Papers

ICMCTF2007 Session TS4-1: Nanostructured Thin Film Assemblies and Composites

Tuesday, April 24, 2007 10:00 AM in Room Royal Palm 1-3

Tuesday Morning

Start	Invited?	Item
10:00 AM		TS4-1-7 New, Engineered Thin Film Structures for Advanced Nanotech Applications S. Jin, A.I. Gapin, H. Chen (University of California, San Diego) Recent advances in nanostructure fabrication such as carbon nanotubes and distributed nanoparticles are important for various nanotech applications including field emission displays, fuel cells, nanosensor arrays, nano probes, etc. Deposited metallic thin films can be manipulated to form nano islands with certain desirable configurations. For synthesis of elongated nanostructures, for example, via chemical vapor deposition (CVD) of carbon nanotubes, a pre-determined, controlled configuration of catalyst nanoparticle size, shape and distribution is essential. In this presentation, we will discuss some novel process of controlled island formation from the deposited metal films and describe mechanisms and possible routes for improving such island formation and resultant nanowire or nanoparticle geometry and physical properties. Implications of such nano-island controls for nanotech and biotech applications will also be discussed.
10:40 AM		TS4-1-11 Understanding of the Barrier and Release Properties of Thin Model HDFD/Ag-Plasma Polymer Nanocomposite Films X. Wang, G. Grundmeier (Max-Planck-Institute for Iron Research, Germany) Antibacterial properties of silver composite films are of increasing interest in medical and household applications. While numerous reports showed the positive antibacterial properties of silver-based coatings, there are only few data in literature about the precise relationship between silver content, released silver ions and toxic effects of silver composite films, the way to achieve sustained release of silver, and the long-term stability of composite films during release process. Plasma deposited thin Heptadecafluoro-1-decene (HDFD) films can be tailored in their chemical composition and barrier properties acting as a rate-limiting barrier to achieve a sustained release of silver. Model HDFD/Ag -plasma polymer nanocomposite films were synthesized by combining plasma polymerization of HDFD and electron beam evaporation of silver. The thickness of the silver nanocomposite films was controlled in-situ by means of quartz crystal microbalance during deposition and calibrated by spectroscopic ellipsometry. The silver nanocomposite films were characterized by the techniques such as FE-SEM, UV-Vis, FT-IR spectroscopy and X-ray photoelectron spectroscopy. Electrochemical impedance spectroscopy was used to analyze the water up-take and the barrier properties of the silver nanocomposite films. Moreover, the release of the silver nanoparticles from the nanocomposite films was investigated by means of atomic absorption spectroscopy. The stability of the silver nanocomposite films during release was studied by TEM, XPS and UV-Vis spectroscopy. The measurements show in which way silver nanoparticles embedded in a highly crosslinked perfluorinated matrix lead to an effective release of Silver.
11:00 AM		TS4-1-13 Deposition of In Situ Structured DLC-Coatings S. Meier, M. Koenig, C. Hormann (Fraunhofer-IWM, Freiburg, Germany) Due to their outstanding properties DLC (diamond-like carbon) coatings are applicable in the prevention of friction and wear in tribological systems. Therefore the DCL coatings are increasingly used in lubricated systems for the realisation of operation after lubricant-system failure. In contrast, the mostly non-optimal lubricant-wetting of the DLC surface under common condition often causes mixed-friction and premature wear. Attempts to improve the microhydrodynamic properties by creating structures after deposition by laser, electron beam and lithographic techniques only succeeded in exceptional cases. Therefore, the required structures should already be originated during the growth of the layer (in situ). With the help of an atomistic/continuum multiscale model the formation of otherwise unexplained DLC surface structures could be explained by ion-induced particle currents. Based on this knowledge parameter studies were carried out, making a controlled in situ deposition of wear-resistant DLC layers with micro and nano structured topographies in laboratory scale possible. The preliminary tests have shown that the spectrum of producible topographies should suffice for many different lubricant conditions. A pre-condition for the necessary deposition parameters is a new RF-PACVD device design, developed at IWM. Unlike commercial RF-PACVD devices, there is a flexible reactor design with easily extendable usable volume. This novel technique operates completely clean (without deposits outside of the substrate electrode) and is upscale-capable.
11:20 AM		TS4-1-12 Magnetron Sputtered Graded Nanostructured TiNi Shape Memory Thin Films A. Kumar, P. Singh, A.K. Chawla, R. Chandra, D. Kaur (IIT Roorkee, India) TiNi-based shape memory alloy thin films offer a combination of novel properties i.e. pseudo elasticity and shape memory effect, which enable them to be widely used in aerospace, and micro-electromechanical systems (MEMS) .The present work focuses on the fabrication and characterization of nanostructured thin films of TiNi on silicon substrate. Magnetron sputtering with two separate Ti and Ni targets had been used to fabricate these films . Film stoichiometry was precisely controlled with the power to each target. By varying the power to the targets compositionally graded films i.e.(Ni-rich, equiatomic TiNi, Ti-rich) were deposited at room temperature and low temperature annealing was performed. The accompanying changes in the microstructure and growth morphology of the phases in these films were investigated in detail using X-ray diffraction and an atomic force microscopy. Crystallization kinetics of as deposited Ti Ni films was analyzed using differential scanning calorimetry. The effects of negative substrate bias voltage during sputtering on the texture development of the films were studied systematically by varying the bias voltage . In addition, the effect of texture on the mechanical properties of the films was also investigated using nanoindentation technique. AFM based in-situ characterization was performed to see the phase transformation behaviour. With change of temperature, the microstructure and surface roughness values changes drastically which reveal the phase transformation between martensite and austenite phases. The surface roughness of the martensite phase was found to be much higher than that of the austenite phase.