Novel spectral band: ultraviolet A mechanoluminescence from Bi3+-doped LiYGeO4

Mechanoluminescent (ML) materials, which can emit light under external mechanical stimuli, have attracted much interest in diverse applications such as stress sensing, anti-counterfeiting and 3D signatures. However, ML materials located within the ultraviolet (UV) spectral range are still limited. In this study, a series of LixY0.995GeO4:0.005Bi3+ (0.898 ≤ x ≤ 1.003) samples are synthesized by a high temperature solid-state reaction method. The crystal structure, ML, persistent luminescence (PersL) and photoluminescence (PL) are systematically studied. The excellent UVA PersL of LiYGeO4:Bi3+ can be ascribed to the existence of abundant trap sites created by the intentional loss of Li+ ions, which can improve the ML properties of the phosphors. This excellent material can make up for the deficiency of PersL materials in the UVA region (315–450 nm), and it may greatly expand the application of ML materials in the biomedical, energy and catalysis fields.