Lattice location and perturbed angular correlation studies of implanted Ag in SrTiO$_{3}$

Lattice site location and local environment characterization of implanted $^{111}\!$Ag in SrTiO$_{3}$ by means of the emission channeling (EC) and $\gamma$-$\gamma$-perturbed angular correlation (PAC) techniques are reported. The angular distribution of $\beta\!^{-}$-particles emitted from the $^{111}\!$Ag decay was monitored with a position-sensitive detector as a function of annealing temperature up to 900 ºC. In the as-implanted state Ag occupies several lattice sites in SrTiO$_{3}$. Upon annealing, near-Sr and near-Ti occupancies increased to 58% and 28%, while an octahedral interstitial fraction vanished. Ag on near-Sr and near-Ti sites are still displaced by $\sim$0.2--0.5 Å from ideal cubic positions. Subsequent PAC measurements confirmed that ~20% of $^{111}\!$Ag atoms are in specific sites of non-cubic environment, characterized by a unique electrical-field-gradient (EFG), while ~80% were subject to a wide EFG distribution.