Consequences of Ca Codoping in YAlO3 :Ce Single Crystals.

The influence of Ca codoping on the optical absorption, photo-, radio-, and thermo-luminescence properties of YAlO3 :Ce (YAP:Ce) crystals has been studied for four different calcium concentrations ranging from 0 to 500 ppm. Ca codoping results in a partial oxidation of Ce3+ into Ce4+ , The luminescence time response under pulsed X-ray excitation of the Ce3+ /Ce4+ admixure clearly demonstrates the role of hole migration on both the rise time and the generally observed slow components. From an application point of view, Ca codoping significantly improves the timing performances, but the induced presence of Ce4+ ions is also the cause of a reduction in scintillation efficiency.