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The evolution of catalyst layer morphology and sub-surface growth of CNTs over the hot filament grown Fe - Cr thin films
Akbarzadeh Pasha, M ; Sharif University of Technology | 2010
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- Type of Document: Article
- DOI: 10.1016/j.apsusc.2010.08.087
- Publisher: 2010
- Abstract:
- In this study a hot filament chemical vapour deposition (HFCVD) technique was used to prepare Fe-Cr films on Si substrate as catalysts for thermal CVD (TCVD) growing of carbon nanotubes (CNTs) from liquid petroleum gas (LPG) at 800 °C. To characterize the catalysts or CNTs, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy were used. The XPS spectra obtained at different stages of Ar+ sputtering revealed that in the depth of catalyst layers, the relative Fe-Cr concentrations are higher than the top-surface. SEM images of samples after TCVD indicate a significant CNT growing at the backside of catalyst layer compared with its top which is accompanied with morphological changes on catalyst layer such as formation of cone-shape structures, rippling, cracking and rolling of the layer. These observations were attributed to the more catalytic activity of the sub-surface beside the poor activity of the top-surface as well as the presence of individual active islands over the surface of the catalyst thin film
- Keywords:
- Catalytic layer ; Catalytic layers ; Growth process ; HFCVD ; Morphology evolution ; TCVD ; Biology ; Carbon films ; Carbon nanotubes ; Catalyst activity ; Catalytic cracking ; Chemical vapor deposition ; Chromium ; Filaments (lamp) ; Film growth ; Morphology ; Raman spectroscopy ; Scanning electron microscopy ; Thin films ; Transmission electron microscopy ; X ray photoelectron spectroscopy ; Surface morphology
- Source: Applied Surface Science ; Volume 257, Issue 5 , 2010 , Pages 1511-1515 ; 01694332 (ISSN)
- URL: http://www.sciencedirect.com/science/article/pii/S0169433210011657