A post annealing effect on SrF2 nano particles: Structural, morphological, functional and dosimetric properties

We report structural, morphological, functional and dosimetric properties of strontium fluoride (SrF2) nanophosphor synthesized by chemical co-precipitation method. The synthesized SrF2 nanophosphors are annealed at different temperatures. Samples annealed at 700 °C are observed to show optimum thermoluminescence and they are used for further processing. X-ray diffraction reveals a cubic structure having crystallite size of ∼21 nm for pristine samples and enhanced size after annealing treatment. Field emission scanning electron microscopy (i.e. FESEM) reveals growth of uniform SrF2 nanophosphors with increase in grain size for 700 °C which is in good agreement with the XRD result. In addition, we have focused on dosimetric properties and have recorded very good results of thermoluminescence (TL) glow curve, dose-response linearity, fading and trapping parameters etc. Based on the experimental results, thermoluminescence glow curve is observed at a deeper side (i.e. 210 °C) and dose-response range is achieved up to 1 kGy. Density of states obtained from density functional based calculations indicate emergence of an extra state on introduction of vacancy point defect. The new state is found to be a result of hybridization of F: d and Sr: s states, and F: p and Sr: d and f states for F and Sr vacancy defects respectively. Therefore, virgin (without any doping) nanophosphors show potential as a powerful independent thermoluminescent dosimeter (TLD) with the vacancy defects playing a key role.