Zhang Pan, Zheng Zhongzhong, Wu Li, Kong Yongfa, Zhang Yi, Xu Jingjun
Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics, Nankai University, Tianjin 300071, China.
College of Electronic Information and Optical Engineering and Tianjin Key Laboratory of Photo-electronic Thin Film Devices and Technology, Nankai University, Tianjin 300071, China.
Inorg Chem. 2021 Dec 6;60(23):18432-18441. doi: 10.1021/acs.inorgchem.1c03022. Epub 2021 Nov 18.
Mechanoluminescent materials have shown great application potential in the fields of stress detection, anti-counterfeiting, and optical storage; however, its development is hindered by the unclear mechanism. Different from the mainstream exploration of new mechanoluminescent materials in non-centrosymmetric structures, a centrosymmetric mechanoluminescent material LiZnGeO:Mn is synthesized by a standard high-temperature solid-state reaction in an ambient atmosphere. Combined with the Rietveld refinement, photoluminescence, electron spin resonance, and X-ray photoelectron spectroscopy, it is proved that the increase in oxygen vacancies is accompanied by the self-reduction process from Mn to Mn, and the mechanism of mechanoluminescence is clarified through the afterglow and thermoluminescence spectra. The carriers trapped by the shallow traps participate in the mechanoluminescence process through the tunneling effect, while the carriers trapped by the deep traps take part in the mechanoluminescence process via conduction band or tunneling. A signature anti-counterfeiting application is designed using the new mechanoluminescent material LiZnGeO:0.004Mn. Utilizing the afterglow characteristics of LiZnGeO:Mn phosphors, we designed an intelligent long-persistent luminescence quick response code (QR-code) and visualized information encoding/decoding model, which provides a fast, simple, and effective method for information encryption, transformation, and dynamic anti-counterfeiting. This study not only analyzes the self-reduction and mechanoluminescence processes in detail but also breaks the limitation of crystal symmetry and provides a new strategy for the exploration of novel mechanoluminescent materials.
机械发光材料在应力检测、防伪和光存储等领域展现出了巨大的应用潜力；然而，其发展受到机理不明的阻碍。与非中心对称结构中新型机械发光材料的主流探索不同，通过在环境气氛中采用标准高温固相反应合成了一种中心对称的机械发光材料LiZnGeO:Mn。结合Rietveld精修、光致发光、电子自旋共振和X射线光电子能谱，证明氧空位的增加伴随着Mn到Mn的自还原过程，并通过余辉和热释光光谱阐明了机械发光的机理。浅陷阱捕获的载流子通过隧穿效应参与机械发光过程，而深陷阱捕获的载流子则通过导带或隧穿参与机械发光过程。利用新型机械发光材料LiZnGeO:0.004Mn设计了一种标志性防伪应用。利用LiZnGeO:Mn荧光粉的余辉特性，我们设计了一种智能长效发光二维码（QR码）以及可视化信息编码/解码模型，为信息加密、转换和动态防伪提供了一种快速、简单且有效的方法。本研究不仅详细分析了自还原和机械发光过程，还突破了晶体对称性的限制，为新型机械发光材料的探索提供了新策略。
