Diffusion of hydrogen and intrinsic point defects in olivine

David L. Kohlstedt, Stephen J. Mackwell

Research output: Contribution to journalArticle

230 Scopus citations

Abstract

We have analyzed the kinetics of hydrogen diffusion in ferromagnesian olivine by measuring the O-H distribution in single crystals annealed under hydrothermal conditions. The hydrogen concentration evolves toward an equilibrium value in two stages. First, hydrogen diffuses rapidly (D11 ≃ 10-10 m2/s at 1000 °C) into olivine probably charge compensated by a flux of polarons or of electrons. The resultant metastable equilibrium concentration of hydrogen is directly related to the imposed hydrogen fugacity and to the preexisting concentration of intrinsic point defects; except for electronic species, intrinsic defects diffuse significantly more slowly than hydrogen. Second, hydrogen and intrinsic point defects such as metal vacancies diffuse more slowly (DVMe ≃ 10-12 m2/s at 1000 °C) into or out of the olivine as the concentrations of all defect species evolve toward equilibrium with the imposed thermochemical environment.

Original languageEnglish (US)
Pages (from-to)147-162
Number of pages16
JournalZeitschrift fur Physikalische Chemie
Volume207
Issue number1-2
DOIs
StatePublished - 1998

Keywords

  • Diffusion
  • Hydrogen
  • Olivine
  • Point defects
  • Vacancy

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