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Nanoparticle Arrangement Controls Electrical CurrentRosario A. Gerhardt, GA Tech Research Corporation – GA Institute of Technology, DMR 0604211

Nanocomposites are ubiquitous in a myriad of electrical, optical and magnetic applications such as components for flat panel displays, solar cells and fuel cell electrodes to name a few. One of the more vexing problems is how to distribute the conducting filler material so as to minimize the amount needed to achieve the desired conductivity and/or other related properties. Prof. Gerhardt’s research group has been able to conclusively demonstrate that in order to achieve the best electrical response, it is necessary to create a segregated network of the nanofillers rather than a homogeneous dispersion. The measured resistivity for two ways of arranging the conducting carbon black (CB) nanofillers shows that percolation can be achieved at much smaller filler volume fractions in the segregated network case. Proof that the fillers form 3D interconnected pathways was obtained by using current-AFM imaging.

Fig. Log of the measured electrical resistivity as a functionof carbon black filler for two different arrangements of thefiller (TOP). AFM images (topography -left and current-right) demonstrating that the fillers occupy only certain pathways is shown (BOTTOM)

Nanocomposites prove popular with many students Rosario A. Gerhardt, GA Tech Research Corporation – GA Institute of Technology, DMR 0604211

The prospect of helping to develop multifunctional composites for a variety of cutting edge applications attracted a large number of students to work in Prof. Gerhardt’s group. Many of the students started out as undergraduate researchers and stayed on to do some graduate work at GT or elsewhere. Throughout the period of this grant, a total of 14 students have been involved (3 PhDs, 4 M.S. and 8 B.S. students). Out of the 14, three were women (21%) and 3 were under-represented minorities (21%). Together with Prof. Gerhardt, many of these students are leaders in the student group organizations and help out with K-12 demonstrations and MSE-related recruitment activities. Extensive collaboration with researchers at Oak Ridge National Labs and Argonne National Labs have resulted in several joint papers and additional fruitful interactions.External Collaborators:S.V. Kalinin, S. Jesse, A.P. Baddorf, I.N. Ivanov,D. Geoghehan and A.P. Borisevich at ORNL. J. Ilavsky and G.G. Long at Argonne , Lyle Levine at NIST, M. Yoonessi at NASA-Glenn and T. Quantrille at ACM-USA.

Research group celebrating the completion of Laurissa’s M.S. Thesis defense in July 2008 before her departure to work at Texas Instruments in Dallas, TX. Pictured from left: Salil Joshi, Brian Bertram, Laurissa Prystaj (M.S. 8/08), Cantwell Carson (PhD 8/09), Ricky Whelchel, Prof. Gerhardt , Charles Capozzi(Ph.D. 5/09) and Surajit Kumar(Ph.D. 8/08). Not Pictured: Jacob Waddell (M.S. 5/08), Kenter Wu(B.S. 8/08),

Shantanu Talapatra (B.S. 12/08), Chunqing Peng, John Boyea, Celeste Mason, Reginald Krow, Alex Sharenko and Justin Brandt.