AVS 51st International Symposium
    Nanometer-scale Science and Technology Wednesday Sessions
       Session NS-WeA

Paper NS-WeA6
Nanoporous Au: Surface Characterization and Mechanical Properties

Wednesday, November 17, 2004, 3:40 pm, Room 213D

Session: Nanotribology and Nanomechanics
Presenter: J. Biener, Lawrence Livermore National Laboratory
Authors: J. Biener, Lawrence Livermore National Laboratory
A.M. Hodge, Lawrence Livermore National Laboratory
K.J.J. Wu, Lawrence Livermore National Laboratory
L.L. Hsiung, Lawrence Livermore National Laboratory
Correspondent: Click to Email
Nanoporous Au prepared by electrochemically-driven dealloying of Ag-Au alloys has attracted considerable interest due to potential sensor and actuator applications. These materials exhibit an open sponge-like structure of interconnecting ligaments with an unimodal pore size distribution on the nanometer length scale. Due to a high surface-area to volume ratio, the properties of nanoporous materials should be influenced strongly by their surface properties. However, little is known about the surface chemistry of these materials. Here we will present our recent results regarding surface characterization and nanomechanical properties of nanoporous Au with a nominal relative density of ~30%. Time-of flight secondary ion mass spectroscopy (TOF-SIMS) was employed to obtain high-resolution, mass-resolved images of as-prepared Au foam surfaces. Our studies reveal the presence of adsorbed species such as chloride and nitrate from the dealloying process. It is well known from single crystal experiments that these species strongly interact with the Au surface, e.g. chlorine lifts the herringbone reconstruction on Au(111). This example demonstrates the necessity of surface science studies to better understand the properties of these nanoscale materials. The mechanical properties such as modulus and hardness of nanoporous gold were studied by nanoindentation combined with scanning electron microscope (SEM) characterization. This work was performed under the auspices of the U. S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.