Amphoteric doping of praseodymium Pr~(3+) in SrTiO_3 grain boundaries

摘要

Charge compensation in rare-earth Praseodymium (Pr~(3+)) doped SrTiO_3 plays an important role in determining the overall photoluminescence properties of the system. Here, the Pr~(3+) doping behavior in SrTiO_3 grain boundaries (GBs) is analyzed using aberration corrected scanning transmission electron microscopy. The presence of Pr~(3+) induces structural variations and changes the statistical prevalence of the GB structures. In contrast to the assumption that Pr~(3+) substitutes on the Sr site in the bulk, Pr~(3+) is found to substitute on both Sr and Ti sites inside the GBs, with the highest concentration at the Ti sites. This amphoteric doping behavior in the boundary plane is further confirmed by first principles theoretical calculations.