Effects of La doping on the crystal growth, phase stability and scintillation properties of Lu3Al5O12 single crystals

The growth process, crystal composition, optical and scintillation properties of Lu3Al5O12:La (La = 0-0.45%) single crystals were investigated in detail. The thermodynamical stability of the garnet phase formation was studied in the undoped and La doped Lu3Al5O12 single crystals. The crystals were grown from the melt using a micro-pulling down method. Detailed composition analysis reviled the complex multiphase character of the samples. Both garnet and alpha-Al2O3 phases were detected in the undoped and slightly La-doped samples, while heavily La-doped crystals contained the mixture of alpha-Al2O3, garnet and perovskites phases. The substitution La for Lu led to the formation of La-Lu centers and increased the concentration of LuAl antisite defects. Both types of centers caused a strong luminescence in the deep UV spectral range. Heavy La-doping significantly enhanced the scintillation performance of Lu3Al5O12 crystals.