Tb³⁺‐Doped Ca₃Ga₄O₉ Phosphors with Color‐Tunable Photoluminescence and Non‐Pre‐Irradiation Mechanoluminescence for Multimodal Applications

Abstract Materials that can emit light under optical/mechanical stimulation are usually called photoluminescent/mechanoluminescent (PL/ML) materials. PL materials are used in diverse fields for half a century. While, ML materials have burst out in the last two decades, and now are showing great application potential in the fields of anti‐counterfeiting, information storage, and stress imaging. It is of great significance to explore new luminescent materials with PL and ML dual response. In this study, Tb³⁺‐doped Ca₃Ga₄O₉ phosphors with color‐tunable PL and non‐pre‐irradiation ML properties are reported. Ca₃Ga₄O₉ exhibits a broadband blue emission centering at 425 nm, which originates from the ⁴T₂‐⁴A₂ transition of electrons in d orbits of Ga³⁺. Due to the energy transfer from host to Tb³⁺, color‐tunable emission from blue to cyan, and ultimately to green can be realized by increasing the concentration of Tb³⁺. Particularly, ML is seen from Ca₃Ga₄O₉:Tb³⁺ under grinding and from the Ca₃Ga₄O₉:Tb³⁺/PDMS film under bending or stretching originated from the triboelectric mechanism. The non‐pre‐irradiation ML behavior is evidenced by the contrast thermoluminescence (TL) experiments. This study not only provides a new candidate toward multi‐purpose luminescent applications, but also demonstrates a good case in which the triboelectric effect can efficiently trigger the non‐pre‐irradiation ML behavior.