Multicolor Mechanoluminescence in Sr₂Ga₂GeO₇: Pr³⁺ for Stress Sensing and Anticounterfeiting

Abstract

Mechanical luminescence (ML) is the conversion of mechanical energy into light energy when a material is subjected to a force. It is challenging to develop ML materials with tunable luminescent properties by single ion doping, which have broad application prospects in the fields of stress sensing and dynamic signature anticounterfeiting. In this study, a Pr3+ doped Sr2Ga2GeO7 tunable ML material is reported. Due to the traps resulting from unequal substitution of Pr3+–Sr2+ in [SrO6] heptahedra, the deep/shallow traps redistribution occurs towards a multicolor ML from red to green. In addition, even after continuous friction sliding force (15 N), the ML intensities can be recovered after ultraviolet pre‐irradiation, indicating that Sr2Ga2GeO7: Pr3+ has excellent ML emission stability. Based on thermoluminescence analysis, potential PersL and ML mechanisms are further elaborated by a lattice engineering (trap regulation) strategy. In all, the development of single‐ion doped multicolor ML materials may have crucial research value and show a variety of potential applications in the fields of anticounterfeiting and information encryption.

Luminescence properties of a green-emitting mechanoluminescent phosphor CaSrGa4O8:xTb3+ without pre-excitation

“…According to the Hume-Rothery rules, a solid solution is viable if the atomic radius difference between the solute and solvent ions is within 30%. The ionic radius difference is calculated using the formula (1): 36,37 where D r is the percentage difference of radius, R m ( C N ) is the radius of the main ion to be replaced, and R d ( C N ) is the radius of the doped ion. Considering the valence and ionic radius of Tb 3+ ions (for C N = 6, r = 0.92 Å) and Ca 2+ ions (for C N = 6, r = 1.00 Å), and the larger difference with Sr 2+ ions (for C N = 6, r = 1.18 Å), Tb 3+ ions are more likely to replace the Ca 2+ ions in the lattice.…”

Multi-Mode Luminescence in Smart Near-Infrared Cr3+/Pr3+ Codoped SrGa12O19 Phosphors Induced by Three Distinct Excitation Mechanisms

“…The ion displacement diagram illustrates the 6-coordination of gallium ions and the 12-coordination of strontium ions forming a [GaO 6 ] octahedron (Figure S3). 25,26 Following the principle of valence balance and ionic radius similarity, Cr 3+ (r = 0.615 Å) preferably replaces Ga 3+ (r = 0.62 Å) and coordinates with 6 O atoms to form [CrO 6 ] octahedron, while Pr 3+ (r = 1.01 Å) replaces Sr 2+ (r = 1.12 Å). 27 To further investigate the microstructure and elemental composition of the material, we selected the SGO:5%Cr 3+ /3% Pr 3+ sample and conducted SEM scanning and EDS elemental analysis.…”

“…The ion displacement diagram illustrates the 6-coordination of gallium ions and the 12-coordination of strontium ions forming a [GaO 6 ] octahedron (Figure S3). , Following the principle of valence balance and ionic radius similarity, Cr 3+ ( r = 0.615 Å) preferably replaces Ga 3+ ( r = 0.62 Å) and coordinates with 6 O atoms to form [CrO 6 ] octahedron, while Pr 3+ ( r = 1.01 Å) replaces Sr 2+ ( r = 1.12 Å) …”

“…Carriers released from deeper traps combine with holes through tunneling, leading to optimized Cr 3+ NIR luminescence. 25,37,45 3.6. To Develop a Multifunctional NIR pc-LED.…”

Visible-to-Near-Infrared Mechanoluminescence in Bi-Activated Spinel Compounds for Multiple Information Anticounterfeiting

“…Mechanoluminescence (ML) is a phenomenon whereby materials (mostly solids) emit light in response to mechanical stimuli, such as friction, tension, compression, impact, bending, and ultrasound. − Since two classic ML materials, SrAl 2 O 4 :Eu 2+ (green, 520 nm) and ZnS:Mn 2+ (yellow, 585 nm), − were reported by Xu et al in 1999, MLs have attracted tremendous interest and passion from researchers. Because of their high recoverability, stability, sensitivity, and real-time capabilities, elastic MLs (EMLs) reveal potential application values in the fields of information anticounterfeiting, − stress sensing, flexible sensors, and wearable devices . Consequently, innumerable emerging EMLs have been developed one after another, with their luminescence characteristics and relevant mechanisms gradually being unveiled.…”