Modeling Polyhedron Distortion for Mechanoluminescence in Mixed-Anion Compounds RE2O2S:Ln~(3+)

摘要

Mechanoluminescent (ML) materials with the characteristics ofphoton emission under mechanical stimulation show broad application prospectsin building structural health diagnosis, biomechanical engineering, and wearabledevices. However, existing ML materials cannot fully meet the requirements ofdifferent stress sensing applications due to the limited understanding of thestructure and mechano-to-photon conversion mechanism of ML materials. Herein,we report novel ML materials with excellent self-recoverable ML performance inthe family of mixed-anion compounds RE2O2S:Ln~(3+) (RE = Y, Lu, La, Gd). TheML intensity is linearly related to the applied force, and the ML wavelength istunable over a broad range of 514-1550 nm. More importantly, we construct apolyhedron distortion model that describes the local symmetry breaking. This model well explains the origin of ML andpiezoelectricity in the compounds with centrosymmetric crystal structures. The findings may deepen the understanding of themicrostructure and the mechano-to-photon conversion mechanism in ML materials and are expected to provide important guidancefor the development of high-performance ML materials.