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Phase Transitions in C:Ni Nanocomposite Templates during Diameter‐Selective CVD Synthesis of SWCNTs
Author(s) -
Krause Matthias,
Melkhanova Svetlana,
Hübner René,
Haluska Miro,
Gemming Sibylle
Publication year - 2017
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.201700228
Subject(s) - non blocking i/o , nanocomposite , materials science , carbon nanotube , nanoparticle , nickel oxide , catalysis , chemical engineering , nickel , carbon fibers , phase (matter) , nanotechnology , oxide , matrix (chemical analysis) , template , composite material , metallurgy , composite number , chemistry , organic chemistry , engineering
Phase transitions in carbon:nickel nanocomposite templates during diameter‐selective CVD synthesis of SWCNTs were studied. While almost conserving their pre‐defined diameter distribution, as‐deposited Ni 3 C nanoparticles transform into fcc‐NiO during activation in low‐pressure air atmosphere, and are reduced to a mixture of fcc‐Ni and Ni 3 C under nanotube growth conditions. The first phase transition leads to a substitutional replacement of the protective carbon matrix by a protective oxide layer. The second one reflects competing reduction processes of NiO. A mechanism for the complementary roles of carbon matrix and Ni species in the three‐step CVD synthesis is proposed that includes nanoparticle immobilization, carbon delivery and catalysis of nanotube growth.