Piezoelectric-induced mechanoluminescence in centrosymmetric Lu3Al5O12: Properties of self-recoverable and tunable near-infrared luminescence

Abstract

Mechanoluminescence (ML) materials with long-wavelength emission bands are essential for future in vivo bioimaging, non-destructive testing. However, most of the near-infrared (NIR) ML materials require pre-irradiation, which may limit their further applications. Generally, piezoelectric-induced ML materials were considered to be related to the piezoelectric effect from non-centrosymmetric structure. Innovatively in this work, a novel piezoelectric-induced near-infrared ML material Lu3Al5O12:Cr3+ with centrosymmetric structure is obtained. In Lu3Al5O12:Cr3+, piezoelectric effect is generated from the distortion of the centrosymmetric structure of the host due to the uneven electron distribution of Cr3+. Here, highly tunable ML FWHM from 7 nm to 118 nm is realized by introducing different content Ga3+ ions to Lu3Al5O12:Cr3+. The ML film fabricated by composite polydimethylsiloxane and Lu3Al2Ga3O12:Cr3+ can penetrate 20 mm pork tissue, which suggests the potential applications of the NIR ML material in the field of optical imaging of stress distribution in organisms. The discovery of distorted crystal structure to induce piezoelectric effect provides a new thinking for exploring ML in centrosymmetric materials. In addition, LuAl5-xGaxO:Cr3+ phosphors have broad prospects in self-powered sensing, temporomandibular disorders diagnosis, information security, and biomedical fields.