A Technique for Observing Oxygen Diffusion Along Grain Boundary Regions in Synthetic Forsterite

  1. Robert N. Schock
  1. R. H. Condit,
  2. H. C. Weed and
  3. A. J. Piwinskii

Published Online: 18 MAR 2013

DOI: 10.1029/GM031p0097

Point Defects in Minerals

Point Defects in Minerals

How to Cite

Condit, R. H., Weed, H. C. and Piwinskii, A. J. (1985) A Technique for Observing Oxygen Diffusion Along Grain Boundary Regions in Synthetic Forsterite, in Point Defects in Minerals (ed R. N. Schock), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM031p0097

Author Information

  1. Lawrence Livermore National Laboratory Livermore, California 94550

Publication History

  1. Published Online: 18 MAR 2013
  2. Published Print: 1 JAN 1985

ISBN Information

Print ISBN: 9780875900568

Online ISBN: 9781118664070

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Keywords:

  • Mineralogical chemistry—Congresses;
  • Crystals—Defects—Congresses

Summary

We describe a technique for observing oxygen diffusion into synthetic forsterite, Mg2SiO4. An oxygen-18 isotope tracer was used in a gas-solid interchange anneal. Tracer penetration into Mg2SiO4 was examined by the technique of proton bombardment activation to convert the oxygen-18 into radioactive fluorine-18, followed by autoradiography. This is the first application of this technique to silicate diffusion studies and is concerned with grain boundary regions which contain other phases than the matrix material. High diffusion rates measured at 1374°C are related to the presence of molten material, while at 1107°C there is evidence for penetration of oxygen gas along cracks in the grain boundary region. Our best diffusion coefficient obtained at 1325°C is in general accord with earlier predictions for grain boundary diffusion, albeit higher. This suggests that the grain boundary material is enriched in dislocations and interphase contacts. This technique for observing oxygen-18 tracer should be applicable to studies of grain boundary and dislocation diffusion and to studies of solid-solid and solid-gas reactions.