In this paper, we have performed comparative analysis of EPR, optical absorption (OA) and luminescence spectra for a series of Gd₃Ga₅O₁₂ (GGG) single crystals irradiated with fast neutrons with fluencies varied from 10¹⁶ to 10²⁰n/cm². In a crystal irradiated with the maximum neutron fluence, the EPR spectra demonstrated the formation of several paramagnetic defects. In particular, EPR spectrum shows a strong resonance at (effective) g ≈ 1.4 with practically isotropic behavior in the crystal rotation around the [1 1 1] direction (magnetic field being perpendicular to [1 1 1]) and several weaker lines in the g ≈ 1.1–2.6 region, which show more pronounced angular dependences. While the photoluminescence of non-irradiated GGG is characterized by uncontrolled impurities, in the case of neutron-irradiated GGG, a broad asymmetric luminescence band was observed with a peak at 725–733 nm, which increased with fluence. Consequently, this band can be associated with the formation of radiation defects.

In this paper, we have performed comparative analysis of EPR, optical absorption (OA) and luminescence spectra for a series of Gd₃Ga₅O₁₂ (GGG) single crystals irradiated with fast neutrons with fluencies varied from 10¹⁶ to 10²⁰n/cm². In a crystal irradiated with the maximum neutron fluence, the EPR spectra demonstrated the formation of several paramagnetic defects. In particular, EPR spectrum shows a strong resonance at (effective) g ≈ 1.4 with practically isotropic behavior in the crystal rotation around the [1 1 1] direction (magnetic field being perpendicular to [1 1 1]) and several weaker lines in the g≈1.1–2.6区域，显示出更明显的角度依赖性。尽管未辐照的GGG的光致发光的特征是不受控制的杂质，但在中子辐照的GGG的情况下，观察到了宽的不对称发光带，其峰值在725-733 nm处，并随着通量的增加而增加。因此，该带可能与辐射缺陷的形成有关。