Ions of Ge, Sn and Pb, having the +4 oxidation state, were implanted into rutile single crystals. The ion profiles and lattice-site locations were determined by means of Rutherford back-scattering and channelling. It had been noted previously that the widths of the angular dip curves for Ge and Sn were wider and deeper than those for Ti, thus indicating the formation of coherent precipitates. The Pb atoms were displaced along the c-axis. Annealing at high temperatures caused the impurities to move to normal substitutional Ti lattice sites. The effect of diffusion upon lattice-site occupancy and the formation of precipitates was studied in detail here for aligned and randomly oriented implants. In the former case, Sn diffusion occurred between 850 and 950K. This was about 200K below the temperature region in which diffusion was observed for random implants. A steep decrease in the Sn peak-area, without broadening, indicated that the diffusion was governed by trap release. The local damage density near to the impurity at the end of the ion track seemed to play a large role. In the case of aligned implants, diffusion occurred within the temperature range where damage annealed out. In the case of random implants, ion diffusion was not linked to damage annealing and occurred due to a substitutional process via cation lattice sites.
Implantation of Group-IVA Elements in TiO2: Lattice Site Location and Diffusion. Fromknecht, R., Khubeis, I., Meyer, O.: Nuclear Instruments & Methods in Physics Research B, 2000, 161-163, 528-33
Table 9
Diffusion coefficient for T diffusion parallel
to the a-axis of rutile (dominant mechanism)
Temperature (C) | Equilibrium O Pressure (atm) | D (cm2/s) |
500 | 1.5 x 10-23 | 1.49 x 10-9 |
501 | 1.5 x 10-23 | 1.13 x 10-9 |
502 | 1.1 x 10-8 | 6.75 x 10-10 |
502 | 1.6 x 10-29 | 1.17 x 10-9 |
502 | 1.5 x 10-23 | 1.23 x 10-9 |
600 | 1.5 x 10-6 | 6.19 x 10-9 |
602 | 2.0 x 10-25 | 7.27 x 10-9 |
603 | 6.5 x 10-20 | 8.18 x 10-9 |
651 | 9.0 x 10-6 | 1.25 x 10-8 |
701 | 3.5 x 10-22 | 3.02 x 10-8 |
705 | 5.1 x 10-17 | 3.87 x 10-8 |
800 | 1.1 x 10-14 | 1.05 x 10-7 |
905 | 2.5 x 10-17 | 2.70 x 10-7 |
910 | 1.7 x 10-8 | 3.87 x 10-7 |
Table 10
Diffusion coefficient for T diffusion parallel
to the a-axis of rutile (slow mechanism)
Temperature (C) | Equilibrium O Pressure (atm) | D (cm2/s) |
651 | 1.5 x 10-6 | 3.27 x 10-12 |
701 | 7.4 x 10-5 | 5.13 x 10-12 |
799 | 1.7 x 10-3 | 5.53 x 10-11 |
800 | 1.7 x 10-3 | 6.76 x 10-11 |
800 | 1.2 x 10-14 | 1.05 x 10-10 |
902 | 2.2 x 10-2 | 5.04 x 10-10 |