Investment casting of carbon tubular structures

Carbon tubular structures (CTSs) were prepared using metal nanowires/nanotubes, either Ag or Te, as templates. The CTSs are formed by electron beam-induced carbon deposition on the nanowires/nanotubes and the subsequent removal of the core material by direct heating or Joule heating. We call this process “investment casting” of CTSs. The length of the fabricated CTSs varies from sub-micron to tens of microns, while the diameter and wall-thickness may vary from less than ten nanometers to over a hundred nanometers and few nanometers to tens of nanometers, respectively. These parameters can be controlled by the templates and the carbon deposition. With Te nanotubes as templates, it is possible to form tube-in-tube hollow CTSs. By designed construction of Ag nanowires, various CTS-based seamless structures can also be obtained. Through thermal annealing or Joule heating, the amorphous CTSs can be converted to graphitized structures, which show excellent mechanical performance on nano-manipulation. The technique provides a new method of constructing carbon-based complex and multifunctional structures.