Testing Performance of Pr3+-doped KLuP2O7 upon UV-, Synchrotron X-Ray and Cathode-Ray Excitation

Abstract

The luminescent characteristics of the double phosphate KLuP2O7 doped with Pr3+ ions, a promising optical material for scintillator applications, were investigated using various experimental spectroscopic techniques. KLuP2O7:Pr3+ shows Pr3+ emission associated with interconfigurational 4f15d1→4f2 transitions located in the UV range (250–320 nm), intraconfigurational 4f2→4f2 transitions (weak lines in the visible spectral range) and defect-related luminescence. The light output of X-ray or cathode ray excited Pr3+ 4f15d1→4f2 luminescence is found to be nearly independent of temperature in the range of 90–400 K. The output of pulsed cathode luminescence shows thermal quenching above 450 K characterized by an activation energy of about 0.5 eV. Upon excitation with pulsed cathode rays or high-frequency (~8 MHz) X-ray synchrotron radiation, the luminescence decay kinetics of Pr3+ 4f15d1→4f2 transitions are dominated by a decay component with lifetime of about 20 ns. An additional slower decay component with lifetime of 75 ns was observed upon cathode ray excitation and was shown to result from delayed host-to-impurity energy transfer. The latter, in turn, originates from re-trapping of charge carriers at defect-related traps whose presence was demonstrated by thermoluminescence measurements. Parameters of the trapping centers were estimated. Peculiarities of host-to-impurity energy transfer are analysed and discussed. © 2020 Elsevier B.V.