Two-Dimensional Au and Au−Cu Alloy Nanocrystals with Orientation in (111) Plane Embedded in Glassy Silica Films

Triangular Au and disk-shaped Au−Cu alloy nanocrystals have been generated in thin SiO2 film matrixes, by sol−gel spin-coating followed by annealing at 800 °C in 10%H2−90%Ar. Transmission electron microscope images confirm the shapes of the embedded nanocrystals. X-ray diffraction patterns reveal that the Au and Au−Cu nanocrystals have a (111) orientation. The disk-shaped alloy nanocrystals exhibit surface plasmon absorption at wavelengths intermediate between those of Au and Cu.