Radioluminescence properties under X-ray excitation of type III Ce3+- and Pr3+-doped KGd(PO3)4 single crystals

The research for new scintillator materials with improved properties is gaining growing interest due to their wide variety of applications, including medical diagnosis. Here, radioluminescence studies under synchrotron X-ray excitation of bulk single crystals of type III Ce:KGd(PO3)4 and Pr:KGd(PO3)4 (Ce:KGdP and Pr:KGdP) with high crystalline quality have been carried out. The X-ray excited radioluminescence spectra show emission bands corresponding to 5d1 → 4f electronic transitions of Ce3+ and of Pr3+ in type III KGdP, being of great interest for scintillation applications. In the case of Ce:KGdP crystals, the absence of the 6PJ → 8S7/2 transitions of Gd3+ (~312 nm) can be ascribed to an efficient energy transfer from Gd3+ to Ce3+. In undoped and Pr3+-doped KGdP crystals, a change in coloration in the irradiated regions was observed after prolonged X-ray irradiation, which could be related to the presence of color centers.