Papers by Keyword: Coprecipitation

Abstract: Eu, Sb doped SnO₂ and quartz compound conductive powders are prepared by the coprecipitation method with SnCl₄·5H₂O, SbCl_3, Eu₂O₃ and quartz powders as the raw materials. The crystal phase and structure of the prepared conductive particles are characterized by FTIR and XRD techniques respectively. The resistivity of the prepared conductive powders are measured with four-point measurement method. The resistivity of Eu, Sb doped SnO₂ and quartz compound condu-ctive powders is 0.37 Ωcm. FTIR spectrum of Eu, Sb doped SnO₂ and quartz compound conductive powders shows that there are the vibration peaks in 546.14 cm^-1, 489.95 cm^-1, 466.71 cm^-1, 430.34 cm^-1 and 418.92 cm^-1 respectively, and have intense absorption in 4000 cm^-1 ~ 1100 cm^-1. Eu, Sb doped SnO₂ conductive powders have a structure of tetragonal rutile. The complex doping is achieved well by coprecipitation method and is recognized as replacement doping or caulking doping. The composition of compound conductive powders are Eu, Sb doped SnO₂ conductive powders and quartz powders.

Abstract: Micro-mesoporous mixed oxides containing nickel, cobalt and aluminum have been synthesized using conventional coprecipitation method. FESEM and HRTEM analyses demonstrated the flower and hexagonal plate-like nanostructured of mixed oxides. Different mixed oxide formation, homogenous metal dispersion, textural properties were investigated using XRD, ICP-MS and BET (N₂ adsorption-desorption) techniques. nanostructured mixed oxides exhibited 2.6 wt% hydrogen adsorption that were studied using temperature programmed reduction-adsorption-desorption (H₂-TPR/TPD) and thermogravimetric and differential thermal analysis (TGA-DTA) techniques. Investigation corresponds that morphologies, textural properties and surface energy of mixed oxides are important in hydrogen adsorption.

Abstract: The Fe₃O₄ magnetic nanoparticles obtained by the aqueous coprecipitation method are characterized systematically using scanning electron microscope, X-ray diffraction and vibrating sample magnetometer. These magnetic nanoparticles are spheric, dispersive, and have average grain size of 50 nm. The size and magnetic properties of Fe₃O₄ nanoparticles can be tuned by the reaction temperature. All samples exhibit high saturation magnetization (M_s=53.4 emu·g^-1) and superparamagnetic behavior with a block temperature (T_B) of 215K. These properties make such Fe₃O₄ magnetic nanoparticles worthy candidates for the magnetic carriers of targeted-drug or gene therapy in future.

Abstract: Based on our previous work of MSA influence on silver nano particles formation we have performed a series of research related to the preparation and characterization of silver nanoparticles which synthesized through coprecipitation process. The silver nano particles was transformed into silver nanoparticles films by spin coating deposition method. The silver nanoparticles were prepared from silver acetate as precursor, reductant agent phenylhydrazine, and dodecylamine as stabilizer. X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDAX), and Electric Four Point Probe have been used to characterize the silver nanoparticles as well as the films. The morphology and the crystal structure have been determined by means of XRD and SEM. The average grain size of silver nanoparticles is found to be 22 nm. The peaks in XRD pattern are in good agreement with that of face-centered-cubic phase of metallic silver. The electrical conductivity films were confirmed in the range of conducting material. The highest conductivity was reached at 3,88 x 10⁹ S/cm associated to 1600 rpm of spin coater rotation.

Abstract: Magnetic nanoparticles of cobalt ferrite (CoFe₂O₄) have been synthesized by co-precipitation method with various synthesis temperatures, concentration of NaOH and stirring duration. The results showed that nanoparticles have well crystallized structure with various grain sizes which depend on synthesis parameters. The grain size increased with increasing synthesis temperature, decreasing concentration of NaOH and decreasing stirring duration. Magnetic characterization of CoFe₂O₄ nanoparticles measured by Vibrating Sample Magnetometer (VSM) showed that coercive field was decrease with the decreasing of particle size. The saturation and remnant magnetization showed increasing when crystallinity increased. However, it also depends on presence of α-Fe₂O₃ phases and their grain size. Based on magnetic characterization analysis, sample with parameter of synthesis temperature 80^°C, concentration of NaOH 5 M and stirring duration 120 minutes have been selected to be modified using polyethylene glycol (PEG)-4000. XRD and TEM analysis showed that surface modification with PEG-4000 could increase the crystallinity of nanoparticles, decrease agglomeration and control the shape to more spherical. VSM analysis showed that modification PEG-4000 could decrease the saturation magnetization which is due to the existence of α-FeO(OH) and γ-FeO(OH) phases from bonds at interface of CoFe₂O₄ as confirmed by XRD and Furrier Transform Infra Red (FTIR) analysis. Keywords: magnetic nanoparticles, CoFe₂O₄, copresipitation, PEG-4000

