles exhibited high SERS effect on the model molecule Rhodamine 6G. And also, two-photon fluorescence images showed that the silver nanoparticles had high performances in fluorescence enhancement.

Hydrothermal synthesis of monodisperse Zn_(x)Cd_(1-x)S spheres and their photocatalytic properties

Monodisperse ZnxCd1-xS spheres were successfully fabricated with a high yield by a facile hydrothermal route.The as-prepared samples were characterized by X-ray diffractometry,scanning electron microscopy and UV-vis diffusion reflectance spectroscopy.The results indicate that all the prepared samples have the same hexagonal wurtzite phase and exhibit good size uniformity and regularity.Degradation of rhodamine-B（RhB） was used to evaluate the photocatalytic activities of ZnxCd1-xS samples.Zn0.4Cd0.6S possessed the best photocatalytic activity and exhibited high stability during the reaction.

Preparation of Electrically Conductive Filler for Anisotropic Conductive Adhesive

The preparation process of electrically conductive filler for anisotropic conductive adhesive was performed and discussed.The spherical filler contains tri-layer structures: resin core,Ni-P intermediate coating layer,Au outer coating layer.The 4 μm resin spherical cores were synthesized by monodispersion polymerization method.Then they were contributed to electrical conductivity by electrolessly plating Ni-P layer and gold layer.These particles have good corrosion resistance,high stability,and enough mechanical strength.When mixed with thermosetting epoxy resin to produce anisotropic conductive adhesive(ACA),it can realize a good conductive bonding between bumps on dies and pads on substrates.This environmentally friendly conductive material offers numerous advantages over conventional solder technology and is an ideal substitute for the lead-contained solder in electronics packaging.