Cationic Substituent Engineering to Enhance Glassy Stability of Manganese Halide Scintillators for Advanced 3D X‐ray Reconstruction

Organic–inorganic hybrid manganese(II) halide glasses exhibit advantages such as exceptional optical transparency, straightforward preparation processes, and potential for large‐scale production. However, the crystallization phenomenon easily occurring in this glass material can induce a marked reduction in transparency, which significantly compromises its X‐ray imaging performance. Herein, a cationic substituent regulation strategy is developed to improve the glassy stability of manganese(II) halides. By replacing the phenyl group in Ph‐Mn cation with methylcyclohexyl substituent, a novel manganese(II) halide MCy‐Mn is successfully synthesized. Such a substitution strategy can effectively weaken both the cation–anion interactions and π–π stacking interactions within the manganese(II) halide lattice, resulting in a remarkable reduction in melting point (Tm). Moreover, the inherent rigid structure of MCy‐Mn also confers an elevated glass transition temperature (Tg). Consequently, the resultant MCy‐Mn crystal demonstrates a high Tg/Tm ratio of 0.82. Besides, the fabricated MCy‐Mn scintillation glass exhibits a high spatial resolution of 19.3 lp mm−1 and has successfully achieved 3D X‐ray reconstruction. As anticipated, MCy‐Mn glass exhibits outstanding environmental stability, with no crystallization observed after being exposed to atmospheric conditions for 30 days. This work provides valuable insights for the development of high‐stability metal halide scintillation glasses.