ELASTIC DRIVING FORCES FOR DOPANT SEGREGATION IN NANOSTRUCTURED DOPED ZIRCONIA CERAMICS

摘要

The effect of zirconium substitution by 3 mol% of oversized trivalent dopants (R~(3+)) from Yb~(3+), Y~(3+), Gd~(3+) to Sm~(3+) was investigated in nanostructured single-phased tetragonal zirconia ceramics on both electrical and structural properties. The grain boundary dopant segregation was strongly marked for larger dopant ionic radius size as shown by Impedance spectroscopy. Equivalent tensile stresses of 2.5 GPa were found in the same batch from frequency shifts of Raman spectra and from XRD compressibility data leading to an expansion of the c lattice parameter. The grain boundary segregation can be driven mainly by elastic driving forces when the size mismatch between the dopant and the host is large.