Influence of Antisite Defects in Yttrium–Aluminum Garnet on Paramagnetic Centers of Ce 3+ and Tb 3+

In yttrium aluminum garnet (YAG) crystals containing terbium and cerium impurities, along with the main EPR signals of Tb 3+ and Се 3+ ions located in the dodecahedral sites of the YAG lattice in a regular environment, EPR lines with a lower (several percent) intensity were observed. They also belong to the paramagnetic centers of terbium and cerium, but are characterized by slightly altered parameters—the initial level splitting for non-Kramers Tb 3+ ions and g-factors for Се 3+ ions. It is shown that the nature of such centers and their number can be explained by the presence of Y Al antisite defects, i.e. yttrium ions in the octahedral aluminum positions, in the environment of Tb 3+ and Се 3+ .