Titania microtubules with high specific surface areas and well-developed framework mesopores forming the tubular walls by a surfactant-mediated template in the sol-gel process were fabricated in a laurylamine hydrochloride (LAHC)/tetra-n-butyl-orthotitanate (TBOT) system. The outer diameter and the wall thickness of titania microtubules are 2-8 and 0.2-2μm, respectively. The walls of the microtubules consisted of nanochannels with exceptionally uniform pore size. This technique is a convenient and facile procedure for fabricating hierarchical ordered hollow tubules. The possible mechanism of the formation of the microtubules in the present system was discussed in detail.

Nickel oxide (NiO) nanotubules were fabricated by a dodecylsulfate-mediated templating method in a homogeneous precipitation process. The nanotubules obtained have diameters of 20-160nm and wall thickness of 8-50 nm with lengths up to several micrometers. The crystallinity, morphology and structure features of the NiO nanotubules were investigated by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), infrared (IR) spectrum, etc.

Semiconductor CdS nanotube arrays were synthesized within the pores of the PAO membranes by using molecular anchor templating synthesis method. The CdS nanotube arrays obtained were characterized using scanning electron microscopy (SEM), X-ray diffractomemter (XRD) and transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopic analyzer (EDS), respectively. The formation mechanism of CdS nanotube was also discussed. This is the first report on the highly ordered CdS nanotube arrays with 60lm in length and 100nm in outer diameter. The present method shows the advantages of simplicity, high efficiency and low cost.

Fluorination-assisted electrothermal vaporization (ETV)-inductively coupled plasma-atomic emission spectrometry (ICPAES) for the direct determination of trace amounts of refractory impurity elements in silicon carbide ceramic powders using slurry sampling has been developed. Investigation indicated that a polytetrafluoroethylene (PTFE) emulsion is a useful fluorinating reagent for the destruction of silicon carbide and simultaneous vaporization of the refractory impurities like B, Mo, Ti, and Zr. The vaporization behaviors of the analytes in slurry and solution were comparatively investigated in the presence of PTFE. The fluorinating vaporization processes and the influence factors for this method have been also studied in detail. The experimental results indicated that 80mg silicon carbide (10ml of 0.8% (m/v) slurry) could be destroyed and vaporized completely with 600mg of PTFE under the selected conditions. Calibrationwas performed using the standard addition method with aqueous standard solutions. The accuracy was checked by comparison of the results with those obtained by solution fluorination-assisted ETV-ICP-AES and pneumatic nebulization (PN)-ICP-AES involving a wet-chemical decomposition of the sample. Detection limits between 0.5mg g−1 (B) and 0.2mg g−1 (Mo) were achieved. In most cases, the precision expressed as relative standard deviation (R.S.D.) was better than 8%. © 2001 Elsevier Science B.V. All rights reserved.

Nanocrystalline alumina powders were prepared by combustion synthesis using glycine as fuel and nitrate as an oxidizer. The effect of the pH values in the precursor solutions on crystallite sizes, surface areas and morphologies of the synthesized alumina powder has been investigated by X-ray diffractometry, thermal analysis, nitrogen adsorption-desorption, and transmission electron microscopy. With decreasing the pH values in the precursor solutions, the obtained materials could be modified from segregated nanoparticles (pH 10.5) to aggregates of nanoparticles (pH 6.0), and finally to a flaky morphology (pH 2.5). The rates of decomposition, the interaction of coordination as well as the hydrogen bonding of the glycine and the Al-hydroxides species at different pH values were found to be responsible for the generation of flake and/or segregated nanoparticles during auto-ignition reactions. The as-prepared combustion ashes were converted into pure nanocrystalline alumina after calcination at elevated temperatures. The specific surface areas of the products calcined at 800 8C ranged from 96 to 39 m2/g with the pH decreased from 10.5 to 2.5.