Combustion synthesis of blue-emitting submicron CaAl4O7:Eu2+, Dy3+ persistence phosphor

Area of Science:

• Materials Science
• Solid State Chemistry
• Luminescence

Background:

• Long persistence phosphors (LPPs) are crucial for applications requiring sustained light emission.
• Calcium aluminate (CaAl4O7) based phosphors offer tunable optical properties.
• Rare-earth doping (Eu2+, Dy3+) is a common strategy to achieve desired luminescence characteristics.

Purpose of the Study:

• To synthesize and characterize a novel long persistence phosphor, CaAl4O7:Eu(2+), Dy(3+).
• To investigate the photoluminescence properties and decay mechanisms of the synthesized phosphor.
• To evaluate the potential applications of this phosphor in signage and defense.

Main Methods:

• Combustion synthesis method for phosphor preparation.
• X-ray diffraction (XRD) for structural analysis.
• Scanning electron microscopy (SEM) for surface morphology.
• Photoluminescence (PL) spectroscopy for emission analysis.
• Decay time measurements for luminescence persistence.

Main Results:

• The CaAl4O7:Eu(2+), Dy(3+) phosphor exhibits broad blue emission peaking at 445 nm upon excitation at 341 nm.
• The blue emission is attributed to the 4f→5d transitions of Eu(2+) ions.
• Decay curves show both fast and slow components, indicating long persistence.
• SEM analysis provided insights into the surface morphology.
• Calculated CIE color coordinates were (0.227, 0.43).

Conclusions:

• The synthesized CaAl4O7:Eu(2+), Dy(3+) phosphor demonstrates promising long-persistence luminescence properties.
• The material's blue emission and sustained light output suggest suitability for practical applications.
• Potential applications include safety signage, emergency exit markers, and defense-related illumination devices.