Site-Dependent Tb³⁺ Luminescence by Energy Transfer from Ce³⁺ in Ce³⁺–Tb³⁺ Codoped LaLuO₃

Ce 3+ –Tb 3+ codoped LaLuO 3 was prepared by doping Tb 3+ site-selectively at a La or Lu site and doping Ce 3+ 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 Ce 3+ and Tb 3+, confirming the occupation of Ce 3+ at a La site and Tb 3+ at a La or Lu site. Photoluminescence due to energy transfer from Ce 3+ to Tb 3+ was investigated by exciting the 4f–5d transition band of Ce 3+ . The site-dependent Tb 3+ luminescence spectra revealed that the energy transfer occurred from Ce 3+ to not only Tb 3+ at La sites but also Tb 3+ at Lu sites. Because Tb 3+ at both sites can show green luminescence by Ce 3+ 4f–5d excitation, as well as Tb 3+ 4f–5d excitation, in Ce 3+ –Tb 3+ codoped LaLuO 3, the excitation wavelength range for Tb 3+ luminescence was widely extended up to 380 nm, which is attainable with near-UV LEDs.