Ultraviolet-C persistent luminescence and defect properties in Ca2Al2SiO7:Pr3+

Abstract

In recent years, significant attention has been focused on the study of materials with ultraviolet (UV) persistent luminescence (PersL) due to their prospective application possibilities. Although novel UV persistent phosphors are being developed, reports on defect properties and PersL mechanisms are limited. In this study, the incorporation of Pr 3+ ions in Ca 2 Al 2 SiO 7 is analyzed using X-ray diffraction (XRD) and X-ray absorption techniques, whereas PersL properties are characterized by photoluminescence (PL), thermostimulated luminescence (TSL) and electron paramagnetic resonance (EPR) methods. Analysis of the Pr L 3 -edge X-ray absorption spectra suggests that praseodymium atoms substitute for calcium atoms. The UV-C PersL of the host results from thermally assisted recombination of charge carriers with trap depths within the 0.50–0.87 eV range. Moreover, a partial correlation of PersL and TSL with the decay of X-ray-induced paramagnetic centers was observed. This study expands the knowledge base on the structure of Ca 2 Al 2 SiO 7 and establishes the optimal Pr 3+ concentration for efficient UV-C PersL. • Trap properties and Pr 3+ local structure in UV-C phosphor Ca 2 Al 2 SiO 7 are analyzed • EXAFS simulations indicate that Pr 3+ substitutes for Ca 2+ • Optimal Pr 3+ concentration for UV-C persistent luminescence is 0.3% • Trap activation energies are continuously distributed within 0.50–0.87 eV range • Decay of three EPR-active centers is partially correlated with TSL