Stepwise Crystallization of Millimeter Scale Thorium Cluster Single Crystals as a Bifunctional Platform for X‐ray Detection and Shielding

Abstract Monitoring and shielding of X‐ray radiation are of paramount importance across diverse fields. However, they are frequently realized in separate protocols and a single material integrating both functions remained elusive. Herein, a hexanuclear cluster [Th₆(µ₃‐OH)₄(µ₃‐O)₄(H₂O)₆](pba)₆(HCOO)₆ (Th‐pba‐0D) incorporating high‐Z thorium cations and 3‐(pyridin‐4‐yl)benzoate ligands that can function as a brand‐new dual‐module platform for visible detection and efficient shielding of ionizing radiation is demonstrated. Th‐pba‐0D exhibits rather unique reversible radiochromism upon alternating X‐ray and UV irradiation. Moreover, the millimeter scale crystal size of Th‐pba‐0D renders the penetration depth of X‐ray visible to naked eye and leads to the unearthing of its high X‐ray attenuation efficiency. Indeed, the shielding efficacy of Th‐pba‐0D is comparable to that of lead glass containing 40% PbO, and a Th‐pba‐0D pellet with a thickness of merely 1.2 mm can shield 99.73% X‐ray (16 keV). These studies portend the possible utilization of thorium‐bearing materials as a bifunctional platform for radiation detection and shielding.