Investigation of the TL response of K2YF5:Dy3+ crystals to X and gamma radiation fields

Double potassium yttrium fluoride crystals doped with optically active rare earth ions have been recently shown to be attractive thermoluminescence (TL) materials for ionizing radiation dosimetry. In this context appropriate studies have been performed to test TL response of K2YF5 crystals doped with Dy3+ ions to photon radiation fields. Within the framework of this research K2YF5 crystals doped with 0.2, 1.0, 2.0, 5.0 and 10.0 at% Dy3+ as well as K2DyF5 and undoped K2YF5 crystals have been synthesized under hydrothermal conditions. Polished crystal platelets with thickness of about 1 mm have been irradiated with X and gamma rays in order to study TL sensitivity as well as dose and energy response properties of these compositions in terms of the Dy3+ concentration. Within this concentration series, K2YF5 crystals doped with 1.0 at% Dy3+ have been found to have maximum TL response due to a main dosimetric TL peak, which can be deconvoluted in three TL glow peaks centered at 96.4, 104.9 and 130.7∘C, with reasonable linearity behavior over the studied dose range and good reproducibility of dose measurements. The sensitivity increase is observed for previously gamma-sensitized samples and this sensitization process seems also to induce the appearing of the TL glow peak at 130.7∘C. As it has been turned, the linear TL signal coefficient for K2Y0.99Dy0.01F5 is comparable to that of a CaSO4:Mn TL dosemeter, irradiated with a 137Cs gamma radiation source at the same conditions. Photon energy dependence of TL response for K2Y0.99Dy0.01F5 has been evaluated and it has been found that TL response of this composition to the 41.1 keV X-rays is 30 times higher than that to the 662 keV gamma rays. This fact points out that K2YF5 crystals doped with Dy3+ have potential as promising materials to be used for low-dose dosimetry in X-rays diagnostic or industrial radiography.