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|Title:||ESR, IR, Raman and optical absorption studies of 60 B2O3 + 10 TeO2 +5TiO2 +24 R2O: 1CuO (where R=Li, Na, K) quaternary glasses|
Mouli, V Chandra
|Abstract:||ESR, IR, Raman and optical absorption spectra of 60 B2O3 + 10 TeO2 +5TiO2+24 R2O (where R = Li, Na and K) quaternary glasses containing Cu2+ spin probe have been studied. IR results show the BO3-BO4- ring structure interconnected by TeO3- and TeO4- groups, where the BO4- groups are neighbours of the TeO3-groups. BO3 → BO4 transition is also observed, which correlates with the conversion of TeO4 →TeO3. From Raman spectra, a weak band recorded at 805 cm-1 clearly indicates the presence of boroxol rings for potassium boro-tellurite glass alone. From ESR spectra, the three weak parallel components are observed in the low field region. However, the perpendicular components are not resolved leading to an intensive line in the high field region. When one kind of alkali oxide is replaced by another, the Spin Hamiltonian parameters have been found to vary drastically. The spin Hamiltonian parameter values indicate that the ground state of Cu2+ is dx2- y2 and the site symmetry around the Cu2+ ion is tetragonally distorted octahedral coordination. Optical absorption peak of Cu2+ is found to be a maximum at around 794 nm for Li2O containing borate rich glasses. This peak shifts towards the lower wavelength side as Li2O is replaced with Na2O, K2O. Bonding parameters indicate a slight covalency for the in-plane σ bonding as compared to in-plane and out-of-plane π bonds.|
|Appears in Collections:||IJPAP Vol.47(03) [March 2009]|
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