Eu3+-doped GAGG scintillating transparent ceramics: optimization of optical, thermal, and X-ray imaging performance

Scintillators, which are critical for X-ray detection, are widely used in medical imaging, radiation detection, and high-energy physics. In this study, Eu3+-doped Gd3Al3Ga2O12 (GAGG: xEu3+) transparent ceramic scintillators were fabricated using a solid-state reaction method combined with pressureless atmosphere sintering. The effect of Eu3+ concentration on the optical quality, scintillation performance, and thermal stability of the ceramics was systematically investigated, and their X-ray imaging performance was preliminarily evaluated. The as-prepared ceramics exhibited high optical transmittance and a uniform grain-size distribution. Photoluminescence (PL) spectra revealed characteristic Eu3+ emission peaks at approximately 590 nm, corresponding to the dominant 5D0 → 7F1 magnetic dipole transition. The optimal Eu3+ concentration was determined to be 2 at%, and the concentration quenching behavior was predominantly governed by electric dipole-dipole interactions. Furthermore, the GAGG: xEu3+ ceramics demonstrated satisfactory thermal stability and radioluminescence performance, with the radioluminescence intensity reaching its maximum at a doping concentration of 3 at%. The discrepancy between the optimal concentrations obtained from PL and radioluminescence measurements is attributed to the different excitation mechanisms involved. These results indicate that GAGG: xEu3+ transparent ceramics are promising candidates for X-ray detection and imaging applications.