Electron Paramagnetic Resonance Study of Radiation-Induced Defects in Ba₃(PO₄)₂.

Area of Science:

• Materials Science
• Solid State Physics
• Radiochemistry

Background:

• Barium phosphate (Ba₃(PO₄)₂) is a promising host material for rare-earth dopants.
• It has potential applications in optical devices and dosimetry.
• Understanding radiation-induced defects is crucial for its stability and performance.

Purpose of the Study:

• Investigate radiation-induced defects in Ba₃(PO₄)₂ using electron paramagnetic resonance (EPR).
• Determine the role of these defects in radio-photoluminescence (RPL).
• Compare the effects of ultraviolet (UV) and X-ray irradiation on defect formation and electron trapping.

Main Methods:

• Electron Paramagnetic Resonance (EPR) spectroscopy, including Q-band and X-band analysis.
• Irradiation of both Eu-doped and undoped Ba₃(PO₄)₂ samples with UV and X-rays.
• Comparative analysis of spectral data to identify defect centers.

Main Results:

• Both UV and X-ray irradiation create Eu²⁺ centers with axial symmetry at a specific Ba lattice site.
• Radiation induces intrinsic defects unrelated to Eu dopants, observed via EPR signals near g≈2.
• An H⁰ center and two electron-trapping defects, including a potential oxygen vacancy (F-type center), were identified.

Conclusions:

• The study elucidates the complex defect landscape in Ba₃(PO₄)₂ under irradiation.
• Identified defects influence charge trapping and stability, critical for RPL applications.
• Findings provide a foundation for optimizing Ba₃(PO₄)₂ for optical and dosimetric applications.