Photoluminescence studies on energy transfer processes in cerium-doped Gd3Al2Ga3O12 crystals

• Photoluminescence properties of Ce:GAGG crystals are studied with use of synchrotron radiation.
• Existence of the Gd3+ → Ce3+ energy transfer is confirmed.
• The extrinsic nature of the Gd3+ emission is clarified.
• Host sensitization processes of the Ce3+ emission are clarified.

We have measured photoluminescence properties of cerium-doped Gd3Al2Ga3O12 (Ce:GAGG) crystals at low temperatures with use of synchrotron radiation. Excitation spectra for the Ce3+ 5d–4f emission exhibit prominent peaks at Gd3+ intra-4f absorption bands. The Gd3+ intra-4f emission band is observed at 3.91 eV, but is not in resonance with the lowest energy Gd3+ intra-4f absorption band at 3.95 eV. The temperature dependence of the Gd3+ emission intensity is not correlated with that of the Ce3+ emission intensity. Decay curves of the Ce3+ emission were also measured at 9 K under excitation at various photon energies. The decay curve is remarkably changed, depending on the excitation photon energies. The present results give us hints to understand the whole of energy transfer processes in Ce:GAGG crystals.