Advanced Materials Research Vols. 634-638

Abstract: Superfine aluminum hydroxide fine powder with sheet-like particle in the range of dozens of nanometers to a few micrometers were prepared in high yields(90%) by spontaneous nucleation which is decompose under 45°C after cooling and diluting the solution of NaAlO₂ abruptly without seeding .The influence of the concentration of NaOH when decomposing on the distribution of particle size were investigated .The vacuum freezing drying oven with vacuum(11pa) and freezing(-45°C) were used .The study showed that the optimum is under the concentration of 2.69 mol/kg.Moreover,the powders dried by the vacuum freezing drying oven has no agglomerative phenomenon and the particle size are much smaller then other ovens.

Abstract: Lanthanum (La) substituted barium ferrite, Ba_1-xLa_xFe₁₂O₁₉ (x=0.00-0.40) has been synthesized by the oxide one pot synthesis (OOPS) process. The crystalline structure and magnetic properties have been investigated by means of XRD, SEM and VSM. The XRD pattern matched with the barium ferrite structure. The saturation magnetization (Ms) and coercive field (Hc) of ferrites increased by substitution of La ions on Ba sites at the content up to x=0.15 and then decrease.

Abstract: A novel method for preparing magnetic activated carbon (MAC) has been investigated in this paper. The MAC was prepared by the follow routes: it was impregnated with a ferric chloride solution in pH=9 which adjusted by ammonia. The precursor of activated carbon loaded the iron hydroxide was prepared by the impregnation-basified method and sealed the sample with charcoal powder. The MAC was prepared by high temperature atmospheric pressure reduction roasting. The results showed that the MAC which was prepared by pyrolytic process of ammonia precipitation and at 600°C under atmospheric pressure for roasting 3-4 hours, the Fe(II)/Fe(III) molar ratio was 0.506 , the MAC accounts for 82.1% of total activated carbon and the ferric ion in MAC was 5.3% . The similar effect of pure activated carbon was observed in acid fuchsin solution test with MAC for decolorization. It subsidented quickly and separated completely under the guidance of magnetic field.

Abstract: In this work optical properties of CuO nanostructure were studied. CuO nanostructure were synthesized by the hydrothermal treatment method. The structural and chemical natures of the obtained materials were studied using powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and study optical properties by UV-visible spectral. The XRD patterns of the CuO nanostructures indicated that CuO phases (JCPDS 05- 0661). The top-view SEM images, it can be seen clearly that high-density, horizontally scattered nanorod were grown on the product prepared at concentration of NaOH (aq) 7.5 M at 180 C for 12 h. The spectral of UV-vis data recorded showed the strong cut off at 341 nm.

Abstract: In this work optical properties of CuO nanostructure were studied. CuO nanostructure were synthesized by the hydrothermal treatment method. The structural and chemical natures of the obtained materials were studied using powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and study optical properties by UV-visible spectral. The XRD patterns of the CuO nanostructures indicated that CuO phases (JCPDS 05- 0661). The top-view SEM images, it can be seen clearly that high-density, horizontally scattered nanorod were grown on the product prepared at concentration of NaOH (aq) 7.5 M at 180 C for 12 h. The spectral of UV-vis data recorded showed the strong cut off at 341 nm.

Abstract: Ammonium polyphosphate (APP) has six crystalline forms, different crystalline forms can transform from one form to another. In this paper, the effect of crystalline seed on crystalline transformation is investigated, results show that adding crystalline seed APP II at higher temperature is helpful to form APP II. The transformation between form II and form V at different reaction conditions are also investigated, including blowing wet ammonia to the reaction mixture. The results are informative for controllable preparation of APP in industrial production.

Abstract: YVO4:Eu3+ nanocrystals were synthesized using a sol-gel method which citric acid was used as complexing agent and ethylene glycol was used as coupler. In order to study the influence of heat treating temperature and time on structure and luminescence properties of YVO4:Eu3 nanocrystals, the dry gels were heated at 400 oC, 500 oC and 600 oC for 1 h, 600 o C for 3 h, respectively. X-ray diffraction, SEM and luminescence spectra were used to characterize the structure and luminescence properties. The results of XRD indicate that YVO4:Eu3+ nanocrystals with tetragonal zircon were obtained. The average crystallite sizes of the samples increase with the increasing heat treating temperatures. The results of excitation and emission spectra show that the broad excitation band is assigned to charge transfer band of Eu-O and V-O, the emissions peaks are from 5D0-7FJ transitions. The emission intensities increase with increasing heat treating temperature and time. The local environments of Eu3+ ions in the samples prepared at different conditions are discussed.

Abstract: Rod-shaped TiO2 was synthesized via homogeneous precipitation by using PEG and urea as the structure directing agent and precipitation agent, respectively. The prepared samples were characterized by XRD, TEM, and FESEM. The XRD patterns of the samples indicated that the crystalline phase was anatase. TEM and FESEM images revealed the morphology of prepared TiO2 samples were rod-shaped, and densely packed with plenty of spherical-shaped units. RTS3 exhibited the highest photocatalytic activity for degradation of papermaking wastewater under UV light irradiation. CODCr percent degradation was about 75% under UV light irradiation in 12 h for RTS3.

Abstract: Monodispersed Fe3O4 magnetite nanoparticles were successfully synthesized via a simple solvothermal method, in which Fe(NO3)3•9H2O was used as the starting materials, KOH as the mineralizer, and ethylene glycol (en) as the solvent. X-ray diffraction (XRD) and selected area electron diffraction (SAED) were employed to characterize the phase composition, transmission electron microscope (TEM) to observe the morphology and the particle size, and physical property measurement system (PPMS) to investigate the magnetic property of the synthesized powders, respectively. The synthesized Fe3O4 magnetite nanoparticles are of 50-100nm in size, and of notable ferromagnetic property. The saturation magnetization, remanent magnetization, and coercive field are 68.8emu•g-1, 12.9emu•g-1, 138.5Oe, respectively. Based on the experimental resuts, the formation mechanism and the well monodispersed reason of the solvothersized Fe3O4 nanoparticles are discussed.

Abstract: Mesoporous silica with different morphological structure had been prepared using cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulfate (SDS) as co-surfactant templates and tetraethoxysilane (TEOS) as silica source. Variation on the morphological structure can be achieved by adjusting the solution conditions. The mesoporous silica with varied morphologies and pore structures were characterized by transmission electron microscopy (TEM), small-angle X-ray diffraction (SAXRD) and N2 adsorption-desorption isotherms. Based on experimental results, the mesoporous silica morphologies including vesicle-like and hollow nanospheres with mesoporous shell has been proposed. It was also observed a transformation from vesicle-like silica to hollow nanospheres with mesoporous shell by regulating the solution conditions.