Cerium-doped gadolinium-scandium-aluminum garnet powders: synthesis and use in X-ray luminescent diamond composites

Powders of single-phase solid solutions based on cerium-doped gadolinium-scandium-aluminum garnet were synthesized by coprecipitation from aqueous solutions followed by annealing at 1600 degrees C. The solubility limit of cerium in gadolinium-scandium-aluminum garnet was determined by X-ray powder diffraction and scanning electron microscopy. It has been demonstrated that the solubility limit of cerium depends not only on the concentration of scandium in the solid solution but also on the fraction of Sc3+ cations in the dodecahedral and octahedral positions of the garnet crystal lattice. Based on the X-ray luminescence spectra of Ce3+ (similar to 575 nm, 5d -> 4f transition) in single-phase samples, the composition (Gd2.73Ce0.02Sc0.5Al4.75O12) with the highest X-ray luminescence was determined. A diamond composite "Diamond-GSAG:Ce" with Gd2.73Ce0.02Sc0.5Al4.75O12 particles has been fabricated, which exhibits intense yellow X-ray luminescence, that is visible to the eye. The investigated class of composites is promising for applications in stable detectors and visualizers of high-intensity X-ray radiation in synchrotrons and free-electron lasers.