Solid State Phenomena Vols. 121-123

Abstract: Te nanomaterials, with different morphologies, such as nanospheres, micro- and nanobranches, and microtrees with tubular nanobranches were prepared by physical vapor deposition method, using elemental Te powder as starting material. The composition and morphology of the nanomaterials were characterized by XRD, SEM/EDX and TEM. The formation mechanism of the above mentioned nanostructures was proposed.

Abstract: CNTs-HDPE composites were prepared by the blend method. SEM was used to investigate the microstructure of the composites. The electrical and tribologic properties of the composites were studied respectively. The experiments showed that the percolation threshold of composites is about 3wt%, which is much lower than that of the carbon black-HDPE composites, and that the temperature-dependent electrical conductivity of composites had the PTC and double NTC characters, being also different from the carbon black-HDPE composites. These results are due to the unique structure and characters of CNTs. The frictional experiments demonstrated that the addition of CNTs would enhance the wear resistance of the composites.

Abstract: An optimum route to synthesize Al2O3-based composite powders with a homogeneous dispersion of carbon nanotubes (CNTs) was investigated. CNT/Metal/Al2O3 nanocomposite powders were fabricated by thermal chemical vapor deposition (CVD) over a metal catalyst homogeneously dispersed into an Al2O3 matrix by the means of chemical and selective reduction processes. The nanocomposite powders were densified by Pulse Electric Current Sintering (PECS). The experimental results show that the CNT/Metal/Al2O3 nanocomposites have unique electrical properties.

Abstract: Ga2O3 nanowires were prepared by vapor-solid process in atmosphere, using commercial Ga ingot and Ga2O3 powder or Al2O3 powder as the starting materials. The influence of preparation conditions such as temperature and starting material on the products was studied. The composition and morphology of the products were characterized by XRD, SEM/EDX, TEM, and HRTEM. The formation mechanism of the products was proposed.

Abstract: In this paper, we report a simple and large-scale fabrication of CuO array films with different nanostructures grown on copper foils. CuO nanotube and nanorod array films were synthesized through the dehydration of the nanostructured Cu(OH)2 arrays in flow of N2, which are prepared in an alkali solution at a low temperature without using any templates and surfactants. The obtained CuO nanotube and nanorod array films retain similar morphology to that of the Cu(OH)2 precursors. While CuO nanosheet and nanobelt array films were prepared directly in the alkali solution. The evolution of the nanostructures as a function of the reaction conditions has been revealed, from nanorods of Cu(OH)2 to nanotubes of Cu(OH)2 to nanosheets of CuO to nanobelts of CuO. Experiments show that the growth temperature plays an important role in the formation of well-aligned Cu(OH)2 nanostructured array films on copper foil. The samples are characterized by XRD, SEM and TEM.

Abstract: Rare earth complex Eu(phen)2Cl3·2H2O synthesized by precipitation method was incorporated into MCM-41 mesoporous molecular sieves which were synthesized via a hydrothermal method. Hybrid inorganic/organic mesoporous luminescent material Eu(phen)2/MCM-41 has been characterized by XRD, TEM, IR, UV-visible spectra and fluorescence spectra. Results indicated that the hybrid mesoporous material has typical structure of MCM-41 and retains the same pore structure as MCM-41 after the assembly process. The fluorescence spectra of these materials present a series of narrow lines assigned to 5D0 → 7F0,1,2,3,4 transitions. The high emission intensity observed is a promising property for application of the rare earth complex in technological luminescent devices.

Abstract: The magnetic Co nanoparticle was prepared by coprecipitation route in aqueous solution and Figlarz’s polyol method which consists of refluxing a solution of the metal precursor in polyol. As the former method, the Co nanoparticle was synthesized by reduction of cobalt chloride with sodium borohydride in aqueous solution. And the latter method, the polyol method can be applied to the production of Co nanoparticle by reducing cobalt chloride and cobalt acetate with polyol such as ethylene glycol, trimethylene glycol. The size of nanoparticle was confirmed by transmission electron microscopy images and scanning electron microscopy images, according to the different methods The crystal structure of nanoparticle according to reaction condition was characterized by X-ray diffraction data. The magnetic properties were characterized with saturation magnetization from hysteresis loop by vibrating sample magnetometer (VSM).

Abstract: A number of experiments were carried out with different Ce-Zr oxides doped La3+、Pr3+ or Mn4+ in order to improve their performance as a promoter for three way catalyst(TWC). The XRD results showed that the thermal stability of Ce-Zr oxide doped lanthanum or praseodymium was improved, especially at high temperature. H2-TPR test detected the low –temperature redox behavior of Ce-Zr oxide was promoted strongly attributed to the MnO2, with calcined temperature increasing, the reduction peaks were moved to high temperature for Ce-Zr oxide doped La3+ and Pr3+. The catalytic activity of Ce-Zr oxide doped Mn4+ was also enhanced, the light-off temperature was lower 10K than Ce-Zr oxide; the conversions of CO and THC were higher 3-4% than Ce-Zr oxide.