Growth and structure analysis of tungsten oxide nanorods using environmental transmission electron microscopy
The WO3 nanorods were fabricated in environmental transmission electron microscopy (ETEM) by simply heating it in oxygen atmosphere. Altough, WO3 nanorod showed high crystalline, but the stacking fault existed in nanorod. Furthermore, the nanorod was grown on tungsten wire through slit of oxide layer on it.
Adsorption and desorption of oxygen on stepped tungsten surfaces
The adsorption and desorption of oxygen on stepped tungsten surfaces with orientations close to the (110) orientation and steps parallel to the most densely packed crystal direction ([111]) is studied with low energy electron diffraction, Auger electron spectroscopy, work function measurements and thermal desorption spectroscopy. With increasing deviation from the (110) orientation, an increasing preference for the formation of the p(2 × 1) domain with the densely packed direction parallel to the steps is noted. The adsorption kinetics does not differ markedly from that on the flat (110) surface, however the desorption behaviour at low coverages (θ < 0.3) is quite different. The results are interpreted in terms of the dissociation of a mobile precursor at terrace and step sites, the competition between the two domains during their growth and a step-induced premature transition to the complex structure observed on flat (110) surfaces at θ ⋍ 8. The steps are believed to play also a significant role in desorption.
Adsorption of Oxygen on Tungsten: Field Emission from Single Planes
The work functions and Fowler–Nordheim pre‐exponentials on the (110), (100), (211), (111), and (210) regions of a tungsten field emitter have been determined by means of a probe‐hole method as function of thermal treatment of full CO layers; as function of coverage in incremental dosing at 100°K; and as functions of readsorption on beta layers. The results shows that virgin, alpha, and beta states are formed on all regions investigated, but that their properties vary with substrate orientation. The results on the close‐packed planes (110) and (100) indicate complex behavior of beta layers on heating, and suggest surface reconstruction at T > 700°K. Temperatures for the onset of surface diffusion of CO were also determined, and indicate that diffusion occurs most readily on the zones (211)–(110) (at 275°–300°K). This is interpreted to mean that diffusion over (110)‐like regions is rapid, but that trapping at the edges of (110) diffusion steps occurs. Adsorption on (110) is not seen below 800°K, and on its ...