X-ray-induced photochromism and luminescence in inorganic materials: mechanisms, defect engineering, and advanced applications

X-ray responsive photochromic and radio luminescent inorganic materials have been emerging as promising multifunctional platforms for radiation responsive optical technologies. Unlike conventional photochromic systems that are activated by UV or visible light, the high energy charge carriers generated by X-ray irradiation can be trapped at intrinsic or engineered defect sites to generate color centers and induce reversible phototropism, or undergo radiative recombination to produce luminescence. This review gives an integrated overview of these inter-related processes, emphasizing the central role of X-ray generated charge carriers, defect trapping, energy transfer and radiative recombination. Recent advances in defect-engineered oxides, halides, ceramics and glass matrices are discussed, where composition, activator ions and defect states regulate the competition and synergy between photochromic and luminescent responses. Their potential applications in anti-counterfeiting, rewritable optical storage, X-ray dosimetry, radiation sensing and X-ray imaging including the emerging multimodal x-ray responsive photochromic and radioluminescence glass-based platforms are analytically studied. In additionally, we discussed the key future challenges in defect control, luminescence efficiency, reversibility, long-term stability, AI accelerated materials, and environmental stability, Integrated sensor and practical implementation are also addressed. This review offers a integrated framework to understand the synergy of X-ray induced photochromism and luminescence and design perspectives for the next-generation of multi-functional inorganic materials driven by a single high-energy X-ray stimulus.