Synthesis and characterization of Fe-containing oxide powders and carbon nanotube-Fe-oxide nanocomposites

Carbon nanotubes (CNTs) are one of the most widely investigated nanomaterial because they show excellent thermal, electrical and mechanical properties besides that they are very small, hollow and monodimensional. The goals of this PhD research project were firstly to prepare Fe/Al2O3 solid solution powders and foams and Fe/Al6Si2O13 powders and to use them as catalytic materials for the synthesis of CNT-Fe-oxyde nanocomposites, and secondly to perform a profound investigation of all the materials by 57Fe Mössbauer spectroscopy and to correlate the results with those obtained by other techniques with the aim to obtain information on the formation of the CNTs, thermal stability, and surface composition of the CNT-nanocomposite powders. The techniques applied in this research, apart from Mössbauer spectroscopy, were carbon analysis, BET gas adsorption measurements, X-ray diffraction, thermal analysis (TGA and DTA), transmission and scanning electron microscopy, and Raman spectroscopy. The value of applying the Mössbauer spectroscopy technique is that the identification and quantification of the various Fe-containing phases can be performed precisely. Moreover, this technique has the advantage of determining the oxidation state of iron. Thus, another important advantage of this technique is that the reduction rate of the starting solid solution(s) can be determined. The combination of the still unique ILEEMS (integral low-energy electron Mössbauer spectroscopy) with conventional transmission Mössbauer spectroscopy has yielded a wealth of information concerning the understanding of the relationship between the starting catalytic material, the location of the reduced iron species (α-Fe, Fe3C and gamma-Fe-C) in the nanocomposite powders and the CNTs. Earlier hypotheses, into how these species may be connected to the formation of the CNTs, were refined: in particular, it was shown that gamma-Fe-C particles are not obviously very small-sized nanometric particles and that the species active for the formation of CNTs are not always detected as Fe3C.

Grantor dc:publisher

Gent

Year dc:date

2009

Author dc:creator

• Gonzaga de Resende, Valdirene

Contributors dc:contributor

• De Grave, Eddy

• Chemistry
• carbon nanotubes
• Mössbauer spectroscopy
• electron microscopy
• nanocomposite

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

eng

Identifier

https://biblio.ugent.be/publication/518451
https://biblio.ugent.be/publication/518451/file/1886124

OAI identifier oai:identifier

oai:archive.ugent.be:518451