Realizing Near Infrared Mechanoluminescence Switch in LAGO:Cr Based on Oxygen Vacancy

Abstract

Mechanoluminescence (ML) materials are featured with the characteristic of “force to light” in response to external stimuli, which have made great progress in artificial intelligence and optical sensing. However, how to effectively enable ML in the material is a daunting challenge. Here, a Lu3Al2Ga3O12:Cr3+ (LAGO: Cr3+) near infrared (NIR) ML material peaked at 706 nm is reported, which successfully realizes the key to unlock ML by the lattice‐engineering strategy Ga3+ substitution for Al3+ to “grow” oxygen vacancy (Ov) defects. Combined with thermoluminescence measurements, the observed ML is due to the formation of defect levels and the ML intensity is proportional to it. It is confirmed by X‐ray photoelectron spectroscopy and electron paramagnetic resonance that such a process is dominated by Ov, which plays a crucial role in turning on ML in this compound. In addition, potential ML emissions from 4T2 and 2E level transitions are discussed from both experimental and theoretical aspects. This study reveals the mechanism of the change in ML behavior after cation substitution, and it may have important implications for the practical application of Ov defect‐regulated turn‐on of ML.

Visible-to-Near-Infrared Mechanoluminescence in Bi-Activated Spinel Compounds for Multiple Information Anticounterfeiting

“…Mechanoluminescence (ML) is a phenomenon whereby materials (mostly solids) emit light in response to mechanical stimuli, such as friction, tension, compression, impact, bending, and ultrasound. − Since two classic ML materials, SrAl 2 O 4 :Eu 2+ (green, 520 nm) and ZnS:Mn 2+ (yellow, 585 nm), − were reported by Xu et al in 1999, MLs have attracted tremendous interest and passion from researchers. Because of their high recoverability, stability, sensitivity, and real-time capabilities, elastic MLs (EMLs) reveal potential application values in the fields of information anticounterfeiting, − stress sensing, flexible sensors, and wearable devices .…”