A method was described for investigating elementary diffusion jumps in crystalline lattices at the atomic scale. The method made use of synchrotron radiation that was coherently scattered in the forward direction after nuclear resonant excitation. The decay of the forward-scattered radiation was faster, when atoms moved within the time-scale of the excited-state lifetime, because of a loss of coherence. The acceleration of the decay rate differed for different crystal orientations relative to the beam. This provided information, not only about the rates, but also about the directions of diffusion jumps. The method was applied to a study of the diffusion of 57Fe parallel to [111] and [113] directions in Fe3Si (table 11). This revealed the diffusion mechanism of Fe, and its diffusion coefficient.
Diffusion in a Crystal Lattice with Nuclear Resonant Scattering of Synchrotron Radiation B.Sepiol, A.Meyer, G.Vogl, H.Franz, R.Rüffer: Physical Review B, 1998, 57[17], 10433-9
Table 11
Diffusivity of 57Fe in Fe3Si
Temperature (K) | Direction | D (m2/s) |
827 | [113] | 1.2 x 10-14 |
858 | [113] | 5.1 x 10-14 |
885 | [113] | 9.1 x 10-14 |
913 | [113] | 1.9 x 10-13 |
939 | [113] | 4.2 x 10-13 |
967 | [113] | 6.6 x 10-13 |
967 | [335] | 5.4 x 10-13 |
827 | [111] | 4.4 x 10-15 |
913 | [111] | 1.9 x 10-13 |
967 | [111] | 6.7 x 10-13 |