Valence regulation in europium-doped fluoride phosphor for high-resolution X-ray time-lapse imaging

X-ray time-lapse imaging technology holds great potentials in healthcare diagnostics, radiation exposure monitoring and optoelectronics. However, classical methods, including optically stimulated luminescence and thermally stimulated luminescence, involve the construction of traps and release of carriers, leading to a short lifetime, instability and so on. Herein, we design a radio-photoluminescence material based on a conceptual model to achieve X-ray time-lapse imaging through X-ray-induced valence regulation in Eu-doped SrF2 phosphor. The experimental results show that the X-ray dose distribution could be accurately obtained through photoluminescence discoloration. Moreover, the time-lapse imaging information written by X-ray could also be read out quickly upon ultraviolet irradiation using a delayed method, achieving a high time-lapse imaging resolution (16.6 lp mm-1) with a short irradiation time. This excellent performance is attributed to the optimized imaging plate prepared by applying the high-temperature melting method, which reduces the spacing between europium atoms, speeds up electron transfer, and improves the reduction rate from Eu3+ to Eu2+. Meanwhile, the imaging plate displays excellent stability and reusability for X-ray time-lapse imaging. Therefore, our findings provide new insights into high-quality time-lapse X-ray imaging and dosimetry through valence regulation. In this work, we designed a RPL material SrF2:Eu which could achieve PL discoloration after X-ray irradiation. The SrF2:Eu bulk was optimized to improve the imaging quality, which is the excellent candidate for time-lapse imaging.