Facile synthesis of KCl:Sm3+ nanophosphor as a new OSL dosimetric material achieved through charge transfer between the defect states

Abstract

Since precise control of nanoscale features is in high demand, it is being exploited to develop and improve OSL dosimetric materials, where striking improvement might also be expected in lanthanide-doped metal halides. The major challenge in the development of a nanophosphor lies in avoiding the aggregation of a dopant element in host materials, which has long prevented an in-depth exploration for the same purpose. This study focuses on the synthesis and characterization of Sm-doped KCl nanophosphors to develop a novel accession to investigate the highly sensitive trivalent Sm-doped KCl phosphor. Herein, we were able to overcome the aggregation phenomena and we showed that Sm-doped KCl with 0.45 mol% of Sm, which is the optimised dopant concentration, exhibits the high-intensity luminescence performance under blue light stimulation for the gamma doses in the range from 100 mGy to 1000 Gy. This sensitivity is attributed to the uniform nanospheres encapsulated in KCl along with the predominant existence of a trivalent (Sm³⁺) state, where these conditions can introduce additional defects centres. The presence of these additional defect centres was confirmed by photoluminescence studies, plausibly supporting the charge transfer due to the optical energy between these states, leading to high sensitivity. To establish KCl:Sm as a good OSL dosimetric materials (DM), we investigated fading, reusability, and reproducibility and compared these with those of commercial DM compounds such as Al₂O₃:C and BeO. Overall, Sm-doped KCl is non-toxic, cost-effective, robust, and a promising candidate for reusable dosimetry.