Fônons ópticos das perovsquitas duplas A2NiB”O6 (A = Ba, Sr e B” = Mo, W)

Abstract

This work reports on room temperature Raman scattering and infrared transmittance and reflectance techniques in Sr2NiWO6 (SNWO), Sr2NiMoO6 (SNMO), Ba2NiWO6 (BNWO) e Ba2NiMO6 (BNMO) double perovskites oxides. The strontium containing compounds crystallize in a tetragonal system with space group I4/m and barium containing compounds crystallize in a cubic ystem with space group Fm3m. These double perovskite structures can be represented as a three-dimensional network of alternating NiO6 and B”O6 octahedra (B” = Mo, W), with Ba and Sr atoms occupying the interstitial spaces. The Raman and infrared spectra of these crystalline perovskite oxides are interpreted by means of factor group analysis in terms of space group I4/m and Fm m. Assignments of the B”- O vibrational stretching and bending modes have been made.