Single-crystal structure, cation distribution, and optical/magnetic properties of Ce3+-doped Gd3Al2Ga3O12 crystal

Ce-doped Gd3Al2Ga3O12 (Ce3+:GAGG) scintillator finds practical application in industrial computed tomography and medical imaging, however a precise understanding of its single-crystal structure has been lacking. In this study, we grew a 1-inch-sized single crystal with the nominal composition 0.5%Ce3+:GAGG using the Czochralski method. To determine the crystal structure, we employed single-crystal XRD along with element analyses using ICP and XRF-WDS techniques. Our analysis revealed the precise formula of the crystal as 0.1% Ce3+: Gd3(Ga0.543Al0.457)2(Ga0.721Al0.279)3O12. Notably, Ga3+ cations exhibit a stronger preference at the tetrahedral sites compared to Al3+ cations. The optical absorption and luminescence resulting from Ce3+ 4f-5d transitions are cross-validated in the transmission and photoluminescence spectra. From 1.8 to 300 K, Ce:GAGG exhibits paramagnetic behavior and obeys the Curie-Weiss law. The 8S7/2 ground state of Gd3+ ion contributes to the overall effective magnetic moment on the one hand and plays a significant role in energy transfer from Gd3+ and Ce3+ upon excitation on the other hand. The magneto-optical Faraday rotation measurement of Ce:GAGG was performed to determine Verdet constants at 532 nm and 633 nm. These results may help a better understanding and the practical exploitation of Ce3+:GAGG as a multifunctional material in optic and magnetic fields.