A SEM, EDS and vibrational spectroscopic study of the tellurite mineral: Sonoraite Fe3+Te4+O3(OH)·H2O

Abstract

We have undertaken a study of the tellurite mineral sonorite using electron microscopy with EDX combined with vibrational spectroscopy. Chemical analysis shows a homogeneous composition, with predominance of Te, Fe, Ce and In with minor amounts of S. Raman spectroscopy has been used to study the mineral sonoraite an examples of group A(XO3), with hydroxyl and water units in the mineral structure. The free tellurite ion has C3v symmetry and four modes, 2A1 and 2E. An intense Raman band at 734cm−1 is assigned to the ν1 (TeO3)2− symmetric stretching mode. A band at 636cm−1 is assigned to the ν3 (TeO3)2− antisymmetric stretching mode. Bands at 350 and 373cm−1 and the two bands at 425 and 438cm−1 are assigned to the (TeO3)2− ν2 (A1) bending mode and (TeO3)2− ν4 (E) bending modes. The sharp band at 3283cm−1 assigned to the OH stretching vibration of the OH units is superimposed upon a broader spectral profile with Raman bands at 3215, 3302, 3349 and 3415cm−1 are attributed to water stretching bands. The techniques of Raman and infrared spectroscopy are excellent for the study of tellurite minerals.