The encapsulation of Ni in graphitic layers using C-60 as a precursor

We have shown that Ni metal particles when melted in the presence of C-60 f orm graphitic layers around their outer surface with the Ni remaining as pu re metal without any evidence of carbide formation. Particles over several orders of magnitude in size with diameters in the range of similar to 10 nm to several microns have been successfully encapsulated in this manner. The process has been observed taking place in real time using transmission ele ctron microscopy (TEM). The electron beam served a dual purpose in this cas e by providing a means of observation as well as the source of thermal ener gy. High resolution transmission electron microscopy (HRTEM) shows the natu re of the encapsulation to be graphitic. The process does not occur when gr aphite 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 c ontrol the process for individual particles. Further research has shown the encapsulation process to occur at temperatures as low as 800 degreesC by a catalytic pathway. (C) 2001 Elsevier Science Ltd. All rights reserved.