Defect reduction in SrTiO3 by Al addition

Defect-reduction process in SrTiO3 by Al addition has been investigated by using high-resolution transmission electron microscope (HRTEM) images, X-ray diffraction (XRD) patterns and photoluminescence (PL) spectra. HRTEM images in SrTiO3 : Pr3+ show the reduction of planar faults by Al addition. The planar faults are probably SrO thin layers. In Eu-doped SrTiO3 reduced by firing in hydrogen atmosphere, Ruddlesden-Popper phases Srn+1TinO3n+1 (n = 1, 2,..., infinity) are precipitated in SrTiO3, as confirmed by XRD patterns. Srn+1TinO3n+1 consists of a SrO planar fault interleaved with SrTiO3 slabs. With Al addition, the planar faults cannot be easily formed. Instead, strontium aluminates, SrAl2O4 or/and SrAl12O19, as well as SrTiO3 are precipitated, as a result of scavenging the SrO planar faults by added Al. The precipitation is confirmed also by PL from Eu2+ in the strontium aluminates. (C) 2000 Elsevier Science B.V. All rights reserved.