Supplementary Information
Equilibrium Cu-Ag nanoalloy structure formation revealed by in situ scanning
transmission electron microscopy heating experiments
Ping Lu, Michael Chandross, Timothy J. Boyle, Blythe G. Clark and Paul Vianco
Sandia National Laboratories, PO Box 5800, Albuquerque, NM 87185 USA
*Corresponding author: plu@sandia.gov
1
100 nm
Figure S1. HAADF image showing Ag NPs after in-situ heating at 160 oC for 5 min. The Ag
NPs had a size of ~ 6nm before the heating. The Ag NPs on the left side of the image were preexposed with the electron beam under a normal STEM mode for about 1 min, and the Ag NPs on
the right side of the image were without prior electron exposure. The image shows that electron
beam exposure makes the NPs inactive during heating.
2
50 nm
Figure S2. TEM image showing a typical monolayer of Cu (~12nm) and Ag (~6nm) NPs
assembled on a carbon film prior to in situ heating.
3
Ag L
Cu K
Figure S3. An EDS spectrum summed from an area of the Ag shell, showing the shell is made of
pure Ag, within the EDS detection limit of about 1%.
4
Ag(111) d =0.236nm
Ag
Cu
Cu(111) d=0.209nm
Ag
5 nm
Figure S4. HAADF image (left) and the HAADF line profile (right) cross a Ag surface layer,
showing that the first two monolayers are the Ag {111} layers with the measured lattice spacing
of about 0.236 nm.
5