Microstructure of Yttria-Stabilized Zirconia Nanomaterials Studied by Positron Annihilation Spectroscopy
Abstract
Investigations of several yttria-stabilized zirconia (YSZ) pressure-compacted nanopowders are reported. Positron annihilation spectroscopy is employed as the main experimental tool.
The defects associated with grain boundaries (GB''s), the mean grain size and its growth during sintering nanopowders, the nanoporosity, an influence of the material composition on the final microstructure and a possible segregation of different kinds of atoms at GB''s are discussed. The main attention will be focused on the role of chromia addition to YSZ.
Positrons are trapped predominantly (i) in the monovacancy-like defects situated along GB''s or (ii) at the triple junctions of GB''s. PAS is then used for estimation of grain size.
A small amount of chromia additive is shown to lead to a lower mean grain size of the initial YSZ nanopowders.