Activator segregation and micro-luminescence properties in GAGG:Ce ceramics

Abstract

ввCeramic scintillators are promising due to their potentially low cost. Here, we report on our study of Ce-doped ceramics. Typical garnet-type ceramics Gd2.97Ce0.03Al2Ga3O12 was fabricated for the study from co-precipitated powders by high-temperature sintering in air. Its structure and composition are characterized using Scanning Electron Microscope (SEM) imaging, Transmission Electron Microscopy (TEM), Electron Energy Loss Spectroscopy (EELS), Electron Backscattered Diffraction (EBSD) mapping, X-Ray Diffraction (XRD) and X-ray Absorption Near Edge Structure (XANES) measurements. The spatial distribution of luminescence properties at the micro-level is studied using scanning confocal microscopy. Cerium segregation at the grain boundaries was revealed by compositional characterization and is in line with enhanced Ce3+ photoluminescence observed at the boundaries. Meanwhile, no excess partitioning of Ce4+ ions at the grain boundaries is observed. It is found that most of Ce ions in the ceramics are stabilized in the state Ce3+, what is encouraging in view of the further development of GAGG:Ce ceramics as a promising luminescence material for lighting and scintillator application.