Raman scattering structural studies of nonlinear optical M(IO3)3(M = Fe, Ga, α-In) and linear optical β-In(IO3)3

Abstract

Raman and infrared spectra of Fe ( IO 3)3, Ga ( IO 3)3 and the α and β phases of In ( IO 3)3 are recorded and analyzed. The Raman signatures of Fe ( IO 3)3 and Ga ( IO 3)3 and α- In ( IO 3)3 are similar due to their isostructural nature and the lifting of degeneracy of ν4 mode indicates the angular distortion of [Formula: see text] anion in the title compounds. The appearance of multiple bands in the stretching region is due to the presence of I – O bonds with varying strength in these compounds. The presence of strong Raman band at 732 cm-1 in β- In ( IO 3)3 suggest that its crystalline structure is different from the structure of Fe ( IO 3)3, Ga ( IO 3)3, α- In ( IO 3)3 and is contributed to weak I – O bond, which is not coordinated to metallic cation. The higher order Raman cross-section corresponds to symmetric stretching vibration of [Formula: see text] anions at 795, 804, 803 cm-1 in Fe ( IO 3)3, Ga ( IO 3)3 and α- In ( IO 3)3, respectively are related to optical nonlinearity of these materials.