Eu ²⁺ ‐Activated KGa ₅ S ₈ : A New Super‐Sensitive Green Emitting Phosphor for Pressure Sensing

ABSTRACT Optical pressure sensing plays a crucial role in high‐pressure research and materials science, yet luminescent manometers that combine high sensitivity with a visually detectable color change remain rare. In this work, a novel Eu ²⁺ ‐activated KGa ₅ S ₈ green‐emitting phosphor has been successfully synthesized, demonstrating remarkable piezochromic properties. When the applied pressure is varied from 1 atm (∼0.1 GPa) to 10.44 GPa, a significant spectral redshift is observed in the sample. This results in a visually striking color transition, shifting from a green emission peaking at 541 nm to a red emission peaking at 697 nm. This transition yields an exceptionally high‐pressure linear sensitivity of d λ/ d P = 14.49 nm/GPa, marking it as the highest value reported to date among pressure‐sensing materials with emission in the visible range. The multicolor emission variation is attributed to pressure‐induced electronic structure modulation, enabling sensitive pressure detection. This study provides a new piezochromic phosphor with record sensitivity and an obvious visual color change, offering a promising candidate for high‐pressure sensing applications.