Synthesis and Characterization of a Compositionally Complex Aluminum Garnet Ceramic Scintillator: (Gd,Y,Tb,Lu) ₃ Al ₅ O ₁₂ :Ce

High‐energy X‐ray radiography plays a critical role in national security as it is used to scan cargo for illicit materials, including special nuclear materials. However, currently used scintillators face cost or performance drawbacks, driving the search for superior alternatives. We propose compositionally complex aluminum garnets, particularly (Gd 0.25 Y 0.25 Tb 0.25 Lu 0.25 ) 3 Al 5 O 12 :Ce 2% (GYTLAG), as a promising candidate for this application. In this work, we synthesized GYTLAG:Ce nanopowders and fabricated a highly dense ceramic via uniaxial hot pressing. Energy‐dispersive X‐ray spectroscopy mapping found a homogeneous elemental distribution within the garnet phase. The photoluminescence and scintillation decay kinetics are assessed. Notably, the 2% Ce‐doped GYTLAG ceramic exhibited a light yield of 13 500 photons per MeV and an afterglow of less than 1% of the initial intensity at 1 ms, making this material promising for high‐energy X‐ray radiography applications.