Force-Induced Ultraviolet C Luminescence of Pr³⁺-Doped Sr₂P₂O₇ for X-Ray Dosimetry

Mechanoluminescent materials have broad application prospects in advanced displays, stress imaging, and anti-counterfeiting owing to their ability to convert mechanical stimuli into light. However, most previous studies have focused on the visible and near-infrared regions. Although natural ultraviolet C (UVC) light is nearly absent on the Earth's surface, it plays an important role in many fields. Therefore, the development of smart materials capable of emitting UVC mechanoluminescence (ML) and expanding the application scenarios of UVC ML are significant but challenging. Here the ML property of Sr₂P₂O₇:Pr³⁺ is examined, which stems from the 5d→4f transition of Pr³⁺ and is located over the UVC region. The peak wavelength of the UVC ML of Sr₂P₂O₇:Pr³⁺ is ≈230 nm, which is, to the best of this knowledge, the shortest ML wavelength reported to date. It is further demonstrated that the UVC ML of Sr₂P₂O₇:Pr³⁺ is associated with trapped charge carriers and can be conveniently regulated by adjusting the X-ray excitation time. Relying on this unique characteristic, the potential of the UVC ML of Sr₂P₂O₇:Pr³⁺ as an indicator of the X-ray radiation dose is demonstrated. This study enriches the family of mechanoluminescent materials and expands the available wavelength of ML to the UVC region.