Diffusional Creep Phenomena in Polycrystalline Oxides

  1. Robert N. Schock
  1. Ronald S. Gordon

Published Online: 18 MAR 2013

DOI: 10.1029/GM031p0132

Point Defects in Minerals

Point Defects in Minerals

How to Cite

Gordon, R. S. (1985) Diffusional Creep Phenomena in Polycrystalline Oxides, in Point Defects in Minerals (ed R. N. Schock), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM031p0132

Author Information

  1. University of Utah Salt Lake City, Utah 84112

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

Examples are given for the kinetic limitation of diffusional creep rates in poly-crystalline oxides by (1) cation lattice diffusion, (2) cation grain boundary diffusion, (3) anion grain boundary diffusion and (4) interfacial effects at grain boundaries. Well defined examples of diffusional creep (Nabarro-Herring, Coble and combinations thereof) have been identified in polycrystalline MgO, Al2O3 and TiO2. The effects of aliovalent substitutional dopants (e.g. Fe in MgO; Fe, Mn, Ti, Fe-Ti, and Mn-Ti in Al2O3; and Ta in TiO2) on processes which are important in diffusional creep are presented. With the exception of Ta additions to TiO2, all dopants increase creep rates by enhancing cation lattice diffusion, cation grain boundary diffusion or both. In the case of TiO2, tantalum doping suppresses lattice diffusion. When lattice diffusion processes are considerably enhanced (e.g. TiO2O3 and Ti-doped Al2O3) and cation grain boundary diffusion is limited, diffusional creep which is rate-limited by interfacial defect reactions at grain boundaries is dominant. Divalent impurities in Al2O3 such as Fe2+ and Mn2+ considerably enhance aluminum grain boundary diffusion and facilitate defect creation/ annihilation reactions at grain boundaries.