  Nanoporous gold is widely used in research and nanotechnology because of its
diverse properties, including high surface area and catalytic activity. The
ligament size is usually considered as the only parameter controlling thermal
stability and mechanical properties of nanoporous gold. Recently we developed a
method for creating nanoporous single crystal gold particles using eutectic
decomposition of Au-Ge, followed by selective etching of Ge. Here, we used this
novel method to create nanoporous gold particles with controlled ligament sizes
by changing the initial sample relative concentrations of gold and germanium.
When investigated from 1 to 4 hour at 250 to 400 degrees C the material was
thermally stable up to 350 degrees C, which is higher than the thermal
stability of classical nanoporous gold with similar ligament sizes prepared by
dealloying. Mechanical properties were examined utilizing nanoindentation of
nanoporous gold before and after annealing. For smaller ligament sizes,
hardness increases with annealing temperature up to 300 degrees C and then
strongly decreases. For larger ligament sizes, hardness decreases with
increasing annealing temperature. Young modulus was unchanged up to 300 degrees
C.
