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1.
Microscopy (Oxf) ; 65(6): 522-526, 2016 12.
Article in English | MEDLINE | ID: mdl-27920166

ABSTRACT

It is known that samples become contaminated in CO gas of high pressure unless care is taken with the gas supply line to an environmental transmission electron microscope. This technical note reveals the heterogeneous formation process of contamination in situ on a nanoparticulate catalyst sample. It is shown that the surface of metal nanoparticles is preferentially contaminated, while the surface of metal oxide supports remains uncontaminated. It is also demonstrated that the contamination is suppressed by introducing a gas purifier in a gas supply line.

3.
Nano Lett ; 9(11): 3810-5, 2009 Nov.
Article in English | MEDLINE | ID: mdl-19731921

ABSTRACT

We have elucidated the synergetic role played by molybdenum in iron-catalyzed chemical vapor deposition growth of carbon nanotubes (CNTs) by in situ environmental transmission electron microscopy. Molybdenum can be well accommodated by Fe-based carbide nanoparticle catalysts of M(23)C(6)-type structure (M = Fe and Mo). We have also shown that molybdenum suppresses the nucleation of iron compounds that are known to exhibit no catalytic activity for the growth of CNTs.

4.
Nano Lett ; 8(7): 2082-6, 2008 Jul.
Article in English | MEDLINE | ID: mdl-18505300

ABSTRACT

We have first observed the nucleation and growth process of carbon nanotubes (CNTs) from iron carbide (Fe 3C) nanoparticles in chemical vapor deposition with C 2H 2 by in situ environmental transmission electron microscopy. Graphitic networks are formed on the fluctuating iron carbide nanoparticles, and subsequently CNTs are expelled from them. Our atomic scale observations suggest that carbon atoms diffuse through the bulk of iron carbide nanoparticles during the growth of CNTs.

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