Tellurium-125 Mössbauer spectra of some mixed oxides of tellurium(IV) and some mixed-valence oxides of tellurium(IV, VI)

Abstract

¹²⁵ Te Mössbauer spectra of 10 tellurium(IV)-oxygen compounds of accurately known crystal structure and six other such compounds of unknown structure have been recorded. Data have also been obtained for the mixed-valence oxides Te₂O₅ and Te₄O₉. The results establish the oxidation states where these were uncertain and show that the mixed-valence oxides are Te^IVTe^VIO₅ and Te^IV₃Te^VIO₉ respectively. Quadrupole splittings generated by the stereochemically active lone pair of electrons on Te^IV have been correlated with the extent of distortion of the oxygen co-ordination polyhedra and decrease in the sequence type (A)(B)(C). The ⁵⁷Fe Mössbauer spectrum of Fe₂Te₃O₉ shows that the compound is magnetically ordered at 4.2 K, but the ¹²⁵Te spectrum indicates that there is no detectable transferred hyperfine field at the tellurium nucleus. The ¹¹⁹Sn Mössbauer spectrum of SnTe₃O₈ confirms the presence of Sn^IV in this compound.