Reflection high energy electron diffraction characterization of Co clusters electrodeposited on Au(100) electrode
CIC nanoGUNE Seminars
- Speaker
-
Mauscheng Zei, Department of Physics, National Central University, Taiwan, Taiwan
- When
-
2010/07/20
13:00 - Place
- nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian
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Cobalt was electrodeposited onto the reconstructed Au(100) electrode in 0.25 M
Na2SO4 \+ 0.1 mM CoSO4, yielding nanometer sized Co clusters of ca. 3 nm in
diameter. The as-prepared Au(100) electrode was transferred via an argon
environment and subsequently examined by reflection high energy electron
diffraction (RHEED) to characterize the epitaxial growth of Co nano-clusters
on Au(100). It is found that Co clusters prefer to pack in the face-centered
cube (fcc) rather the hexagonal-closed pack (hcp) phase on Au(100), and grow
with their (-110) plane parallel to the Au(100) substrate and their [110] axis
aligned parallel to the [011] direction of the Au(100) substrate. The
preferential growth of the fcc Co phase is apparently driven by the lower
lattice strain between the (-110) plane of Co clusters and the Au(100)
substrate network.
(2) Investigations of the initial stages of the twinned Pt nano-clusters
formation and their epitaxial growth on Ru(0001) as well as the epitaxial
growth of Ru nano-particles on Pt(111)
M.S. Zei
Department of Physics, National Central University, No. 300 Jungda Rd.,
Jungli 32054, Taiwan, zei@phy.ncu.edu.tw
** **
**Abstract**
The epitaxial growth of Pt and Ru deposits by spontaneous, as well as by
dynamic, electrodeposition onto Ru(0001) and Pt(111), respectively, have been
studied by reflection high energy electron diffraction (RHEED) and Auger
electron spectroscopy (AES). For the Pt deposit on Ru(0001), at submonolayer
range, it preferably grows compressed commensurate bilayer thick islands on
Ru(0001). This is the first time that RHEED observation of the onset of Pt
twinning occurs in ca. 2-3 layer thick islands on Ru at room temperature, at
which the surface strain due to the 2.5% lattice mismatch of Pt and Ru remains
intact. For multilayer thick islands (> 6 ML) ordered reflection twins
(diameter of ~ 3 nm) develop and are embedded in a (111) matrix with an
incoherent (11-2) twin plane normal to Ru(0001) and aligned with their [-110]
direction parallel to the [11-20] Ru(0001) substrate direction. For the Ru
deposit on Pt(111), at ~0.2 ML a strained (1x1) monoatomic layer is formed due
to the 2.5 % lattice mismatch of Ru and Pt. Increasing the coverage up to
~0.64, the second Ru layer is found to relieve the strain in the first layer,
giving rise to dislocations and Ru relaxes to its bulk lattice constant.
Multilayers of Ru (> 1ML) result in (0001) nanocluster formation aligned with
its [11-20] direction parallel to the [-110] Pt(111) substrate direction. The
Pt and Ru clusters grow epitaxially with facets of a hexagonal unit cell on
Ru(0001) and Pt(111), respectively, to decrease the interface strain.