Cr3+-activated broadband near-infrared mechanoluminescence in garnet compound

Near-infrared (NIR) mechanoluminescence (ML) materials have been of great interest within biological tissues due to their biocompatibility and suitability for biostress imaging. However, the reported NIR MLs have predominantly been featured with narrowband ML emissions, which may limit their further applications. In this work, a novel broadband NIR ML material of Lu3Ga4.88O12:0.12Cr3+ (FWHM > 120 nm) is reported. By substituting Al3+ for Ga3+, the local crystal field strength and the defect concentration are reasonably regulated, which further improves the NIR ML (650–1000 nm) intensity of Cr3+ ion by 475 %. In addition, by compounding polydimethylsiloxane with this phosphor, the obtained Cr3+ NIR ML film can penetrate 10 mm pork tissues quite well, indicating potential applications for stress distribution optical imaging within living organisms. Expectingly, broadband NIR ML from Cr3+ ions can be obtained by further solid-solution multiple lattice sites substitution, which may provide a new approach to improve the performance of NIR ML materials towards expanded biological applications.