Oxygen self-diffusion in forsterite: Implications for the high-temperature creep mechanism |
| |
| Authors: | O Jaoul C Froidevaux WB Durham M Michaut |
| |
| Institution: | 1. Laboratoire de Géophysique et Géodynamique interne, Universitéde Paris Sud, Ba?timent 510, Orsay 91405France;2. University of California, Lawrence Livermore Laboratory, Livermore, CA 94450, U.S.A. |
| |
| Abstract: | The diffusivity of18O in forsterite Mg2SiO4 has been measured in the temperature range 1150–1600°C. The activation energy of oxygen self-diffusion in this silicate is found to equal0.32 ± 0.04MJ/mol(77 ± 10kcal/mol), and there is no dependence of the diffusivity upon the oxygen partial pressure surrounding the samples. The diffusion profiles were analysed either with an ion probe or by means of the18O(p, α)15N nuclear reaction. The latter method made use of a resonance in the nuclear cross-section in the case of diffusion profiles shorter than 100 nm (1000Å); for diffusion profiles up to 4 μm the same reaction was used, but in a non-resonant mode. New data on creep in forsterite and natural olivine are also given, including the influence of the oxygen partial pressurepO2 which is zero for forsterite and proportional to(pO2)16 for natural olivine. From this set of data we infer the possible relationship between diffusion and creep for these materials. This relationship may be more complicated than that predicted by simple climb mechanism. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
