Effect of Ge:Si ratio and charging energy on carriers trapping in Y2(Ge,Si)O5:Pr powders observed with thermoluminescence methods

Oxyorthosilicates have long history in luminescent applications e.g. as phosphors, scintillators and in emerging technologies like luminescence thermometry. In this study we report detailed research on the thermoluminescent (TL) properties of Y-2(Ge-x,Si1-x)O-5:Pr. Despite regular TL measurements, T-max-T-stop, initial rise analysis, fading, decay of persistent luminescence, and dose effect are presented and analyzed. The possibility to deliberately manage the electron trap depths adjusting the Ge/Si ratio is explored. Glow curve of each composition consists of two main TL peaks. In the (Ge,Si) solid continuous distribution of trap energies is observed. Strong thermoluminescence is observed from all compositions after charging with X-ray radiation. Efficiency of charging traps with UV-C photons (fitting the 4f -> 5d(1) transition energy) lowers systematically as the Si content increases. A growing coupling of the excited 5d(1) level of Pr3+ and the host conduction band with the increase of Ge content is responsible for this effect. A scheme of the TL-related processes is presented using the vacuum referred binding energy (VRBE) approach for all the Y-2(Ge-x,Si1-x)O-5:Pr phosphors. (C) 2020 Elsevier B.V. All rights reserved.