Site-Selective Doping and Site-Sensitive Photoluminescence of Eu and Tb in Perovskite-Type LaLuO.

Eu and Tb ions were site-selectively doped into LaLuO with the orthorhombic perovskite-type structure (ABO), and their luminescence properties were examined considering the doping sites (A or B sites). The X-ray diffraction analysis revealed the expansion or contraction of the unit cell volumes of the materials depending on the doping sites. The spectra of X-ray absorption near edge structure for the Eu and Tb L edge exhibited different shapes for the ions at A and B sites, confirming the site-selective doping of Eu and Tb in LaLuO. The photoluminescence (PL) and PL excitation (PLE) spectra of the materials also showed some differences caused by the doping sites. The intensities of the Eu PL peaks derived from the D-F transitions and those from the D-F transitions were markedly different between Eu at A sites and those at B sites because of the different site symmetries. The splitting of the intense Tb PL peaks originating from the D-F transitions and the absence of PL peaks from D-F transitions were found only for Tb at B sites because of the strong crystal field at B sites. In addition to the PL spectra, the positions of PLE peaks originating from charge transfer transitions in Eu and the 4f-5d transitions in Tb depended on the doping sites. The successful site-selective doping enabled us to clarify the site-sensitive luminescence properties of Eu and Tb doped in the perovskite-type LaLuO.