Lattice vibration spectra. LIX. Single crystal infrared and Raman studies of spinel type oxides

The infrared reflection and Raman spectra of spinel type oxides MCr 2O 4 ( M = Mg, Mn, Fe, Co, Ni, Cu, Zn), MFe 2O 4 ( M = Ni, Cu), and Mn 3O 4 (single crystals, pressed pellets) including Kramers-Kronig analyses and oscillator-fit calculations are presented. The spectra are discussed with respect to the true space group and ionicities of these compounds as well as the vibrational modes, phonon energies, and resonance Raman effects compared with the respective spectra of spinel type halides, sulfides, and selenides. Because of the relatively high porosity of the pellets obtainable the true frequencies of the IR allowed phonons can only be determined from single crystal spectra.