Eu3+-site occupation in CaTiO3 perovskite material at low temperature

Abstract In order to clarify the site occupancy of rare-earth ions in rare-earth doped perovskite materials, the un-doped pure CaTiO 3 and Eu 3+ -doped CaTiO 3 samples with a series of Ca/Ti ratio were synthesized via high-temperature solid-state reaction method. X-ray diffraction (XRD) powder patterns confirm that the crystal structure keeps invariant at various Ca/Ti ratios. Measurement results of unit-cell parameters and X-ray photoelectron spectroscopy (XPS) indicate that Eu 3+ ions enter into the Ca 2+ site. The high-resolution photoluminescence spectra of Eu 3+ ions at 20 K in all samples did not witness a significant change under the excitation at different wavelength, implying that Eu 3+ ions occupy only one type of site. Considering the small spectral splitting range of 5 D 0  →  7 F 2 transition and the large intensity ratio of 5 D 0  →  7 F 2 / 5 D 0  →  7 F 1 , it can be concluded that Eu 3+ occupies Ca 2+ site with larger coordinate numbers rather than Ti 4+ site.