Host-to-Activator Energy Transfer Developed by Eu3+ Doping at B Sites in Perovskite-Type Strontium Stannate Phosphor

Site-selective doping and site-dependent luminescence of Eu3+ were examined in the perovskite-type strontium stannate host, SrSnO3, which is reported as a transparent oxide semiconductor (TOS). The X-ray diffraction patterns and the spectra of the X-ray absorption near edge structure (XANES) for the Eu L-3 edge revealed that the site-selective doping of Eu3+ was achieved almost completely by Mg2+ and La3+ or Nb5+ codoping. The site-dependent Eu3+ luminescence was clearly observed in the codoped samples, and the luminescence derived from the magnetic dipole transitions from the D-5(0) to F-7(1) states was seen intensively from Eu3+ at the B sites, Eu3+(B). The intense luminescence from Eu3+(B) was found to occur only in the samples with a high Eu3+(B) proportion attained by La3+ or Nb5+ codoping. It is also noteworthy that the intense Eu3+(B) luminescence was obtained not by the charge transfer excitation for Eu3+(B) but by the excitation for the host of the SrSnO3 TOS, revealing the efficient energy transfer from the host to Eu3+(B). The finding indicates that both the Eu3+ luminescence and semiconducting features could be available in SrSnO3, which is preferable for optoelectronic applications such as cathodoluminescence and electroluminescence.