%0 Journal Article %T Anisotropy of oxygen diffusion in diopside %A Ingrin, Jannick %A Pacaud, Laure %A Jaoul, Olivier %< avec comité de lecture %@ 0012-821X %J Earth and Planetary Science Letters %I Elsevier %V 192 %P 347-361 %8 2001 %D 2001 %Z 2001E&PSL.192..347I %R 10.1016/S0012-821X(01)00460-5 %Z Sciences of the Universe [physics]Journal articles %X 18O diffusion coefficients have been measured by nuclear reaction analysis (NRA) in Fe-free synthetic diopside single crystals along the three crystallographic directions and in Fe-bearing natural diopside single crystals along the c direction at room pressure in the range 1050-1370°C and under controlled oxygen partial pressure (10 -3-10 -12 atm). Diffusion along a and c crystallographic directions is one order of magnitude faster than along b direction. Diffusion along c in natural diopside is about two times faster than in the synthetic sample. The activation energy along b is 323±27 kJ mol -1 and diffusion is insensitive to oxygen fugacity. For a and c directions activation energies are around 250 kJ mol -1 and the diffusion coefficients are slightly dependent on fO 2 (≈ fO 20.04). We suggest that the observed diffusion anisotropy is related to the oxygen diffusion paths within the crystallographic structure that prefer the under-bonded O2 oxygen sites. We propose a single law to describe diffusion along the two fast crystallographic directions a and c in diopside for natural conditions close to the QFM buffer: log D a,c ( m2s-1)=-10.0±0.6-(259±15 kJ mol-1)/2.303 RT, and D b≪D a,c %G English %L insu-03642944 %U https://insu.hal.science/insu-03642944 %~ INSU