Tunable and enhanced mechanoluminescence in LiYGeO4:Tb3+via Bi3+ → Tb3+ energy transfer

Abstract

Mechanoluminescence (ML) materials, which can emit light under external mechanical stimuli, have attracted wide attention in diverse applications such as displays, anti-counterfeiting and 3D signatures. However, weak ML intensity and limited ML regulation methods are still limiting the development of ML materials. In this study, a series of Li_0.997YGeO₄:0.5% Bi³⁺,xTb³⁺ samples are synthesized by a high temperature solid-state reaction method. Based on photoluminescence (PL), crystal structures, ML, persistent luminescence (PersL), diffuse reflectance (DR) spectra and thermoluminescence (TL) analysis, the inherent relationship between PL, PersL and ML is further clarified in detail. The existence of abundant trap sites created by the vacancy of Li⁺ ions and the Bi³⁺ → Tb³⁺ energy transfer can improve the ML properties of phosphors. These excellent materials can open up a new approach for enhancing the ML intensity and expand the application of ML materials in the anti-counterfeiting fields.