Activation of luminescent-dosimetric properties of a single-crystal lithium-doped potassium chloride matrix.

An intense high-temperature thermally stimulated luminescence (TSL) dosimetric peak at 505 K was discovered in KCl:Li crystals. At a lithium concentration of 400 ppm, its integral light yield (ηKCl:Li) associated with the TSL505К peak exceeds the integral light yield (ηKCl) of the TSL400К peak, characteristic of pure KCl crystals, by more than two orders of magnitude. Furthermore, it significantly surpasses the corresponding light yield of the conventional dosimetric crystal LiF:Mg,Ti (ηLiF:Mg,Ti). The integral light yield (η), defined as the area under the TSL curve, was determined by integrating the intensity signals over the temperature range of 300–650 K. Long-term storage of KCl:Li crystals leads to a decrease in the integral light yield of the TSL peaks at 400 K and 505 K, which is attributed to the reduction of lithium ions from regular cationic lattice sites ( ). Regeneration of the sample by annealing at 650°C restores the maximum TSL light yield. Estimates of the tetrahedral void radius (rₜ), the radius of the "window" (rₓ) into the tetrahedral void, and the lithium ion radius ( ) indicate that the lithium ion can easily move through interstitial sites in the KCl matrix after leaving the regular lattice site ( ), since < rx < rt. The observed effect of enhancement in the integral TSL light yield at 505 K in KCl:Li crystals is promising for the development of new dosimetric detectors based on alkali halide crystals (AHCs) doped with light homologous cations (Li⁺), which are capable of localizing mobile electronic excitations and radiation defects.