Abstract
A positron annihilation study of the tetragonal yttria stabilized zirconia (YSZ) nanopowder compacted under a high pressure and subjected to a sintering at temperatures ranging from 1000 to 1350 oC were investigated. The conventional positron lifetime and coincidence Doppler broadening measurements were performed.
In the compacted nanopowder, positrons were found to annihilate mainly as trapped at vacancy-like defects (most likely the Zr vacancies) situated in the negative space-charge layers along grain boundaries (GB-s) or at larger defects associated with GB intersections (triple points). Moreover, pores of a few-nanometer size were detected via positronium pick-off annihilation in the YSZ nanopowders.
These pores, however, disappeared after sintering at 1000 oC and a significant grain growth takes place above this temperature.