Highly ordered tungsten trioxide nanotube arrays were synthesized by the combination of (NH 4) 2WO 4 solution and anodic aluminum oxide(AAO) templating method. The morphology and the chemical composition of tungsten t...Highly ordered tungsten trioxide nanotube arrays were synthesized by the combination of (NH 4) 2WO 4 solution and anodic aluminum oxide(AAO) templating method. The morphology and the chemical composition of tungsten trioxide nanotube arrays were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS) and X-ray diffraction(XRD). The results show that the diameter of the tungsten trioxide nanotube arrays is about 165 nm and just equals to the diameter of pores of AAO template, which reveals that the diameter of the tungsten trioxide nanotube arrays is dependable on the size of the pores in the AAO template. The tungsten trioxide nanotubes are composed by tungsten trioxide nanoparticles formed by reaction (NH 4) 2WO 4550 ℃2NH 3↑+WO 3+H 2O↑ in the heating process.展开更多
The lowest-energy structures and the electronic properties of CdnSn （n = 1 - 8） clusters have been studied by using denslty-functional theory simulating package DMol^3 in the generalized gradient approximation （GGA...The lowest-energy structures and the electronic properties of CdnSn （n = 1 - 8） clusters have been studied by using denslty-functional theory simulating package DMol^3 in the generalized gradient approximation （GGA）. The ring-like structures are the lowest-energy configurations for n = 2, 3 and the three-dimensional spheroid configurations for n = 4 - 8. The three-dimensional structures may be considered as being built from the Cd2S2 and Cd3S3 rings. Compared to the previous reports, we have found the more stable structures for CdnSn（n = 7, 8）. Calculations show that the magic numbers of CdnSn （n = 1-8） clusters are n = 3 and 6. As cluster size increases, the properties of CdnSn clusters tend to bulk-like ones in binding energy per CdS unit and Mulliken atomic charge, obtained by comparing with the calculated results of the wurtzite and zinc blende CdS for the same simulating parameters.展开更多
文摘Highly ordered tungsten trioxide nanotube arrays were synthesized by the combination of (NH 4) 2WO 4 solution and anodic aluminum oxide(AAO) templating method. The morphology and the chemical composition of tungsten trioxide nanotube arrays were characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS) and X-ray diffraction(XRD). The results show that the diameter of the tungsten trioxide nanotube arrays is about 165 nm and just equals to the diameter of pores of AAO template, which reveals that the diameter of the tungsten trioxide nanotube arrays is dependable on the size of the pores in the AAO template. The tungsten trioxide nanotubes are composed by tungsten trioxide nanoparticles formed by reaction (NH 4) 2WO 4550 ℃2NH 3↑+WO 3+H 2O↑ in the heating process.
基金supported by the National Natural Science Foundation of China (Grant Nos 90306010 and 20371015)the Program for New Century Excellent Talents in University,Chinese Ministry of Education (Grant No NCET-04-0653)
文摘The lowest-energy structures and the electronic properties of CdnSn （n = 1 - 8） clusters have been studied by using denslty-functional theory simulating package DMol^3 in the generalized gradient approximation （GGA）. The ring-like structures are the lowest-energy configurations for n = 2, 3 and the three-dimensional spheroid configurations for n = 4 - 8. The three-dimensional structures may be considered as being built from the Cd2S2 and Cd3S3 rings. Compared to the previous reports, we have found the more stable structures for CdnSn（n = 7, 8）. Calculations show that the magic numbers of CdnSn （n = 1-8） clusters are n = 3 and 6. As cluster size increases, the properties of CdnSn clusters tend to bulk-like ones in binding energy per CdS unit and Mulliken atomic charge, obtained by comparing with the calculated results of the wurtzite and zinc blende CdS for the same simulating parameters.
