A multi-color persistent luminescent phosphor β-NaYF₄:RE³⁺ (RE = Sm, Tb, Dy, Pr) for dynamic anti-counterfeiting

Area of Science:

• Materials Science
• Solid State Chemistry
• Luminescence

Background:

• Conventional luminescent materials often lack multi-color and persistent emission, limiting their use in advanced anti-counterfeiting.
• High-level anti-counterfeiting strategies require materials with complex and durable luminescent properties.

Purpose of the Study:

• To develop novel multi-color and ultra-long persistent luminescent phosphors for advanced anti-counterfeiting.
• To investigate the influence of rare earth doping on the properties of β-NaYF₄ phosphors.
• To explore the mechanism behind the persistent luminescence.

Main Methods:

• Synthesis of β-NaYF₄:RE³⁺ (RE = Sm, Tb, Dy, Pr) phosphors.
• Characterization of crystal structure, size, and morphology.
• Evaluation of radioluminescence and persistent luminescence properties under X-ray excitation.
• Analysis of defect generation and electron trapping mechanisms.

Main Results:

• Multi-color emission and ultra-long persistent luminescence (up to 7 days) observed in β-NaYF₄:RE³⁺ phosphors under X-ray irradiation.
• β-NaYF₄:Tb³⁺ crystals demonstrated strong X-ray response and extended afterglow.
• Frenkel defects (F vacancies and interstitials) were identified as key to electron trapping and slow release, enabling persistent luminescence.
• Dynamic anti-counterfeiting patterns with time-resolved information were successfully designed.

Conclusions:

• The developed β-NaYF₄:RE³⁺ phosphors exhibit exceptional radioluminescence and persistent luminescence properties.
• These phosphors are highly suitable for sophisticated anti-counterfeiting applications due to their multi-color and long-lasting emission.
• The understanding of defect-induced persistent luminescence provides a pathway for designing next-generation luminescent materials.