Luminescence and scintillation properties of praseodymium poly and diphosphates

Abstract

Abstract Single crystals of Pr(PO3)3 polyphosphate and NaPrP2O7 diphosphate were grown for the first time using the flux method. In both materials, selective excitation in the Pr3+ (4f2) 3PJ (J=0, 1 and 2) levels using an excimer-pumped dye laser results in an intense red-orange fluorescence originating mainly from transitions between 3P0 and 4f2 lower lying levels. The observed emissions decay exponentially whatever the temperature may be. The 3P0 fluorescence decay time τ experiences a significant lengthening as the temperature is decreased from 300 to 6 K. This is especially true in the case of NaPrP2O7 for which τ increases from 25 up to 275 ns, while τ increases from 23 up to 76 ns only for Pr(PO3)3. Both compounds exhibit intense ultraviolet 4f15d1 → 4f2 band emissions in the 200–300 nm spectral range under X-ray excitation both at room and low temperatures. Comparing the intensities of these ultraviolet emissions with that of the bismuth germanate Bi4Ge3O12 fluorescence leads to relative light yields in the order of 30% and 11% for Pr(PO3)3 and NaPrP2O7, respectively.