Broadband near-infrared mechanoluminescence in Cr3+ doped Mg3Ga2GeO8

Recently, in situ and real time near-infrared mechanoluminescence (NIR ML) materials are attracting increased attention, which has potential applications such as in biostress sensing. However, most of the NIR ML materials so far are limited to narrow band emission, making it challenging to meet the requirements for specific biological applications. In this study, a novel broadband NIR ML material of Mg3GaInGeO8: 0.04Cr3+ (FWHM (full width at half maxima) = 179.4 nm,) is obtained through multi-lattice occupation and lattice engineering strategies. The crystal field strength, time decay curve and Gaussian fitting analysis reveal that the varied FWHM are attributed to the three emission Cr3+ lattice site centers. Using In3+ ion to substitute Ga3+ ion lattice site, the NIR ML peak is red-shifted (786.1 → 803.5 nm), and the FWHM value is expanded (168.0 → 179.4 nm). NIR ML signal from Mg3Ga2GeO8:Cr3+/polydimethylsiloxane (PDMS) film can easily penetrate 10 mm thick pork tissue, which may find potential applications in biostress sensing.