Site-Dependent Tb<sup>3+</sup> Luminescence by Energy Transfer from Ce<sup>3+</sup> in Ce<sup>3+</sup>–Tb<sup>3+</sup> Codoped LaLuO<sub>3</sub>
Shoichiro Nagashima, Kazushige Ueda, Takahisa Omata
Abstract
Ce3+–Tb3+ codoped LaLuO3 was prepared by doping Tb3+ site-selectively at a La or Lu site and doping Ce3+ simultaneously at a La site. X-ray diffraction analysis revealed the expansion and contraction of the unit-cell volume according to the substituting sites of Ce3+ and Tb3+, confirming the occupation of Ce3+ at a La site and Tb3+ at a La or Lu site. Photoluminescence due to energy transfer from Ce3+ to Tb3+ was investigated by exciting the 4f–5d transition band of Ce3+. The site-dependent Tb3+ luminescence spectra revealed that the energy transfer occurred from Ce3+ to not only Tb3+ at La sites but also Tb3+ at Lu sites. Because Tb3+ at both sites can show green luminescence by Ce3+ 4f–5d excitation, as well as Tb3+ 4f–5d excitation, in Ce3+–Tb3+ codoped LaLuO3, the excitation wavelength range for Tb3+ luminescence was widely extended up to 380 nm, which is attainable with near-UV LEDs.