Raman characterisation of powder of cubic RE2O3 (RE = Nd, Gd, Dy, Tm, and Lu), Sc2O3 and Y2O3

Raman spectra of cubic Sc2O3, Y2O3 and C-type rare earth oxides are presented. Cubic Nd2O3 is prepared by thermal decomposition of its hydroxide. The decomposition mechanism happens in two steps. At the end of this process cubic Nd2O3 form. All Raman spectra are characterised by the presence of a very strong band in the range 320–420 cm−1, depending on the lattice parameter of each oxide. Frequency of this line decreases increasing the cell constant, meaning that the structure becomes less rigid. A simply approach is used in order to give a consistent evaluation of the force constant of each oxide. The position of the low wave number bands depends mainly on the cationic mass, meaning that these bands are not due to stretching vibrations, but rather to bending vibrations.