By using high-angle annular dark-field imaging in aberration-corrected scanning transmission electron microscopy it was directly observed that, at low concentrations, Au atoms implanted into SrTiO3 were in a substitutional lattice position for both Sr and Ti. The congregation of Au atoms by diffusion to a critical concentration led to the nucleation of an Au lattice within the SrTiO3. The Au nanocluster and SrTiO3 were found to maintain an orientation relationship of the form, Au[001]||SrTiO3[001] and Au(100)||SrTiO3(100). This confirmed the results of a first-principles total-energy calculation. The interface between the Au cluster and SrTiO3 was bridged by an O/Ti plane. The Au-O bond length was found to be 2.2Å, which was the same as the Au-O bond length in AuO. The atomic planes adjacent to the interface in both Au and SrTiO3 were found to be slightly stretched. The high concentration of vacancies generated during Au implantation aggregated to form cavities in the SrTiO3 lattice, and were faceted mostly along the SrTiO3 {100} and (110) planes. The Au and vacancy clusters were spatially associated; indicating a strong interaction. The formation of cavities in Au-implanted materials indicated that the vacancy-clustering process dominated Frenkel-pair recombination.

Direct Observation of Substitutional Au Atoms in SrTiO3. C.M.Wang, V.Shutthanandan, Y.Zhang, S.Thevuthasan, G.Duscher: Physical Review B, 2004, 70[17], 172201 (4pp)