Graphitic encapsulation of catalyst particles in carbon nanotube production

• A new model is proposed for the encapsulation of catalyst metal particles by graphite layers that are obtained, for example, in low-temperature chemical vapor deposition production of carbon nanotubes (CNTs). In this model graphite layers are primarily formed from the dissolved carbon atoms in the metal-carbide particle when the particle cools. This mechanism is in good agreement with molecular dynamics simulations (which show that precipitated carbon atoms preferentially form graphite sheets instead of CNTs at low temperatures) and experimental results (e.g., encapsulated metal particles are found in low-temperature zones and CNTs in high-temperature regions of production apparatus, very small catalyst particles are generally not encapsulated, and the ratio of the number of graphitic layers to the diameter of the catalyst particle is typically 0.25 nm(-1)).

Ämnesord

NATURVETENSKAP  -- Kemi -- Fysikalisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Physical Chemistry (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Annan materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Other Materials Engineering (hsv//eng)

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

MAGNETIC-PROPERTIES

SWNT GROWTH

NANOPARTICLES

NI

SINGLE-WALLED NANOTUBES

SIZE

MOLECULAR-DYNAMICS

METAL PARTICLES

GAS-PHASE

NANOCAPSULES

SINGLE-WALLED NANOTUBES; METAL PARTICLES; MAGNETIC-PROPERTIES; MOLECULAR-DYNAMICS; SWNT GROWTH; GAS-PHASE; NANOPARTICLES; NANOCAPSULES; SIZE; NI

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