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Radiation-induced property changes in materials originate from the energy transfer from an incoming particle to the existing lattice, displacing atoms. The displaced atoms can cause the formation of extended defects including dislocation loops, voids, or precipitates. The non-equilibrium defects created during damage events determine the extent of these larger defects and are a function of dose rate, material, and temperature. However, these defects are transient and can only be probed indirectly. This work presents direct experimental measurements and evidence of irradiated non-equilibrium vacancy formation, where in situ positron annihilation spectroscopy was used to prove the generation of non-equilibrium defects in silicon.

Investigation of zirconia nanopowders, doped with metal cations of different valence (Mg2+, Ce4+), and ceramics, obtained by sintering these nanopowders, will be reported. The nanopowders were prepared by the co- precipitation method. The Doppler broadening (DB) measurements were carried out using a slow-positron beam and combined with the conventional positron lifetime spectroscopy and electron microscopy. Nano- and mesopore data, obtained in this study, suggest that small agglomerates of nanoparticles occurs in the pressure-compacted zirconia nanopowder doped with Mg2+ cation, while only relatively small nanopores seem to be contained in the nanopowder of ZrO2, doped with Ce4+, after pressure compaction, indicating thus an absence of significant nanoparticle agglomeration in this system.Investigation of zirconia nanopowders, doped with metal cations of different valence (Mg2+, Ce4+), and ceramics, obtained by sintering these nanopowders, will be reported. The nanopowders were prepared by the co- precipitation method. The Doppler broadening (DB) measurements were carried out using a slow-positron beam and combined with the conventional positron lifetime spectroscopy and electron microscopy. Nano- and mesopore data, obtained in this study, suggest that small agglomerates of nanoparticles occurs in the pressure-compacted zirconia nanopowder doped with Mg2+ cation, while only relatively small nanopores seem to be contained in the nanopowder of ZrO2, doped with Ce4+, after pressure compaction, indicating thus an absence of significant nanoparticle agglomeration in this system.