Positron annihilation study of defect distribution in 8YSZ nanostructure

The impact of the interfacial contribution on overall properties increases with decreasing grain size of polycrystalline materials. It is well known that distribution and size of cluster defects are rather different in bulk than grain boundaries. In light of “bottom-up” approaches, a study at the atomic level determining the distribution of crystallographic defects could clarify their contribution to the macroscopic properties, and then differentiate materials for outstanding or precise applications. In this work, Positron Annihilation Spectroscopy (PAS) is used to characterize the distribution of defects within 8 mol% Y2O3-stabilized zirconia (8YSZ) structures prepared by sintering through three different thermal treatments, i.e. a conventional thermal cycle in air and N2/H2 atmosphere, and a fast firing cycle in air, which lead to average grain sizes < 260 nm.

Research highlights
► Positron spectroscopy relates microstructure of 8YSZ to theories on ionic materials.
► Space charge region distribution in nanostructures is investigated.
► Sintering in reducing atmosphere favors densification and grain size retention.
► Increase of electronic density due to defect re-distribution in the grain is verified.