Positron annihilation characterization of nanocrystalline ZnO

► Nanocrystalline (3-4 nm) ZnO has been synthesized by chemical route. ► Defects in nanocrystalline ZnO have been characterized by positron annihilation technique. ► Positron lifetime data indicates presence of large open volume Zn vacancy complexes. ► A large percentage (19%) of positronium formation has also been observed.