Site-Selective Eu³⁺ Doping and Enhanced Luminescence from Eu³⁺ at B Sites in Perovskite-Type Strontium Zirconate and Hafnate

To achieve efficient Eu3+ luminescence, site-selective doping of Eu3+ was attempted in perovskite-type (ABO3) SrMO3 (M = Zr, Hf). In contrast to CaMO3 and BaMO3, it was found that the doping sites of Eu3+ (EuSr or Eu'Zr/Eu'Hf) could be highly controlled in SrMO3 by a codoping technique. This was mainly because the size of Sr2+ was suitable for the site-selective doping of Eu3+ in SrMO3. The codoping of small Ga3+ at B sites (Ga'Zr/Ga'Hf) was carried out for A-site doping of Eu3+, whereas the codoping of large La3+ at A sites (LaSr) or small Nb5+ at B sites (NbZr /NbHf) was conducted for B-site doping of Eu3+. As a result, the proportion of Eu3+ at A and B sites became more than 90% by the Asite and B-site doping, respectively, from the analysis of X-ray absorption near-edge structures for the Eu L3 edge. Eu3+ ions were driven to intentional sites by codoping due to the dual effects of charge compensation and ionic size balance. The high Eu3+ proportion at B sites, viz. the almost complete B-site doping, led to the findings of significant enhancement of Eu3+ luminescence, which was derived from the magnetic dipole transitions from 5D0 to 7F1 states. The quantum efficiencies of the enhanced luminescence from SrMO3 doped with Eu3+ at B sites exceeded 50% at room temperature.