Microstructural changes induced in "stacked cup" carbon nanofibers by heat treatment

Systematic studies of structural changes in stacked cup carbon nanofibers by heat treatment from 1800 to 3000 degreesC are carried out. The most prominent feature upon heat treatment of these nanofibers is the formation of energetically stable loops between adjacent active end planes both on the inner and outer surfaces. The appearance of the jagged outer and inner surfaces at 3000 degreesC is due to a combinational effect, perhaps caused by improved stacking within domains connected by loops having limited crystallite size, accompanied by structural reorganization between domains. Consequently, a low degree of graphitizability is ascribed to this unusual stacked cup morphology of pristine carbon nanofibers. (C) 2003 Elsevier Ltd. All rights reserved.