Self-recoverable broadband near-infrared mechanoluminescence in Cr3+-doped MgO
Near-infrared mechanoluminescent (ML) materials enable nondestructive stress detection and biological imaging, but practical deployment is constrained by narrow emission bandwidth, ultraviolet preirradiation requirements, and high stress thresholds. This study introduces Cr3+ into the simple, earth-abundant oxide host MgO to achieve self-recoverable broadband NIR ML. The optimized composition MgO:0.008Cr3+ exhibits a dominant ML peak at 809 nm with a full width at half maximum of 209 nm, and detectable emission under a 1 N stress threshold. The ML mechanism is attributed to localized piezoelectricity induced by Cr3+ incorporation. The material enables nondestructive wine quality assessment and demonstrates superior tissue penetration in a simulated biological stress imaging model. These results expand the library of self-recoverable NIR ML materials and provide a cost-effective pathway for practical NIR ML technologies.