NIR Mechanoluminescence from Cr3+ Activated Y3Al5O12 with Intense Zero Phonon line

Mechanoluminescence (ML) materials with long‐wavelength emission bands are essential for future in vivo bioimaging, non‐destructive testing of solids, etc. The lack of a defined mechanism, however, prevents the application of near infrared ML materials above 650 nm in several new fields. Here, the addition of Ga3+ ions to Y3Al5O12: Cr3+ manipulates matrix microstructure evolution, boosting near‐infrared (NIR) zero‐phonon line (ZPL) stress optical output of the Cr3+ ion at 688 nm. The key factor changing the crystal field intensity Dq/B due to the addition of Ga3+ ions is what causes the luminescence amplification of ZPL. The ML fabricated by composite polydimethylsiloxane and Y3Al4GaO12: Cr3+ (YAGG: Cr3+) may penetrate chicken feet epidermal tissue and 4 mm pork tissue thanks to the strong NIR ZPL emission of YAGG: Cr3+ phosphor. This discovery of enhancing near‐infrared ZPL intensity by solid solution provides us with a new technique for optimizing NIR ML materials, as well as a new prospect for NIR ML materials in biological applications.