Computational Investigation of the Electronic Structure of Molybdenum-Doped Lead Tungstate (PbW1−xMoxO4) Scintillators

Abstract

Lead tungstate (PbWO₄) is a prominent scintillator used in high-energy physics experiments owing to its rapid decay time (5 ns) and excellent radiation hardness. However, its low light yield (≈ 200 ph/MeV) limits its utility in medical imaging applications, such as positron emission tomography (PET), which requires higher scintillation efficiency. This study investigates the effects of molybdenum (Mo) doping on the electronic properties of PbW_1−xMo_xO₄ (x = 0.25, 0.5, 0.75) using density functional theory (DFT). Calculations were performed within the GGA+U framework as implemented in the VASP software, utilizing the projector-augmented-wave (PAW) method. Our results reveal a bandgap transition dependent on the doping concentration: x = 0.25 exhibits a direct bandgap of 3.82 eV, while x = 0.5 and x = 0.75 demonstrate indirect bandgaps of 3.62 eV and 3.58 eV, respectively. We observe a systematic decrease in the bandgap as the Mo concentration increases, suggesting a tunable electronic structure. These findings provide a theoretical foundation for the optimization of PbWO₄-based scintillators.