Key Engineering Materials Vols. 336-338

Abstract: Lead titanate (PbTiO3) nanowires have been synthesized by hydrothermal method at 200°C for 48h using lead acetic and tetrabutyl titanate as the starting materials and NaOH served as a mineralizer. The phase composition and microstructure of PbTiO3 nanowires were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED). The results showed that the obtained nanowires are of single crystalline, tetragonal perovskite structure with diameters of ac. 12 nm and lengths ranging from 500 nm up to 5 μm. The PbTiO3 nanowires have good optical transmissivity. Photoluminescence (PL) study at room temperature for wavelength between 400 and 700 nm reveals a strong light emission band peaking at ac. 471.4 nm (2.63 eV).

Abstract: Branched SnO2 nanowires were prepared by heating Sn powders. SEM images indicated that the single branched nanowires had diameters in the range 50-300 nm. XRD and SAED analysis revealed that the SnO2 nanowires were crystalline with tetragonal rutile structure. PL spectrum showed visible light emission.

Abstract: Sulfide nanowire arrays have been synthesized by DC electrodeposition from an electrolyte containing S in DMSO. The AAO membrane with the barrier layer has been directly used as template in electrodeposition. The as-synthesized products are characterized by SEM, TEM and resonance Raman spectroscopy. CdS and ZnS nanowires have been obtained, respectively.

Abstract: Boron carbide nanobelts have been synthesized successfully by carbothermal growth method. Boron oxide, activated carbon, gallium oxide and sodium chloride in the molar ratios of 1: 5: 0.03: 0.2 were used as raw materials. The width and thickness of the nanobelts range from 1 to 10 μm, and 80 to 150 nm respectively. The length is up to 50–200 μm. Diffraction peaks in the XRD pattern can be indexed to rhombohedral boron carbide with lattice parameters of a=5.616Å, c=12.067 Å. SAED pattern recorded along [ 010 ] zone axis shows (104 ) growth direction. A vapor–liquid–solid (VLS) growth process on the active catalyst surface is supposed to interpret the growth mechanism of as–synthesized nanobelts.

Abstract: In this paper, nanostructure zinc oxide (ZnO) hexagonal rods arrays on ZnO granular films coated substrates were fabricated by a simple chemical solution method. The shapes and structures can be controlled by changing the reactants and experimental conditions. X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) equipped with energy dispersive spectrometer (EDS), and fluorescence spectrum were used to characterize the structures and luminescent properties. The best reacting condition has been discussed. Urea was found playing an important role in forming rods. The granular films acting as the seed films were proved.

Abstract: Yttrium oxide hydroxide nitrate (Y4O(OH)9NO3), which was prepared by polyvinyl alcoholassisted hydrothermal method from the Y(NO3)3 and KOH starting solution, was characterized by XRD and FE-SEM. The results revealed that pH value of the starting solution is an important factor which determines the morphology and size of the products. The obtained products varied from lamina microprisms to circular nanorods when the pH value increased from 7.0 to 8.0. In the high pH value above 8.0, the size of nanorods decreased with increasing pH value. A primary mechanism was proposed to explain the evolution of morphology and size of Y4O(OH)9NO3 products prepared under various pH values.

Abstract: One-dimensional LaNiO3 nanochains can be generated with high yield by a simple calcination process using La(OH)3/Ni(OH)2 coaxial nanocables as parent template. Those coaxial nanocables can be synthesized by a simple hydrothermal method. The final LaNiO3 ceramics keep the morphology of parent precursor.

Abstract: Cerium hydrate fiber (CHF), which showed an aspect ratio greater than 100, was synthesized by a novel method, which used the mixing of cerium nitrate (Ce(NO3)3), sodium hydrate (NaOH) and citric acid (C6H8O7) synthesized at a relative low temperature and ambient pressure. The precipitates were characterized by XRD, SEM and TEM. The results showed that in addition to fibers, two morphologies could be obtained depending on the synthesizing conditions. Aging time and formulation were two key factors for the control of the aspect ratio of the precipitates. By a heating treatment at 600oC for 2 h, the homogenous and well-crystallized cerium dioxide (CeO2) fiber can be fabricated. The effects of synthesis parameters, such as the concentration of the starting solution, aging period, and pH value were reported and discussed.

Abstract: A novel nano-material of carbon rod studded iron granules on its surface was prepared from needle coke with iron as catalyst by arc method in the vacuum condition. Its structure and composition was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). In the SEM images the carbon material showed cotton-like. The TEM results showed that the nano-material was bar-like with diameter of 20nm to 50nm and there were lots of iron particles studded on its surface. The analytical result of EDS showed that the chemical composition of materials mainly consisted of carbon and iron elements. The XRD analysis revealed that there were two sharp diffraction peaks, one was at 26.2° which corresponded to the (002) plane of graphite structure and the other was at 43.2° which corresponded to the (fcc) γ-Fe structure. The nano-material might be used as catalyst in the chemical reaction.