Ce-doped yttrium aluminum garnet (YAG) is among the efficient rare-earth garnet scintillators and phosphors. Herein, a computational and experimental study of complex F-type defect centers formed in YAG by doping with cerium and carbon is addressed. The formation energies determined by ab initio calculations of different defects and atomic chemical potentials in YAG:Ce,C are discussed in O-poor and O-rich conditions corresponding to the crystal growth under Ar+CO reducing atmosphere, and postgrowth annealing in air, respectively. It is shown that as-grown crystals contain numerous positively charged defects responsible for F-type center formation, whereas mainly negative-charged defects are remained after the annealing in air. The negatively charged defects located nearby Ce luminescence center occupying Y site may stabilize cerium in the tetravalent state and promote a hole transport to this luminescence center. This describes a high scintillation efficiency of Ce,C-doped garnets. Furthermore, YAG:C and YAG:Ce,C with a high carbon concentration, in addition to luminescence peaked at 400 ns ascribed to F⁺-type centers, possess a fast luminescence peaked around 650 nm that may be attributed to the complex defect centers. These unveiled features of the luminescence process in rare-earth garnets may contribute to the development of efficient luminescence materials.

中文翻译：

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碳掺杂对 YAG 和 YAG:Ce 晶体中 F 型缺陷的影响

Ce 掺杂的钇铝石榴石 (YAG) 是高效的稀土石榴石闪烁体和荧光粉之一。在此，对通过掺杂铈和碳在 YAG 中形成的复杂 F 型缺陷中心进行了计算和实验研究。通过对 YAG:Ce,C 中不同缺陷和原子化学势的从头计算确定的形成能在对应于 Ar+CO 还原气氛下的晶体生长和空气中的后生长退火的贫氧和富氧条件下进行了讨论，分别。结果表明，生长的晶体包含许多导致 F 型中心形成的带正电荷的缺陷，而在空气中退火后主要保留带负电荷的缺陷。位于占据 Y 位点的 Ce 发光中心附近的带负电荷的缺陷可以稳定四价状态的铈并促进空穴传输到该发光中心。这描述了 Ce、C 掺杂的石榴石的高闪烁效率。此外，具有高碳浓度的 YAG:C 和 YAG:Ce,C，除了归因于 F 的发光在 400 ns 达到峰值⁺型中心，具有在 650 nm 附近达到峰值的快速发光，这可能归因于复杂的缺陷中心。稀土石榴石发光过程的这些揭示特征可能有助于开发高效发光材料。