明るく素早く応答するX線検出用 新規ガーネット型シンチレータの開発に成功

2026-10-14 東北大学

図1. Y3(Al,Ga)5O12ガーネット構造にCeのみ、Ce,Mgを共添加した結晶の外観(左図)と、各試料の X線吸収分光スペクトル(右図)。Mgを共添加したサンプルでは、Ce3＋に加えてCe4＋の存在が確認できる。

＜関連情報＞

• https://www.tohoku.ac.jp/japanese/2026/10/press20261014-01-garnet.html
• https://onlinelibrary.wiley.com/doi/10.1002/lpor.71959

高性能X線イメージングのためのCe4+優勢Y3 ( Al,Ga) 5O12 : Ce,Mgシンチレーターのホスト-ドーパントエンジニアリング Host–Dopant Engineering of Ce4+-Dominant Y3(Al,Ga)5O12:Ce,Mg Scintillators for High-Performance X-Ray Imaging

Hisato Suezumi, Kei Kamada, Karol Bartosiewicz, Masao Yoshino, Liudmila Gushchina, Vladimir Babin, Yevheniia Smortsova, Nadiya Zhutova, …
Laser & Photonics Reviews  Published: 03 October 2026
DOI:https://doi.org/10.1002/lpor.71959

ABSTRACT

Fast scintillators are essential for advanced X-ray imaging and time-of-flight techniques. Although stabilizing Ce⁴⁺ ions in garnet hosts is an effective strategy for suppressing the afterglow and accelerating scintillation, it often introduces quenching pathways that reduce the light yield. This study demonstrates that synergistic host-dopant engineering in Mg²⁺ co-doped Y₃(Al,Ga)₅O₁₂:Ce enables controlled Ce⁴⁺-ion stabilization and reveals a strong Ga-dependent efficiency of Ce³⁺ to Ce⁴⁺ conversion. The X-ray absorption near edge structure spectroscopy results indicate Ce⁴⁺ fractions of 64% and 25% in Y₃Al₃Ga₂O₁₂:Ce,Mg and Y₃Al₂Ga₃O₁₂:Ce,Mg, respectively. Moreover, vacuum–UV spectroscopy demonstrates that Ce⁴⁺ ions strongly suppress trap-mediated energy transfer to the Ce³⁺ fraction, indicating a redistribution of carrier capture away from defect-related pathways. This valence state control yields an accelerated scintillation response (30–50 ns), representing a 7.1- and 3.6-fold increase in light yield for Y₃Al₃Ga₂O₁₂ and Y₃Al₂Ga₃O₁₂ respectively, and > 10² reduction in the afterglow. The X-ray imaging of biological specimens and electronic components demonstrates an improvement in spatial resolution relative to a standard Lu₃Al₅O₁₂:Ce scintillator. These results establish Ce charge-state engineering as a composition-sensitive design principle for achieving superior garnet scintillators with both fast response and high light output.