AVS 61st International Symposium & Exhibition
    Surface Science Monday Sessions
       Session SS+EN-MoA

Paper SS+EN-MoA8
In Situ Imaging of the Dynamic Interaction of the Oxide with the Atomic Steps During the Oxide Growth on NiAl(100)

Monday, November 10, 2014, 4:20 pm, Room 309

Session: Metals, Alloys and Oxides: Structure, Reactivity & Catalysis
Presenter: Hailang Qin, SUNY Binghamton
Authors: H. Qin, SUNY Binghamton
X. Chen, Biola University
P. Sutter, Brookhaven National Laboratory
G.W. Zhou, SUNY Binghamton
Correspondent: Click to Email
Ultrathin oxide films on metal supports represent a unique combination of materials systems with potential applications ranging from heterogeneous catalysis to electronic devices. In particular, the oxidation of NiAl alloys has received extensive interest for its ability to form a well-ordered Al2O3 film. Here we study the dynamic interaction of the atomic steps with the oxide stripes during their growth on single-crystal NiAl(100) at high temperature. With in-situ low-energy electron microscopy (LEEM) imaging and theoretical modeling, it is shown that the oxygen surface diffusion is the main mechanism controlling the oxide growth kinetics while the migration and shape evolution of the substrate steps follows the fluid-like Hele-Shaw flow governed by the attachment/detachment of Al atoms at step edges. When the oxide stripe encounters a series of step edges, the step edges are “pushed” along with the oxide stripe growth and bent towards the growth direction of the stripe. However, the growing oxide stripes do not cross over the substrate steps; instead, they stay on the same terrace even after encountering a number of step edges. Such a process is reversible during the oxide decomposition. The scanning tunneling microscopy (STM) images of the oxide stripes and the atomic steps after the interaction further confirm that the oxide stripes stay on the same terrace after encountering multiple substrate steps, instead of crossing the step edges.