Abstract: Dye-sensitized Solar Cells (DSSCs) have been successfully fabricated by using ZnO nanoparticles (NPs). The ZnO photoelectrode was prepared by using pastes solved in water-based and ethanol-based solvent. The ZnO NPs was synthesized by copresipitation method, prepared by reaction from Zinc Acetate with diethylene glycol (DEG). The obtained ZnO NPs has 13.93 nm particle diameter. Scanning Electron Microscopy (SEM) showed that ZnO NPs from monodisperse spherical aggregate with particle diameter of approximately 300nm. The band gap was found of 3.29eV. Variations of annealing temperature were carried out in photo-electrode fabrication. This work employs extracts from mangosteen pericarp as natural dye for fabrication of DSSCs. DSSCs were fabricated in sandwich structure with redox couple electrolyte I₃^-/I^- and Pt-catalyst counter electrode. The best efficiency of 0.11% (V_oc = 232.4 mV, J_sc = 111.6 µA/cm², FF = 61.41 %) was obtained for DSSCs using ZnO photo-electrode prepared by ethanol-based paste and 200°C of annealing temperature.

Abstract: In this paper, we discuss experimental method of synthetic HTLcs by coprecipitation method,and factors of this HTLcs catalytic decomposition of methylene blue. Experimental results show that the Optimal catalytic conditions is: Catalyst is 0.75g/L, H₂O₂ concentration is 0.75% and Reaction time was2.5h when the initial concentration of methylene blue is 20mg/L and the PH value of solution is 2.The decolorization rate of Methylene blue can reach 96.56%.

Abstract: Nano-structured hydrotalcite based mixed oxides have been synthesized using coprecipitation method under variable pH and low supersaturation condition. XRD technique has been used to confirm the hydrotalcite structure and its derived different phase of mixed oxides. The metal dispersion of mixed oxides was analyzed using ICP-MS. The nanostructures of the mixed oxides have been investigated using FESEM and HRTEM. The textural properties of mixed oxides were analyzed using N₂ adsorption-desorption (BET) technique. The Characterizations have revealed that the developed mixed oxides were consisted with hexagonal/rhombohedral well dispersed nano-particles. Polycrystalline mixed oxides formed mesopore surface and narrower pore size distribution.

Abstract: CaO-ZrO₂ composite powders were synthesized by liquid phase coprecipitation using ethanol as reaction medium and washing solution. The green compacts were formed by dry pressing and were sintered by pressureless sintering. The morphology, size and distribution of the particles were studied by transmission electron microscopy (TEM); the microstructure of sintered bodies was analyzed by scanning electron microscopy (SEM), the density of green compacts and sintered bodies were tested by the mass and dimension. The results showed that 5 mol% CaO-ZrO₂ composite powders with good dispersion, particle size distribution were obtained. The fractured surfaces of sintered bodies prepared by the powders were smooth without any cracks. When contained 5-15mol% CaO, the relative density of sintered bodies exceeded 95%. When the molding pressure was 20Mpa, the relative densities of sintered bodies were all above 97%.

Abstract: Co/CeO₂ catalysts showed good catalytic performances in terms of activity, selectivity and stability for intermediate temperature ethanol steam reforming, while low temperature activity should be improved. Thus, effect of nickel incorporation into Co/CeO₂ catalysts for ethanol steam reforming was investigated on the consideration of high activity for CC bond cleavage at low temperature of nickel, while cobalt may improve yield of hydrogen due to the depression of CH₄ formation. A series of Co-Ni/CeO₂ catalysts were prepared by coprecipitation, characterized by low temperature N₂ adsorption, X-ray diffraction, temperature programmed reduction, and catalytic performance measurement for ethanol steam reforming. The results indicated that 10.0% nickel incorporation into Co/CeO₂ resulted in much better catalytic performances, complete conversion of ethanol into C₁ species and hydrogen yield about 60.0% at 350°C were obtained. Further increase of nickel content decreased catalytic performance. The high performance of the Co₁₀-Ni₁₀/CeO₂ was attributed to enhancement of surface Ce⁴⁺ reduction and fine particles of metal.