Inclusions of Na, with diameters that ranged from 2 to 15nm, were created by implanting Na ions into 70nm-thick monocrystalline Pt foils and annealing them. The structures of solid inclusions, and the diffusion of molten inclusions, were studied by means of transmission electron microscopy. It was found that, at room temperature, the inclusions were faceted and crystalline, with a body-centered cubic structure. They were aligned topotactically with the face-centered cubic Pt matrix. The diffusion of inclusions which were in the liquid state was investigated by annealing at temperatures of 1227, 1432 or 1534K. The diffusion coefficient was found to depend upon the inclusion radius and to have an activation energy of 2.8eV. This was consistent with a mechanism in which the volume self-diffusion of Pt controlled the diffusion rate of the inclusions. The diffusion of Pt at the interfaces between the Pt matrix and the liquid Na inclusions was found to be strongly inhibited, as compared with the free-surface self-diffusion of Pt.
J.R.Poulsen, A.Horsewell, M.Eldrup, E.Johnson, A.Johansen: Journal of Physics - Condensed Matter, 1994, 6[28], 5397-408
Table 243
Arrhenius Parameters for the Grain Boundary Diffusivity of Ti in Pt Films
Thickness (nm) | Technique | Do (cm2/s) | E (kJ/mol) |
80 | Holloway-McGuire | 7.6 x 10-6 | 121 |
80 | Hwang-Balluffi | 2.2 x 10-6 | 122 |
50 | Holloway-McGuire | 4.7 x 10-6 | 114 |
50 | Hwang-Balluffi | 3.5 x 10-8 | 105 |
20 | Holloway-McGuire | 1.4 x 10-8 | 99.5 |
20 | Hwang-Balluffi | 2.5 x 10-9 | 94.3 |
6.5 | Holloway-McGuire | 2.1 x 10-11 | 57.7 |
6.5 | Hwang-Balluffi | 1.2 x 10-11 | 61.8 |
3.5 | Holloway-McGuire | 8.4 x 10-15 | 19.8 |
3.5 | Hwang-Balluffi | 3.7 x 10-15 | 21.5 |