AVS 53rd International Symposium
    Nanometer-scale Science and Technology Wednesday Sessions
       Session NS+SS+TF-WeM

Paper NS+SS+TF-WeM10
Deformation Behavior of Low-Density Nanoporous Dielectrics

Wednesday, November 15, 2006, 11:00 am, Room 2016

Session: Nanotribology and Nanomechanics
Presenter: S.O. Kucheyev, Lawrence Livermore National Laboratory
Authors: S.O. Kucheyev, Lawrence Livermore National Laboratory
P.M. Bythrow, Lawrence Livermore National Laboratory
T.F. Baumann, Lawrence Livermore National Laboratory
C.A. Cox, Lawrence Livermore National Laboratory
Y.M. Wang, Lawrence Livermore National Laboratory
T. van Buuren, Lawrence Livermore National Laboratory
A.V. Hamza, Lawrence Livermore National Laboratory
J.E. Bradby, The Australian National University
Correspondent: Click to Email
Understanding deformation behavior of nanoporous glasses has recently regained tremendous interest in the community, primarily due to its importance for the development of a new generation of low-k dielectrics. Aerogels are sol-gel-derived nanoporous dielectric materials formed by nanometer size particles randomly interconnected into a solid network with a large degree of porosity and very high surface area. For these materials, the density can be varied from the theoretical maximum density (of a full density solid) to extreme cases of very high porosities (~99 %). Thus, aerogels represent a very attractive model system for studying the deformation mechanisms in nanoporous dielectrics. In this presentation, we discuss the use a combination of sound velocity measurements and nanoindentation with large spherical indenters (1-2 mm diameter) to study the deformation behavior of alumina and tantala aerogels with porosities up to 99%. In particular, we focus on how the deformation behavior is affected by (i) the average density of monoliths, (ii) the morphology and connectivity of nanoligaments, and (iii) the crystallographic phase. Results show that all of the above parameters can strongly affect the mechanical properties of nanoporous solids. Based on our results, we discuss the underlying deformation mechanisms and demonstrate an effective way to control mechanical properties of the nanoporous solids that can be synthesized with ligaments having a quasi-two-dimensional shape, such as platelets, ribbons, or leaflets. Work at LLNL was performed under the auspices of the U.S. DOE by the University of California, LLNL under Contract No. W-7405-Eng-48.