AVS 46th International Symposium
    Surface Science Division Monday Sessions
       Session SS1+EM-MoA

Invited Paper SS1+EM-MoA3
Kinetics and Dynamics of Substrate and Metal Atoms on TiO@sub2@

Monday, October 25, 1999, 2:40 pm, Room 606

Session: Metals on Oxides
Presenter: G. Thornton, Manchester University, UK
Authors: G. Thornton, Manchester University, UK
I. Brookes, Manchester University, UK
H. Raza, Manchester University, UK
C.L. Pang, Manchester University, UK
S. Haycock, Manchester University, UK
Correspondent: Click to Email
TiO@sub2@ substrates have been used as platforms to test ideas about oxide surface reconstruction and metal growth on oxides. This work is motivated by the importance of such interfaces in a number of applications which include catalysis and gas-sensing. As part of this work we have recently studied two aspects of TiO@sub2@ surface science associated with temperature and time dependent structural changes using STM and non-contact AFM. The first involves the study of the 1x1 to 1x3 phase transition of TiO@sub2@(100). In addition to the 1x1 and the high temperature equilibrium 1x3 microfacet termination previously observed, intermediate 1x3 structures are imaged. The relationship between the 1x1 termination and the 1x3 microfacet phase suggests that the latter reconstruction is formed by removing material rather than growing from a lower lying terrace. Intermediate structures point to a mechanism of the phase transition which involves discrete bond breaking steps. Turning to Cu growth on TiO@sub2@(110), at room temperature and at <0.1 ML most of the metal atoms are initially mobile, with some 2D island formation. The cluster size of about 6 Å diameter suggests that they consist of 7 atoms arranged in a centred hexagon. Such an arrangement fits between the bridging O rows. 3D clusters are formed at higher coverage consistent with Volmer-Weber growth. At lower temperatures 1D metastable strings of Cu atoms are formed in the [001] direction, which collapse to 2D islands and subsequently 3D clusters at higher coverage.