Diffusional Creep Phenomena in Polycrystalline Oxides
- Robert N. Schock
Published Online: 18 MAR 2013
Copyright 1985 by the American Geophysical Union.
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
- Published Online: 18 MAR 2013
- Published Print: 1 JAN 1985
Print ISBN: 9780875900568
Online ISBN: 9781118664070
- Mineralogical chemistry—Congresses;
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.