Rare-earth antisites in lutetium aluminum garnets: Influence on lattice parameter and Ce³⁺ multicenter structure

Low temperature, infrared transmission spectra of lutetium aluminum garnet (LuAG) bulk crystals and epitaxial layers doped with Ce are presented. In the region of intra-configurational 4f-4f transitions the spectra of the bulk LuAG crystal exhibit the signatures of several different Ce³⁺ related centers. Apart from the dominant center, associated with Ce substituting lutetium, at least six other centers are found, some of them attributed to so-called antisite locations of rare-earth ions in the garnet host, i.e., ions in the Al positions. X-ray diffraction data prove lattice expansion of bulk LuAG crystals due presence of rare-earth antisites.