A novel heterogeneous system which consisted of a metal on a highly corrugated transition-metal oxide surface was examined by scanning tunnelling microscopy. The Pt formed 3-dimensional nanoclusters, with a narrow size distribution, on the anatase (001)-(1x4) surface. Upon annealing in a vacuum, the Pt clusters (which initially existed on terraces) migrated to step edges, without coalescing, via a cluster diffusion mechanism. Time-dependent autocorrelation analyses revealed that the diffusion occurred preferentially along atomic rows. The diffusion barrier and pre-exponential factor along this direction were deduced to be about 0.27eV and about 400Å2/s, respectively.

Formation and Diffusion of Pt Nanoclusters on Highly Corrugated Anatase TiO2(001)-(1x4) Surface. S.Gan, A.El-Azab, Y.Liang: Surface Science, 2001, 479[1-3], L369-74

Table 199

Diffusion of O in TiO2-x at 1373K

 

PO2 (atm)

x

D (m2/s)

3.31 x 10-10

5 x 10-4

1.45 x 10-16

3.80 x 10-11

7 x 10-4

1.87 x 10-16

3.39 x 10-12

1.1 x 10-3

2.70 x 10-16

3.80 x 10-13

1.7 x 10-3

2.95 x 10-16

3.38 x 10-14

2.8 x 10-3

4.09 x 10-16

5.37 x 10-15

4.1 x 10-3

5.01 x 10-16

1.35 x 10-15

5.6 x 10-3

6.85 x 10-16

4.17 x 10-16

7.0 x 10-3

7.58 x 10-16

1.70 x 10-16

8.4 x 10-3

9.20 x 10-16