Advanced Materials Research Vols. 554-556

Abstract: Synthesis and characterization of microsheets, microrods, microflowers and microspheres of orthorhombic phase molybdenum oxide (MoO₃) were reported. The reaction between ammonium molybdate and hydrochloric acid was used to prepare MoO₃ microstructures and followed by annealing in air at 400^oC for 2h. The combined techniques of X-ray powder diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM) and Raman spectroscopy were used to investigate the effect of pH and additives on the as-prepared samples. Results indicated that they were of microsize. With alcohol as an additive, the sample was plate-like MoO₃ at pH=2.5, and it was a mixture of MoO₃ and MoO₃•0.55H₂O of irradiative corolla at pH=1. The sample obtained by hydrothermal was MoO₃ flowers. Meanwhile, when silane coupling agent was introduced as the additive, the sample was MoO₃ spheres.

Abstract: Mesoporous Al₂O₃ was synthesized from aluminum nitrate using different surfactants as structure-directing agents. The adsorption capability of prepared Al₂O₃ was studied in methyl orange solution. The Al₂O₃ prepared by Tween80-mediated has the best adsorption capability. The surfactant dosage influences the pore structure and adsorption capability of Al₂O₃, the best Tween80 dosage is 0.3g. Pore size distribution shows that the prepared Al₂O₃ has mesoporous structure, the pore diameter mainly centers at 1-4nm. For the inner diffusional resistance of the pore canal to achieve adsorption balance, suitable adsorption time is 80 minutes.

Abstract: Chromium doped rutile TiO₂ was synthesized by either co-precipitation or impregnation (surface-doping) and characterized by XRD and reflectance spectroscopy. Chromium addition did not change the TiO₂ structure nor did the structure of the co-precipitated products differ from that of the impregnated samples. However, chromium doping moved the absorption of both sets of products into the visible and significantly affected the TiO₂ photocatalytic activity for isopropanol (IPA) oxidation. At high chromium concentrations the photoactivity of the co-precipitated samples was reduced by a larger amount than that of the impregnated samples; this was attributed to a higher concentration of Cr³⁺ ions in the rutile lattice. Unexpectedly, increased photoactivity was measured for low Cr levels of surface-doped rutile. This may be caused by increased electron-trapping, at surface Cr⁶⁺ ions, and correspondingly reduced, electron-hole recombination.

Abstract: In this paper, the fabrication of TiAl alloy powders by high-energy ball milling and heat preservation at low temperature and high vacuum using titanium powders of 30 micron and aluminum powders in the size of 9-12 micron. After being heated under the different time and temperature, the alloying of milled and heated powders of titanium and aluminum were investigated. The results show that the alloy powders with the main intermetallic compounds of TiAl and a small quantity of aluminum tri- titanium can be obtained through one hour high-energy ball milling and preserving heat 2 hours at 500°C, 3 hours at 600 °C in high vacuum. Furthermore, the transitional alloy phase Al2Ti was formed at 550 °C~600 °C, and it has an effect on the density of Ti-Al alloy powders in the diffusion synthesis. The fabrication of TiAl alloy powders with different density by sintering diffusion at low temperature and high vacuum is effective.

Abstract: PAMAMG4-1,2-octenoxid dendrimer was prepared and used as carrier in ELM to extract copper ions. The membrane was prepared by dissolving PAMAMG4-1,2-octenoxid dendrimer and Span 80 in chloroform. The internal phase is aqueous solution of hydrochloric acid. Effects of operating parameters such as carrier concentration, surfactant concentration, hydrochloric acid concentration in the internal phase, emulsification time and emulsification speed on the membrane stability were studied. In addition, the effect of carrier concentration, surfactant concentration and hydrochloric acid concentration in the internal phase on the extraction efficiency was also investigated. The results showed that PAMAMG4-1,2-octenoxid dendrimer is a suitable carrier for copper ions in ELM system.

