Currently, most of the mechanoluminescence (ML) phosphors strongly
depend on postirradiation stimulation using ultraviolet light (denoted as
“UV exposure” from hereon) to show the ML. However, only a few transition
metal cations are proven to be effective luminescence centers, which hinder
the development of more ML phosphors. This study reports a self-recoverable
deep-red-to-near-infrared ML using Cr
3
+
-doped LiGa
5
O
8
phosphor with fully
recoverable ML performance. The ML performance can be further optimized
by tuning the trap redistributions by codoping the phosphor with Al
3
+
and
Cr
3
+
cations. Theoretical calculations reveal the important role of Cr dopants
in the modulation of local electronic environments for achieving the ML.
Owing to the induced interelectronic levels and shallow electron trap distribu
tions, the electron recombination efficiency is enhanced both through direct
tunneling and energy transfer toward the dopant levels. Moreover, the ML of
Cr
3
+
-doped LiGa
5
O
8
can penetrate a 2-mm-thick pork slice, showing that it
can have wide-ranging in vivo applications, including the optical imaging of
intracorporal stress/strain distribution and dynamics. Therefore, this work
fabricates a novel ML material with self-recoverable luminescence in an
extended wavelength range, increasing the number of potential ML
candidates and promoting the fundamental understanding and practical
applications of ML materials.
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