Multimodal Mechanoluminescence Regulation and Mechanism Study of CaYAl₃O₇:Eu²⁺, Eu³⁺ Under Light Irradiation

Abstract

The application of mechanoluminescence (ML) in stress sensing faces certain limitations, as sensing scenarios typically involve multiple excitation conditions such as illumination, loading, and temperature. Therefore, multi-modal regulation of ML under varying conditions is important. This study investigates the ML mechanism under dual photo-load excitation conditions, examining the influence patterns of light fields and loads on the ML properties of CaYAl₃O₇:Eu²⁺, Eu³⁺ under illumination. Results demonstrate that this material enables a strong deep-red 5 D₀-7 F₄ transition without pre-excitation. Under illumination, energy stored in introduced defects (>0.726 eV) significantly enhances Eu²⁺ luminescence intensity, accompanied by pronounced blue stress afterglow; Under varying load excitations, Eu²⁺ and Eu³⁺ luminescence intensities exhibit differential sensitivity to external loads, enabling effective color tuning of ML by modulating their relative emission intensities; CaYAl₃O₇:Eu²⁺, Eu³⁺ exhibits a synergistic mechanism of trap-controlled piezoelectric ML under illumination/non-illumination conditions and triboelectric ML without pre-excitation. This enables multi-modal coupling within a single substrate, effectively suppressing signal crosstalk interference, and provides data support for enhancing the sensitivity and adaptability of stress sensing under multi-stimulus conditions.