Bright exciton luminescence from La doped Lu₃Al₅O₁₂ single crystals

This research dealt with the investigation of luminescence properties of undoped and La doped Lu₃Al₅O₁₂ single crystals using synchrotron radiation excitation. The influence of La³⁺ doping on the exciton emission and decay kinetics properties of Lu₃Al₅O₁₂ single crystals was studied at 7 K and room temperature. Undoped and La³⁺ doped samples showed bright luminescence in the UV spectral range. In undoped Lu₃Al₅O₁₂ crystal, the UV luminescence was associated with Lu_Al antisite defects, which acted as luminescence centers in the band peaked at 295 nm La³⁺ doping in Lu₃Al₅O₁₂ crystals caused the formation of La_Lu luminescence centers and increased the concentration of Lu_Al antisite defects. Therefore, the luminescence of La doped Lu₃Al₅O₁₂ crystals was a superposition of the emission coming from both La_Lu and Lu_Al centers. Furthermore, La³⁺ doping significantly enhanced the intensity and shifted the UV luminescence of Lu₃Al₅O₁₂ crystals towards higher energy due to the dominant contribution of La_Lu luminescent centers in the band peaked at 275 nm. The decay time of heavily La³⁺ doped LuAG crystals was also significantly accelerated due to the prevailing luminescence of La_Lu centers.