Phonon and Electronic Raman Spectra of Cubic Rare-Earth Oxides and Isomorphous Yttrium Oxide*

Laser-excited Raman spectra have been observed in single crystals of Y2O3, Y2O3(Eu3+), Er2O3, and YB2O3 at 10, 80, and 300 K. In Y2O3(Eu3+) the symmetries of the excited levels have been determined. The optically active phonons can be separated into two groups; in one group (above 300 cm−1) the internal vibrations of (R.E.-O6) octahedrons are preponderant, whereas in the other group (below 200 cm−1) the translational motions of these octahedrons and the R.E. ions are dominant. In Y2O3(Eu3+) electronic transitions (2F0 → 2F2) of the Eu ions in C3i-site symmetry have been observed and the symmetries of the crystal-field-split levels have been determined. Other effects, which may also be attributed to electronic Raman transitions, have been observed in Er2O3 and Yb2O3.