Crystal growth and characterization of Ce:Gd3(Ga,Al)5O12 single crystal using floating zone method in different O2 partial pressure

• Ce:Gd3(Ga,Al)5O12 single crystals grown by floating zone method under atmosphere with different O2 content.
• Ga evaporation from melt suppressed in oxygen-rich atmosphere.
• Highest light yield obtained for 100% oxygen atmosphere.
• Intense slow decay component observed for oxygen-free atmosphere.

Multicomponent garnet Ce:Gd3(Ga,Al)5O12 (Ce:GAGG) single crystals show very high light yield with reasonably fast scintillation response. Therefore, they can be promising scintillators for gamma-ray detection. However, in the decay curve a very slow component does exist. Therefore, it is necessary to optimize further the crystal growth technology of Ce:GAGG. In this study, Ce:GAGG single crystals were grown by the floating zone (FZ) method under atmospheres of various compositions such as Ar 100%, Ar 80% + O2 20%, Ar 60% + O2 40% and O2 100%. Radioluminescence spectra are dominated by the band at about 540 nm due to Ce3+ 5d1–4f transition. The Ce:GAGG single crystal grown under Ar atmosphere shows an intense slower decay component. It can be related to the processes of the delayed radiative recombination and thermally induced ionization of 5d1 level of Ce3+ center possibly further affected by oxygen vacancies. This slower decay process is significantly suppressed in the samples grown under the O2 containing atmosphere.