Vibrational spectra of oxides with the C-type rare earth oxide structure

Infrared and Raman spectra for Mn2O3, Sc2O3,Y2O3, and In2O3 and Raman spectra for the rare earth oxides Sm2O3, Eu2O3, Dy2O3 and Yb2O3 have been measured. All compounds belong to space group Ia3,T7h. Factor group analysis predicts 4Ag, (Raman) + 4Eg (Raman) + 14Tg, (Raman) + 5Au, (inactive) + 5Eu, (inactive) + 16Tu (i.r.) modes. The predicted i.r. bands were found, whereas only about half of the 22 predicted Raman bands were observed. The highest frequency band varies linearly with the metal-oxygen distance, as observed previously in the rare earth oxides. In2O3 exhibits an anomalous splitting of the high-frequency band.