Raman scattering and X-ray powder diffraction studies of hydrate layered perovskites: dirubidium aquapentafluoromanganate(III) and dipotassium aquapentafluoroferrate(III)

摘要

The structural and vibrational properties of above mentioned crystals were determined using X-ray powder diffraction and Raman scattering experiments. At room temperature hydrate layered perovskites: Rb_2MnF_5·H_2O and K_2FeF_5·H_2O exhibit orthorhombic-Cmcm (D_(2h)~(17)) and monoclinic-C2/c (C_(2h)~6) symmetry. Their structure is built up of MnF_6 or FeF_5·H_2O octahedra forming trans-linked zig-zag chains or hydrogen bonded zig-zag chains along the major crystallographic direction [001], respectively. To confirm crystal structures and to describe lattice dynamics of these compounds the vibrational normal modes (in Γ point of first Brillouin zone) were calculated on the base of the group theory analysis and compared with the spectra obtained from Raman scattering experiments. A relatively good reliability was obtained for both X-ray powder diffraction and Raman scattering.