Solution-Processed Hybrid Europium (II) Iodide Scintillator for Sensitive X-Ray Detection

Area of Science:

• Materials Science
• Solid-State Physics
• Radiological Physics

Background:

• Lead halide perovskites show promise as X-ray scintillators but suffer from toxicity and self-absorption issues, limiting light yield.
• Bivalent europium ions (Eu²⁺) offer a non-toxic alternative with efficient, self-absorption-free d-f transitions for scintillator applications.

Purpose of the Study:

• To demonstrate solution-processed organic-inorganic hybrid halide BA₁₀EuI₁₂ single crystals as a novel X-ray scintillator.
• To evaluate the photoluminescence, scintillation, and imaging performance of BA₁₀EuI₁₂.

Main Methods:

• Crystallization of BA₁₀EuI₁₂ in a monoclinic space group (P2₁/c) with isolated [EuI₆]^4- octahedra.
• Characterization of photoluminescence quantum yield, Stokes shift, and excited-state lifetime.
• Measurement of light yield, linear scintillation response, and detection limit.
• X-ray imaging using a BA₁₀EuI₁₂/polystyrene composite film.

Main Results:

• BA₁₀EuI₁₂ single crystals exhibited a high photoluminescence quantum yield (72.5%) and large Stokes shift (97 nm).
• Achieved a light yield of 79.6% of LYSO (~27,000 photons/MeV) with a short excited-state lifetime (151 ns).
• Demonstrated a decent linear scintillation response and a low detection limit (5.83 nGy_air s^-1).
• Clear X-ray images with a spatial resolution of 8.95 lp mm^-1 were obtained using a composite film.

Conclusions:

• BA₁₀EuI₁₂ represents a promising non-toxic, high-performance scintillator material for X-ray detection.
• The d-f transition in Eu²⁺ enables efficient scintillation with potential for real-time dynamic imaging and CT applications.
• This work encourages further research into d-f transition lanthanide metal halides for advanced X-ray scintillators.