High Internal Stresses in Sr1-xLa1+xAl1-xMgxO4 Solid Solution (0 ≤ x ≤ 0.7) Characterized by Infrared and Raman Spectroscopies Coupled with Crystal Structure Refinement

The Sr1-xLa1+xAl1-xMgxO4 (0 ≤ x ≤ 0.7) solid solution with the K2NiF4 structure has been prepared by a new “Chimie Douce” route for the first time. The crystal structures have been refined, from X-ray diffraction patterns, in a tetragonal lattice with the I4/mmm space group. The evolution of Raman and infrared spectra as a function of the composition and the excitation wavelength are observed. These results are discussed on the basis of the interatomic distances. An assignment of the Raman and IR spectra is given for all the compositions.