X-ray diffraction and Raman spectroscopy studies of BaSrMWO6 (MNi, Co, Mg) double perovskite oxides

In this work we report on the crystal structure and Raman spectroscopy of BaSrMWO6 (MNi, Co, Mg) double perovskite oxides. The results showed that the Ni, Co and Mg containing compounds crystallize in a cubic system with the space group Fm-3 m. The double perovskite structure can be represented as a three-dimensional network of alternating MO6 and WO6 octahedra, with Ba- and Sr-atoms occupying the interstitial spaces. The Raman spectra of this crystalline perovskite oxides are interpreted by means of factor group analysis in terms of space group Fm-3 m. Assignments of the WO vibrational stretching and bending modes have been made. High temperature Raman spectroscopy of BaSrNiWO6 showed that all lattice modes illustrate a linear decrease in wavenumbers while temperature is increased. No discontinuities, in the temperature changes, in wavenumber observed for all modes recorded: indicating that the structure remains cubic and stable up the highest temperature studied here.