Structural effects and 5d→4f emission transition shifts induced by Y co-doping in Pr-doped K3Lu1−xYx(PO4)2

In this work the structural and spectroscopic properties of several materials belonging to the K3Lu1-xY x (PO4)2 family and activated with 1% of Pr3+ have been studied in detail. The structural characterization has been performed by X-ray diffraction. The crystal structure of the host has been determined by means of Rietveld refinement of the powder diffraction pattern, in the case of K3Y(PO4)2 doped with 1%of Pr3+.The optical emission upon UV direct excitation into the dopant ion is dominated by the Pr3+4f15d1→4f2 interconfigurational transitions; the substitution of Lu by Y causes the blue shift of the 4f15d1→4f2 emission band. This is due to an important change of the Pr3+ local environment. Upon X-ray excitation it has been found that the ratio between the 4f15d1→4f2 and 4f2→4f2 emission intensities varies progressively when Y3+ concentration is increased. This behavior is explained in terms of the favorable overlap between the defect-related luminescence of the host and the Pr3+4f2→4f2 intraconfigurational transitions. No thermal quenching of the Pr3+ luminescence has been observed up to 500K