Blue-Light Activated Eu²⁺-Doped Green Ultra-Stable Persistent Luminescence Material for Emergency Lighting

Area of Science:

• Materials Science
• Solid-State Chemistry
• Luminescence

Background:

• Persistent luminescence (PL) materials are crucial for safety, security, and anti-counterfeiting applications.
• Current PL materials often require ultraviolet excitation, limiting their practical use.
• Developing phosphors excitable by visible light, specifically blue light, is a significant research goal.

Purpose of the Study:

• To synthesize and characterize novel persistent luminescence phosphors (PLPs) based on Ca_8-xMg₃AlGaSi₇O₂₈:x%Eu²⁺.
• To investigate the structural, optical, and luminescence properties of these newly developed PLPs.
• To evaluate the potential applications of these blue-light-excitable phosphors.

Main Methods:

• High-temperature solid-state reaction method for phosphor synthesis.
• Rietveld refinement for crystal structure analysis (R_wp=7.85%, R_p=5.36%, χ²=2.12).
• Diffuse reflectance spectroscopy and thermoluminescence analysis to determine optical bandgap and trap depth.

Main Results:

• Successfully synthesized bright green light emitting Ca_8-xMg₃AlGaSi₇O₂₈:x%Eu²⁺ phosphors.
• Determined the crystal structure with space group P-421m, featuring CaO₈ polyhedra.
• Calculated an optical band energy (Eg) of approximately 4.02 eV for CMAGSO:0.1%Eu²⁺.
• Identified a single trap level with a depth between 0.65 and 0.66 eV.

Conclusions:

• The synthesized Ca_8-xMg₃AlGaSi₇O₂₈:x%Eu²⁺ phosphors exhibit efficient blue-light excitation and persistent luminescence.
• The materials possess suitable structural and optical properties for advanced applications.
• These phosphors demonstrate significant potential for use in security systems, information encryption, and anti-counterfeiting technologies.