High silicon self-diffusion coefficient in dry forsterite

Hongzhan Fei, Chamathni Hegoda, Daisuke Yamazaki, Michael Wiedenbeck, Hisayoshi Yurimoto, Svyatoslav Shcheka, Tomoo Katsura

Research output: Contribution to journalArticlepeer-review

47 Citations (Scopus)

Abstract

Silicon self-diffusion coefficients (D Si) in dry synthetic forsterite single crystals were measured at temperatures of 1600 and 1800K, from ambient pressure up to 13GPa using an ambient pressure furnace and Kawai-type multi-anvil apparatus. The water contents in the samples were carefully controlled at <1μg/g. Diffusion profiles were obtained by secondary ion mass spectrometry (SIMS) in depth profiling mode. Small negative pressure dependence of D Si is determined with an activation volume of 1.7±0.4cm 3/mol. The activation energy is found to be 410±30kJ/mol. LogD Si values (D Si in m 2/s) at 1600 and 1800K at ambient pressure are determined to be -19.7±0.4 and -18.1±0.3, respectively. These values are ~2.4 orders of magnitude higher than those reported by Jaoul et al. (1981). We speculate that their low D Si might reflect the effects of a horizontal migration of the isotopically enriched thin films applied on the sample surfaces, which may inhibit diffusion into the substrate during annealing. Our results for D Si resolve the inconsistency between D Si measured in diffusion experiments and those deduced from creep rates measured in deformation experiments.

Original languageEnglish
Pages (from-to)95-103
Number of pages9
JournalEarth and Planetary Science Letters
Volume345-348
DOIs
Publication statusPublished - Sep 1 2012

Keywords

  • Forsterite
  • Self-diffusion coefficient
  • Silicon

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

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