Influence of precursor purity on the low-dose TL and OSL response of flux-grown pure α-Al₂O₃

Luminescence dosimetry continues to advance through efforts to improve detector sensitivity, stability, and cost-effectiveness. Within this scope, Al₂O₃ crystals were produced by the flux-growth method, a low-cost crystal growth technique, using MoO₃ precursors with purities from 99.0% to 99.95%, and Al₂O₃ of 99.99% and 99.999% purity. Elemental characterization was pursued using μ-PIXE and PIGE. The thermoluminescence (TL) and optically stimulated luminescence (OSL) characteristic response to ⁹⁰Sr/⁹⁰Y β-radiation over the dose range of 30 mGy to 15 Gy was investigated, with emphasis on the role of precursor purity, using the Risø-DA20 reader. Variations in MoO₃ purity resulted in differences in trap distribution, reflected in both TL and OSL behavior. All samples showed supralinear TL and OSL dose-response without saturation within the studied range and demonstrated high signal reproducibility (< 5%). Increasing MoO₃ and Al₂O₃ precursor purity led to substantial improvements to TL and OSL intensity by up to 67× and 14×, respectively, and significantly improved low-dose sensitivity. The results confirm that precursor purity is a critical parameter controlling luminescence efficiency in flux-grown sapphire. Overall, the flux-growth method emerges as a promising and economically attractive route for producing Al₂O₃ dosimetric materials, including for low-dose applications, using the appropriate starting materials. Further optimization of growth conditions or targeted doping strategies may enable additional improvements in detector sensitivity and performance.