ИСТИНА

Garnet crystals with cubic symmetry Gd3Al2Ga3O12:Ce (GAGG:Ce) are high potential scintillation crystals with remarkable properties [1]. Garnet structure contains 160 elements in unit cell and one of the specific types of defects in garnets is antisite defect [2], which significantly influence on their physical properties [2, 3]. The nature of the defect structure and the mechanism of defect formation in GAGG:Ce is not clear yet. To get insight into the origin of GAGG:Ce defect structure, it is necessary to study the undoped crystal matrix in initial state. Here we present the results of our studies of the effect of the partial substitution of gallium with aluminum in gadolinium-aluminum-gallium garnet single crystals on its optical properties for the crystals in initial state and after proton irradiation. Crystals of the charge composition Gd3AlxGa5-xO12 (x=1, 2, 3) were grown in FOMOS-MATERIALS. Samples were investigated in initial state and after proton irradiation, performed at linear accelerator I-2 at the Center of Collective Use «Kamiks» of ITEP. Spectral dependences of absorption and refractive coefficients were measured using «Cary-5000» spectrophotometer with «UMA» accessory. Luminescence properties were studied using specialized set-up for VUV luminescence spectroscopy. The modification of optical band gap was determined by the Tauc method from the transmission spectra as well as by analysis of excitation spectra of Gd3+ luminescence. The dependence of optical properties on proton irradiation is shown for the samples with different composition. The origin of irradiation-induced defect centers is analysed. References [1] K. Kamada. IEEE NSS/MIC. 2011. P. 1927 – 1929. [2] E. V. Zharikov. Proc. of the USSR Ac. of Sc. Inorg. mat. 1984. V. 20. No. 6. P. 984-991. [3] K. Kamada. Optical Materials. 2014. V. 36. № 12. P. 1942–1945.