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

Ce³⁺-Tb³⁺codoped LaLuO₃was 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.