New mode of stress sensing in multicolor (Ca_1-xSr_x)₈Mg₃Al₂Si₇O₂₈:Eu²⁺ solid-solution compounds

Multicolor-emitting elastico-mechanoluminescent (elastico-ML) solid solution compounds (Ca_1-xSr_x)₈Mg₃Al₂Si₇O₂₈:Eu²⁺ were developed. By adjusting the Sr substitution in (Ca_1-xSr_x)₈Mg₃Al₂Si₇O₂₈:Eu²⁺, the elastico-ML emission could be tuned from green to blue under the elastic stress. To realize stress-induced ML spectral migration, the ML pellet both contained Ca₈Mg₃Al₂Si₇O₂₈:Eu²⁺ and Sr₈Mg₃Al₂Si₇O₂₈:Eu²⁺ was prepared. Different from the friction induced color change, this ML pellet could realize the ML spectral migration under the elastic stress. These properties were ideal for overhauling the stress sensing method by ML technology based on the detection of ML intensity, which played a good role in promoting the practicality and diversification of the future ML technology. DFT calculations reveal that the increasing doping of Sr modulates the electronic structures of the materials, which not only activates the site-to-site p-p couplings to prolong the electron-hole recombination but also improves the electron transfer efficiency to achieve remarkable ML performance. This work has supplied new insights into the design and modulations of novel ML functional materials to realize broad applications.