Carbon nanotube heterojunctions :

1. Inter-American Materials Collaboration: Large Scale Synthesis of N-doped Carbon Nanotubes for the Fabrication of Novel Polymer Composites and Related Low Dimensional MaterialsPulickel M. Ajayan, Rensselaer Polytechnic Institute, DMR-0303174 CNx nanotube Carbon nanotube heterojunctions: Continuous bi-phasic nanotubes were synthesized using chemical vapor deposition (CVD) using two sources of hydrocarbon precursors and vapor phase catalyst (ferrocene) delivery. The nanotube (NT) / nitrogen doped nanotube (CNx) junctions were made by the two-step feeding process. First, xylene/ferrocene was fed to grow CNTs. Then, xylene/ dimethylfamamide (DMF) / ferrocene was fed to grow CNx. The CNx grows from the catalyst particles previously present on the NT films grown in the prior sequence. Contiguous NT/CNx junction are thus created efficiently. Electron microscopy (TEM) revealed that the CNx nanotubes showed different internal structure and morphology compared to NT, with a bamboo-like structure for the former. Shematic showing the CVD furnace (top) with two different hydrocarbon precursors. The nanotubes with junctions of pure NT and CNx grows vertically on the quartz substrates placed inside the furnace (bottom schematic). TEM image (top right) shows the bamboo morphology of CNx nanotubes (Scale bar is 100 nm)

2. Inter-American Materials Collaboration: Large Scale Synthesis of N-doped Carbon Nanotubes for the Fabrication of Novel Polymer Composites and Related Low Dimensional MaterialsPulickel M. Ajayan, Rensselaer Polytechnic Institute, DMR-0303174 Outreach: * The program supported a high school student (Manisha Padi from Niskayuna high school, close to RPI) to spend considerable amount of time in our laboratory, both during the summer of 2004 and 2005 and part time during the academic year. She completed significant amount of work on the electrodeposition of magnetic nanowires in porous alumina templates and has been trained on several instrumentation in the laboratory. She will co-author a full research paper, which will be submitted to a peer reviewed journal. * In July 2004, we (PIs from RPI and IPICyT) organized a joint international conference in Mexico (Nanotube 04) which was attended by well over 300 attendees from around the world and was a great success. NSF, CONACYT, and Industry had strong participation at the conference and was attended by several students from the Latin American countries. Education and Training: The project provided excellent opportunities for student exchanges and training between RPI and IPICyT in Mexico. Three Mexican undergraduate student visitors who spent brief durations of time at RPI, completed their courses in Mexico and received admissions to prestigious international universities for graduate study; Federico Villalpado was admitted to graduate study at MIT, Felipe Cervantes Sodi and Juan-Jose Vilatela-Garcia, both got admission to Cambridge University in England. Another Mexican graduate student visitor, Ana Laura Elias Arriaga has returned to RPI for the second time and is presently staying at RPI to complete her thesis work. Several graduate students in our laboratory worked with these visiting students from Mexico and the collaboration was mutually beneficial for students from both sides. The visiting students received training on all the nanotube synthesis facilities and the microscopy and scanning probe microscopy facilities at RPI.