TY - JOUR
T1 - Molten and glassy tellurium(IV) oxosulfato complexes in the TeO2 –K2S2O7 system studied by Raman spectroscopy
T2 - Stoichiometry, vibrational properties and molecular structure
AU - Kalampounias, Angelos G.
AU - Tsilomelekis, George
AU - Boghosian, Soghomon
N1 - Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/7
Y1 - 2018/7
N2 - Tellurium(IV) oxide dissolves in molten potassium pyrosulfate following a reaction that leads to TeIV oxosulfato complexes. High temperature Raman spectroscopy is used under static equilibrium conditions at temperatures of 550 – 740oC for inferring the structural properties of the complex(es) formed in TeO2-K2S2O7 molten mixtures (XTeO2 0 = 0 – 0.70) under O2 atmosphere. The composition effects on the Raman spectra together with the outcome of a quantitative exploitation of the relative Raman band intensities point to a 3:1 TeO2:K2S2O7 stoichiometry, which combined with the observed vibrational properties is suggestive of a (Te=O)3O2(SO4)2 2- structural formula for the simplest building unit formed. A 3-fold coordination around Te becomes evident comprising an oxide ligand and two oxygen atoms bridging to adjacent Te or S atoms. A gradual association of building units takes place with increasing XTeO2 0. Cooling results in formation of stable glasses with a concomitant change in the coordination number of TeIV from 3 to 4 by means of a structural mechanism suggestively involving a TeO2/2(=O)→ TeO4/2 transformation. Totally ten bands are attributed to the TeIV oxosulfato complex; the most characteristic ones pertain to the 1040 cm-1 band assigned to symmetric stretching unidentate sulphate and to the 850 cm-1 band assigned to Te=O terminal stretching, the latter band being attenuated on going from the molten to the glassy state due to the TeO2/2(=O)→ TeO4/2 interconversion.
AB - Tellurium(IV) oxide dissolves in molten potassium pyrosulfate following a reaction that leads to TeIV oxosulfato complexes. High temperature Raman spectroscopy is used under static equilibrium conditions at temperatures of 550 – 740oC for inferring the structural properties of the complex(es) formed in TeO2-K2S2O7 molten mixtures (XTeO2 0 = 0 – 0.70) under O2 atmosphere. The composition effects on the Raman spectra together with the outcome of a quantitative exploitation of the relative Raman band intensities point to a 3:1 TeO2:K2S2O7 stoichiometry, which combined with the observed vibrational properties is suggestive of a (Te=O)3O2(SO4)2 2- structural formula for the simplest building unit formed. A 3-fold coordination around Te becomes evident comprising an oxide ligand and two oxygen atoms bridging to adjacent Te or S atoms. A gradual association of building units takes place with increasing XTeO2 0. Cooling results in formation of stable glasses with a concomitant change in the coordination number of TeIV from 3 to 4 by means of a structural mechanism suggestively involving a TeO2/2(=O)→ TeO4/2 transformation. Totally ten bands are attributed to the TeIV oxosulfato complex; the most characteristic ones pertain to the 1040 cm-1 band assigned to symmetric stretching unidentate sulphate and to the 850 cm-1 band assigned to Te=O terminal stretching, the latter band being attenuated on going from the molten to the glassy state due to the TeO2/2(=O)→ TeO4/2 interconversion.
KW - Glasses
KW - Molten salts
KW - Oxo Te complexes
KW - Oxo-sulfato
KW - Raman spectra
KW - Te(IV) complexes
KW - Tellurium–oxygen bond
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U2 - 10.1016/j.vibspec.2018.06.005
DO - 10.1016/j.vibspec.2018.06.005
M3 - Article
AN - SCOPUS:85048519759
SN - 0924-2031
VL - 97
SP - 85
EP - 90
JO - Vibrational Spectroscopy
JF - Vibrational Spectroscopy
ER -