Microstructure of pitch-based carbon fiber and its control OM Photograph 10m SEM photograph Transverse texture I um Core section Middle section Outer section 0. 1 um HR- SEM photographs Fig. 1.(cont. No looped or bent shaped domains were found ere identified from closer examination(See smalle the outer area. The length and thickness of domain arrows in Fig. 2). Such a smaller unit, defined as a were above 300 nm and below 100 nm, respectively. micro-domain, had thickness and length around 10 Figure 2 showed further higher magnification and 10-100 nm in the transverse section, respectively HR-SEM photographs of F-A. The loop and lincar Such units were confirmed in TEM bright ficld (BF) aped domains in the core and outer areas of the and inge images(Figs. 3 and 4). Particularly, transverse sections, respectively were well observed. the TEM BF image showed that a domain unit was The smaller units which composed the domain unit composed of several pieces of micro-domain units.Microstructure of mesophase pitch-based carbon fiber and its control 945 OM photograph 10 p,rn H SEM photograph 1 Fm H Transverse texture 1 pm Core section Middle section Outer section 0.1 p,m H (4 HR-SEM photographs Fig. 1. (cont.). No looped or bent shaped domains were found in the outer area. The length and thickness of domain were above 300 nm and below 100 nm, respectively. Figure 2 showed further higher magnification HR-SEM photographs of F-A. The loop and linear shaped domains in the core and outer areas of the transverse sections, respectively were well observed. The smaller units which composed the domain unit were identified from closer examination (See smaller arrows in Fig. 2). Such a smaller unit, defined as a micro-domain, had thickness and length around 10 and lo-100 nm in the transverse section, respectively. Such units were confirmed in TEM bright field (BF) and lattice fringe images (Figs. 3 and 4). Particularly, the TEM BF image showed that a domain unit was composed of several pieces of micro-domain units