Effects of dopant segregation on lattice-diffusional creep of nanocrystalline ceramics
Journal
Physical Review B - Condensed Matter and Materials Physics
Journal Volume
71
Journal Issue
1
Date Issued
2005
Author(s)
Abstract
The segregation of dopants whose electric charge is different from that of the parent ions and the formation of a space-charge layer induce a local electric field in the grain-boundary region. Depending upon the valence and local electrostatic potential, the charge carriers controlling diffusional creep can be either accumulated or depleted in this space-charge layer, and the creep rate is enhanced or diminished accordingly. A model was recently developed to examine the effects of a segregation-induced local electric field on the lattice-diffusional creep of nanocrystalline ceramics for spherical grains. However, in order to obtain closed-form solutions, the grain size was assumed to be much greater than the width of the space-charge layer in the existing analysis. This assumption can become inappropriate for nanocrystalline materials as the grain size is reduced; thus, a numerical method is used in the present study to resolve the existing equations without that assumption. Using yttria tetragonal zirconia as an example, the difference between the existing approximate closed-form solutions and the present numerical results is shown to be significant when the grain size is less than 50 nm. ? 2005 The American Physical Society.
Type
journal article