Positron annihilation lifetime studies of SrTiO$_{3}$ crystal and ceramic materials

Positron annihilation lifetime spectroscopy (PALS) measurements on high density ceramic SrTiO$_{3}$ are reported and compared to measurements on single crystal substrates. PALS has specific sensitivity to vacancy-related defects as these are traps for positrons; the lifetime of vacancy trapped positrons is increased with respect to those that annihilate from the perfect lattice. Positrons are found to be saturation trapped at vacancy defects in the ceramic samples, with over 90% annihilating with a lifetime of $\sim $175 ps, and the remainder annihilating with a lifetime in the 270–310 ps range consistent with A-site or larger open volume sites. The dominant component at $\sim $175 ps may represent a single vacancy trap, or it may be the average of one or more unresolved lifetime states