Shaped single crystals of (LuxGd1-x) 3Ga5O12 (0.0≤x≤1.0) and (Yb 0.05LuxGd0.95-x)3Ga 5O12 (0.0≤x≤0.9) were grown by the modified micro-pulling-down method. Continuous solid solutions with garnet structure and a linear compositional dependency of crystal lattice parameter in the system Yb:(Gd,Lu)3Ga5O12 are formed. Measured optical absorption spectra of the samples show 4f-4f transitions related to Gd 3+ ion at 275 and 310 nm, and also an onset of charge transfer transitions from oxygen ligands to Gd3+ or Yb3+ cations below 240 nm. A complete absence of Yb3+ charge transfer luminescence under X-ray excitation in any of the investigated samples was explained by the overlapping of charge transfer absorption of Yb3+ by that of Gd 3+ ions. For specific composition of Lu1.5Gd 1.5Ga5O12 an intense defect-host lattice-related emission, which achieve of about 40% integrated intensity compared with Bi4Ge3O12, was found.
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