Raman scattering study of RETiTaO6 dielectric ceramics

In this work we have investigated microwave-dielectric ceramics RETiTaO6 (RE=Al, Y, In, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er or Yb) by Raman scattering measurements at room temperature. The observed Raman-active phonons were analysed in conformity with two orthorhombic structures proposed for these ceramics, namely aeschynite (for lanthanide ions with atomic number between 58 and 66) or euxenite (for Y, Ho, Er and Yb). The results indicate that the phonon spectra remained relatively unchanged with respect to the RE ion substitution within each structure. For the three remaining materials with RE=La, Al and In, which are known to present multiphases, the Raman phonon spectra showed significant differences in comparison with those of ceramics with aeschynite and euxenite structure.