Abstract: In this study, Schiff base ligands of (E)-3-(2-aminophenylimino)indolin-2-one, (L1); (E)-3-(2-amino-5-nitrophenylimino)indolin-2-one, (L2); and (E)-3-(2-amino-5-chlorophenylimino) indolin-2-one, (L3) were synthesized via condensation reaction of isatin with o-phenylenediamine, 4-nitro-o-phenylenediamine and 4-chloro-o-phenylenediamine respectively. All the synthesized compounds were characterized by various of physicochemical techniques such as melting point, elemental analysis, infrared spectroscopy, and ¹H nuclear magnetic spectroscopy. Conductivity studies of these ligands were investigated by impedance analyzer which the samples were prepared in the form of tablets. The electrical conductivities of the prepared compounds were measured by applying alternating current (ac) voltage. The conductivity values were calculated and result obtained shows that L2 has the highest conductivity value, followed by L3 and L1.

Abstract: Nano-CuO particles are prepared by using Cu(NO3)2 and NH4HCO3 as the starting materials and pure water as the solvent. And use high-energy ball milling method to make nano-CuO particles embeded in the crystalloid surface of graphite to form composite particles. The products of nano-CuO and composite particles are characterized by using techniques such as X-ray powder diffraction, FTIR-spectroscopy, scanning electron microscopy, and separator-size analyzer. The results show that the average size of CuO particles is 11.2nm, the Median diameter of composite particles is 8.43μm. After the graphite is rapidly ball milled and loaded nano-CuO particles. The lamellar and pore structure of graphite are well maintained, And nano-CuO particles are loaded on the top of the hole and the hole wall.

Abstract: AlN powders were synthesized by carbothermal reduction method using a combustion synthesis precursor derived from aluminum nitrate (oxidizer), glucose (carbon source), and urea (fuel) mixed solution. Effects of carbon source content on the combustion temperature of solutions, the particle size and morphology of the precursors and the synthesized AlN were studied in detail. The results indicated that a regular variation in the particle size and morphology of precursors had been observed with the increasing molar ratio of glucose to aluminum nitrate (C/Al). The products prepared with (C/Al=8–12), calcined at 1500 oC for 2 h, could have completed the nitridation reaction, while the nitridation products prepared with (C/Al=4 and 16) are opposite. The nitridation products prepared with (C/Al=8–12), calcined at 1500 oC for 2 h, are comprised of well-distributed spherical particles of AlN with the average size ranging from 50 to 80 nm.

Abstract: Cu-containing Layered Double Hydroxides (Cu-LDHs) prepared in a microwave field (Cu-LDHs-b) differs drastically according to the appearance, chemical component and the catalytic activity when compared with conventionally prepared sample (Cu-LDHs-a). From the TEM images, it is obvious that the particle size range of Cu-LDHs-b with 30～90 nm is narrower than that of Cu-LDHs-a with 30～120 nm, and the dispersibility of Cu-LDHs-b is better than that of Cu-LDHs-a. ICP-AES characterization shows that raw material utilization ratio of Cu-LDHs-b is higher than that of Cu-LDHs-a. Furthermore, Cu-LDHs-b exhibites higher catalytic activity than Cu-LDHs-a in the phenol hydroxylation with H2O2. Therefore, the microwave-assisted synthesis is an ideal method for synthesis of nano-Cu-LDHs.

Abstract: A hetrobimentallic complex of Zn[Bi(edta)]₂•8H₂O was synthesized under hydrothermal condition and characterized by means of X-ray single crystal diffraction, element analysis, FT-IR spectra and thermal analysis. The complex is monoclinic, space group C2/c with a =2.3532(8) nm, b=0.8675(3) nm, c=1.6116(6) nm, β=98.114(6) °, V=3.2569(19) nm3, Z=4，Dc= 2.455 g•cm^－3，μ= 11.615mm－1. Bridging edta4－ anions between Bi(III) atoms result into infinite 1D zigzag chain. [Bi(edta)]－anions and [Zn(H₂O)₆]²⁺ cations are bonded through hydrogen bonds to form network structure. The thermal decomposition of the complex proceeds dehydration, pyrolysis of ligand, and decomposition of salt, and the final residue is inorganic oxide. The thermodynamic parameters ( ΔH、ΔG and ΔS) and kinetic parameters (activation energy Ea and the pre-exponential factor A) for the pyrolysis of ligand have been calculated.