Raman spectroscopic study of the tellurite minerals: Rajite and denningite

Raman bands for rajite observed at 740, and 676 and 667 cm−1 are attributed to the ν1 (Te2O5)2− symmetric stretching mode and the ν3 (TeO3)2− antisymmetric stretching modes, respectively. A second rajite mineral sample provided a more complex Raman spectrum with Raman bands at 754 and 731 cm−1 assigned to the ν1 (Te2O5)2− symmetric stretching modes and two bands at 652 and 603 cm−1 are accounted for by the ν3 (Te2O5)2− antisymmetric stretching mode. The Raman spectrum of dennigite displays an intense band at 734 cm−1 attributed to the ν1 (Te2O5)2− symmetric stretching mode with a second Raman band at 674 cm−1 assigned to the ν3 (Te2O5)2− antisymmetric stretching mode. Raman bands for rajite, observed at (346, 370) and 438 cm−1 are assigned to the (Te2O5)2−ν2 (A1) bending mode and ν4 (E) bending modes.