Fourier transform Raman spectroscopic study of Ba(SO4)(x)(CrO4)(1-x) solidsolution

Ba(SO4)(x)(CrO4)(1-x) solid solution (nature: hashemite) gel-grown crystals were studied using Fourier transform Raman spectroscopy. The complex Raman spectrum of the end-member BaCrO4 was studied in detail by means of bandsh ape analysis and component fitting procedures. Important effects of the cry stalline field (both static and dynamic) were observed that could explain t he evolution of the chromate anion Raman-active internal modes under the in fluence of a second anion. Significant modifications were likewise detected in the sulphate anion normal modes. The hindrance of the sulphate intermol ecular couplings (dynamic effect of the crystalline field) when chromate an ion replaces it in the unit cell could be the cause of the resorted observa tions. It was possible to propose a qualitative assignment of the observed barium chromate Raman-active lattice modes by studying the evolution of suc h bands with the anion content. The six bands observed in the region 80-200 cm(-1) of the barium chromate Raman spectrum can be interpreted as anion l ibration tone banal, chromate anion translational vibrations (two bands) an d barium-oxygen vibrations (three bands). Copyright (C) 1999 John Wiley & S ons, Ltd.