Raman and infrared spectra of doped La8+xSr2-y(SiO4)6O2+d compounds compared to the ab initio obtained spectroscopic characteristics of fully stoichiometric La8Sr2(SiO4)6O2

International audience; Vibrational spectroscopy data were used to gain insight into the possible locations of extra oxygen ions introduced into La8+xSr2−y(SiO4)6O2+δ compounds to raise their ionic conductivity. Perturbations observed in the Raman and infrared spectra of these compounds with increasing δ were explained by using the ab initio calculation results for the fully stoichiometric (x = y = δ = 0) lattice. This allowed the inference that the extra oxygen ions are incorporated into La–O tunnel-like fragments inherent in the studied structures.