Raman scattering studies of sodalite for crystal structure and coloration mechanism

Summary Group-theoretical study of the vibrational modes of chlorosodalite [Na₄Al₃(SiO₄)₃]₂ has been carried out for theT _d ¹ space group. The Raman-active modes are evaluated and comparison is made with the experimental results on sodalite. It is shown that the experimental Raman spectrum does not support the structure of sodalite to beT _d ¹ but confirms it to beT _d ¹ . Raman scattering studies were performed on X-ray irradiated As-grown single crystal of chloro-sodalite to identify the coloration mechanism. Enhancement of oxygen twisting and stretching mode intensities on X-ray irradiation indicates the formation of neutral sodium colloidal aggregate during the coloration process. The authors of this paper have agreed to not receive the proofs for correction.