Lifetime of Positrons in Nanostructured Nonstoichiometric Silver Sulfide Ag_2-δS

The lifetime of positrons in nanostructured nonstoichiometric silver sulfide Ag2–δS samples with average nanoparticle sizes from 44 to 230 nm has been measured. It has been found that the lifetime spectra of Ag2‒δS nanoparticles include two components corresponding to the capture and annihilation of positrons in two types of defects: structural vacancies of the metallic sublattice and vacancy clusters at the interfaces between nanoparticles. The long surface component depends on the size of silver sulfide particles and indicates a difference in their defect structure.