Impact of Sc3+concentration in dodecahedral and octahedral sites of the garnet crystal lattice on the optical properties of YSAG:Sm3+powders and ceramics

Abstract

Yttrium scandium aluminum garnets doped with samarium cations (YSAG:Sm), featuring a predominant inclusion of scandium cations (Sc3+) in either the dodecahedral or octahedral sites of the crystal lattice, were investigated. The phase composition and transformation of the precursor powders were examined as a function of scandium concentration at different lattice sites, using simultaneous thermogravimetric analysis and X-ray powder diffraction. The emission and photoexcitation spectra of YSAG:Sm powders were studied in detail at both room temperature and liquid nitrogen temperature, along with the luminescence kinetics. A red shift in the luminescence maximum was observed with increasing Sc3+concentration in the dodecahedral sites, while a blue shift in the emission spectra occurred when scandium cations were incorporated into the octahedral sites. Additionally, an increase in emission intensity was noted with a higher proportion of Sc3+in the dodecahedral sites. Based on the analysis of absorption bands in the ceramics and the luminescence spectra of the powders, the energy structure of Sm3+cations was characterized.