Carbon nanostructures such as carbon nanoparticle (CNP), carbon nanotube (CNT), and carbon nanofiber (CNF) were synthesized via hot-filament chemical vapor deposition using various catalysts. CNPs were grown with sputter coated permalloy catalysts on Cr or W buffer layers, whereas unaligned CNTs were synthesized on Ti or Ta buffer layers. Aligned CNTs were synthesized using H-2-plasma-treated Fe and Fe-impregnated silica or alumina as catalysts. However, CNFs were synthesized using electroplated Ni catalysts. In general, the quality of the graphene layers of the CNFs was inferior to those of CNT, and CNPs. However, all these carbon nanostructures showed good field emission properties. (c) 2005 Published by Elsevier B.V.