The encapsulation of Ni in graphitic layers using C_(60) as a precursor

摘要

We have shown that Ni metal particles when melted in the presence of C_(60) form graphitic layers around their outer surface with the Ni remaining as pure metal without any evidence of carbide formation. Particles over several orders of magnitude in size with diameters in the range of (approx) 10 nm to several microns have been successfully encapsulated in this manner. The process has been observed taking place in real time using transmission electron microscopy (TEM). The electron beam served a dual puropse in this case by providing a means of observation as well as the source of thermal energy. High resolution transmission electron microscopy (HRTEM) shows the nature of the encapsulation to be graphitic. The process does not occur when graphite powder is used instead of C_(60) powder and the Ni similarly heated to melting point. The encapsulation method using C_(60) as a carbon source also occurs on heating a mixture in a conventional manner and shows the effect is thermal in nature although the electron beam does offer the ability to control the process for individual particles. Further research has shown the encapsulation process to occur at temperatures as low as 800 deg C by a catalytic pathway.