Bi3+-Pr3+ energy transfer processes and luminescent properties of LuAG:Bi,Pr and YAG:Bi,Pr single crystalline films

Absorption, cathodoluminescence, excitation spectra of photoluminescence (PL) and PL decay kinetics were studied at 300 K for the double doped with Bi3+-Pr3+ and separately doped with Bi3+ and Pr3+ Lu3Al5O12 (LuAG) and Y3Al5O12 (YAG) single crystalline film (SCF) phosphors grown by the liquid phase epitaxy method. The emission bands in the UV range arising from the intrinsic radiative transitions of Bi3+ based centers, and emission bands in the visible range, related to the luminescence of excitons localized around Bi3+ based centers, were identified both in Bi-Pr and Bi-doped LuAG and YAG SCFs. The energy transfer processes from the host lattice simultaneously to Bi3+ and Pr3+ ions and from Bi3+ to Pr3+ ions were investigated. Competition between Pr3+ and Bi3+ ions in the energy transfer processes from the LuAG and YAG hosts was evidenced. The strong decrease of the intensity of Pr3+ luminescence both in LuAG:Pr and YAG:Pr SCFs phosphors, grown from Bi2O3 flux, is observed due to the quenching influence of Bi3+ flux related impurity. Due to overlap of the UV emission band of Bi3+ centers with the f-d absorption bands of Pr3+ ions in the UV range and the luminescence of excitons localized around Bi ions with the f-f absorption bands of Pr3+ ions in the visible range, an effective energy transfer from Bi3+ ions to Pr3+ ions takes place in LuAG:Bi,Pr and YAG:Bi,Pr SCFs, resulting in the appearance of slower component in the decay kinetics of the Pr3+ d-f luminescence.