Vibrational Raman and FTIR Studies of Some Double Alkali Molybdates/Tungstates

Abstract

In this paper, we present the analysis of room temperature IR and Raman spectra of CsLiMoO4/ CsLiWO4 stabilize in cubic structural
form. The expected vibrational modes in infrared and Raman spectra are estimated using factor group analysis and assignment of observed modes is attempted based on FGA predictions, reported assignments of internal modes of MoO4/WO4 in various compounds and splitting of degenerate internal modes. The results are discussed in terms of their effect on electronic band structure. Infrared and Raman spectra of polycrystalline alkali metal double molybdates CsLiMoO4/ CsLiWO4 were measured in the range 40-1000 cm-1 at room temperature. To determine the symmetries and nature of the observed modes a factor group analysis has
been performed. The crystal structure of the compounds studied depends on the type of cation and changes from trigonal to monoclinic and triclinic (for the lithium and sodium derivatives). The assignment of the observed bands to the respective internal and external vibrational modes is proposed.