A series of (CexGd1–x)3Ga2Al3O12 (x = 0–0.8%) (Ce/GGAG) crystals were grown by the optical floating zone (OFZ) method. Ce/GGAG single crystals with good crystallinity were successfully obtained by introducing oxygen atmosphere (100%) and auxiliary pressure (0.3 MPa) to suppress Ga2O3 volatilization in a container-free environment. The photoluminescence (PL) and scintillation properties of those Ce/GGAG crystals with different Ce3+ doping concentrations were investigated. In the 0.2–0.8 at. % Ce concentration range, the integral PL intensities were found to vary according to the approximate Gaussian distribution with Ce concentration, and the 0.6 at. % Ce/GGAG crystal has the highest integral PL intensity. Gd3+ emission was observed under X-ray excitation, which was rarely reported before. The maximum light yield reaches to 38,848 pho/MeV in the 0.6 at. % Ce/GGAG crystal. More importantly, fast decay and high ratio of the fast component (71 ns 66%) were successfully obtained in Ce/GGAG crystals with a Ga/Al = 2/3 ratio, which might be attributed to the suppression of composition deviation by introducing O2 (100%) atmosphere during crystal growth. It indicates that the optical floating zone method is effective in the composition engineering study of Ce/GGAG crystals to optimize the scintillation performance. © 2021 American Chemical Society

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