Giant Pressure‐Induced Spectral Shift in Cyan‐Emitting Eu ²⁺ ‐Activated Sr ₈ Si ₄ O ₁₂ Cl ₈ Microspheres for Ultrasensitive Visual Manometry

Abstract To address the unsatisfactory pressure sensitivity of luminescent manometers, Eu 2+ ‐activated supersensitive microspheres operating in the visible range are developed. A series of Eu 2+ ‐doped Sr 8 Si 4 O 12 C l8 materials are synthesized as microspheres, and their structural and spectroscopic properties are studied theoretically and experimentally. Excited at 350 nm, the samples emit a bright cyan luminescence at ambient conditions that, upon pressure, changes to green emission and finally to yellow light above 7 GPa. Most importantly, a huge red‐shift of the emission band from 497.3 to 568.8 nm is observed as the pressure increases, leading to an ultrahigh‐pressure sensitivity of 9.69 nm/GPa, which is the highest sensitivity ever reported. The designed microspheres with polychromatic emissions and high‐pressure sensitivity are suitable for visual optical pressure sensing, and the applied strategy provides some important guidelines for the development of new optical manometers, allowing pressure monitoring with unprecedented accuracy.