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.

A new analytical procedure for the direct determination of metal impurities (Cr, Cu, Fe and V) in aluminium oxide ceramic powders by slurry sampling fluorination assisted electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry (ETV-ICPAES) is reported. A polytetrafluoroethylene (PTFE) emulsion was used as a fluorinating reagent to promote the vaporization of impurity elements in aluminium oxide ceramic powders from the graphite tube. A vaporization stage with a long ramp time and a short hold time provided the possibility of temporal analyte-matrix separation. The experimental results indicated that a 10μL1% m/v slurry of aluminium oxide could be destroyed and vaporized completely with 600μg PTFE under the selected conditions. Two aluminium oxide ceramic powder samples were used without any additional pretreatment. Analytical results obtained by using standard addition method with aqueous standard solution were checked by comparison of the results with pneumatic nebulization (PN)-ICP-AES based on the wet-chemical decomposition and analyte-matrix separation. The limits of detection (LODs) between 0.30μg g-1 (Fe ) and 0.08μgg-1 (Cu) were achieved, and, the repeatability of measurements was mainly better than 10%.

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.

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.

Eu2 +,Dy3 + co-doped strontium aluminate (SrAl2O4) phosphor nanoparticles with high brightness and long afterglow were prepared by glycine-nitrate solution combustion synthesis at 500℃, followed by heating the resultant combustion ash at 1100℃ in a weak reductive atmosphere of active carbon. The average particle size of the SrAl2O4:Eu,Dy phosphor nanoparticles ranges from 15 to 45nm as indicated by transmission electron microscopy (TEM). The broad-band UV-excited luminescence of the SrAl2O4:Eu,Dy phosphor nanoparticles was observed at kmax=513nm due to transitions from the 4f65d1 to the 4f7 configuration of the Eu2+ion. The results indicated that the main peaks in the emission and excitation spectrum of phosphor nanoparticles shifted to the short wavelength compared with the phosphor obtained by the solid-state reaction synthesis method. The decay speed of the afterglow for phosphor nanoparticles was faster than that obtained by the solid-state reaction method.