The migration of Cr in monocrystals was studied by using X-ray microprobe techniques. The coefficients which were determined at temperatures of between 1273 and 1673K could be described by:
D (cm2/s) = 0.00073 exp[-204(kJ/mol)/RT]
The diffusion coefficients which were obtained were about an order of magnitude higher than those found for polycrystalline CoO. The difference was explained in terms of the effect of a segregation-induced diffusive resistance in polycrystalline specimens.
F.Adam, B.Dupre, K.Kowalski, C.Gleitzer, J.Nowotny: Journal of the Physics and Chemistry of Solids, 1995, 56[8], 1063-8
Table 56
Chemical Diffusion Data for CoO Monocrystals
Crystal Size (mm) | Atmosphere | PO2 (atm) | D (cm2/s) |
1 x 1.1 x 15 | pure O2 | 1.03 x 10-1 | 6.16 x 10-7 |
1 x 1.1 x 15 | pure O2 | 4.73 x 10-2 | 4.90 x 10-7 |
1 x 1.1 x 15 | pure O2 | 9.76 x 10-1 | 8.27 x 10-7 |
1 x 1.1 x 15 | pure O2 | 1.06 x 10-1 | 6.48 x 10-7 |
1 x 1.1 x 15 | pure O2 | 9.99 x 10-1 | 6.69 x 10-7 |
1 x 1.1 x 15 | pure O2 | 9.78 x 10-1 | 5.66 x 10-7 |
1 x 1.1 x 15 | pure O2 | 7.02 x 10-1 | 6.10 x 10-7 |
1 x 1.1 x 15 | pure O2 | 5.73 x 10-1 | 6.71 x 10-7 |
1 x 1.1 x 15 | pure O2 | 9.97 x 10-1 | 4.51 x 10-7 |
1 x 1.1 x 15 | pure O2 | 9.40 x 10-11 | 9.10 x 10-7 |
1 x 1.1 x 15 | pure O2 | 9.30 x 10-11 | 9.03 x 10-7 |
4.4 x 4.4 x 16 | pure O2 | 1.33 x 100 | 9.27 x 10-7 |
4.4 x 4.4 x 16 | pure O2 | 1.01 x 100 | 9.57 x 10-7 |
4.4 x 4.4 x 16 | pure O2 | 3.05 x 10-1 | 9.38 x 10-7 |
4.4 x 4.4 x 16 | pure O2 | 1.04 x 100 | 7.53 x 10-7 |
4.4 x 4.4 x 16 | pure O2 | 1.02 x 100 | 9.19 x 10-7 |
continued
Table 56 (continued)
Chemical Diffusion Data for CoO Monocrystals
Crystal Size (mm) | Atmosphere | PO2 (atm) | D (cm2/s) |
4.4 x 4.4 x 16 | pure O2 | 9.40 x 10-11 | 9.01 x 10-7 |
1 x 1.1 x 15 | N2-1.14%O2 | 1.25 x 10-2 | 1.34 x 10-7 |
1 x 1.1 x 15 | N2-1.14%O2 | 1.24 x 10-2 | 5.23 x 10-8 |
1 x 1.1 x 15 | N2-1.14%O2 | 1.13 x 10-2 | 9.30 x 10-8 |
4.4 x 4.4 x 16 | N2-1.13%O2 | 1.19 x 10-2 | 7.26 x 10-7 |
4.4 x 4.4 x 16 | N2-1.13%O2 | 1.13 x 10-2 | 7.35 x 10-7 |
4.4 x 4.4 x 16 | N2-1.13%O2 | 1.29 x 10-2 | 5.72 x 10-7 |
4.4 x 4.4 x 16 | N2-1.13%O2 | 3.48 x 10-3 | 6.80 x 10-7 |
4.4 x 4.4 x 16 | N2-1.13%O2 | 9.38 x 10-4 | 6.32 x 10-7 |
4.4 x 4.4 x 16 | N2-1.13%O2 | 7.87 x 10-3 | 4.09 x 10-7 |