▎ 摘　　要

The present study confirmed that highly crystalline nanofibers with controlled structure may be prepared over Fe and Fe-Ni alloy catalysts. The degree of graphitization of various carbon nanofibers (CNFs) was analyzed by using C(002) peaks from the XRD profiles. The C(002) peaks of CNFs over Fe catalyst shifted to higher angle and became narrower as the preparation temperature increased from 560 to 620 degreesC. Tubular CNFs prepared at temperature higher than 630 degreesC showed lower 2theta angles compared to those of platelet fibers. CNFs prepared over Fe-Ni catalysts tended to resemble those prepared over Fe catalysts. The degree of graphitization of platelet CNFs resembled natural graphite, while d(002) of the tubular CNFs showed values below the 3.39 A reported as a theoretical minimum for a cylindrical alignment. Lc(002) of platelet and tubular CNFs increased by heat treatment at 2000 and 2800 degreesC though d(002) changed little. A transverse section of platelet and tubular CNFs had a hexagonal shape, not a round shape. The hexagonal column allows AB stacking of hexagonal planes that can give perfect hexagonal alignment. (C) 2003 Elsevier Ltd. All rights reserved.