Loiseau, A. (Chatillon, France): Formation and growth of SWCNTs
Role and nature of metallic catalyst has been explored by different electron microscopy techniques: high resolution imaging and chemical mapping through energy loss imaging.
The proposed CNT formation mechanism: 1.: C saturated liquid metal particles of 5-20 nm are formed 2.: segregation of C at particle surface (C has low surface tension). 3.: growth of C nuclei.
They used not only Ni but REM (rear earth metal, 20-50%). With Ni only long ropes are made, with REM sea urchin forms. Chemical mapping shows that the REM is at the surface of carbide particles, Y is in their core. Direct link with the growing rope! With few REM only few C particles nucleate at the particle surface. Carbide particles linked to sea urchins have cores containing not only Ni but REM.