Papers

ICMCTF2002 Session H1-1: Science & Applications of Nanoscale Structures

Monday, April 22, 2002 1:30 PM in Room Royal Palm 4-6

Monday Afternoon

Start	Invited?	Item
1:30 PM		H1-1-1 Engineering Multilayered Nanostructures of Intermetallics for Applications H.L. Fraser, G.B. Thompson, R. Banerjee, S.A. Dregia (Ohio State University) Structural transitions occur in metallic multilayers when the bilayer thickness is reduced to the nanometer scale. An example involves the transition from hcp Zr to bcc Zr in Zr/Nb multilayers when the bilayer thickness is reduced below a critical thickness. The phase stability in these multilayers has been described using a simple model based on classical thermodynamics. Using this model, the notion of a biphase diagram has been introduced to describe these phase transitions as a function of scale and composition of the given multiplayer system. Such biphase diagrams can be used as a basis for engineering specific structural combinations. This is illustrated by consideration of transitions in Zr/Nb multilayers. Thus, using a previously reported single experimental observation of hcp to bcc transformation in these multilayers, a partial phase biphase diagram has been proposed. Subsequently, a range of multilayers with varying compositions and bilayer thicknesses, distributed in different regions of phase stability, have been sputter deposited. The crystal structures in these multilayers have been determined using x-ray and electron diffraction. The results are in excellent agreement with the predictions afforded by the proposed biphase diagram. Additionally, the reduction in the interfacial energy accompanying the transformation from hcp to bcc Zr has been evaluated.
2:30 PM		H1-1-4 Nanostructured Metal/Glass Interfaces by Ion-induced Dewetting and Burrowing D.G. Cahill (University of Illinois) If the surface energy of a planar film is greater than one-half the work of adhesion between the film and substrate, then a finite contact angle is thermodynamically favored and the film can dewet to form 3-dimensional structures. We are studying the dewetting of nanometer thick metal films on glass substrates induced by processing with energetic heavy ions: patterned morphologies with lateral lengths scales on the order of 100 nm form first, followed by isolated 15 nm diameter metal nanoparticles that burrow into the glass substrate. We quantify the evolution of these nanostructured interfaces using atomic-force microscopy, cross-sectional TEM, and real-time plan-view TEM at Argonne National Laboratory. We have also recently developed picosecond pump-probe acoustics and interferometry for the rapid characterization of the morphologies and particle sizes of these metallic nanostructures.
3:30 PM		H1-1-7 Nanocomposite Coatings for Nonlinear Optical Applications D. Carroll (Clemson University) Matrix nanocomposites based on a fluoropolymer matrix dispersed with high aspect ratio nanoparticles (carbon nanotubes, VO_x nanotubes, etc.) have been developed for use in a nonlinear optics applications. These thin films can exhibit extraordinary nonlinear susceptibility and optical limiting, as well as unusual photo charge generation properties. Through comparative picosecond and nanosecond z-scan studies, we show that thermal effects in these materials can be quantitatively separated from intrinsic nonlinear behavior due to photon-nanostructure coupling. Generally, optical nonlinearities (from either electronic transitions or scattering mechanisms) can be modified by the local response of the host matrix. In this presentation, PMMA hosts will be compared to a set of hosts based on PVDF copolymers that exhibit pyro-electric and piezo-electric response. These results point to the exciting possibility of tailoring large optical nonlinearities into organic thin films and coatings through nanocomposite formation. Applications in optical switching and other nonlinear optical elements will be discussed.
4:10 PM		H1-1-9 Intellectual Property Rights in Nanotechnology B. Bastani, D. Fernandez, P. Su (Fernandez & Associates, LLP) Intellectual property (IP) rights are essential in today's technology-driven age. Building a strategic IP portfolio is economically important from both an offensive and a defensive standpoint, and especially vital in the field of Nanotechnology given the anticipated radical and wide-ranging technological and economic changes derived from this emerging field. After an introduction to intellectual property rights and acquisitions, we provide an overview of current computational and manufacturing efforts in nanotechnology. Laboratory research into nano-scale materials and devices as well as requirements for their efficient mass production are outlined, with a focus on the applicable IP rights and strategies. We proceed to present current and future applications of nanotechnology to such fields as electronics, aerospace, medicine, environment and sanitation, together with the IP rights that can be brought to bear in each application. Finally, some challenging issues surrounding the acquisition of intellectual property rights in nanotechnology are presented.
4:30 PM		H1-1-10 Formation of One-dimensional Nano-structures by Rapid Thermal Processing from Ion Beam Sputtering Deposited Films L.C. Chen, C.H. Yang, J.S. Wu, Y.F. Chen (National Taiwan University, Taiwan, ROC); K.H. Chen (Institute of Atomic and Molecular Sciences, Academia Sinica, Taiwan) While it is now relatively easy to generate one-dimensional (1D) nanomaterials such as nanowires and nanorods, controlling their density and size has never been easily achieved. We report here an efficient method to produce these 1D nanomaterials by using rapid thermal processing (RTP) of thin films deposited by ion beam sputtering (IBS). Both RTP and IBS are convenient and robust techniques suitable for large-area wafer process and are well established in the industry. Carbon nanotubes and nanofibers, SiC nanowires, and Si nanowires with and without Au decoration have been demonstrated in our laboratory. The formation of these 1D nanomaterials by RTP of IBS film is primarily a solid-state-conversion (SSC) process. The "end product" derived from such an SSC process depends on the specific structure of the "source". A series of "source" materials have been experimented, e.g., iron containing amorphous carbon (or silicon) film prepared by IBS from graphite-Fe (or Si-Fe) composite target, bi-layer Fe/C and Au/Si laminated structures prepared by sequential IBS from respective elemental targets. Investigation of the morphology and structure of the RTP derived "end product" indicated that the number density and the formation rate are strongly dependent on the process temperature and ambient gas. Owing to the precision control of the RTP temperature and time, the present approach offers an unprecedented opportunity for studying the dimension changes of the 1D nanomaterials so produced in a controllable manner.