Morphology and Structure of Carbon Nanocoils Synthesized via the Flame Combustion of Ethanol

Carbon nanocoils(CNCs)were in situ synthesized by the flame combustion of ethanol using stannic chloride as catalyst precursor.The morphology and structure of CNCs were characterized by means of scanning electron microscope,transmission electron microscope,X-ray diffraction and Raman spectrum.The coil diameter of the CNCs is calculated to be ca.100nm and its fiber diameter is 50nm with a pitch of ca.80nm.The CNC develops along the direction of growth and comprises carbon layers that are peripheral and circulate around the axes of the fiber,similar to a fishbone and the interlayer spacing between carbon sheets is ca.0.34nm.High-resolution transmission electron micrograph(HRTEM)analyse reveals that the crystal face(101)of SnO_2 is the most favored face for carbon precipitation and it is situated on the outer side of the CNCs,while crystal face(110)with the lowest carbon extrusion speed is situated on the inner side.The nonuniformity of the carbon extrusion speed at different crystal faces of the SnO_2 grain leads to the helical growth of the coil.