A HRTEM STUDY OF DEFECTS IN SILVER-DOPED GALENA

Synthetic Ag-doped PbS samples were Ar ion beam milled and examined by HRTEM. The silver was found to aggregate in inclusions which have no crystallographic relationship to the PbS host, rather than forming cry stallographic defects. The Ag2S inclusions are 500 angstrom in diamete r or larger. The limit of Ag substitution into PbS in solid solution i n the absence of Bi or Sb is less than 0.1 mol %. The ion beam milling process introduced a large number of small dislocations in both Ag-do ped and pure PbS specimens. These dislocations are thought to be forme d through coalescences of point defects.